OA2023/OASystem/OASystem.Infrastructure/Tools/AdvancedSearchHelper.cs

using System.ComponentModel;
using System.Text.RegularExpressions;

namespace OASystem.Infrastructure.Tools
{
    /// <summary>
    /// 增强版高级搜索助手（支持智能拆分组合词）
    /// 支持组合查询：多词条/单词条 + 单字 混合搜索
    /// 提供智能搜索条件构建、相关性分析、分阶段搜索等功能
    /// </summary>
    public class AdvancedSearchHelper
    {
        #region 公共方法 - 主要搜索功能

        /// <summary>
        /// 构建增强搜索条件（支持组合查询和智能拆分）
        /// </summary>
        /// <param name="searchTerm">搜索关键词</param>
        /// <param name="searchFields">搜索字段列表</param>
        /// <param name="prefix">参数前缀，用于避免参数名冲突</param>
        /// <param name="searchMode">搜索模式，默认为自动检测</param>
        /// <param name="combinationMode">组合模式，默认智能混合</param>
        /// <param name="config">搜索配置选项</param>
        /// <returns>构建的SQL条件和参数</returns>
        /// <example>
        /// <code>
        /// var fields = new List&lt;string&gt; { "Name", "Description" };
        /// var config = new SearchConfig { 
        ///     EnableSmartSplitting = true,  // 启用智能拆分
        ///     RequireAllWordsForSplit = false 
        /// };
        /// var (condition, parameters) = AdvancedSearchHelper.BuildEnhancedSearchCondition(
        ///     "重庆科学", 
        ///     fields, 
        ///     "search_",
        ///     SearchMode.AutoDetect,
        ///     CombinationMode.SmartMix,
        ///     config
        /// );
        /// </code>
        /// </example>
        public static (string Condition, List<SugarParameter> Parameters) BuildEnhancedSearchCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix = "",
            SearchMode searchMode = SearchMode.AutoDetect,
            CombinationMode combinationMode = CombinationMode.SmartMix,
            SearchConfig config = null)
        {
            // 参数验证
            if (searchFields == null || !searchFields.Any())
                throw new ArgumentException("搜索字段列表不能为空", nameof(searchFields));

            if (string.IsNullOrWhiteSpace(searchTerm))
                return (string.Empty, new List<SugarParameter>());

            searchTerm = searchTerm.Trim();
            config ??= new SearchConfig();

            // 检查搜索词长度
            if (searchTerm.Length > config.MaxSearchTermLength)
                searchTerm = searchTerm.Substring(0, config.MaxSearchTermLength);

            // 分析搜索词结构
            var structure = AnalyzeSearchStructure(searchTerm);

            // 根据组合模式构建条件
            return combinationMode switch
            {
                CombinationMode.SmartMix => BuildSmartMixCondition(structure, searchFields, prefix, searchMode, config),
                CombinationMode.WordsAndChars => BuildWordsAndCharsCondition(structure, searchFields, prefix, config),
                CombinationMode.WordsOnly => BuildWordsOnlyCondition(structure, searchFields, prefix, config),
                CombinationMode.CharsOnly => BuildCharsOnlyCondition(structure, searchFields, prefix, config),
                _ => BuildSmartMixCondition(structure, searchFields, prefix, searchMode, config)
            };
        }

        /// <summary>
        /// 构建带相关性信息的搜索条件
        /// </summary>
        /// <param name="searchTerm">搜索关键词</param>
        /// <param name="searchFields">搜索字段列表</param>
        /// <param name="prefix">参数前缀</param>
        /// <param name="searchMode">搜索模式</param>
        /// <param name="config">搜索配置</param>
        /// <returns>包含条件、参数和相关性的完整结果</returns>
        public static (string Condition, List<SugarParameter> Parameters, RelevanceInfo Relevance)
            BuildRelevanceSearchCondition(
                string searchTerm,
                List<string> searchFields,
                string prefix = "",
                SearchMode searchMode = SearchMode.AutoDetect,
                SearchConfig config = null)
        {
            config ??= new SearchConfig();

            var structure = AnalyzeSearchStructure(searchTerm);
            var (condition, parameters) = BuildEnhancedSearchCondition(
                searchTerm, searchFields, prefix, searchMode, CombinationMode.SmartMix, config);

            var relevance = new RelevanceInfo
            {
                SearchStructure = structure,
                ExpectedMatches = CalculateExpectedMatches(structure, searchFields.Count),
                BoostFields = GetBoostFields(structure, searchFields),
                ScoringRules = GetScoringRules(structure, config),
                MatchStrategy = GetMatchStrategy(structure, config),
                GeneratedAt = DateTime.Now
            };

            return (condition, parameters, relevance);
        }

        /// <summary>
        /// 构建分阶段搜索条件（用于分阶段匹配和降级搜索）
        /// </summary>
        /// <param name="searchTerm">搜索关键词</param>
        /// <param name="searchFields">搜索字段列表</param>
        /// <param name="prefix">参数前缀</param>
        /// <param name="config">搜索配置</param>
        /// <returns>按优先级排序的搜索阶段列表</returns>
        public static List<SearchStage> BuildStagedSearchConditions(
            string searchTerm,
            List<string> searchFields,
            string prefix = "",
            SearchConfig config = null)
        {
            config ??= new SearchConfig();
            var structure = AnalyzeSearchStructure(searchTerm);
            var stages = new List<SearchStage>();

            // 阶段1：精确匹配（完全相等）
            if (structure.Words.Any() && config.EnableExactMatch)
            {
                foreach (var word in structure.Words.Where(w => w.Length >= config.MinExactMatchLength))
                {
                    var (condition, parameters) = BuildExactCondition(word, searchFields, $"{prefix}exact_{stages.Count}");
                    if (!string.IsNullOrEmpty(condition))
                    {
                        stages.Add(new SearchStage
                        {
                            Stage = 1,
                            Name = $"精确匹配: {word}",
                            Condition = condition,
                            Parameters = parameters,
                            Priority = 100,
                            Description = $"完全匹配词语'{word}'",
                            FallbackToNext = false
                        });
                    }
                }
            }

            // 阶段2：开头匹配
            if (structure.Words.Any() && config.EnablePrefixMatch)
            {
                foreach (var word in structure.Words)
                {
                    var (condition, parameters) = BuildPrefixCondition(word, searchFields, $"{prefix}prefix_{stages.Count}");
                    if (!string.IsNullOrEmpty(condition))
                    {
                        stages.Add(new SearchStage
                        {
                            Stage = 2,
                            Name = $"开头匹配: {word}",
                            Condition = condition,
                            Parameters = parameters,
                            Priority = 80,
                            Description = $"以'{word}'开头",
                            FallbackToNext = true
                        });
                    }
                }
            }

            // 阶段3：词语模糊匹配
            if (structure.Words.Any() && config.EnableFuzzySearch)
            {
                var wordsText = string.Join(" ", structure.Words);
                var (condition, parameters) = BuildMultiWordCondition(
                    wordsText, searchFields, $"{prefix}fuzzy_{stages.Count}",
                    config.RequireAllWords);

                if (!string.IsNullOrEmpty(condition))
                {
                    stages.Add(new SearchStage
                    {
                        Stage = 3,
                        Name = "词语模糊匹配",
                        Condition = condition,
                        Parameters = parameters,
                        Priority = 60,
                        Description = $"包含词语: {wordsText}",
                        FallbackToNext = true
                    });
                }
            }

            // 阶段4：单字匹配
            if (structure.SingleChars.Any() && config.EnableCharSearch)
            {
                var charsText = string.Join("", structure.SingleChars);
                var (condition, parameters) = BuildSingleCharCondition(
                    charsText, searchFields, $"{prefix}chars_{stages.Count}",
                    config.RequireAllChars);

                if (!string.IsNullOrEmpty(condition))
                {
                    stages.Add(new SearchStage
                    {
                        Stage = 4,
                        Name = "单字匹配",
                        Condition = condition,
                        Parameters = parameters,
                        Priority = 40,
                        Description = $"包含单字: {charsText}",
                        FallbackToNext = true
                    });
                }
            }

            // 阶段5：智能拆分匹配（新增阶段）
            if (config.EnableSmartSplitting && structure.Words.Any(w => w.Length >= config.MinSplitLength))
            {
                var longWords = structure.Words.Where(w => w.Length >= config.MinSplitLength).ToList();
                foreach (var longWord in longWords)
                {
                    if (IsSplittableCombinationWord(longWord))
                    {
                        var (condition, parameters) = BuildSmartSplitConditionForWord(
                            longWord, searchFields, $"{prefix}split_{stages.Count}", config);

                        if (!string.IsNullOrEmpty(condition))
                        {
                            stages.Add(new SearchStage
                            {
                                Stage = 5,
                                Name = $"智能拆分: {longWord}",
                                Condition = condition,
                                Parameters = parameters,
                                Priority = 50, // 优先级在词语模糊匹配和单字匹配之间
                                Description = $"智能拆分'{longWord}'为子词或单字",
                                FallbackToNext = true
                            });
                        }
                    }
                }
            }

            // 阶段6：宽松混合匹配
            if (stages.Any(s => s.Stage >= 3 && s.Stage <= 5))
            {
                var mixedConditions = stages
                    .Where(s => s.Stage >= 3 && s.Stage <= 5)
                    .Select(s => s.Condition)
                    .ToList();

                var mixedParameters = stages
                    .Where(s => s.Stage >= 3 && s.Stage <= 5)
                    .SelectMany(s => s.Parameters)
                    .ToList();

                if (mixedConditions.Any())
                {
                    stages.Add(new SearchStage
                    {
                        Stage = 6,
                        Name = "宽松混合匹配",
                        Condition = $"({string.Join(" OR ", mixedConditions)})",
                        Parameters = mixedParameters,
                        Priority = 20,
                        Description = "词语或单字的任意匹配",
                        FallbackToNext = false
                    });
                }
            }

            return stages.OrderByDescending(s => s.Priority).ToList();
        }

        #endregion

        #region 核心构建方法

        /// <summary>
        /// 智能混合构建条件（支持智能拆分组合词）
        /// </summary>
        private static (string, List<SugarParameter>) BuildSmartMixCondition(
            SearchStructure structure,
            List<string> searchFields,
            string prefix,
            SearchMode searchMode,
            SearchConfig config)
        {
            var parameters = new List<SugarParameter>();
            var conditions = new List<string>();

            // 分析结构复杂度
            var complexity = CalculateComplexityScore(structure);

            // 检查是否有需要智能拆分的组合词
            var longWords = structure.Words.Where(w => w.Length >= config.MinSplitLength).ToList();
            var shouldSplitLongWords = longWords.Any() && config.EnableSmartSplitting;

            if (shouldSplitLongWords && longWords.Any(w => IsSplittableCombinationWord(w)))
            {
                // 使用智能拆分策略处理组合词
                return BuildSmartSplitCondition(structure, searchFields, prefix, config, longWords);
            }

            // 智能分析混合类型的特点
            var hasLongWords = structure.Words.Any(w => w.Length >= 2);
            var hasManyChars = structure.SingleChars.Count >= 3;
            var isCharDominant = structure.SingleChars.Count > structure.Words.Count;
            var hasMixedTypes = structure.HasWords && structure.HasSingleChars;

            // 根据混合特点选择更精细的策略
            string strategy;
            if (hasMixedTypes)
            {
                if (isCharDominant && hasManyChars)
                {
                    strategy = "char_optimized"; // 单字主导，优化单字搜索
                }
                else if (hasLongWords && !hasManyChars)
                {
                    strategy = "word_focused"; // 词语为主，单字为辅
                }
                else
                {
                    strategy = complexity >= 6 ? "strict_mixed" :
                              complexity >= 3 ? "balanced_mixed" : "loose_mixed";
                }
            }
            else
            {
                strategy = complexity >= 7 ? "strict" :
                          complexity >= 4 ? "balanced" : "loose";
            }

            // 处理词语部分
            if (structure.HasWords)
            {
                if (structure.Words.Count == 1)
                {
                    // 单个词语
                    var (wordCondition, wordParams) = BuildSingleWordCondition(
                        structure.Words[0], searchFields, $"{prefix}word", config);
                    if (!string.IsNullOrEmpty(wordCondition))
                    {
                        conditions.Add(wordCondition);
                        parameters.AddRange(wordParams);
                    }
                }
                else
                {
                    // 多个词语
                    var wordsText = string.Join(" ", structure.Words);

                    // 根据策略动态调整词语匹配要求
                    bool requireAllWords;
                    if (strategy == "char_optimized" && isCharDominant)
                    {
                        // 单字主导时，放宽词语要求
                        requireAllWords = false;
                    }
                    else
                    {
                        requireAllWords = strategy.Contains("strict") || config.RequireAllWords;
                    }

                    var (wordsCondition, wordsParams) = BuildMultiWordCondition(
                        wordsText, searchFields, $"{prefix}words", requireAllWords);

                    if (!string.IsNullOrEmpty(wordsCondition))
                    {
                        conditions.Add(wordsCondition);
                        parameters.AddRange(wordsParams);
                    }
                }
            }

            // 处理单字部分 - 优化策略
            if (structure.HasSingleChars)
            {
                var charsText = string.Join("", structure.SingleChars);

                // 根据策略动态调整单字匹配要求
                bool requireAllChars;
                string charStrategy;

                if (strategy == "char_optimized")
                {
                    // 单字优化策略：多个单字时放宽要求
                    requireAllChars = structure.SingleChars.Count <= 3; // 3个及以下单字要求全部匹配
                    charStrategy = "optimized";
                }
                else if (strategy.Contains("loose"))
                {
                    requireAllChars = false;
                    charStrategy = "loose";
                }
                else if (strategy.Contains("strict"))
                {
                    requireAllChars = true;
                    charStrategy = "strict";
                }
                else
                {
                    requireAllChars = strategy.Contains("balanced") && structure.SingleChars.Count <= 2;
                    charStrategy = "balanced";
                }

                var (charsCondition, charsParams) = BuildEnhancedCharCondition(
                    charsText, searchFields, $"{prefix}chars",
                    requireAllChars, charStrategy);

                if (!string.IsNullOrEmpty(charsCondition))
                {
                    conditions.Add(charsCondition);
                    parameters.AddRange(charsParams);
                }
            }

            // 构建最终条件
            if (!conditions.Any())
                return (string.Empty, parameters);

            string finalCondition = BuildMixedConditionByStrategy(
                conditions, structure, strategy);

            return (finalCondition, parameters);
        }

        /// <summary>
        /// 构建智能拆分条件（针对长词如"重庆科学"）
        /// </summary>
        private static (string, List<SugarParameter>) BuildSmartSplitCondition(
            SearchStructure structure,
            List<string> searchFields,
            string prefix,
            SearchConfig config,
            List<string> longWords)
        {
            var parameters = new List<SugarParameter>();
            var conditions = new List<string>();

            // 处理所有长词（需要拆分的词）
            foreach (var longWord in longWords)
            {
                if (IsSplittableCombinationWord(longWord))
                {
                    // 为每个长词构建多层次条件
                    var (wordConditions, wordParams) = BuildMultiLevelConditionForWord(
                        longWord, searchFields, $"{prefix}word_{longWord.GetHashCode()}", config);

                    conditions.AddRange(wordConditions);
                    parameters.AddRange(wordParams);
                }
                else
                {
                    // 普通长词，直接搜索
                    var (wordCondition, wordParams) = BuildSingleWordCondition(
                        longWord, searchFields, $"{prefix}long_{parameters.Count}", config);

                    if (!string.IsNullOrEmpty(wordCondition))
                    {
                        conditions.Add(wordCondition);
                        parameters.AddRange(wordParams);
                    }
                }
            }

            // 处理剩余的非长词
            var normalWords = structure.Words.Where(w => w.Length < config.MinSplitLength).ToList();
            if (normalWords.Any())
            {
                var wordsText = string.Join(" ", normalWords);
                var (normalCondition, normalParams) = BuildMultiWordCondition(
                    wordsText, searchFields, $"{prefix}normal", config.RequireAllWords);

                if (!string.IsNullOrEmpty(normalCondition))
                {
                    conditions.Add(normalCondition);
                    parameters.AddRange(normalParams);
                }
            }

            // 处理原有的单字
            if (structure.SingleChars.Any())
            {
                var charsText = string.Join("", structure.SingleChars);
                var (charCondition, charParams) = BuildSingleCharCondition(
                    charsText, searchFields, $"{prefix}single", false);

                if (!string.IsNullOrEmpty(charCondition))
                {
                    conditions.Add(charCondition);
                    parameters.AddRange(charParams);
                }
            }

            // 构建最终条件：使用层次化OR连接
            if (conditions.Count == 0)
                return (string.Empty, parameters);

            if (conditions.Count == 1)
                return (conditions[0], parameters);

            // 对条件进行分组和优先级排序
            var groupedConditions = GroupConditionsByPriority(conditions, longWords);
            return (BuildHierarchicalCondition(groupedConditions), parameters);
        }

        /// <summary>
        /// 为单个长词构建多层次条件
        /// </summary>
        private static (List<string> Conditions, List<SugarParameter> Parameters) BuildMultiLevelConditionForWord(
            string longWord,
            List<string> searchFields,
            string prefix,
            SearchConfig config)
        {
            var conditions = new List<string>();
            var parameters = new List<SugarParameter>();

            // 第一层：完整词匹配（最高优先级）
            var (fullCondition, fullParams) = BuildSingleWordCondition(
                longWord, searchFields, $"{prefix}_full", config);

            if (!string.IsNullOrEmpty(fullCondition))
            {
                conditions.Add(fullCondition);
                parameters.AddRange(fullParams);
            }

            // 第二层：智能拆分成子词
            var subWords = SplitCombinationWord(longWord);
            if (subWords.Count >= 2)
            {
                var (splitCondition, splitParams) = BuildMultiWordCondition(
                    string.Join(" ", subWords),
                    searchFields,
                    $"{prefix}_split",
                    config.RequireAllWordsForSplit);

                if (!string.IsNullOrEmpty(splitCondition))
                {
                    conditions.Add($"({splitCondition})"); // 用括号包裹
                    parameters.AddRange(splitParams);
                }
            }

            // 第三层：拆分成单字作为备选
            var chars = longWord.ToCharArray().Select(c => c.ToString()).ToList();
            var (charCondition, charParams) = BuildSingleCharCondition(
                string.Join("", chars),
                searchFields,
                $"{prefix}_chars",
                config.RequireAllCharsForSplit);

            if (!string.IsNullOrEmpty(charCondition))
            {
                conditions.Add($"({charCondition})");
                parameters.AddRange(charParams);
            }

            // 如果有多层条件，构建OR连接
            if (conditions.Count > 1)
            {
                var combinedCondition = $"({string.Join(" OR ", conditions)})";
                return (new List<string> { combinedCondition }, parameters);
            }

            return (conditions, parameters);
        }

        /// <summary>
        /// 构建智能拆分条件（用于分阶段搜索）
        /// </summary>
        private static (string, List<SugarParameter>) BuildSmartSplitConditionForWord(
            string longWord,
            List<string> searchFields,
            string prefix,
            SearchConfig config)
        {
            var (conditions, parameters) = BuildMultiLevelConditionForWord(longWord, searchFields, prefix, config);

            if (conditions.Any())
            {
                return (conditions[0], parameters);
            }

            return (string.Empty, new List<SugarParameter>());
        }

        /// <summary>
        /// 词语和单字组合条件
        /// </summary>
        private static (string, List<SugarParameter>) BuildWordsAndCharsCondition(
            SearchStructure structure,
            List<string> searchFields,
            string prefix,
            SearchConfig config)
        {
            var parameters = new List<SugarParameter>();
            var conditions = new List<string>();

            // 词语部分（必须满足）
            if (structure.Words.Any())
            {
                var wordsText = string.Join(" ", structure.Words);
                var (wordsCondition, wordsParams) = BuildMultiWordCondition(
                    wordsText, searchFields, $"{prefix}w", true);

                if (!string.IsNullOrEmpty(wordsCondition))
                {
                    conditions.Add(wordsCondition);
                    parameters.AddRange(wordsParams);
                }
            }

            // 单字部分（作为增强条件）
            if (structure.SingleChars.Any())
            {
                var charsText = string.Join("", structure.SingleChars);
                var (charsCondition, charsParams) = BuildSingleCharCondition(
                    charsText, searchFields, $"{prefix}c", false);

                if (!string.IsNullOrEmpty(charsCondition))
                {
                    // 单字作为加分项，用OR连接
                    conditions.Add($"({charsCondition})");
                    parameters.AddRange(charsParams);
                }
            }

            if (!conditions.Any())
                return (string.Empty, parameters);

            // 构建条件：词语必须满足，单字作为增强
            string finalCondition = conditions.Count > 1
                ? $"({conditions[0]} AND ({string.Join(" OR ", conditions.Skip(1))}))"
                : conditions[0];

            return (finalCondition, parameters);
        }

        /// <summary>
        /// 仅词语条件
        /// </summary>
        private static (string, List<SugarParameter>) BuildWordsOnlyCondition(
            SearchStructure structure,
            List<string> searchFields,
            string prefix,
            SearchConfig config)
        {
            if (!structure.Words.Any())
                return (string.Empty, new List<SugarParameter>());

            var wordsText = string.Join(" ", structure.Words);

            if (structure.Words.Count == 1)
            {
                return BuildSingleWordCondition(wordsText, searchFields, prefix, config);
            }
            else
            {
                return BuildMultiWordCondition(wordsText, searchFields, prefix, config.RequireAllWords);
            }
        }

        /// <summary>
        /// 仅单字条件
        /// </summary>
        private static (string, List<SugarParameter>) BuildCharsOnlyCondition(
            SearchStructure structure,
            List<string> searchFields,
            string prefix,
            SearchConfig config)
        {
            if (!structure.SingleChars.Any())
                return (string.Empty, new List<SugarParameter>());

            var charsText = string.Join("", structure.SingleChars);
            return BuildSingleCharCondition(charsText, searchFields, prefix, config.RequireAllChars);
        }

        #endregion

        #region 基础条件构建方法

        /// <summary>
        /// 构建单词条查询条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildSingleWordCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix,
            SearchConfig config = null)
        {
            config ??= new SearchConfig();
            var parameters = new List<SugarParameter>();
            var fieldConditions = new List<string>();
            var paramName = $"{prefix}word";

            foreach (var field in searchFields)
            {
                fieldConditions.Add($"{field} LIKE @{paramName}");
            }

            string condition = $"({string.Join(" OR ", fieldConditions)})";
            parameters.Add(new SugarParameter($"@{paramName}", $"%{searchTerm}%"));

            return (condition, parameters);
        }

        /// <summary>
        /// 构建多词条查询条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildMultiWordCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix,
            bool requireAll = true)
        {
            var parameters = new List<SugarParameter>();
            var separators = new[] { ' ', '，', '、', ',', ';', '；' };
            var words = searchTerm.Split(separators, StringSplitOptions.RemoveEmptyEntries)
                                 .Select(w => w.Trim())
                                 .Where(w => !string.IsNullOrEmpty(w))
                                 .Distinct()
                                 .ToList();

            if (!words.Any())
                return (string.Empty, parameters);

            var wordConditions = new List<string>();

            foreach (var word in words)
            {
                var fieldConditions = new List<string>();
                var paramName = $"{prefix}word_{parameters.Count}";

                foreach (var field in searchFields)
                {
                    fieldConditions.Add($"{field} LIKE @{paramName}");
                }

                wordConditions.Add($"({string.Join(" OR ", fieldConditions)})");
                parameters.Add(new SugarParameter($"@{paramName}", $"%{word}%"));
            }

            // 构建条件
            string condition;
            if (requireAll && words.Count > 1)
            {
                condition = $"({string.Join(" AND ", wordConditions)})";
            }
            else if (!requireAll && words.Count > 1)
            {
                condition = $"({string.Join(" OR ", wordConditions)})";
            }
            else
            {
                condition = wordConditions.FirstOrDefault() ?? "";
            }

            return (condition, parameters);
        }

        /// <summary>
        /// 构建单字查询条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildSingleCharCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix,
            bool requireAll = true)
        {
            var parameters = new List<SugarParameter>();
            var cleanTerm = RemoveSeparators(searchTerm);
            var chars = cleanTerm.ToCharArray().Distinct().ToArray();

            if (chars.Length == 0)
                return (string.Empty, parameters);

            var charConditions = new List<string>();

            foreach (char c in chars)
            {
                var fieldConditions = new List<string>();
                var paramName = $"{prefix}char_{parameters.Count}";

                foreach (var field in searchFields)
                {
                    fieldConditions.Add($"{field} LIKE @{paramName}");
                }

                charConditions.Add($"({string.Join(" OR ", fieldConditions)})");
                parameters.Add(new SugarParameter($"@{paramName}", $"%{c}%"));
            }

            // 构建条件
            string condition;
            if (requireAll && chars.Length > 1)
            {
                condition = $"({string.Join(" AND ", charConditions)})";
            }
            else if (!requireAll && chars.Length > 1)
            {
                condition = $"({string.Join(" OR ", charConditions)})";
            }
            else
            {
                condition = charConditions.FirstOrDefault() ?? "";
            }

            return (condition, parameters);
        }

        /// <summary>
        /// 构建增强的单字搜索条件（支持不同策略）
        /// </summary>
        private static (string, List<SugarParameter>) BuildEnhancedCharCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix,
            bool requireAll,
            string strategy)
        {
            var parameters = new List<SugarParameter>();
            var cleanTerm = RemoveSeparators(searchTerm);
            var chars = cleanTerm.ToCharArray().Distinct().ToArray();

            if (chars.Length == 0)
                return (string.Empty, parameters);

            // 根据策略调整处理方式
            var charConditions = new List<string>();

            foreach (char c in chars)
            {
                var fieldConditions = new List<string>();
                var paramName = $"{prefix}char_{parameters.Count}";

                foreach (var field in searchFields)
                {
                    // 根据不同策略使用不同的匹配方式
                    if (strategy == "optimized" && IsChineseCharacter(c))
                    {
                        // 优化策略：中文单字更宽松
                        fieldConditions.Add($"({field} LIKE @{paramName} OR {field} LIKE @{paramName}_prefix)");
                        parameters.Add(new SugarParameter($"@{paramName}", $"%{c}%"));
                        parameters.Add(new SugarParameter($"@{paramName}_prefix", $"{c}%"));
                    }
                    else
                    {
                        fieldConditions.Add($"{field} LIKE @{paramName}");
                        parameters.Add(new SugarParameter($"@{paramName}", $"%{c}%"));
                    }
                }

                charConditions.Add($"({string.Join(" OR ", fieldConditions)})");
            }

            // 根据策略构建条件
            string condition;
            if (requireAll && chars.Length > 1)
            {
                // 必须包含所有单字
                condition = $"({string.Join(" AND ", charConditions)})";
            }
            else if (!requireAll && chars.Length > 1)
            {
                // 任意一个单字即可
                condition = $"({string.Join(" OR ", charConditions)})";
            }
            else if (strategy == "optimized" && chars.Length > 2)
            {
                // 优化策略：3个以上单字时，至少匹配一半
                int requiredCount = (int)Math.Ceiling(chars.Length / 2.0);
                var orConditions = new List<string>();

                // 生成所有可能的组合（限制数量避免爆炸）
                var combinations = GetCharCombinations(charConditions, chars.Length, requiredCount, 5);

                foreach (var combination in combinations)
                {
                    orConditions.Add($"({string.Join(" AND ", combination)})");
                }

                condition = orConditions.Any() ? $"({string.Join(" OR ", orConditions)})" : charConditions.FirstOrDefault() ?? "";
            }
            else
            {
                condition = charConditions.FirstOrDefault() ?? "";
            }

            return (condition, parameters);
        }

        /// <summary>
        /// 构建精确匹配条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildExactCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix)
        {
            var parameters = new List<SugarParameter>();
            var fieldConditions = new List<string>();
            var paramName = $"{prefix}exact";

            foreach (var field in searchFields)
            {
                fieldConditions.Add($"{field} = @{paramName}");
            }

            string condition = $"({string.Join(" OR ", fieldConditions)})";
            parameters.Add(new SugarParameter($"@{paramName}", searchTerm.Trim()));

            return (condition, parameters);
        }

        /// <summary>
        /// 构建开头匹配条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildPrefixCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix)
        {
            var parameters = new List<SugarParameter>();
            var fieldConditions = new List<string>();
            var paramName = $"{prefix}prefix";

            foreach (var field in searchFields)
            {
                fieldConditions.Add($"{field} LIKE @{paramName}");
            }

            string condition = $"({string.Join(" OR ", fieldConditions)})";
            parameters.Add(new SugarParameter($"@{paramName}", $"{searchTerm}%"));

            return (condition, parameters);
        }

        /// <summary>
        /// 构建结尾匹配条件
        /// </summary>
        public static (string Condition, List<SugarParameter> Parameters) BuildSuffixCondition(
            string searchTerm,
            List<string> searchFields,
            string prefix)
        {
            var parameters = new List<SugarParameter>();
            var fieldConditions = new List<string>();
            var paramName = $"{prefix}suffix";

            foreach (var field in searchFields)
            {
                fieldConditions.Add($"{field} LIKE @{paramName}");
            }

            string condition = $"({string.Join(" OR ", fieldConditions)})";
            parameters.Add(new SugarParameter($"@{paramName}", $"%{searchTerm}"));

            return (condition, parameters);
        }

        #endregion

        #region 智能拆分方法

        /// <summary>
        /// 判断是否为可拆分的组合词
        /// </summary>
        private static bool IsSplittableCombinationWord(string word)
        {
            if (word.Length < 4)
                return false;

            // 检查是否由常见的地名+名词等组成
            var commonPatterns = new HashSet<string>
            {
                "重庆", "北京", "上海", "广州", "深圳", "天津", "武汉", "成都", "杭州", "南京",
                "科学", "技术", "研究", "发展", "教育", "培训", "管理", "系统", "工程", "设计",
                "大学", "学院", "学校", "公司", "集团", "中心", "研究所", "实验室", "医院", "银行"
            };

            // 尝试找到明显的组合边界
            for (int i = 2; i <= word.Length - 2; i++)
            {
                var part1 = word.Substring(0, i);
                var part2 = word.Substring(i);

                if (commonPatterns.Contains(part1) || commonPatterns.Contains(part2))
                    return true;

                // 检查是否都是常见词汇
                if (IsCommonWord(part1) && IsCommonWord(part2))
                    return true;
            }

            return false;
        }

        /// <summary>
        /// 拆分组合词
        /// </summary>
        private static List<string> SplitCombinationWord(string word)
        {
            var result = new List<string>();

            if (word.Length <= 2)
            {
                result.Add(word);
                return result;
            }

            // 优先按2+2模式拆分（如"重庆科学" -> "重庆", "科学"）
            if (word.Length == 4)
            {
                result.Add(word.Substring(0, 2));
                result.Add(word.Substring(2, 2));
                return result;
            }

            // 尝试按常见模式拆分
            var commonTwoCharWords = new HashSet<string>
            {
                "重庆", "北京", "上海", "广州", "深圳", "天津", "武汉", "成都", "杭州", "南京",
                "科学", "技术", "研究", "发展", "教育", "培训", "管理", "系统", "工程", "设计",
                "大学", "学院", "学校", "公司", "集团", "中心", "医院", "银行", "保险", "证券",
                "软件", "硬件", "网络", "数据", "信息", "智能", "数字", "电子", "通信", "互联网"
            };

            // 检查前缀
            for (int i = 2; i <= Math.Min(4, word.Length - 2); i++)
            {
                var prefix = word.Substring(0, i);
                var suffix = word.Substring(i);

                if (commonTwoCharWords.Contains(prefix) ||
                    (i == 2 && IsLikelyWord(prefix)))
                {
                    result.Add(prefix);

                    // 递归拆分剩余部分
                    if (suffix.Length >= 2)
                    {
                        var subSplits = SplitCombinationWord(suffix);
                        result.AddRange(subSplits);
                    }
                    else
                    {
                        result.Add(suffix);
                    }

                    return result;
                }
            }

            // 无法智能拆分，按固定长度拆分
            int splitLength = word.Length >= 6 ? 3 : 2;
            for (int i = 0; i < word.Length; i += splitLength)
            {
                var part = word.Substring(i, Math.Min(splitLength, word.Length - i));
                result.Add(part);
            }

            return result;
        }

        /// <summary>
        /// 检查是否可能是常见词汇
        /// </summary>
        private static bool IsLikelyWord(string word)
        {
            if (word.Length != 2) return false;

            // 检查是否为常见的中文二字词
            // 这里可以扩展更复杂的判断逻辑
            return IsChineseCharacter(word[0]) && IsChineseCharacter(word[1]);
        }

        /// <summary>
        /// 检查是否是常见词汇
        /// </summary>
        private static bool IsCommonWord(string word)
        {
            // 这里可以扩展更复杂的常见词判断逻辑
            // 例如从词典加载、使用统计等
            var commonWords = new HashSet<string>
            {
                "中国", "国家", "人民", "社会", "经济", "文化", "教育", "科技", "发展",
                "企业", "公司", "市场", "产品", "服务", "技术", "管理", "工作", "生活"
            };

            return commonWords.Contains(word) ||
                   (word.Length == 2 && IsChineseCharacter(word[0]) && IsChineseCharacter(word[1]));
        }

        /// <summary>
        /// 按优先级分组条件
        /// </summary>
        private static Dictionary<string, List<string>> GroupConditionsByPriority(
            List<string> conditions, List<string> longWords)
        {
            var groups = new Dictionary<string, List<string>>
            {
                ["original"] = new List<string>(),  // 原词条件
                ["split"] = new List<string>(),     // 拆分子词条件
                ["chars"] = new List<string>(),     // 单字条件
                ["normal"] = new List<string>()     // 普通词条件
            };

            // 简单分组逻辑，实际使用中可能需要更复杂的判断
            int longWordCount = longWords.Count;
            int currentIndex = 0;

            // 原词条件（每个长词一个）
            for (int i = 0; i < longWordCount && currentIndex < conditions.Count; i++)
            {
                groups["original"].Add(conditions[currentIndex]);
                currentIndex++;
            }

            // 拆分子词条件
            for (int i = 0; i < longWordCount && currentIndex < conditions.Count; i++)
            {
                groups["split"].Add(conditions[currentIndex]);
                currentIndex++;
            }

            // 单字条件
            for (int i = 0; i < longWordCount && currentIndex < conditions.Count; i++)
            {
                groups["chars"].Add(conditions[currentIndex]);
                currentIndex++;
            }

            // 剩余的都是普通词条件
            while (currentIndex < conditions.Count)
            {
                groups["normal"].Add(conditions[currentIndex]);
                currentIndex++;
            }

            return groups;
        }

        /// <summary>
        /// 构建层次化条件
        /// </summary>
        private static string BuildHierarchicalCondition(Dictionary<string, List<string>> groups)
        {
            var parts = new List<string>();

            // 第一层：原词匹配（最高优先级）
            if (groups["original"].Any())
            {
                parts.Add($"({string.Join(" OR ", groups["original"])})");
            }

            // 第二层：拆分子词匹配
            if (groups["split"].Any())
            {
                var splitCondition = groups["split"].Count == 1
                    ? groups["split"][0]
                    : $"({string.Join(" AND ", groups["split"])})";
                parts.Add($"({splitCondition})");
            }

            // 普通词条件（插入到合适位置）
            if (groups["normal"].Any())
            {
                var normalCondition = groups["normal"].Count == 1
                    ? groups["normal"][0]
                    : $"({string.Join(" AND ", groups["normal"])})";

                // 如果已经有原词条件，放在第二层；否则放在第一层
                if (parts.Count >= 1)
                    parts.Insert(1, normalCondition);
                else
                    parts.Add(normalCondition);
            }

            // 第三层：单字匹配（最低优先级）
            if (groups["chars"].Any())
            {
                var charCondition = groups["chars"].Count == 1
                    ? groups["chars"][0]
                    : $"({string.Join(" OR ", groups["chars"])})";
                parts.Add($"({charCondition})");
            }

            if (parts.Count == 0)
                return string.Empty;

            if (parts.Count == 1)
                return parts[0];

            // 构建层次化OR条件
            return $"({string.Join(" OR ", parts)})";
        }

        /// <summary>
        /// 根据策略构建混合条件
        /// </summary>
        private static string BuildMixedConditionByStrategy(
            List<string> conditions,
            SearchStructure structure,
            string strategy)
        {
            if (conditions.Count == 1)
                return conditions[0];

            switch (strategy)
            {
                case "char_optimized":
                    // 单字优化策略：词语作为主要条件，单字作为增强
                    return BuildCharOptimizedCondition(conditions, structure);

                case "word_focused":
                    // 词语聚焦策略：词语必须，单字作为加分
                    return BuildWordFocusedCondition(conditions, structure);

                case "strict_mixed":
                    // 严格混合：所有条件必须满足
                    return BuildStrictCondition(conditions, structure);

                case "balanced_mixed":
                    // 平衡混合：词语必须，单字推荐
                    return BuildBalancedCondition(conditions, structure);

                case "loose_mixed":
                    // 宽松混合：任意条件满足即可
                    return BuildLooseCondition(conditions, structure);

                default:
                    return BuildBalancedCondition(conditions, structure);
            }
        }

        /// <summary>
        /// 构建单字优化条件
        /// </summary>
        private static string BuildCharOptimizedCondition(List<string> conditions, SearchStructure structure)
        {
            var wordConditions = conditions
                .Where((c, i) => i < structure.Words.Count)
                .ToList();

            var charConditions = conditions
                .Skip(structure.Words.Count)
                .ToList();

            if (wordConditions.Any() && charConditions.Any())
            {
                // 词语必须，单字作为重要补充（至少匹配一定比例）
                if (charConditions.Count > 2)
                {
                    // 多个单字时，要求至少匹配一半
                    int requiredChars = (int)Math.Ceiling(charConditions.Count / 2.0);
                    var charCombinations = GetConditionCombinations(charConditions, requiredChars, 3);

                    if (charCombinations.Any())
                    {
                        var charCombinationStrings = charCombinations
                            .Select(comb => $"({string.Join(" AND ", comb)})")
                            .ToList();

                        return $"({string.Join(" AND ", wordConditions)} AND ({string.Join(" OR ", charCombinationStrings)}))";
                    }
                }

                return $"({string.Join(" AND ", wordConditions)} AND ({string.Join(" OR ", charConditions)}))";
            }
            else if (charConditions.Any())
            {
                // 只有单字时，至少匹配一半
                if (charConditions.Count > 1)
                {
                    int requiredChars = (int)Math.Ceiling(charConditions.Count / 2.0);
                    var combinations = GetConditionCombinations(charConditions, requiredChars, 3);

                    if (combinations.Any())
                    {
                        var combinationStrings = combinations
                            .Select(comb => $"({string.Join(" AND ", comb)})")
                            .ToList();

                        return $"({string.Join(" OR ", combinationStrings)})";
                    }
                }

                return $"({string.Join(" OR ", charConditions)})";
            }

            return conditions.FirstOrDefault() ?? "";
        }

        /// <summary>
        /// 构建词语聚焦条件
        /// </summary>
        private static string BuildWordFocusedCondition(List<string> conditions, SearchStructure structure)
        {
            var wordConditions = conditions
                .Where((c, i) => i < structure.Words.Count)
                .ToList();

            var charConditions = conditions
                .Skip(structure.Words.Count)
                .ToList();

            if (wordConditions.Any() && charConditions.Any())
            {
                // 词语必须满足，单字作为加分项（OR连接）
                return $"({string.Join(" AND ", wordConditions)} AND ({string.Join(" OR ", charConditions)}))";
            }

            return $"({string.Join(" AND ", conditions)})";
        }

        /// <summary>
        /// 获取条件组合（限制数量避免爆炸）
        /// </summary>
        private static List<List<string>> GetConditionCombinations(
            List<string> conditions,
            int requiredCount,
            int maxCombinations = 10)
        {
            var result = new List<List<string>>();

            if (conditions.Count <= requiredCount || conditions.Count <= 1)
            {
                result.Add(conditions);
                return result;
            }

            // 生成C(n, requiredCount)组合，但限制数量
            var indices = Enumerable.Range(0, conditions.Count).ToArray();
            var combinations = GetCombinations(indices, requiredCount, maxCombinations);

            foreach (var combination in combinations)
            {
                var selectedConditions = combination
                    .Select(idx => conditions[idx])
                    .ToList();

                result.Add(selectedConditions);
            }

            return result;
        }

        /// <summary>
        /// 获取字符条件组合
        /// </summary>
        private static List<List<string>> GetCharCombinations(
            List<string> charConditions,
            int totalChars,
            int requiredCount,
            int maxCombinations)
        {
            return GetConditionCombinations(charConditions, requiredCount, maxCombinations);
        }

        /// <summary>
        /// 获取索引组合（算法）
        /// </summary>
        private static List<List<int>> GetCombinations(int[] indices, int k, int maxCombinations)
        {
            var result = new List<List<int>>();
            var combination = new List<int>();

            void Backtrack(int start)
            {
                if (result.Count >= maxCombinations)
                    return;

                if (combination.Count == k)
                {
                    result.Add(new List<int>(combination));
                    return;
                }

                for (int i = start; i < indices.Length; i++)
                {
                    combination.Add(indices[i]);
                    Backtrack(i + 1);
                    combination.RemoveAt(combination.Count - 1);

                    if (result.Count >= maxCombinations)
                        break;
                }
            }

            Backtrack(0);
            return result;
        }

        #endregion

        #region 分析工具方法

        /// <summary>
        /// 分析搜索词结构
        /// </summary>
        public static SearchStructure AnalyzeSearchStructure(string searchTerm)
        {
            var structure = new SearchStructure
            {
                OriginalTerm = searchTerm,
                CleanTerm = searchTerm.Trim(),
                AnalyzedAt = DateTime.Now
            };

            // 移除分隔符获取所有字符
            var cleanTerm = RemoveSeparators(searchTerm);
            structure.AllCharacters = cleanTerm.ToCharArray().ToList();

            // 分割成词条（保持原始分割）
            var separators = new[] { ' ', '，', '、', ',', ';', '；', '|', '/', '\\' };
            var rawSegments = searchTerm.Split(separators, StringSplitOptions.RemoveEmptyEntries)
                                       .Select(s => s.Trim())
                                       .Where(s => !string.IsNullOrEmpty(s))
                                       .ToList();

            structure.Segments = rawSegments;

            // 分析每个段落的类型
            foreach (var segment in rawSegments)
            {
                if (segment.Length == 1 && IsChineseCharacter(segment[0]))
                {
                    structure.SingleChars.Add(segment);
                    structure.HasSingleChars = true;
                }
                else
                {
                    structure.Words.Add(segment);
                    structure.HasWords = true;
                }
            }

            // 设置组合类型
            if (structure.HasWords && structure.HasSingleChars)
            {
                structure.CombinationType = CombinationType.WordsAndChars;
                structure.Notes = "混合查询：包含词语和单字";
            }
            else if (structure.HasWords && !structure.HasSingleChars)
            {
                structure.CombinationType = CombinationType.WordsOnly;
                structure.Notes = structure.Words.Count > 1 ? "多词查询" : "单词查询";
            }
            else if (!structure.HasWords && structure.HasSingleChars)
            {
                structure.CombinationType = CombinationType.CharsOnly;
                structure.Notes = structure.SingleChars.Count > 1 ? "多字查询" : "单字查询";
            }
            else
            {
                structure.CombinationType = CombinationType.Unknown;
                structure.Notes = "无法识别的查询类型";
            }

            // 计算复杂度评分
            structure.ComplexityScore = CalculateComplexityScore(structure);

            return structure;
        }

        /// <summary>
        /// 计算搜索复杂度评分
        /// </summary>
        private static int CalculateComplexityScore(SearchStructure structure)
        {
            int score = 0;

            // 词条数量（1-5分）
            int segmentCount = structure.Words.Count + structure.SingleChars.Count;
            score += Math.Min(segmentCount, 5);

            // 是否混合类型（加3分）
            if (structure.HasWords && structure.HasSingleChars)
                score += 3;

            // 单字数量（每3个加1分，最多2分）
            if (structure.SingleChars.Count >= 3)
                score += Math.Min(structure.SingleChars.Count / 3, 2);

            // 词语平均长度（长词加2分）
            if (structure.Words.Any())
            {
                double avgLength = structure.Words.Average(w => w.Length);
                if (avgLength > 4) score += 2;
            }

            // 总字符数（10个以上加1分）
            if (structure.AllCharacters.Count > 10)
                score += 1;

            return Math.Min(score, 10); // 最高10分
        }

        /// <summary>
        /// 获取搜索策略
        /// </summary>
        private static MatchStrategy GetMatchStrategy(SearchStructure structure, SearchConfig config)
        {
            var complexity = CalculateComplexityScore(structure);

            return new MatchStrategy
            {
                StrategyName = complexity >= 7 ? "strict" :
                              complexity >= 4 ? "balanced" : "loose",
                ComplexityScore = complexity,
                UseExactMatch = config.EnableExactMatch && structure.Words.Any(w => w.Length >= 3),
                UsePrefixMatch = config.EnablePrefixMatch,
                UseFuzzySearch = config.EnableFuzzySearch,
                UseCharSearch = config.EnableCharSearch && structure.SingleChars.Any(),
                UseSmartSplitting = config.EnableSmartSplitting && structure.Words.Any(w => w.Length >= config.MinSplitLength),
                RecommendedPageSize = complexity >= 7 ? 10 : 20
            };
        }

        /// <summary>
        /// 获取计分规则
        /// </summary>
        private static List<ScoringRule> GetScoringRules(SearchStructure structure, SearchConfig config)
        {
            var rules = new List<ScoringRule>();

            // 词语匹配规则
            foreach (var word in structure.Words)
            {
                rules.Add(new ScoringRule
                {
                    Type = "word",
                    Value = word,
                    BaseScore = 10,
                    Bonus = word.Length >= 3 ? 5 : 2,
                    Multiplier = 1.0,
                    Condition = $"包含词语'{word}'"
                });
            }

            // 单字匹配规则
            foreach (var ch in structure.SingleChars)
            {
                rules.Add(new ScoringRule
                {
                    Type = "char",
                    Value = ch,
                    BaseScore = 3,
                    Bonus = 1,
                    Multiplier = 1.0,
                    Condition = $"包含单字'{ch}'"
                });
            }

            // 混合匹配奖励
            if (structure.HasWords && structure.HasSingleChars)
            {
                rules.Add(new ScoringRule
                {
                    Type = "combo",
                    Value = "words_and_chars",
                    BaseScore = 0,
                    Bonus = 8,
                    Multiplier = 1.2,
                    Condition = "同时匹配词语和单字"
                });
            }

            // 智能拆分奖励
            if (config.EnableSmartSplitting && structure.Words.Any(w => w.Length >= config.MinSplitLength))
            {
                rules.Add(new ScoringRule
                {
                    Type = "smart_split",
                    Value = "smart_split_match",
                    BaseScore = 0,
                    Bonus = 5,
                    Multiplier = 1.1,
                    Condition = "智能拆分匹配"
                });
            }

            // 完全匹配奖励
            rules.Add(new ScoringRule
            {
                Type = "exact",
                Value = "exact_match",
                BaseScore = 0,
                Bonus = 15,
                Multiplier = 1.5,
                Condition = "完全匹配搜索词"
            });

            return rules;
        }

        /// <summary>
        /// 获取需要提升权重的字段
        /// </summary>
        private static List<string> GetBoostFields(SearchStructure structure, List<string> searchFields)
        {
            var boostFields = new List<string>();

            if (structure.HasWords && structure.Words.Any(w => w.Length >= 2))
            {
                // 长词语在名称字段中效果更好
                boostFields.AddRange(searchFields.Where(f =>
                    f.Contains("name", StringComparison.OrdinalIgnoreCase) ||
                    f.Contains("title", StringComparison.OrdinalIgnoreCase) ||
                    f.Contains("subject", StringComparison.OrdinalIgnoreCase)));
            }

            if (structure.HasSingleChars)
            {
                // 单字在描述、内容字段中效果更好
                boostFields.AddRange(searchFields.Where(f =>
                    f.Contains("desc", StringComparison.OrdinalIgnoreCase) ||
                    f.Contains("content", StringComparison.OrdinalIgnoreCase) ||
                    f.Contains("remark", StringComparison.OrdinalIgnoreCase) ||
                    f.Contains("note", StringComparison.OrdinalIgnoreCase)));
            }

            return boostFields.Distinct().ToList();
        }

        /// <summary>
        /// 计算预期匹配数
        /// </summary>
        private static int CalculateExpectedMatches(SearchStructure structure, int fieldCount)
        {
            int baseMatches = structure.Words.Count + structure.SingleChars.Count;
            int expected = baseMatches * fieldCount;

            // 调整预期值
            if (structure.CombinationType == CombinationType.WordsAndChars)
                expected = (int)(expected * 1.5);
            else if (structure.CombinationType == CombinationType.CharsOnly)
                expected = (int)(expected * 0.7);

            return Math.Max(expected, 1);
        }

        #endregion

        #region 条件构建策略

        /// <summary>
        /// 构建严格条件（所有条件必须满足）
        /// </summary>
        private static string BuildStrictCondition(List<string> conditions, SearchStructure structure)
        {
            if (conditions.Count == 1)
                return conditions[0];

            // 词语条件在前，单字条件在后
            var wordConditions = conditions
                .Where((c, i) => i < structure.Words.Count)
                .ToList();

            var charConditions = conditions
                .Skip(structure.Words.Count)
                .ToList();

            if (wordConditions.Any() && charConditions.Any())
            {
                return $"({string.Join(" AND ", wordConditions)} AND ({string.Join(" OR ", charConditions)}))";
            }

            return $"({string.Join(" AND ", conditions)})";
        }

        /// <summary>
        /// 构建平衡条件
        /// </summary>
        private static string BuildBalancedCondition(List<string> conditions, SearchStructure structure)
        {
            if (conditions.Count == 1)
                return conditions[0];

            // 词语优先，单字作为增强
            if (structure.HasWords && structure.HasSingleChars)
            {
                var wordCondition = conditions.First();
                var charConditions = conditions.Skip(1).ToList();

                return $"({wordCondition} AND ({string.Join(" OR ", charConditions)}))";
            }

            return $"({string.Join(" AND ", conditions)})";
        }

        /// <summary>
        /// 构建宽松条件（提高召回率）
        /// </summary>
        private static string BuildLooseCondition(List<string> conditions, SearchStructure structure)
        {
            if (conditions.Count == 1)
                return conditions[0];

            // 所有条件OR连接
            return $"({string.Join(" OR ", conditions)})";
        }

        #endregion

        #region 实用工具方法

        /// <summary>
        /// 检查字符是否为中文字符
        /// </summary>
        public static bool IsChineseCharacter(char c)
        {
            // 基本汉字（0x4E00-0x9FFF）
            if (c >= 0x4E00 && c <= 0x9FFF)
                return true;

            // 扩展A区（0x3400-0x4DBF）
            if (c >= 0x3400 && c <= 0x4DBF)
                return true;

            // 基本汉字补充（0x9FA6-0x9FFF）
            if (c >= 0x9FA6 && c <= 0x9FFF)
                return true;

            return false;
        }

        /// <summary>
        /// 移除字符串中的分隔符
        /// </summary>
        private static string RemoveSeparators(string text)
        {
            if (string.IsNullOrEmpty(text))
                return text;

            var separators = new[] { ' ', '，', '、', ',', ';', '；', '-', '_', '.', '。', '·', '|', '/', '\\' };
            return new string(text.Where(c => !separators.Contains(c)).ToArray());
        }

        /// <summary>
        /// 验证搜索字段列表
        /// </summary>
        public static (bool IsValid, string Message, List<string> ValidFields) ValidateSearchFields(
            List<string> searchFields, List<string> allFields)
        {
            if (searchFields == null || !searchFields.Any())
                return (false, "搜索字段列表不能为空", new List<string>());

            if (allFields == null || !allFields.Any())
                return (true, "无验证字段列表，接受所有输入", searchFields);

            var validFields = searchFields.Intersect(allFields).ToList();
            var invalidFields = searchFields.Except(allFields).ToList();

            if (invalidFields.Any())
            {
                return (false,
                    $"发现无效字段: {string.Join(", ", invalidFields)}",
                    validFields);
            }

            return (true, "所有字段有效", validFields);
        }

        /// <summary>
        /// 生成搜索统计信息
        /// </summary>
        public static SearchStats GenerateSearchStats(SearchStructure structure, int resultCount)
        {
            return new SearchStats
            {
                SearchTerm = structure.OriginalTerm,
                CombinationType = structure.CombinationType,
                WordCount = structure.Words.Count,
                CharCount = structure.SingleChars.Count,
                TotalSegments = structure.Segments.Count,
                ComplexityScore = structure.ComplexityScore,
                ResultCount = resultCount,
                GeneratedAt = DateTime.Now
            };
        }

        #endregion
    }

    #region 数据模型和枚举

    /// <summary>
    /// 搜索模式枚举
    /// </summary>
    public enum SearchMode
    {
        /// <summary>
        /// 自动检测搜索类型
        /// </summary>
        [Description("自动检测")]
        AutoDetect = 0,

        /// <summary>
        /// 单词条搜索
        /// </summary>
        [Description("单词条搜索")]
        SingleWord = 1,

        /// <summary>
        /// 多词条搜索
        /// </summary>
        [Description("多词条搜索")]
        MultiWord = 2,

        /// <summary>
        /// 单字搜索
        /// </summary>
        [Description("单字搜索")]
        SingleChar = 3,

        /// <summary>
        /// 精确匹配
        /// </summary>
        [Description("精确匹配")]
        Exact = 4,

        /// <summary>
        /// 高级查询
        /// </summary>
        [Description("高级查询")]
        Advanced = 5
    }

    /// <summary>
    /// 组合模式枚举
    /// </summary>
    public enum CombinationMode
    {
        /// <summary>
        /// 智能混合（自动调整权重和连接方式）
        /// </summary>
        [Description("智能混合")]
        SmartMix = 0,

        /// <summary>
        /// 词语和单字组合（词语必须，单字增强）
        /// </summary>
        [Description("词语+单字")]
        WordsAndChars = 1,

        /// <summary>
        /// 仅词语
        /// </summary>
        [Description("仅词语")]
        WordsOnly = 2,

        /// <summary>
        /// 仅单字
        /// </summary>
        [Description("仅单字")]
        CharsOnly = 3
    }

    /// <summary>
    /// 组合类型
    /// </summary>
    public enum CombinationType
    {
        [Description("未知")]
        Unknown,

        [Description("仅词语")]
        WordsOnly,

        [Description("仅单字")]
        CharsOnly,

        [Description("词语和单字混合")]
        WordsAndChars
    }

    /// <summary>
    /// 搜索结构分析结果
    /// </summary>
    public class SearchStructure
    {
        public string OriginalTerm { get; set; } = "";
        public string CleanTerm { get; set; } = "";
        public DateTime AnalyzedAt { get; set; }
        public List<string> Segments { get; set; } = new List<string>();
        public List<string> Words { get; set; } = new List<string>();
        public List<string> SingleChars { get; set; } = new List<string>();
        public List<char> AllCharacters { get; set; } = new List<char>();
        public bool HasWords { get; set; }
        public bool HasSingleChars { get; set; }
        public CombinationType CombinationType { get; set; }
        public string Notes { get; set; } = "";
        public int ComplexityScore { get; set; }

        // 统计信息
        public int TotalWordLength => Words.Sum(w => w.Length);
        public int MaxWordLength => Words.Any() ? Words.Max(w => w.Length) : 0;
        public double AvgWordLength => Words.Any() ? Words.Average(w => w.Length) : 0;
        public int TotalCharacterCount => AllCharacters.Count;
    }

    /// <summary>
    /// 搜索配置类（增强版）
    /// 控制搜索行为、匹配策略和性能优化的参数集合
    /// </summary>
    public class SearchConfig
    {
        /// <summary>
        /// 是否启用精确匹配
        /// 默认值: true
        /// 说明: 当设置为true时，系统会尝试使用等号(=)进行完全匹配
        /// 适用场景: 搜索ID、编码、精确名称等唯一标识
        /// 示例: 搜索"1001"时，只匹配完全等于"1001"的记录
        /// 性能影响: 精确匹配通常使用索引，性能最好
        /// </summary>
        public bool EnableExactMatch { get; set; } = true;

        /// <summary>
        /// 是否启用前缀匹配
        /// 默认值: true
        /// 说明: 当设置为true时，系统会尝试匹配以搜索词开头的记录
        /// 适用场景: 自动补全、拼音首字母搜索、编码前缀搜索
        /// 示例: 搜索"北京"时，会匹配"北京市"、"北京旅游"等
        /// 性能影响: 前缀匹配可以使用索引，性能良好
        /// </summary>
        public bool EnablePrefixMatch { get; set; } = true;

        /// <summary>
        /// 是否启用模糊搜索
        /// 默认值: true
        /// 说明: 当设置为true时，系统会使用LIKE '%关键词%'进行模糊匹配
        /// 适用场景: 通用全文搜索、包含关系搜索
        /// 示例: 搜索"长城"时，会匹配"长城旅游"、"八达岭长城"等
        /// 性能影响: 模糊搜索不能使用普通索引，建议配合全文索引使用
        /// 注意: 大数据量时可能会影响性能，建议合理设置搜索字段
        /// </summary>
        public bool EnableFuzzySearch { get; set; } = true;

        /// <summary>
        /// 是否启用单字搜索
        /// 默认值: true
        /// 说明: 当设置为true时，系统会将搜索词拆分成单个字符进行匹配
        /// 适用场景: 中文单字搜索、记忆不完整的模糊搜索
        /// 示例: 搜索"北上广"时，会分别匹配包含"北"、"上"、"广"的记录
        /// 注意: 启用后会生成多个LIKE条件，可能影响性能
        /// 建议: 单字数量较多时，考虑使用RequireAllChars控制匹配逻辑
        /// </summary>
        public bool EnableCharSearch { get; set; } = true;

        /// <summary>
        /// 是否要求所有词语都必须匹配
        /// 默认值: true
        /// 说明: 当设置为true时，多词搜索中所有词语都必须在记录中出现
        ///        当设置为false时，任意一个词语出现即可匹配
        /// 适用场景: 
        ///   true - 精确搜索，如"北京 长城"要求同时包含"北京"和"长城"
        ///   false - 宽松搜索，如"北京 长城"匹配包含"北京"或"长城"的记录
        /// 性能影响: true时可能返回更少结果，但条件更复杂
        /// 用户体验: true时结果更精确，false时召回率更高
        /// </summary>
        public bool RequireAllWords { get; set; } = true;

        /// <summary>
        /// 是否要求所有单字都必须匹配
        /// 默认值: true
        /// 说明: 当设置为true时，单字搜索中所有字符都必须在记录中出现
        ///        当设置为false时，任意一个字符出现即可匹配
        /// 适用场景: 
        ///   true - 如"北上广"要求同时包含"北"、"上"、"广"
        ///   false - 如"北上广"匹配包含"北"或"上"或"广"的记录
        /// 注意: 单字数量较多时，建议设为false以提高召回率
        /// </summary>
        public bool RequireAllChars { get; set; } = true;

        /// <summary>
        /// 精确匹配的最小长度要求
        /// 默认值: 2
        /// 说明: 只有当搜索词长度大于等于此值时，才会尝试精确匹配
        /// 适用场景: 避免短词（如"a"、"的"）使用精确匹配
        /// 示例: 设置为3时，"北京"不会使用精确匹配，"北京市"会使用
        /// 单位: 字符数
        /// 建议值: 2-5之间，根据业务需求调整
        /// </summary>
        public int MinExactMatchLength { get; set; } = 2;

        /// <summary>
        /// 搜索词的最大长度限制
        /// 默认值: 200
        /// 说明: 超过此长度的搜索词会被自动截断
        /// 目的: 
        ///   1. 防止恶意输入导致性能问题
        ///   2. 避免过长的SQL语句
        ///   3. 提高系统安全性
        /// 注意: 实际截断时保留前面部分，不会影响搜索意图
        /// 单位: 字符数
        /// 建议值: 50-500之间，根据业务场景调整
        /// </summary>
        public int MaxSearchTermLength { get; set; } = 200;

        /// <summary>
        /// 匹配度的最低分数要求
        /// 默认值: 0
        /// 说明: 只有匹配度分数大于等于此值的记录才会被返回
        /// 适用场景: 质量控制，过滤掉相关性太低的结果
        /// 分数范围: 通常为0-100，具体取决于评分算法
        /// 示例: 设置为10时，匹配度低于10分的记录会被过滤
        /// 注意: 需要EnableRelevanceScoring=true才会生效
        /// </summary>
        public double MinScore { get; set; } = 0;

        /// <summary>
        /// 是否启用相关性评分
        /// 默认值: true
        /// 说明: 当设置为true时，系统会计算每条记录的匹配度分数
        /// 功能:
        ///   1. 按匹配度排序（分数高的在前）
        ///   2. 可以设置MinScore过滤低分记录
        ///   3. 提供MatchScore字段供前端显示
        /// 性能影响: 会增加计算开销，但用户体验更好
        /// 建议: 搜索结果需要排序时启用，简单列表查询可关闭
        /// </summary>
        public bool EnableRelevanceScoring { get; set; } = true;

        /// <summary>
        /// 是否启用分阶段搜索
        /// 默认值: false
        /// 说明: 当设置为true时，系统会按优先级分阶段执行搜索
        /// 搜索阶段:
        ///   1. 精确匹配（最高优先级）
        ///   2. 前缀匹配
        ///   3. 模糊匹配
        ///   4. 单字匹配（最低优先级）
        /// 优点:
        ///   1. 优先返回最相关的结果
        ///   2. 可以设置降级策略
        ///   3. 提高搜索成功率
        /// 缺点:
        ///   1. 可能执行多次查询
        ///   2. 逻辑更复杂
        /// 适用场景: 对搜索结果质量要求较高的场景
        /// </summary>
        public bool EnableStagedSearch { get; set; } = false;

        /// <summary>
        /// 字段权重配置
        /// 默认值: 预定义的权重字典
        /// 说明: 控制不同字段在匹配度计算中的重要性
        /// 权重范围: 建议0.5-2.0之间
        /// 示例配置:
        ///   "name": 1.5    // 名称字段权重高
        ///   "title": 1.5   // 标题字段权重高
        ///   "code": 1.3    // 编码字段权重中
        ///   "desc": 1.0    // 描述字段权重正常
        ///   "remark": 0.7  // 备注字段权重低
        /// 使用方式:
        ///   1. 匹配度分数 = 基础分 × 字段权重
        ///   2. 权重高的字段对总分影响更大
        /// 建议: 根据业务重要性调整权重
        /// </summary>
        public Dictionary<string, double> FieldWeights { get; set; } = new Dictionary<string, double>
    {
        { "name", 1.5 },
        { "title", 1.5 },
        { "code", 1.3 },
        { "description", 1.0 },
        { "content", 0.8 },
        { "remark", 0.7 }
    };

        /// <summary>
        /// 是否启用同义词扩展
        /// 默认值: false
        /// 说明: 当设置为true时，系统会自动扩展搜索词的同义词
        /// 示例: 搜索"电脑"时，也会搜索"计算机"、"微机"等
        /// 实现方式: 需要配合同义词词典使用
        /// 优点: 提高召回率，改善搜索体验
        /// 缺点: 可能引入不相关结果
        /// 适用场景: 专业术语搜索、方言词汇搜索
        /// </summary>
        public bool EnableSynonymExpansion { get; set; } = false;

        /// <summary>
        /// 是否启用拼音搜索
        /// 默认值: false
        /// 说明: 当设置为true时，系统会将中文转换为拼音进行搜索
        /// 示例: 搜索"beijing"可以匹配"北京"
        /// 实现方式: 需要拼音转换库
        /// 适用场景: 
        ///   1. 输入拼音搜索中文
        ///   2. 首字母搜索（如"bj"匹配"北京"）
        /// 注意: 会增加搜索复杂度和索引大小
        /// </summary>
        public bool EnablePinyinSearch { get; set; } = false;

        /// <summary>
        /// 搜索结果的最大数量限制
        /// 默认值: 1000
        /// 说明: 限制单次搜索返回的最大记录数
        /// 目的:
        ///   1. 防止返回过多数据影响性能
        ///   2. 避免内存溢出
        ///   3. 提高响应速度
        /// 注意: 分页查询时，此限制针对总记录数
        /// 建议值: 500-5000之间，根据系统承载能力调整
        /// </summary>
        public int MaxResultCount { get; set; } = 1000;

        /// <summary>
        /// 是否启用搜索缓存
        /// 默认值: false
        /// 说明: 当设置为true时，相同的搜索条件会使用缓存结果
        /// 缓存策略:
        ///   1. 基于搜索词和参数的哈希值
        ///   2. 可设置缓存时间
        ///   3. 支持滑动过期
        /// 适用场景: 
        ///   1. 热门搜索词
        ///   2. 数据更新频率低的场景
        ///   3. 性能要求高的搜索
        /// 注意: 数据频繁更新时，需要合理设置缓存时间
        /// </summary>
        public bool EnableSearchCache { get; set; } = false;

        /// <summary>
        /// 缓存时间（分钟）
        /// 默认值: 5
        /// 说明: 搜索结果的缓存保留时间
        /// 单位: 分钟
        /// 使用条件: 需要EnableSearchCache=true
        /// 建议值: 
        ///   - 高频搜索: 1-5分钟
        ///   - 低频搜索: 10-30分钟
        ///   - 静态数据: 60分钟以上
        /// </summary>
        public int CacheDurationMinutes { get; set; } = 5;

        /// <summary>
        /// 是否启用搜索词分析
        /// 默认值: true
        /// 说明: 当设置为true时，系统会对搜索词进行智能分析
        /// 分析内容:
        ///   1. 去除停用词（的、了、在等）
        ///   2. 提取关键词
        ///   3. 识别搜索意图
        ///   4. 分析词性
        /// 优点: 提高搜索准确性和智能性
        /// 性能影响: 轻微，主要消耗在分析算法上
        /// 建议: 一般保持启用状态
        /// </summary>
        public bool EnableQueryAnalysis { get; set; } = true;

        /// <summary>
        /// 是否记录搜索日志
        /// 默认值: false
        /// 说明: 当设置为true时，系统会记录搜索行为日志
        /// 记录内容:
        ///   1. 搜索词
        ///   2. 搜索时间
        ///   3. 返回结果数
        ///   4. 响应时间
        ///   5. 用户信息（可选）
        /// 用途:
        ///   1. 分析用户搜索习惯
        ///   2. 优化搜索算法
        ///   3. 监控搜索性能
        ///   4. 安全审计
        /// 注意: 涉及隐私时需谨慎处理
        /// </summary>
        public bool EnableSearchLogging { get; set; } = false;

        /// <summary>
        /// 搜索超时时间（秒）
        /// 默认值: 30
        /// 说明: 搜索操作的最大执行时间
        /// 目的: 
        ///   1. 防止长时间运行的查询
        ///   2. 提高系统稳定性
        ///   3. 改善用户体验
        /// 单位: 秒
        /// 建议值: 
        ///   - 实时搜索: 5-10秒
        ///   - 后台搜索: 30-60秒
        ///   - 大数据搜索: 120秒以上
        /// 注意: 超时后会取消查询，返回已有结果或错误
        /// </summary>
        public int SearchTimeoutSeconds { get; set; } = 30;

        /// <summary>
        /// 是否启用异步搜索
        /// 默认值: true
        /// 说明: 当设置为true时，搜索操作会异步执行
        /// 优点:
        ///   1. 不阻塞主线程
        ///   2. 提高并发处理能力
        ///   3. 更好的用户体验
        /// 适用场景: 
        ///   1. 复杂搜索条件
        ///   2. 大数据量搜索
        ///   3. 高并发场景
        /// 注意: 需要合理的线程管理和资源控制
        /// </summary>
        public bool EnableAsyncSearch { get; set; } = true;

        /// <summary>
        /// 是否启用智能提示
        /// 默认值: false
        /// 说明: 当设置为true时，系统会根据输入提供搜索建议
        /// 功能:
        ///   1. 自动补全
        ///   2. 热门搜索建议
        ///   3. 相关搜索推荐
        ///   4. 拼写纠正
        /// 实现方式: 基于搜索历史、词典、算法模型
        /// 适用场景: 搜索框智能提示功能
        /// 注意: 需要额外的数据处理和存储
        /// </summary>
        public bool EnableSmartSuggestions { get; set; } = false;

        /// <summary>
        /// 是否启用搜索结果高亮
        /// 默认值: false
        /// 说明: 当设置为true时，搜索结果中的匹配部分会被高亮显示
        /// 高亮方式:
        ///   1. HTML标记（如<em>关键词</em>）
        ///   2. 特殊字符包裹
        ///   3. 前端处理
        /// 适用场景: 需要突出显示匹配内容的搜索
        /// 注意: 会增加数据传输量和前端处理复杂度
        /// </summary>
        public bool EnableResultHighlighting { get; set; } = false;

        /// <summary>
        /// 是否启用搜索结果分组
        /// 默认值: false
        /// 说明: 当设置为true时，搜索结果会按指定字段进行分组
        /// 分组方式:
        ///   1. 按类型分组
        ///   2. 按时间分组
        ///   3. 按相关度分组
        /// 适用场景: 
        ///   1. 多类型混合搜索
        ///   2. 时间线展示
        ///   3. 分类浏览
        /// 注意: 会增加查询复杂度和处理时间
        /// </summary>
        public bool EnableResultGrouping { get; set; } = false;

        /// <summary>
        /// 是否启用智能拆分
        /// 默认值: true
        /// 说明: 当设置为true时，系统会自动将长词拆分成合理的子词组合
        /// 适用场景: 搜索"重庆科学"这类组合词时，会自动尝试"重庆"+"科学"的组合
        /// 工作方式:
        ///   1. 检测长度为MinSplitLength及以上的词语
        ///   2. 使用智能算法判断是否为可拆分组合词
        ///   3. 如果可拆分，生成多层次搜索条件
        /// 多层次条件示例: "重庆科学" → 
        ///   - 完整词匹配（最高优先级）
        ///   - 拆分子词匹配（"重庆" AND "科学"）
        ///   - 单字匹配（"重" OR "庆" OR "科" OR "学"）
        /// 优点: 
        ///   1. 提高组合词的搜索成功率
        ///   2. 保持搜索结果的准确性
        ///   3. 提升用户体验
        /// 性能影响: 会增加搜索条件复杂度，但能显著提高召回率
        /// 建议: 中文搜索场景建议启用
        /// </summary>
        public bool EnableSmartSplitting { get; set; } = true;

        /// <summary>
        /// 智能拆分时是否要求所有子词都匹配
        /// 默认值: false
        /// 说明: 控制智能拆分时对拆分子词的匹配严格度
        /// 示例: 
        ///   - true: "重庆科学"拆分为"重庆"和"科学"，要求同时包含这两个词
        ///   - false: "重庆科学"拆分为"重庆"和"科学"，包含任意一个即可匹配
        /// 适用场景: 
        ///   true: 需要精确拆分匹配的场景
        ///   false: 需要提高召回率的场景
        /// 建议: 通常设置为false以获得更好的搜索结果覆盖率
        /// 注意: 此设置仅影响智能拆分的子词匹配，不影响原始词语匹配
        /// </summary>
        public bool RequireAllWordsForSplit { get; set; } = false;

        /// <summary>
        /// 智能拆分时是否要求所有单字都匹配
        /// 默认值: false
        /// 说明: 控制智能拆分成单字时的匹配严格度
        /// 示例: 
        ///   - true: "重庆科学"拆分为单字时，要求同时包含"重"、"庆"、"科"、"学"
        ///   - false: "重庆科学"拆分为单字时，包含任意一个单字即可匹配
        /// 适用场景: 
        ///   true: 需要完全匹配所有单字的严格场景
        ///   false: 需要宽松匹配以提高召回率的场景
        /// 建议: 通常设置为false，因为单字完全匹配要求较高，容易漏掉相关结果
        /// 注意: 此设置仅影响智能拆分的单字匹配阶段
        /// </summary>
        public bool RequireAllCharsForSplit { get; set; } = false;

        /// <summary>
        /// 最小拆分长度
        /// 默认值: 4
        /// 说明: 只有长度大于等于此值的词才会被考虑进行智能拆分
        /// 单位: 字符数
        /// 示例: 
        ///   - 设置为4时，"重庆科学"（4字）会被考虑拆分
        ///   - 设置为5时，"北京长城游"（5字）会被考虑拆分
        /// 适用场景: 
        ///   - 较低值（3-4）：适用于短词较多的场景
        ///   - 较高值（5-6）：适用于长词较多的专业场景
        /// 建议值: 
        ///   - 中文搜索: 4
        ///   - 英文搜索: 8（对应4个英文单词）
        ///   - 混合搜索: 根据主要语言调整
        /// 注意: 设置过低可能导致过多词语被拆分，影响性能；设置过高可能错过可拆分的组合词
        /// </summary>
        public int MinSplitLength { get; set; } = 4;

        /// <summary>
        /// 最大拆分组合数
        /// 默认值: 3
        /// 说明: 限制一个词的最大拆分方式数量，防止组合爆炸
        /// 示例: 
        ///   - 设置为3时，一个6字词最多尝试3种拆分方式
        ///   - 设置为1时，只使用最优的拆分方式
        /// 适用场景: 
        ///   - 性能敏感场景: 1-2
        ///   - 平衡场景: 3
        ///   - 准确性优先场景: 5-10
        /// 性能影响: 每增加一个拆分组合，会增加一个搜索条件分支
        /// 建议: 
        ///   - 实时搜索: 1-3
        ///   - 后台搜索: 3-5
        ///   - 复杂分析: 5-10
        /// 注意: 过高的值可能导致SQL条件过于复杂，影响数据库性能
        /// </summary>
        public int MaxSplitCombinations { get; set; } = 3;
    }

    /// <summary>
    /// 搜索阶段
    /// </summary>
    public class SearchStage
    {
        public int Stage { get; set; }
        public string Name { get; set; } = "";
        public string Condition { get; set; } = "";
        public List<SugarParameter> Parameters { get; set; } = new List<SugarParameter>();
        public int Priority { get; set; }
        public string Description { get; set; } = "";
        public bool FallbackToNext { get; set; } = true;
    }

    /// <summary>
    /// 相关性信息（增强版）
    /// </summary>
    public class RelevanceInfo
    {
        public SearchStructure SearchStructure { get; set; }
        public int ExpectedMatches { get; set; }
        public List<string> BoostFields { get; set; } = new List<string>();
        public List<ScoringRule> ScoringRules { get; set; } = new List<ScoringRule>();
        public MatchStrategy MatchStrategy { get; set; }
        public DateTime GeneratedAt { get; set; }
        public bool HasSmartSplitting { get; set; }
        public List<string> SplittableWords { get; set; } = new List<string>();
    }

    /// <summary>
    /// 匹配策略（增强版）
    /// </summary>
    public class MatchStrategy
    {
        public string StrategyName { get; set; } = "";
        public int ComplexityScore { get; set; }
        public bool UseExactMatch { get; set; }
        public bool UsePrefixMatch { get; set; }
        public bool UseFuzzySearch { get; set; }
        public bool UseCharSearch { get; set; }
        public bool UseSmartSplitting { get; set; }
        public int RecommendedPageSize { get; set; } = 20;
        public string Description { get; set; } = "";
    }

    /// <summary>
    /// 计分规则
    /// </summary>
    public class ScoringRule
    {
        public string Type { get; set; } = ""; // word, char, combo, exact, smart_split
        public string Value { get; set; } = "";
        public int BaseScore { get; set; }
        public int Bonus { get; set; }
        public double Multiplier { get; set; } = 1.0;
        public string Condition { get; set; } = "";
    }

    /// <summary>
    /// 搜索统计信息
    /// </summary>
    public class SearchStats
    {
        public string SearchTerm { get; set; } = "";
        public CombinationType CombinationType { get; set; }
        public int WordCount { get; set; }
        public int CharCount { get; set; }
        public int TotalSegments { get; set; }
        public int ComplexityScore { get; set; }
        public int ResultCount { get; set; }
        public DateTime GeneratedAt { get; set; }

        public double MatchRatio => TotalSegments > 0 ? (double)ResultCount / TotalSegments : 0;
        public string ComplexityLevel => ComplexityScore >= 7 ? "高" :
                                        ComplexityScore >= 4 ? "中" : "低";
    }

    #endregion

    #region 扩展方法

    /// <summary>
    /// AdvancedSearchHelper 扩展方法
    /// </summary>
    public static class EnhancedSearchExtensions
    {
        /// <summary>
        /// 获取组合类型的详细说明
        /// </summary>
        public static string GetDetail(this CombinationType type)
        {
            return type switch
            {
                CombinationType.WordsOnly => "仅使用词语进行搜索，适合精确的关键词匹配",
                CombinationType.CharsOnly => "仅使用单字进行搜索，适合模糊或记忆不完整的搜索",
                CombinationType.WordsAndChars => "混合使用词语和单字，提供更灵活的搜索体验",
                _ => "未知的搜索类型"
            };
        }

        /// <summary>
        /// 获取搜索模式的推荐使用场景
        /// </summary>
        public static string GetUsageScenario(this SearchMode mode)
        {
            return mode switch
            {
                SearchMode.AutoDetect => "适用于通用搜索场景，系统自动识别最佳搜索方式",
                SearchMode.SingleWord => "适用于已知确切名称或关键词的搜索",
                SearchMode.MultiWord => "适用于多个相关关键词的组合搜索",
                SearchMode.SingleChar => "适用于模糊搜索或拼音首字母搜索",
                SearchMode.Exact => "适用于需要完全匹配的精确搜索",
                SearchMode.Advanced => "适用于专业用户的高级搜索需求",
                _ => "通用搜索场景"
            };
        }
    }

    #endregion
}