package repository

import (
	"errors"
	"time"

	"gorm.io/gorm"

	"nex/backend/internal/config"
	"nex/backend/internal/domain"
)

type statsRepository struct {
	db *gorm.DB
}

func NewStatsRepository(db *gorm.DB) StatsRepository {
	return &statsRepository{db: db}
}

func (r *statsRepository) Record(providerID, modelName string) error {
	today := time.Now().Format("2006-01-02")
	todayTime, _ := time.Parse("2006-01-02", today)

	return r.db.Transaction(func(tx *gorm.DB) error {
		var stats config.UsageStats
		err := tx.Where("provider_id = ? AND model_name = ? AND date = ?",
			providerID, modelName, todayTime).First(&stats).Error

		if errors.Is(err, gorm.ErrRecordNotFound) {
			stats = config.UsageStats{
				ProviderID:   providerID,
				ModelName:    modelName,
				RequestCount: 1,
				Date:         todayTime,
			}
			return tx.Create(&stats).Error
		} else if err != nil {
			return err
		}

		return tx.Model(&stats).Update("request_count", gorm.Expr("request_count + 1")).Error
	})
}

func (r *statsRepository) Query(providerID, modelName string, startDate, endDate *time.Time) ([]domain.UsageStats, error) {
	var stats []config.UsageStats
	query := r.db.Model(&config.UsageStats{})

	if providerID != "" {
		query = query.Where("provider_id = ?", providerID)
	}
	if modelName != "" {
		query = query.Where("model_name = ?", modelName)
	}
	if startDate != nil {
		query = query.Where("date >= ?", startDate)
	}
	if endDate != nil {
		query = query.Where("date <= ?", endDate)
	}

	err := query.Order("date DESC").Find(&stats).Error
	if err != nil {
		return nil, err
	}

	result := make([]domain.UsageStats, len(stats))
	for i := range stats {
		result[i] = domain.UsageStats{
			ID:           stats[i].ID,
			ProviderID:   stats[i].ProviderID,
			ModelName:    stats[i].ModelName,
			RequestCount: stats[i].RequestCount,
			Date:         stats[i].Date,
		}
	}
	return result, nil
}