EmailBill/Service/SmartClassify.cs

namespace Service;

public interface ISmartHandleService
{
    Task SmartClassifyAsync(long[] transactionIds, Action<(string , string)> chunkAction);
}

public class SmartHandleService(
    ITransactionRecordRepository transactionRepository,
    ITextSegmentService textSegmentService,
    ILogger<SmartHandleService> logger,
    ITransactionCategoryRepository categoryRepository,
    IOpenAiService openAiService
) : ISmartHandleService
{
    public async Task SmartClassifyAsync(long[] transactionIds, Action<(string , string)> chunkAction)
    {
        try
        {
            // 获取指定ID的账单（作为样本）
            var sampleRecords = await transactionRepository.GetByIdsAsync(transactionIds);

            if (sampleRecords.Length == 0)
            {
                // await WriteEventAsync("error", "找不到指定的账单");
                chunkAction(("error", "找不到指定的账单"));
                return;
            }

            // 重新按Reason分组所有待分类账单
            var groupedRecords = sampleRecords
                .GroupBy(r => r.Reason)
                .Select(g => new
                {
                    Reason = g.Key,
                    Ids = g.Select(r => r.Id).ToList(),
                    Count = g.Count(),
                    TotalAmount = g.Sum(r => r.Amount),
                    SampleType = g.First().Type
                })
                .OrderByDescending(g => Math.Abs(g.TotalAmount))
                .ToList();

            // 【增强功能】对每个分组的摘要进行分词，查询已分类的相似账单
            var referenceRecords = new Dictionary<string, List<TransactionRecord>>();
            foreach (var group in groupedRecords)
            {
                // 使用专业分词库提取关键词
                var keywords = textSegmentService.ExtractKeywords(group.Reason);

                if (keywords.Count > 0)
                {
                    // 查询包含这些关键词且已分类的账单（带相关度评分）
                    // minMatchRate=0.4 表示至少匹配40%的关键词才被认为是相似的
                    var similarClassifiedWithScore = await transactionRepository.GetClassifiedByKeywordsWithScoreAsync(keywords, minMatchRate: 0.4, limit: 10);

                    if (similarClassifiedWithScore.Count > 0)
                    {
                        // 只取前5个最相关的
                        var topSimilar = similarClassifiedWithScore.Take(5).Select(x => x.record).ToList();
                        referenceRecords[group.Reason] = topSimilar;

                        // 记录调试信息
                        logger.LogDebug("摘要 '{Reason}' 提取关键词: {Keywords}, 找到 {Count} 个相似账单，相关度分数: {Scores}",
                            group.Reason,
                            string.Join(", ", keywords),
                            similarClassifiedWithScore.Count,
                            string.Join(", ", similarClassifiedWithScore.Select(x => $"{x.record.Reason}({x.relevanceScore:F2})")));
                    }
                    else
                    {
                        logger.LogDebug("摘要 '{Reason}' 提取关键词: {Keywords}, 未找到高相关度的相似账单",
                            group.Reason,
                            string.Join(", ", keywords));
                    }
                }
            }

            // 获取所有分类
            var categories = await categoryRepository.GetAllAsync();

            // 构建分类信息
            var categoryInfo = new StringBuilder();
            foreach (var type in new[] { 0, 1, 2 })
            {
                var typeName = GetTypeName((TransactionType)type);
                categoryInfo.AppendLine($"{typeName}: ");
                var categoriesOfType = categories.Where(c => (int)c.Type == type).ToList();
                foreach (var category in categoriesOfType)
                {
                    categoryInfo.AppendLine($"- {category.Name}");
                }
            }

            // 构建账单分组信息
            var billsInfo = new StringBuilder();
            foreach (var (group, index) in groupedRecords.Select((g, i) => (g, i)))
            {
                billsInfo.AppendLine($"{index + 1}. 摘要={group.Reason}, 当前类型={GetTypeName(group.SampleType)}, 当前分类={(string.IsNullOrEmpty(group.SampleType.ToString()) ? "未分类" : group.SampleType.ToString())}, 涉及金额={group.TotalAmount}");

                // 如果有相似的已分类账单，添加参考信息
                if (referenceRecords.TryGetValue(group.Reason, out var references))
                {
                    billsInfo.AppendLine("   【参考】相似且已分类的账单：");
                    foreach (var refer in references.Take(3)) // 最多显示3个参考
                    {
                        billsInfo.AppendLine($"      - 摘要={refer.Reason}, 分类={refer.Classify}, 类型={GetTypeName(refer.Type)}, 金额={refer.Amount}");
                    }
                }
            }

            var systemPrompt = $$"""
                你是一个专业的账单分类助手。请根据提供的账单分组信息和分类列表，为每个分组选择最合适的分类。

                可用的分类列表：
                {{categoryInfo}}

                分类规则：
                1. 根据账单的摘要和涉及金额，选择最匹配的分类
                2. 如果提供了【参考】信息，优先参考相似账单的分类，这些是历史上已分类的相似账单
                3. 如果无法确定分类，可以选择"其他"
                4. 每个分组可能包含多条账单，你需要为整个分组选择一个分类

                请对每个分组进行分类，每次输出一个分组的分类结果，格式如下：
                {"reason": "交易摘要", "type": 0:支出/1:收入/2:不计入收支(Type为Number枚举值) ,"classify": "分类名称"}

                只输出JSON，不要有其他文字说明。
                """;

            var userPrompt = $$"""
                请为以下账单分组进行分类：

                {{billsInfo}}

                请逐个输出分类结果。
                """;

            // 流式调用AI
            chunkAction(("start", $"开始分类，共 {sampleRecords.Length} 条账单"));

            // 用于存储AI返回的分组分类结果
            var classifyResults = new List<(string Reason, string Classify, TransactionType Type)>();
            var buffer = new StringBuilder();
            var sendedIds = new HashSet<long>();
            await foreach (var chunk in openAiService.ChatStreamAsync(systemPrompt, userPrompt))
            {
                buffer.Append(chunk);

                // 尝试解析完整的JSON对象
                var bufferStr = buffer.ToString();
                var startIdx = 0;
                while (startIdx < bufferStr.Length)
                {
                    var openBrace = bufferStr.IndexOf('{', startIdx);
                    if (openBrace == -1) break;

                    var closeBrace = FindMatchingBrace(bufferStr, openBrace);
                    if (closeBrace == -1) break;

                    var jsonStr = bufferStr.Substring(openBrace, closeBrace - openBrace + 1);
                    try
                    {
                        var result = JsonSerializer.Deserialize<GroupClassifyResult>(jsonStr);
                        if (result != null && !string.IsNullOrEmpty(result.Reason))
                        {
                            classifyResults.Add((result.Reason, result.Classify ?? "", result.Type));
                            // 每一条结果单独通知
                            var group = groupedRecords.FirstOrDefault(g => g.Reason == result.Reason);
                            if (group != null)
                            {
                                // 为该分组的所有账单ID返回分类结果
                                foreach (var id in group.Ids)
                                {
                                    if (!sendedIds.Contains(id))
                                    {
                                        sendedIds.Add(id);
                                        var resultJson = JsonSerializer.Serialize(new { id, result.Classify, result.Type });
                                        chunkAction(("data", resultJson));
                                    }
                                }
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        logger.LogWarning(ex, "解析AI分类结果失败: {JsonStr}", jsonStr);
                    }

                    startIdx = closeBrace + 1;
                }
            }

            chunkAction(("end", "分类完成"));
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "智能分类失败");
            chunkAction(("error", $"智能分类失败: {ex.Message}"));
        }
    }

    /// <summary>
    /// 查找匹配的右括号
    /// </summary>
    private static int FindMatchingBrace(string str, int startPos)
    {
        int braceCount = 0;
        for (int i = startPos; i < str.Length; i++)
        {
            if (str[i] == '{') braceCount++;
            else if (str[i] == '}')
            {
                braceCount--;
                if (braceCount == 0) return i;
            }
        }
        return -1;
    }

    private static string GetTypeName(TransactionType type)
    {
        return type switch
        {
            TransactionType.Expense => "支出",
            TransactionType.Income => "收入",
            TransactionType.None => "不计入收支",
            _ => "未知"
        };
    }
}

/// <summary>
/// 分组分类结果DTO（用于AI返回结果解析）
/// </summary>
public record GroupClassifyResult
{
    [JsonPropertyName("reason")]
    public string Reason { get; set; } = string.Empty;

    [JsonPropertyName("classify")]
    public string? Classify { get; set; }

    [JsonPropertyName("type")]
    public TransactionType Type { get; set; }
}