// Package mongo 实现基于 MongoDB 的账单存储
package mongo

import (
	"context"
	"fmt"
	"time"

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

	"billai-server/config"
	"billai-server/model"
	"billai-server/repository"
)

// Repository MongoDB 账单存储实现
type Repository struct {
	client            *mongo.Client
	db                *mongo.Database
	rawCollection     *mongo.Collection
	cleanedCollection *mongo.Collection
}

// NewRepository 创建 MongoDB 存储实例
func NewRepository() *Repository {
	return &Repository{}
}

// Connect 连接 MongoDB
func (r *Repository) Connect() error {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	// 创建客户端选项
	clientOptions := options.Client().ApplyURI(config.Global.MongoURI)

	// 连接 MongoDB
	client, err := mongo.Connect(ctx, clientOptions)
	if err != nil {
		return fmt.Errorf("连接 MongoDB 失败: %w", err)
	}

	// 测试连接
	if err := client.Ping(ctx, nil); err != nil {
		return fmt.Errorf("MongoDB Ping 失败: %w", err)
	}

	// 设置实例变量
	r.client = client
	r.db = client.Database(config.Global.MongoDatabase)
	r.rawCollection = r.db.Collection(config.Global.MongoRawCollection)
	r.cleanedCollection = r.db.Collection(config.Global.MongoCleanedCollection)

	fmt.Printf("🍃 MongoDB 连接成功: %s\n", config.Global.MongoDatabase)
	fmt.Printf("   📄 原始数据集合: %s\n", config.Global.MongoRawCollection)
	fmt.Printf("   📄 清洗数据集合: %s\n", config.Global.MongoCleanedCollection)
	return nil
}

// Disconnect 断开 MongoDB 连接
func (r *Repository) Disconnect() error {
	if r.client == nil {
		return nil
	}

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := r.client.Disconnect(ctx); err != nil {
		return fmt.Errorf("断开 MongoDB 连接失败: %w", err)
	}

	fmt.Println("🍃 MongoDB 连接已断开")
	return nil
}

// SaveRawBills 保存原始账单数据
func (r *Repository) SaveRawBills(bills []model.RawBill) (int, error) {
	if len(bills) == 0 {
		return 0, nil
	}

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 转换为 interface{} 切片
	docs := make([]interface{}, len(bills))
	for i, bill := range bills {
		docs[i] = bill
	}

	result, err := r.rawCollection.InsertMany(ctx, docs)
	if err != nil {
		return 0, fmt.Errorf("插入原始账单失败: %w", err)
	}

	return len(result.InsertedIDs), nil
}

// SaveCleanedBills 保存清洗后的账单数据（带去重）
func (r *Repository) SaveCleanedBills(bills []model.CleanedBill) (saved int, duplicates int, err error) {
	if len(bills) == 0 {
		return 0, 0, nil
	}

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	for _, bill := range bills {
		// 检查是否重复
		isDup, err := r.CheckCleanedDuplicate(&bill)
		if err != nil {
			return saved, duplicates, err
		}
		if isDup {
			duplicates++
			continue
		}

		// 插入新记录
		_, err = r.cleanedCollection.InsertOne(ctx, bill)
		if err != nil {
			return saved, duplicates, fmt.Errorf("插入清洗后账单失败: %w", err)
		}
		saved++
	}

	return saved, duplicates, nil
}

// CheckRawDuplicate 检查原始数据是否重复
func (r *Repository) CheckRawDuplicate(fieldName, value string) (bool, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	filter := bson.M{"raw_data." + fieldName: value}
	count, err := r.rawCollection.CountDocuments(ctx, filter)
	if err != nil {
		return false, err
	}

	return count > 0, nil
}

// CheckCleanedDuplicate 检查清洗后数据是否重复
func (r *Repository) CheckCleanedDuplicate(bill *model.CleanedBill) (bool, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	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 := r.cleanedCollection.CountDocuments(ctx, filter)
	if err != nil {
		return false, err
	}

	return count > 0, nil
}

// CountRawByField 按字段统计原始数据数量
func (r *Repository) CountRawByField(fieldName, value string) (int64, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	filter := bson.M{"raw_data." + fieldName: value}
	return r.rawCollection.CountDocuments(ctx, filter)
}

// GetCleanedBills 获取清洗后的账单列表
func (r *Repository) GetCleanedBills(filter map[string]interface{}) ([]model.CleanedBill, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 转换 filter
	bsonFilter := bson.M{}
	for k, v := range filter {
		bsonFilter[k] = v
	}

	// 按时间倒序排列
	opts := options.Find().SetSort(bson.D{{Key: "time", Value: -1}})

	cursor, err := r.cleanedCollection.Find(ctx, bsonFilter, opts)
	if err != nil {
		return nil, fmt.Errorf("查询账单失败: %w", err)
	}
	defer cursor.Close(ctx)

	var bills []model.CleanedBill
	if err := cursor.All(ctx, &bills); err != nil {
		return nil, fmt.Errorf("解析账单数据失败: %w", err)
	}

	return bills, nil
}

// GetCleanedBillsPaged 获取清洗后的账单列表（带分页）
func (r *Repository) GetCleanedBillsPaged(filter map[string]interface{}, page, pageSize int) ([]model.CleanedBill, int64, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 转换 filter
	bsonFilter := bson.M{}
	for k, v := range filter {
		bsonFilter[k] = v
	}

	// 计算总数
	total, err := r.cleanedCollection.CountDocuments(ctx, bsonFilter)
	if err != nil {
		return nil, 0, fmt.Errorf("统计账单数量失败: %w", err)
	}

	// 计算跳过数量
	skip := int64((page - 1) * pageSize)

	// 查询选项：分页 + 按时间倒序
	opts := options.Find().
		SetSort(bson.D{{Key: "time", Value: -1}}).
		SetSkip(skip).
		SetLimit(int64(pageSize))

	cursor, err := r.cleanedCollection.Find(ctx, bsonFilter, opts)
	if err != nil {
		return nil, 0, fmt.Errorf("查询账单失败: %w", err)
	}
	defer cursor.Close(ctx)

	var bills []model.CleanedBill
	if err := cursor.All(ctx, &bills); err != nil {
		return nil, 0, fmt.Errorf("解析账单数据失败: %w", err)
	}

	return bills, total, nil
}

// GetBillsAggregate 获取账单聚合统计（总收入、总支出）
func (r *Repository) GetBillsAggregate(filter map[string]interface{}) (totalExpense float64, totalIncome float64, err error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 转换 filter
	bsonFilter := bson.M{}
	for k, v := range filter {
		bsonFilter[k] = v
	}

	// 使用聚合管道按 income_expense 分组统计金额
	pipeline := mongo.Pipeline{
		{{Key: "$match", Value: bsonFilter}},
		{{Key: "$group", Value: bson.D{
			{Key: "_id", Value: "$income_expense"},
			{Key: "total", Value: bson.D{{Key: "$sum", Value: "$amount"}}},
		}}},
	}

	cursor, err := r.cleanedCollection.Aggregate(ctx, pipeline)
	if err != nil {
		return 0, 0, fmt.Errorf("聚合统计失败: %w", err)
	}
	defer cursor.Close(ctx)

	// 解析结果
	var results []struct {
		ID    string  `bson:"_id"`
		Total float64 `bson:"total"`
	}
	if err := cursor.All(ctx, &results); err != nil {
		return 0, 0, fmt.Errorf("解析聚合结果失败: %w", err)
	}

	for _, result := range results {
		switch result.ID {
		case "支出":
			totalExpense = result.Total
		case "收入":
			totalIncome = result.Total
		}
	}

	return totalExpense, totalIncome, nil
}

// GetBillsNeedReview 获取需要复核的账单
func (r *Repository) GetBillsNeedReview() ([]model.CleanedBill, error) {
	filter := map[string]interface{}{
		"review_level": bson.M{"$in": []string{"HIGH", "LOW"}},
	}
	return r.GetCleanedBills(filter)
}

// GetMonthlyStats 获取月度统计（全部数据，不受筛选条件影响）
func (r *Repository) GetMonthlyStats() ([]model.MonthlyStat, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// 使用聚合管道按月份分组统计
	// 先按月份和收支类型分组，再汇总
	pipeline := mongo.Pipeline{
		// 添加月份字段
		{{Key: "$addFields", Value: bson.D{
			{Key: "month", Value: bson.D{
				{Key: "$dateToString", Value: bson.D{
					{Key: "format", Value: "%Y-%m"},
					{Key: "date", Value: "$time"},
				}},
			}},
		}}},
		// 按月份和收支类型分组
		{{Key: "$group", Value: bson.D{
			{Key: "_id", Value: bson.D{
				{Key: "month", Value: "$month"},
				{Key: "income_expense", Value: "$income_expense"},
			}},
			{Key: "total", Value: bson.D{{Key: "$sum", Value: "$amount"}}},
		}}},
		// 按月份重新分组，汇总收入和支出
		{{Key: "$group", Value: bson.D{
			{Key: "_id", Value: "$_id.month"},
			{Key: "expense", Value: bson.D{
				{Key: "$sum", Value: bson.D{
					{Key: "$cond", Value: bson.A{
						bson.D{{Key: "$eq", Value: bson.A{"$_id.income_expense", "支出"}}},
						"$total",
						0,
					}},
				}},
			}},
			{Key: "income", Value: bson.D{
				{Key: "$sum", Value: bson.D{
					{Key: "$cond", Value: bson.A{
						bson.D{{Key: "$eq", Value: bson.A{"$_id.income_expense", "收入"}}},
						"$total",
						0,
					}},
				}},
			}},
		}}},
		// 按月份排序
		{{Key: "$sort", Value: bson.D{{Key: "_id", Value: 1}}}},
	}

	cursor, err := r.cleanedCollection.Aggregate(ctx, pipeline)
	if err != nil {
		return nil, fmt.Errorf("月度统计聚合失败: %w", err)
	}
	defer cursor.Close(ctx)

	// 解析结果
	var results []struct {
		Month   string  `bson:"_id"`
		Expense float64 `bson:"expense"`
		Income  float64 `bson:"income"`
	}
	if err := cursor.All(ctx, &results); err != nil {
		return nil, fmt.Errorf("解析月度统计结果失败: %w", err)
	}

	// 转换为 MonthlyStat
	stats := make([]model.MonthlyStat, len(results))
	for i, r := range results {
		stats[i] = model.MonthlyStat{
			Month:   r.Month,
			Expense: r.Expense,
			Income:  r.Income,
		}
	}

	return stats, nil
}

// GetClient 获取 MongoDB 客户端（用于兼容旧代码）
func (r *Repository) GetClient() *mongo.Client {
	return r.client
}

// GetDB 获取数据库实例（用于兼容旧代码）
func (r *Repository) GetDB() *mongo.Database {
	return r.db
}

// GetRawCollection 获取原始数据集合（用于兼容旧代码）
func (r *Repository) GetRawCollection() *mongo.Collection {
	return r.rawCollection
}

// GetCleanedCollection 获取清洗后数据集合（用于兼容旧代码）
func (r *Repository) GetCleanedCollection() *mongo.Collection {
	return r.cleanedCollection
}

// 确保 Repository 实现了 repository.BillRepository 接口
var _ repository.BillRepository = (*Repository)(nil)