package persistence

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

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

type VariantFileRepository struct {
	db *gorm.DB
}

var _ domain.VariantFileRepository = &VariantFileRepository{}
var _ domain.VariantCacheRepository = &VariantFileRepository{}

func NewVariantFileRepository(db *gorm.DB) *VariantFileRepository {
	return &VariantFileRepository{db}
}

func (v *VariantFileRepository) Find(variantName string, sourceName string) (domain.VariantFile, bool, error) {
	var model entity.ImageVariantFile
	err := v.db.Where("variant_name = ? AND source_name = ?", variantName, sourceName).First(&model).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return domain.VariantFile{}, false, nil
	}
	if err != nil {
		return domain.VariantFile{}, false, err
	}
	return mappers.VariantFileToDomain(model), true, nil
}

func (v *VariantFileRepository) Save(file domain.VariantFile) (domain.VariantFile, error) {
	model := mappers.VariantFileToModel(file)
	model.ID = 0
	err := v.db.Clauses(clause.OnConflict{
		Columns:   []clause.Column{{Name: "variant_name"}, {Name: "source_name"}},
		DoUpdates: clause.AssignmentColumns([]string{"cached_name", "content_type", "size", "fingerprint"}),
	}).Create(&model).Error
	if err != nil {
		return domain.VariantFile{}, err
	}
	saved, _, err := v.Find(file.VariantName, file.SourceName)
	return saved, err
}

func (v *VariantFileRepository) ListByVariant(variantName string) ([]domain.VariantFile, error) {
	return v.list("variant_name = ?", variantName)
}

func (v *VariantFileRepository) ListBySource(sourceName string) ([]domain.VariantFile, error) {
	return v.list("source_name = ?", sourceName)
}

func (v *VariantFileRepository) list(condition string, value string) ([]domain.VariantFile, error) {
	var found []entity.ImageVariantFile
	if err := v.db.Where(condition, value).Order("id asc").Find(&found).Error; err != nil {
		return nil, err
	}
	files := make([]domain.VariantFile, 0, len(found))
	for _, model := range found {
		files = append(files, mappers.VariantFileToDomain(model))
	}
	return files, nil
}

func (v *VariantFileRepository) Delete(id uint32) error {
	return v.db.Delete(&entity.ImageVariantFile{}, id).Error
}

func (v *VariantFileRepository) TotalsBySource() (map[string]domain.VariantFileTotals, error) {
	var rows []struct {
		SourceName string
		Files      int
		Bytes      int64
	}
	err := v.db.Model(&entity.ImageVariantFile{}).
		Select("source_name, COUNT(*) AS files, COALESCE(SUM(size), 0) AS bytes").
		Group("source_name").
		Scan(&rows).Error
	if err != nil {
		return nil, err
	}
	totals := make(map[string]domain.VariantFileTotals, len(rows))
	for _, row := range rows {
		totals[row.SourceName] = domain.VariantFileTotals{Files: row.Files, Bytes: row.Bytes}
	}
	return totals, nil
}

const (
	unusedCondition = "variant_name IN ? AND COALESCE(last_requested_at, created_at) < ?"
	topSourcesOrder = "bytes DESC, source_name ASC"
)

func (v *VariantFileRepository) UnusedTotals(filter domain.UnusedFilter) (domain.VariantFileTotals, error) {
	if len(filter.VariantNames) == 0 {
		return domain.VariantFileTotals{}, nil
	}
	var row struct {
		Files int
		Bytes int64
	}
	err := v.db.Model(&entity.ImageVariantFile{}).
		Select("COUNT(*) AS files, COALESCE(SUM(size), 0) AS bytes").
		Where(unusedCondition, filter.VariantNames, filter.Cutoff.UTC()).
		Scan(&row).Error
	if err != nil {
		return domain.VariantFileTotals{}, err
	}
	return domain.VariantFileTotals{Files: row.Files, Bytes: row.Bytes}, nil
}

func (v *VariantFileRepository) TopSources(limit int) ([]domain.SourceTotals, error) {
	var rows []struct {
		SourceName string
		Files      int
		Bytes      int64
	}
	err := v.db.Model(&entity.ImageVariantFile{}).
		Select("source_name, COUNT(*) AS files, COALESCE(SUM(size), 0) AS bytes").
		Group("source_name").
		Order(topSourcesOrder).
		Limit(limit).
		Scan(&rows).Error
	if err != nil {
		return nil, err
	}
	sources := make([]domain.SourceTotals, 0, len(rows))
	for _, row := range rows {
		sources = append(sources, domain.SourceTotals{SourceName: row.SourceName, Files: row.Files, Bytes: row.Bytes})
	}
	return sources, nil
}

func (v *VariantFileRepository) ListPage(filter domain.VariantFileFilter, afterID uint32, limit int) ([]domain.VariantFile, error) {
	statement := v.db.Where("id > ?", afterID)
	if filter.VariantName != "" {
		statement = statement.Where("variant_name = ?", filter.VariantName)
	}
	if filter.SourceName != "" {
		statement = statement.Where("source_name = ?", filter.SourceName)
	}
	if filter.Unused != nil {
		if len(filter.Unused.VariantNames) == 0 {
			return []domain.VariantFile{}, nil
		}
		statement = statement.Where(unusedCondition, filter.Unused.VariantNames, filter.Unused.Cutoff.UTC())
	}
	var found []entity.ImageVariantFile
	if err := statement.Order("id asc").Limit(limit).Find(&found).Error; err != nil {
		return nil, err
	}
	files := make([]domain.VariantFile, 0, len(found))
	for _, model := range found {
		files = append(files, mappers.VariantFileToDomain(model))
	}
	return files, nil
}

func (v *VariantFileRepository) Totals() (map[string]domain.VariantFileTotals, error) {
	var rows []struct {
		VariantName string
		Files       int
		Bytes       int64
	}
	err := v.db.Model(&entity.ImageVariantFile{}).
		Select("variant_name, COUNT(*) AS files, COALESCE(SUM(size), 0) AS bytes").
		Group("variant_name").
		Scan(&rows).Error
	if err != nil {
		return nil, err
	}
	totals := make(map[string]domain.VariantFileTotals, len(rows))
	for _, row := range rows {
		totals[row.VariantName] = domain.VariantFileTotals{Files: row.Files, Bytes: row.Bytes}
	}
	return totals, nil
}