package dao

import (
	"context"
	"fmt"
	dto "opencatd-open/internal/dto/team"
	"opencatd-open/internal/model"
	"opencatd-open/pkg/config"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

var _ UsageRepository = (*UsageDAO)(nil)
var _ DailyUsageRepository = (*DailyUsageDAO)(nil)

type UsageRepository interface {
	// Create
	Create(ctx context.Context, usage *model.Usage) error
	BatchCreate(ctx context.Context, usages []*model.Usage) error

	// Read
	ListByUserID(ctx context.Context, userID int64, limit, offset int) ([]*model.Usage, error)
	ListByTokenID(ctx context.Context, tokenID int64, limit, offset int) ([]*model.Usage, error)
	ListByDateRange(ctx context.Context, start, end time.Time) ([]*model.Usage, error)
	ListByCapability(ctx context.Context, capability string, limit, offset int) ([]*model.Usage, error)

	// Delete
	Delete(ctx context.Context, id int64) error

	// Statistics
	CountByUserID(ctx context.Context, userID int64) (int64, error)
}

type DailyUsageRepository interface {
	// Create
	Create(ctx context.Context, usage *model.DailyUsage) error
	BatchCreate(ctx context.Context, usages []*model.DailyUsage) error

	// Read
	ListByUserID(ctx context.Context, userID int64, limit, offset int) ([]*model.DailyUsage, error)
	ListByTokenID(ctx context.Context, tokenID int64, limit, offset int) ([]*model.DailyUsage, error)
	ListByDateRange(ctx context.Context, start, end time.Time) ([]*model.DailyUsage, error)
	GetByDate(ctx context.Context, userID int64, date time.Time) (*model.DailyUsage, error)

	// Delete
	Delete(ctx context.Context, id int64) error

	// Statistics
	CountByUserID(ctx context.Context, userID int64) (int64, error)
	StatUserUsages(ctx context.Context, start, end time.Time, filters map[string]interface{}) ([]*dto.UsageInfo, error)
}

type UsageDAO struct {
	db *gorm.DB
}

type DailyUsageDAO struct {
	cfg *config.Config
	db  *gorm.DB
}

func NewUsageDAO(cfg *config.Config, db *gorm.DB) *UsageDAO {
	return &UsageDAO{db: db}
}

func NewDailyUsageDAO(cfg *config.Config, db *gorm.DB) *DailyUsageDAO {
	return &DailyUsageDAO{db: db}
}

// Usage DAO implementations
func (d *UsageDAO) Create(ctx context.Context, usage *model.Usage) error {
	return d.db.WithContext(ctx).Create(usage).Error
}

func (d *UsageDAO) BatchCreate(ctx context.Context, usages []*model.Usage) error {
	return d.db.WithContext(ctx).Create(usages).Error
}

func (d *UsageDAO) GetByID(ctx context.Context, id int64) (*model.Usage, error) {
	var usage model.Usage
	err := d.db.WithContext(ctx).First(&usage, id).Error
	if err != nil {
		return nil, err
	}
	return &usage, nil
}

func (d *UsageDAO) ListByUserID(ctx context.Context, userID int64, limit, offset int) ([]*model.Usage, error) {
	var usages []*model.Usage
	err := d.db.WithContext(ctx).
		Where("user_id = ?", userID).
		Limit(limit).
		Offset(offset).
		Find(&usages).Error
	return usages, err
}

func (d *UsageDAO) ListByTokenID(ctx context.Context, tokenID int64, limit, offset int) ([]*model.Usage, error) {
	var usages []*model.Usage
	err := d.db.WithContext(ctx).
		Where("token_id = ?", tokenID).
		Limit(limit).
		Offset(offset).
		Find(&usages).Error
	return usages, err
}

func (d *UsageDAO) ListByDateRange(ctx context.Context, start, end time.Time) ([]*model.Usage, error) {
	var usages []*model.Usage
	err := d.db.WithContext(ctx).
		Where("date BETWEEN ? AND ?", start, end).
		Find(&usages).Error
	return usages, err
}

func (d *UsageDAO) ListByCapability(ctx context.Context, capability string, limit, offset int) ([]*model.Usage, error) {
	var usages []*model.Usage
	err := d.db.WithContext(ctx).
		Where("capability = ?", capability).
		Limit(limit).
		Offset(offset).
		Find(&usages).Error
	return usages, err
}

func (d *UsageDAO) Delete(ctx context.Context, id int64) error {
	return d.db.WithContext(ctx).Delete(&model.Usage{}, id).Error
}

func (d *UsageDAO) CountByUserID(ctx context.Context, userID int64) (int64, error) {
	var count int64
	err := d.db.WithContext(ctx).Model(&model.Usage{}).Where("user_id = ?", userID).Count(&count).Error
	return count, err
}

// DailyUsage DAO implementations
func (d *DailyUsageDAO) Create(ctx context.Context, usage *model.DailyUsage) error {
	return d.db.WithContext(ctx).Create(usage).Error
}

func (d *DailyUsageDAO) BatchCreate(ctx context.Context, usages []*model.DailyUsage) error {
	return d.db.WithContext(ctx).Create(usages).Error
}

func (d *DailyUsageDAO) ListByUserID(ctx context.Context, userID int64, limit, offset int) ([]*model.DailyUsage, error) {
	var usages []*model.DailyUsage
	err := d.db.WithContext(ctx).
		Where("user_id = ?", userID).
		Limit(limit).
		Offset(offset).
		Find(&usages).Error
	return usages, err
}

func (d *DailyUsageDAO) ListByTokenID(ctx context.Context, tokenID int64, limit, offset int) ([]*model.DailyUsage, error) {
	var usages []*model.DailyUsage
	err := d.db.WithContext(ctx).
		Where("token_id = ?", tokenID).
		Limit(limit).
		Offset(offset).
		Find(&usages).Error
	return usages, err
}

func (d *DailyUsageDAO) ListByDateRange(ctx context.Context, start, end time.Time) ([]*model.DailyUsage, error) {
	var usages []*model.DailyUsage
	err := d.db.WithContext(ctx).
		Where("date BETWEEN ? AND ?", start, end).
		Find(&usages).Error
	return usages, err
}

func (d *DailyUsageDAO) GetByDate(ctx context.Context, userID int64, date time.Time) (*model.DailyUsage, error) {
	var usage model.DailyUsage
	err := d.db.WithContext(ctx).
		Where("user_id = ? AND date = ?", userID, date).
		First(&usage).Error
	if err != nil {
		return nil, err
	}
	return &usage, nil
}

// UpsertDailyUsage 根据不同数据库类型执行 Upsert
func (d *DailyUsageDAO) UpsertDailyUsage(ctx context.Context, usage *model.Usage) error {
	date := usage.Date.Truncate(24 * time.Hour)
	dailyUsage := &model.DailyUsage{
		UserID:           usage.UserID,
		TokenID:          usage.TokenID,
		Capability:       usage.Capability,
		Model:            usage.Model,
		Stream:           usage.Stream,
		PromptTokens:     usage.PromptTokens,
		CompletionTokens: usage.CompletionTokens,
		TotalTokens:      usage.TotalTokens,
		Cost:             usage.Cost,
	}

	updateColumns := map[string]interface{}{
		"prompt_tokens":     gorm.Expr("prompt_tokens + VALUES(prompt_tokens)"),
		"completion_tokens": gorm.Expr("completion_tokens + VALUES(completion_tokens)"),
		"total_tokens":      gorm.Expr("total_tokens + VALUES(total_tokens)"),
	}

	db := d.db.WithContext(ctx)

	switch d.cfg.DB_Type {
	case "mysql":
		// MySQL: INSERT ... ON DUPLICATE KEY UPDATE
		return db.Clauses(clause.OnConflict{
			Columns: []clause.Column{
				{Name: "user_id"},
				{Name: "date"},
			},
			DoUpdates: clause.Assignments(updateColumns),
		}).Create(dailyUsage).Error

	case "postgres":
		// PostgreSQL: INSERT ... ON CONFLICT DO UPDATE
		updateColumns := map[string]interface{}{
			"prompt_tokens":     gorm.Expr("daily_usages.prompt_tokens + EXCLUDED.prompt_tokens"),
			"completion_tokens": gorm.Expr("daily_usages.completion_tokens + EXCLUDED.completion_tokens"),
			"total_tokens":      gorm.Expr("daily_usages.total_tokens + EXCLUDED.total_tokens"),
		}
		return db.Clauses(clause.OnConflict{
			Columns: []clause.Column{
				{Name: "user_id"},
				{Name: "date"},
			},
			DoUpdates: clause.Assignments(updateColumns),
		}).Create(dailyUsage).Error
	case "sqlite":
		fallthrough
	default:
		return db.Transaction(func(tx *gorm.DB) error {
			var existing model.DailyUsage
			err := tx.Where("user_id = ? AND date = ?",
				usage.UserID, date).
				First(&existing).Error

			if err == gorm.ErrRecordNotFound {
				// 记录不存在，创建新记录
				return tx.Create(dailyUsage).Error
			} else if err != nil {
				return err // 返回其他错误
			}

			// 记录存在，更新
			return tx.Model(&existing).Updates(map[string]interface{}{
				"prompt_tokens":     gorm.Expr("prompt_tokens + ?", usage.PromptTokens),
				"completion_tokens": gorm.Expr("completion_tokens + ?", usage.CompletionTokens),
				"total_tokens":      gorm.Expr("total_tokens + ?", usage.TotalTokens),
			}).Error
		})
	}
}

func (d *DailyUsageDAO) Delete(ctx context.Context, id int64) error {
	return d.db.WithContext(ctx).Delete(&model.DailyUsage{}, id).Error
}

func (d *DailyUsageDAO) CountByUserID(ctx context.Context, userID int64) (int64, error) {
	var count int64
	err := d.db.WithContext(ctx).Model(&model.DailyUsage{}).Where("user_id = ?", userID).Count(&count).Error
	return count, err
}

func (d *DailyUsageDAO) StatUserUsages(ctx context.Context, from, to time.Time, filters map[string]interface{}) ([]*dto.UsageInfo, error) {
	var usages []*dto.UsageInfo

	query := d.db.WithContext(ctx).
		Model(&model.DailyUsage{}).
		Select("user_id as userId, sum(total_tokens) as totalUnit, sum(cast(cost as decimal(20,6))) as cost")
	for key, value := range filters {
		query = query.Where(fmt.Sprintf("%s = ?", key), value)
	}
	query = query.Group("user_id").Where("date >= ? AND date <= ?", from, to)

	err := query.Group("user_id").Find(&usages).Error
	if err != nil {
		return nil, fmt.Errorf("failed to list usages: %w", err)
	}

	return usages, nil
}