package persistence

import (
	domain "RenewCMS/internal/domain/image"
	entity "RenewCMS/internal/infrastructure/persistence/models"
	"time"

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

type VariantUsageRepository struct {
	db *gorm.DB
}

var _ domain.VariantUsageRepository = &VariantUsageRepository{}

func NewVariantUsageRepository(db *gorm.DB) *VariantUsageRepository {
	return &VariantUsageRepository{db}
}

func (v *VariantUsageRepository) Record(batch domain.VariantUsageBatch) error {
	return v.db.Transaction(func(tx *gorm.DB) error {
		for _, hit := range batch.Hits {
			if err := recordHit(tx, hit); err != nil {
				return err
			}
		}
		for _, rejection := range batch.Rejections {
			if err := recordRejections(tx, rejection); err != nil {
				return err
			}
		}
		if batch.PruneBefore.IsZero() {
			return nil
		}
		return tx.Where("day < ?", batch.PruneBefore.UTC().Format(domain.RejectionDayLayout)).Delete(&entity.ImageVariantRejectionDay{}).Error
	})
}

func recordHit(tx *gorm.DB, hit domain.VariantHit) error {
	at := hit.At.UTC()
	query := tx.Model(&entity.ImageVariantFile{})
	query = query.Where("variant_name = ? AND source_name = ?", hit.VariantName, hit.SourceName)
	query = query.Where("last_requested_at IS NULL OR last_requested_at < ?", at)
	return query.Update("last_requested_at", at).Error
}

func recordRejections(tx *gorm.DB, rejection domain.RejectionCount) error {
	row := entity.ImageVariantRejectionDay{Day: rejection.Day.UTC().Format(domain.RejectionDayLayout), Count: rejection.Count}
	return tx.Clauses(clause.OnConflict{
		Columns:   []clause.Column{{Name: "day"}},
		DoUpdates: clause.Assignments(map[string]any{"count": gorm.Expr("? + ?", clause.Column{Table: clause.CurrentTable, Name: "count"}, rejection.Count)}),
	}).Create(&row).Error
}

func (v *VariantUsageRepository) RejectedSince(day time.Time) (int, error) {
	var total int
	query := v.db.Model(&entity.ImageVariantRejectionDay{})
	query = query.Select("COALESCE(SUM(count), 0)")
	query = query.Where("day >= ?", day.UTC().Format(domain.RejectionDayLayout))
	err := query.Scan(&total).Error
	return total, err
}