package service

import (
	"context"
	"encoding/csv"
	"encoding/json"
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"go.mongodb.org/mongo-driver/bson"

	"billai-server/database"
	"billai-server/model"
)

// SaveResult 存储结果
type SaveResult struct {
	RawCount       int // 原始数据存储数量
	CleanedCount   int // 清洗后数据存储数量
	DuplicateCount int // 重复数据跳过数量
}

// checkDuplicate 检查记录是否重复
// 优先使用 transaction_id 判断，如果为空则使用 时间+金额+商户 组合判断
func checkDuplicate(ctx context.Context, bill *model.CleanedBill) bool {
	var filter bson.M

	if bill.TransactionID != "" {
		// 优先用交易订单号判断
		filter = bson.M{"transaction_id": bill.TransactionID}
	} else {
		// 回退到 时间+金额+商户 组合判断
		filter = bson.M{
			"time":     bill.Time.Time(), // 转换为 time.Time 用于 MongoDB 查询
			"amount":   bill.Amount,
			"merchant": bill.Merchant,
		}
	}

	count, err := database.CleanedBillCollection.CountDocuments(ctx, filter)
	if err != nil {
		return false // 查询出错时不认为是重复
	}

	return count > 0
}

// DeduplicateResult 去重结果
type DeduplicateResult struct {
	OriginalCount  int    // 原始记录数
	DuplicateCount int    // 重复记录数
	NewCount       int    // 新记录数
	DedupFilePath  string // 去重后的文件路径（如果有去重则生成新文件）
	BillType       string // 检测到的账单类型
}

// DeduplicateRawFile 对原始文件进行去重检查，返回去重后的文件路径
// 如果全部重复，返回错误
func DeduplicateRawFile(filePath, uploadBatch string) (*DeduplicateResult, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return nil, fmt.Errorf("打开文件失败: %w", err)
	}
	defer file.Close()

	reader := csv.NewReader(file)
	rows, err := reader.ReadAll()
	if err != nil {
		return nil, fmt.Errorf("读取 CSV 失败: %w", err)
	}

	if len(rows) < 2 {
		return nil, fmt.Errorf("文件没有数据行")
	}

	header := rows[0]
	dataRows := rows[1:]

	// 检测账单类型和去重字段
	billType, idFieldIdx := detectBillTypeAndIdField(header)

	result := &DeduplicateResult{
		OriginalCount: len(dataRows),
		BillType:      billType,
	}

	// 如果找不到去重字段，不进行去重，直接返回原文件
	if idFieldIdx < 0 {
		result.NewCount = len(dataRows)
		result.DedupFilePath = filePath
		return result, nil
	}

	// 创建上下文
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 检查每行是否重复
	var newRows [][]string
	for _, row := range dataRows {
		if len(row) <= idFieldIdx {
			continue
		}

		transactionID := strings.TrimSpace(row[idFieldIdx])
		if transactionID == "" {
			// 没有交易号的行，保留
			newRows = append(newRows, row)
			continue
		}

		// 检查是否已存在
		count, err := database.RawBillCollection.CountDocuments(ctx, bson.M{
			"raw_data." + header[idFieldIdx]: transactionID,
		})
		if err != nil {
			// 查询出错，保留该行
			newRows = append(newRows, row)
			continue
		}

		if count == 0 {
			// 不重复，保留
			newRows = append(newRows, row)
		} else {
			result.DuplicateCount++
		}
	}

	result.NewCount = len(newRows)

	// 如果没有新数据
	if len(newRows) == 0 {
		result.DedupFilePath = ""
		return result, nil
	}

	// 如果没有重复，直接返回原文件
	if result.DuplicateCount == 0 {
		result.DedupFilePath = filePath
		return result, nil
	}

	// 有重复，生成去重后的新文件
	dedupFilePath := strings.TrimSuffix(filePath, ".csv") + "_dedup.csv"
	dedupFile, err := os.Create(dedupFilePath)
	if err != nil {
		return nil, fmt.Errorf("创建去重文件失败: %w", err)
	}
	defer dedupFile.Close()

	writer := csv.NewWriter(dedupFile)
	writer.Write(header) // 写入表头
	for _, row := range newRows {
		writer.Write(row)
	}
	writer.Flush()

	result.DedupFilePath = dedupFilePath
	return result, nil
}

// detectBillTypeAndIdField 检测账单类型和用于去重的字段索引
func detectBillTypeAndIdField(header []string) (billType string, idFieldIdx int) {
	idFieldIdx = -1

	for i, col := range header {
		// 支付宝特征
		if col == "交易分类" || col == "对方账号" {
			billType = "alipay"
		}
		// 微信特征
		if col == "交易类型" || col == "金额(元)" {
			billType = "wechat"
		}

		// 查找去重字段（优先使用交易订单号/交易号）
		if col == "交易订单号" || col == "交易号" || col == "交易单号" {
			idFieldIdx = i
		}
	}

	// 如果没找到主要去重字段，尝试商户订单号
	if idFieldIdx < 0 {
		for i, col := range header {
			if col == "商家订单号" || col == "商户单号" || col == "商户订单号" {
				idFieldIdx = i
				break
			}
		}
	}

	return billType, idFieldIdx
}

// SaveRawBillsFromFile 从原始上传文件读取数据并存入原始数据集合
func SaveRawBillsFromFile(filePath, billType, sourceFile, uploadBatch string) (int, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return 0, fmt.Errorf("打开文件失败: %w", err)
	}
	defer file.Close()

	reader := csv.NewReader(file)
	rows, err := reader.ReadAll()
	if err != nil {
		return 0, fmt.Errorf("读取 CSV 失败: %w", err)
	}

	if len(rows) < 2 {
		return 0, nil // 没有数据行
	}

	// 获取表头
	header := rows[0]
	now := time.Now()

	// 构建原始数据文档
	var rawBills []interface{}
	for rowIdx, row := range rows[1:] {
		rawData := make(map[string]interface{})
		for colIdx, col := range header {
			if colIdx < len(row) {
				// 清理空白字符，确保去重查询能匹配
				rawData[col] = strings.TrimSpace(row[colIdx])
			}
		}

		rawBill := model.RawBill{
			BillType:    billType,
			SourceFile:  sourceFile,
			UploadBatch: uploadBatch,
			RowIndex:    rowIdx + 1, // 从1开始计数
			RawData:     rawData,
			CreatedAt:   now,
		}
		rawBills = append(rawBills, rawBill)
	}

	if len(rawBills) == 0 {
		return 0, nil
	}

	// 批量插入原始数据集合
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	result, err := database.RawBillCollection.InsertMany(ctx, rawBills)
	if err != nil {
		return 0, fmt.Errorf("插入原始数据失败: %w", err)
	}

	return len(result.InsertedIDs), nil
}

// SaveCleanedBillsFromFile 从清洗后的文件读取数据并存入清洗后数据集合
// 返回: (插入数量, 重复跳过数量, 错误)
func SaveCleanedBillsFromFile(filePath, format, billType, sourceFile, uploadBatch string) (int, int, error) {
	if format == "json" {
		return saveCleanedBillsFromJSON(filePath, billType, sourceFile, uploadBatch)
	}
	return saveCleanedBillsFromCSV(filePath, billType, sourceFile, uploadBatch)
}

// saveCleanedBillsFromCSV 从 CSV 文件读取并存储清洗后账单
// 返回: (插入数量, 重复跳过数量, 错误)
func saveCleanedBillsFromCSV(filePath, billType, sourceFile, uploadBatch string) (int, int, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return 0, 0, fmt.Errorf("打开文件失败: %w", err)
	}
	defer file.Close()

	reader := csv.NewReader(file)
	rows, err := reader.ReadAll()
	if err != nil {
		return 0, 0, fmt.Errorf("读取 CSV 失败: %w", err)
	}

	if len(rows) < 2 {
		return 0, 0, nil // 没有数据行
	}

	// 构建列索引映射
	header := rows[0]
	colIdx := make(map[string]int)
	for i, col := range header {
		colIdx[col] = i
	}

	// 创建上下文用于去重检查
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()

	// 解析数据行
	var bills []interface{}
	duplicateCount := 0
	now := time.Now()

	for _, row := range rows[1:] {
		bill := model.CleanedBill{
			BillType:    billType,
			SourceFile:  sourceFile,
			UploadBatch: uploadBatch,
			CreatedAt:   now,
			UpdatedAt:   now,
		}

		// 提取字段 - 订单号（用于去重判断）
		if idx, ok := colIdx["交易订单号"]; ok && len(row) > idx {
			bill.TransactionID = strings.TrimSpace(row[idx])
		} else if idx, ok := colIdx["交易单号"]; ok && len(row) > idx {
			bill.TransactionID = strings.TrimSpace(row[idx])
		}
		if idx, ok := colIdx["商家订单号"]; ok && len(row) > idx {
			bill.MerchantOrderNo = strings.TrimSpace(row[idx])
		} else if idx, ok := colIdx["商户单号"]; ok && len(row) > idx {
			bill.MerchantOrderNo = strings.TrimSpace(row[idx])
		}
		if idx, ok := colIdx["交易时间"]; ok && len(row) > idx {
			bill.Time = parseTime(row[idx])
		}
		if idx, ok := colIdx["交易分类"]; ok && len(row) > idx {
			bill.Category = row[idx]
		} else if idx, ok := colIdx["交易类型"]; ok && len(row) > idx {
			bill.Category = row[idx]
		}
		if idx, ok := colIdx["交易对方"]; ok && len(row) > idx {
			bill.Merchant = row[idx]
		}
		if idx, ok := colIdx["商品说明"]; ok && len(row) > idx {
			bill.Description = row[idx]
		} else if idx, ok := colIdx["商品"]; ok && len(row) > idx {
			bill.Description = row[idx]
		}
		if idx, ok := colIdx["收/支"]; ok && len(row) > idx {
			bill.IncomeExpense = row[idx]
		}
		if idx, ok := colIdx["金额"]; ok && len(row) > idx {
			bill.Amount = parseAmount(row[idx])
		} else if idx, ok := colIdx["金额(元)"]; ok && len(row) > idx {
			bill.Amount = parseAmount(row[idx])
		}
		if idx, ok := colIdx["收/付款方式"]; ok && len(row) > idx {
			bill.PayMethod = row[idx]
		} else if idx, ok := colIdx["支付方式"]; ok && len(row) > idx {
			bill.PayMethod = row[idx]
		}
		if idx, ok := colIdx["交易状态"]; ok && len(row) > idx {
			bill.Status = row[idx]
		} else if idx, ok := colIdx["当前状态"]; ok && len(row) > idx {
			bill.Status = row[idx]
		}
		if idx, ok := colIdx["备注"]; ok && len(row) > idx {
			bill.Remark = row[idx]
		}
		if idx, ok := colIdx["复核等级"]; ok && len(row) > idx {
			bill.ReviewLevel = row[idx]
		}

		// 检查是否重复
		if checkDuplicate(ctx, &bill) {
			duplicateCount++
			continue // 跳过重复记录
		}

		bills = append(bills, bill)
	}

	if len(bills) == 0 {
		return 0, duplicateCount, nil
	}

	// 批量插入清洗后数据集合
	result, err := database.CleanedBillCollection.InsertMany(ctx, bills)
	if err != nil {
		return 0, duplicateCount, fmt.Errorf("插入清洗后数据失败: %w", err)
	}

	return len(result.InsertedIDs), duplicateCount, nil
}

// saveCleanedBillsFromJSON 从 JSON 文件读取并存储清洗后账单
// 返回: (插入数量, 重复跳过数量, 错误)
func saveCleanedBillsFromJSON(filePath, billType, sourceFile, uploadBatch string) (int, int, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return 0, 0, fmt.Errorf("打开文件失败: %w", err)
	}
	defer file.Close()

	var data []map[string]interface{}
	decoder := json.NewDecoder(file)
	if err := decoder.Decode(&data); err != nil {
		return 0, 0, fmt.Errorf("解析 JSON 失败: %w", err)
	}

	if len(data) == 0 {
		return 0, 0, nil
	}

	// 创建上下文用于去重检查
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()

	// 解析数据
	var bills []interface{}
	duplicateCount := 0
	now := time.Now()

	for _, item := range data {
		bill := model.CleanedBill{
			BillType:    billType,
			SourceFile:  sourceFile,
			UploadBatch: uploadBatch,
			CreatedAt:   now,
			UpdatedAt:   now,
		}

		// 订单号（用于去重判断）
		if v, ok := item["交易订单号"].(string); ok {
			bill.TransactionID = strings.TrimSpace(v)
		} else if v, ok := item["交易号"].(string); ok {
			bill.TransactionID = strings.TrimSpace(v)
		}
		if v, ok := item["商家订单号"].(string); ok {
			bill.MerchantOrderNo = strings.TrimSpace(v)
		} else if v, ok := item["商户单号"].(string); ok {
			bill.MerchantOrderNo = strings.TrimSpace(v)
		}
		if v, ok := item["交易时间"].(string); ok {
			bill.Time = parseTime(v)
		}
		if v, ok := item["交易分类"].(string); ok {
			bill.Category = v
		}
		if v, ok := item["交易对方"].(string); ok {
			bill.Merchant = v
		}
		if v, ok := item["商品说明"].(string); ok {
			bill.Description = v
		}
		if v, ok := item["收/支"].(string); ok {
			bill.IncomeExpense = v
		}
		if v, ok := item["金额"]; ok {
			switch val := v.(type) {
			case string:
				bill.Amount = parseAmount(val)
			case float64:
				bill.Amount = val
			}
		}
		if v, ok := item["支付方式"].(string); ok {
			bill.PayMethod = v
		}
		if v, ok := item["交易状态"].(string); ok {
			bill.Status = v
		}
		if v, ok := item["备注"].(string); ok {
			bill.Remark = v
		}
		if v, ok := item["复核等级"].(string); ok {
			bill.ReviewLevel = v
		}

		// 检查是否重复
		if checkDuplicate(ctx, &bill) {
			duplicateCount++
			continue // 跳过重复记录
		}

		bills = append(bills, bill)
	}

	if len(bills) == 0 {
		return 0, duplicateCount, nil
	}

	result, err := database.CleanedBillCollection.InsertMany(ctx, bills)
	if err != nil {
		return 0, duplicateCount, fmt.Errorf("插入清洗后数据失败: %w", err)
	}

	return len(result.InsertedIDs), duplicateCount, nil
}

// parseTime 解析时间字符串
// 使用本地时区解析，返回 model.LocalTime 类型
// 支持支付宝格式: 2026/1/13 20:08 (月份和日期可能没有前导零)
func parseTime(s string) model.LocalTime {
	s = strings.TrimSpace(s)
	if s == "" {
		return model.LocalTime(time.Time{})
	}

	// 先尝试标准化支付宝格式（将单数日期/月份补零）
	// 例如: "2026/1/13 20:08" -> "2026/01/13 20:08"
	if strings.Contains(s, "/") && !strings.Contains(s, "-") {
		// 匹配格式: YYYY/M/D 或 YYYY/M/D HH:mm 或 YYYY/M/D HH:mm:ss
		parts := strings.Split(s, " ")
		if len(parts) > 0 {
			datePart := parts[0]
			// 使用正则表达式将单数日期/月份补零
			// 例如: "2026/1/13" -> "2026/01/13"
			dateParts := strings.Split(datePart, "/")
			if len(dateParts) == 3 {
				year := dateParts[0]
				month := dateParts[1]
				day := dateParts[2]
				// 补零
				if len(month) == 1 {
					month = "0" + month
				}
				if len(day) == 1 {
					day = "0" + day
				}
				datePart = year + "/" + month + "/" + day
				if len(parts) > 1 {
					s = datePart + " " + strings.Join(parts[1:], " ")
				} else {
					s = datePart
				}
			}
		}
	}

	// 尝试多种时间格式（使用本地时区）
	formats := []string{
		"2006-01-02 15:04:05",
		"2006/01/02 15:04:05",
		"2006-01-02 15:04",
		"2006/01/02 15:04",
		"2006-01-02",
		"2006/01/02",
	}

	for _, format := range formats {
		if t, err := time.ParseInLocation(format, s, time.Local); err == nil {
			return model.LocalTime(t)
		}
	}

	return model.LocalTime(time.Time{})
}

// parseAmount 解析金额字符串
func parseAmount(s string) float64 {
	s = strings.TrimSpace(s)
	s = strings.ReplaceAll(s, ",", "")
	s = strings.ReplaceAll(s, "¥", "")
	s = strings.ReplaceAll(s, "￥", "")

	if amount, err := strconv.ParseFloat(s, 64); err == nil {
		return amount
	}
	return 0
}

// GetCleanedBillsByBatch 根据批次获取清洗后账单
func GetCleanedBillsByBatch(uploadBatch string) ([]model.CleanedBill, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	cursor, err := database.CleanedBillCollection.Find(ctx, bson.M{"upload_batch": uploadBatch})
	if err != nil {
		return nil, fmt.Errorf("查询失败: %w", err)
	}
	defer cursor.Close(ctx)

	var bills []model.CleanedBill
	if err := cursor.All(ctx, &bills); err != nil {
		return nil, fmt.Errorf("解析结果失败: %w", err)
	}

	return bills, nil
}

// GetRawBillsByBatch 根据批次获取原始账单
func GetRawBillsByBatch(uploadBatch string) ([]model.RawBill, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	cursor, err := database.RawBillCollection.Find(ctx, bson.M{"upload_batch": uploadBatch})
	if err != nil {
		return nil, fmt.Errorf("查询失败: %w", err)
	}
	defer cursor.Close(ctx)

	var bills []model.RawBill
	if err := cursor.All(ctx, &bills); err != nil {
		return nil, fmt.Errorf("解析结果失败: %w", err)
	}

	return bills, nil
}

// GetBillStats 获取账单统计信息
func GetBillStats() (map[string]interface{}, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	// 原始数据总数
	rawTotal, err := database.RawBillCollection.CountDocuments(ctx, bson.M{})
	if err != nil {
		return nil, err
	}

	// 清洗后数据总数
	cleanedTotal, err := database.CleanedBillCollection.CountDocuments(ctx, bson.M{})
	if err != nil {
		return nil, err
	}

	// 支出总额（从清洗后数据统计）
	expensePipeline := []bson.M{
		{"$match": bson.M{"income_expense": "支出"}},
		{"$group": bson.M{"_id": nil, "total": bson.M{"$sum": "$amount"}}},
	}
	expenseCursor, err := database.CleanedBillCollection.Aggregate(ctx, expensePipeline)
	if err != nil {
		return nil, err
	}
	defer expenseCursor.Close(ctx)

	var expenseResult []bson.M
	expenseCursor.All(ctx, &expenseResult)
	totalExpense := 0.0
	if len(expenseResult) > 0 {
		if v, ok := expenseResult[0]["total"].(float64); ok {
			totalExpense = v
		}
	}

	// 收入总额（从清洗后数据统计）
	incomePipeline := []bson.M{
		{"$match": bson.M{"income_expense": "收入"}},
		{"$group": bson.M{"_id": nil, "total": bson.M{"$sum": "$amount"}}},
	}
	incomeCursor, err := database.CleanedBillCollection.Aggregate(ctx, incomePipeline)
	if err != nil {
		return nil, err
	}
	defer incomeCursor.Close(ctx)

	var incomeResult []bson.M
	incomeCursor.All(ctx, &incomeResult)
	totalIncome := 0.0
	if len(incomeResult) > 0 {
		if v, ok := incomeResult[0]["total"].(float64); ok {
			totalIncome = v
		}
	}

	return map[string]interface{}{
		"raw_records":     rawTotal,
		"cleaned_records": cleanedTotal,
		"total_expense":   totalExpense,
		"total_income":    totalIncome,
	}, nil
}