using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.Extensions.Options;
using Microsoft.Identity.Client;

namespace OASystem.API.OAMethodLib.MicrosoftGraphMailbox;

public class MicrosoftGraphMailboxService : IMicrosoftGraphMailboxService
{
    private readonly IHttpClientFactory _httpClientFactory;
    private readonly IOptionsMonitor<MicrosoftGraphMailboxOptions> _options;
    private readonly ILogger<MicrosoftGraphMailboxService> _logger;

    private const string HttpClientName = "MicrosoftGraph";

    public MicrosoftGraphMailboxService(
        IHttpClientFactory httpClientFactory,
        IOptionsMonitor<MicrosoftGraphMailboxOptions> options,
        ILogger<MicrosoftGraphMailboxService> logger)
    {
        _httpClientFactory = httpClientFactory;
        _options = options;
        _logger = logger;
    }

    public async Task<string?> GetMeRawJsonAsync(string graphAccessToken, CancellationToken cancellationToken = default)
    {
        using var client = CreateAuthenticatedClient(graphAccessToken);
        using var response = await client.GetAsync("me", cancellationToken).ConfigureAwait(false);
        var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
        if (!response.IsSuccessStatusCode)
            _logger.LogWarning("Graph GET /me 失败: {Status} {Body}", (int)response.StatusCode, body);
        return body;
    }

    public async Task<string?> GetInboxMessagesJsonSinceAsync(DateTime startUtc, string graphAccessToken, CancellationToken cancellationToken = default)
    {
        var opt = _options.CurrentValue;
        var startTime = startUtc.ToString("o");
        var url =
            "me/mailFolders/inbox/messages" +
            "?$select=id,subject,from,receivedDateTime,bodyPreview,conversationId" +
            $"&$filter=receivedDateTime ge {startTime}" +
            "&$orderby=receivedDateTime desc" +
            $"&$top={opt.TopMessages}";

        using var client = CreateAuthenticatedClient(graphAccessToken);
        using var response = await client.GetAsync(url, cancellationToken).ConfigureAwait(false);
        var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
        if (!response.IsSuccessStatusCode)
            _logger.LogWarning("Graph 拉取收件箱失败: {Status} {Body}", (int)response.StatusCode, body);
        return body;
    }

    public async Task SendMailAsync(string toEmail, string subject, string textBody, string graphAccessToken, CancellationToken cancellationToken = default)
    {
        var payload = new GraphSendMailRequest
        {
            Message = new GraphSendMailMessage
            {
                Subject = subject,
                Body = new GraphSendMailBody
                {
                    ContentType = "Text",
                    Content = textBody
                },
                ToRecipients = new List<GraphSendMailRecipient>
                {
                    new()
                    {
                        EmailAddress = new GraphSendMailEmail { Address = toEmail }
                    }
                }
            },
            SaveToSentItems = true
        };

        var json = System.Text.Json.JsonSerializer.Serialize(payload, new JsonSerializerOptions
        {
            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
        });

        using var client = CreateAuthenticatedClient(graphAccessToken);
        using var content = new StringContent(json, Encoding.UTF8, "application/json");
        using var response = await client.PostAsync("me/sendMail", content, cancellationToken).ConfigureAwait(false);
        var responseText = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);

        if (!response.IsSuccessStatusCode)
        {
            _logger.LogError("Graph sendMail 失败: {Status} {Body}", (int)response.StatusCode, responseText);
            response.EnsureSuccessStatusCode();
        }
    }

    private HttpClient CreateAuthenticatedClient(string graphAccessToken)
    {
        if (string.IsNullOrWhiteSpace(graphAccessToken))
            throw new ArgumentException("Graph 访问令牌不能为空。", nameof(graphAccessToken));

        var client = _httpClientFactory.CreateClient(HttpClientName);
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", graphAccessToken.Trim());
        return client;
    }


    public async Task<string> RefreshAccessTokenAsync(
        string clientId,
        string tenant,
        string[] scopes,
        string tokenCacheBase64,   // 从Redis拿到的缓存（Base64字符串）
        string homeAccountId       // 用户标识（建议存这个）
    )
    {
        // 1️⃣ 创建 MSAL 应用
        var app = PublicClientApplicationBuilder
            .Create(clientId)
            .WithAuthority($"https://login.microsoftonline.com/{tenant}")
            .WithDefaultRedirectUri()
            .Build();

        // 2️⃣ 恢复 TokenCache
        if (!string.IsNullOrEmpty(tokenCacheBase64))
        {
            var cacheBytes = Convert.FromBase64String(tokenCacheBase64);

            app.UserTokenCache.SetBeforeAccess(args =>
            {
                args.TokenCache.DeserializeMsalV3(cacheBytes, false);
            });

            app.UserTokenCache.SetAfterAccess(args =>
            {

            });
        }
        else
        {
            throw new InvalidOperationException("TokenCache 为空，无法刷新");
        }

        // 3️⃣ 找到对应用户
        var accounts = await app.GetAccountsAsync();
        var account = accounts.FirstOrDefault(a =>
            string.Equals(a.HomeAccountId?.Identifier, homeAccountId, StringComparison.Ordinal));

        if (account == null)
        {
            throw new InvalidOperationException("未找到匹配的用户账号，需要重新登录");
        }

        // 4️⃣ 刷新（核心）
        try
        {
            var result = await app
                .AcquireTokenSilent(scopes, account)
                .ExecuteAsync();

            return result.AccessToken;
        }
        catch (MsalUiRequiredException ex)
        {
            throw new InvalidOperationException("刷新失败，需要重新登录", ex);
        }
    }
}