package app

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"image"
	_ "image/gif"
	_ "image/jpeg"
	_ "image/png"
	"net/http"
	"path/filepath"
	"slices"
	"sort"
	"strings"
	"time"

	"github.com/chai2010/webp"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
	"go.uber.org/zap"
	_ "golang.org/x/image/webp"

	"github.com/geo-platform/tenant-api/internal/shared/auth"
	"github.com/geo-platform/tenant-api/internal/shared/messaging/rabbitmq"
	"github.com/geo-platform/tenant-api/internal/shared/middleware"
	"github.com/geo-platform/tenant-api/internal/shared/objectstorage"
	"github.com/geo-platform/tenant-api/internal/shared/response"
	"github.com/geo-platform/tenant-api/internal/tenant/repository"
)

const (
	maxImageUploadSizeBytes  = 10 * 1024 * 1024
	maxImageDimension        = 16384
	maxImageDecodePixels     = 40_000_000
	webpEncodeQuality        = 82
	defaultImageQuotaBytes   = 104857600
	imageAssetQueueIOTimeout = 5 * time.Second
	timeLayoutRFC3339        = "2006-01-02T15:04:05Z07:00"
)

var allowedImageMIMEs = map[string]struct{}{
	"image/gif":  {},
	"image/jpeg": {},
	"image/png":  {},
	"image/webp": {},
}

type ImageService struct {
	pool          *pgxpool.Pool
	objectStorage objectstorage.Client
	rabbitMQ      *rabbitmq.Client
	logger        *zap.Logger
}

func NewImageService(pool *pgxpool.Pool, objectStorage objectstorage.Client, rabbitMQClient *rabbitmq.Client, logger *zap.Logger) *ImageService {
	return &ImageService{pool: pool, objectStorage: objectStorage, rabbitMQ: rabbitMQClient, logger: logger}
}

type ImageUploadResult struct {
	ID        int64  `json:"id"`
	URL       string `json:"url"`
	Name      string `json:"name"`
	SizeBytes int64  `json:"size_bytes"`
	Reused    bool   `json:"reused"`
}

type ImageListResult struct {
	Items    []ImageListItem `json:"items"`
	Total    int             `json:"total"`
	Page     int             `json:"page"`
	PageSize int             `json:"page_size"`
}

type ImageListItem struct {
	ID        int64  `json:"id"`
	FolderID  *int64 `json:"folder_id"`
	Name      string `json:"name"`
	URL       string `json:"url"`
	SizeBytes int64  `json:"size_bytes"`
	CreatedAt string `json:"created_at"`
}

type NullableInt64Input struct {
	Set   bool
	Value *int64
}

func (n *NullableInt64Input) UnmarshalJSON(data []byte) error {
	n.Set = true
	var value *int64
	if err := json.Unmarshal(data, &value); err != nil {
		return err
	}
	n.Value = value
	return nil
}

type ImageUpdateRequest struct {
	Name     *string            `json:"name"`
	FolderID NullableInt64Input `json:"folder_id"`
}

type ImageReferenceDetail struct {
	Total        int                          `json:"total"`
	ArticleBody  int                          `json:"article_body"`
	ArticleCover int                          `json:"article_cover"`
	Articles     []ImageReferenceArticleBrief `json:"articles"`
}

type StorageUsageResponse struct {
	UsedBytes  int64   `json:"used_bytes"`
	QuotaBytes int64   `json:"quota_bytes"`
	UsedPct    float64 `json:"used_pct"`
}

func (s *ImageService) Upload(ctx context.Context, fileName string, content []byte, folderID *int64, buildURL func(string) string) (*ImageUploadResult, error) {
	if err := s.objectStorage.Validate(); err != nil {
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return nil, response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return nil, response.ErrInternal(50010, "image_storage_validation_failed", "failed to validate object storage")
	}
	if len(content) == 0 {
		return nil, response.ErrBadRequest(40010, "invalid_image", "image file is required")
	}
	if len(content) > maxImageUploadSizeBytes {
		return nil, response.ErrBadRequest(40011, "image_too_large", "image size cannot exceed 10 MB")
	}

	contentType := http.DetectContentType(content)
	if _, ok := allowedImageMIMEs[contentType]; !ok {
		return nil, response.ErrBadRequest(40012, "invalid_image_type", "only PNG, JPEG, GIF, and WebP images are supported")
	}

	imageConfig, _, err := image.DecodeConfig(bytes.NewReader(content))
	if err != nil {
		return nil, response.ErrBadRequest(40013, "invalid_image", "unable to decode image")
	}
	if imageConfig.Width <= 0 || imageConfig.Height <= 0 {
		return nil, response.ErrBadRequest(40013, "invalid_image", "unable to decode image")
	}
	if imageConfig.Width > maxImageDimension || imageConfig.Height > maxImageDimension {
		return nil, response.ErrBadRequest(40014, "image_dimensions_too_large", "image dimensions exceed the maximum allowed size")
	}
	if int64(imageConfig.Width)*int64(imageConfig.Height) > maxImageDecodePixels {
		return nil, response.ErrBadRequest(40014, "image_dimensions_too_large", "image pixel count exceeds the maximum allowed")
	}

	folderID, err = normalizeAssignableFolderID(folderID)
	if err != nil {
		return nil, err
	}

	tenantID := middleware.TenantIDFromCtx(ctx)
	actor := auth.MustActor(ctx)
	if folderID != nil {
		if err := s.ensureFolderExists(ctx, tenantID, *folderID); err != nil {
			return nil, err
		}
	}

	webpBytes := content
	if contentType != "image/webp" {
		decodedImage, _, err := image.Decode(bytes.NewReader(content))
		if err != nil {
			return nil, response.ErrBadRequest(40013, "invalid_image", "unable to decode image")
		}

		var webpBuffer bytes.Buffer
		if err := webp.Encode(&webpBuffer, decodedImage, &webp.Options{Quality: float32(webpEncodeQuality)}); err != nil {
			return nil, response.ErrInternal(50011, "image_encode_failed", "failed to encode image")
		}
		webpBytes = webpBuffer.Bytes()
	}

	sizeBytes := int64(len(webpBytes))
	contentHash := hashImageContent(webpBytes)
	existingAsset, err := s.findActiveImageAssetByContentHash(ctx, tenantID, contentHash)
	if err != nil {
		return nil, response.ErrInternal(50012, "image_asset_lookup_failed", "failed to check existing image asset")
	}
	if existingAsset != nil {
		return &ImageUploadResult{
			ID:        existingAsset.ID,
			URL:       buildURL(existingAsset.ObjectKey),
			Name:      existingAsset.Name,
			SizeBytes: existingAsset.SizeBytes,
			Reused:    true,
		}, nil
	}

	displayName := deriveImageName(fileName)
	objectKey := buildImageObjectKey(tenantID)

	usageRepo := repository.NewImageUsageRepository(s.pool)
	if err := usageRepo.EnsureRow(ctx, tenantID); err != nil {
		return nil, response.ErrInternal(50013, "image_usage_init_failed", "failed to initialize image storage usage")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, response.ErrInternal(50014, "image_upload_tx_begin_failed", "failed to start upload transaction")
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	usageTx := repository.NewImageUsageRepository(tx)
	if _, err := usageTx.AtomicReserve(ctx, tenantID, sizeBytes); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40903, "image_storage_quota_exceeded", "image storage quota exceeded")
		}
		return nil, response.ErrInternal(50015, "image_quota_reserve_failed", "failed to reserve image storage quota")
	}

	assetID, err := s.insertPendingImageAsset(ctx, tx, tenantID, folderID, objectKey, displayName, sizeBytes, contentHash, actor.UserID)
	if err != nil {
		if isConstraintError(err, "fk_image_assets_folder") {
			return nil, response.ErrNotFound(40402, "image_folder_not_found", "folder not found")
		}
		return nil, response.ErrInternal(50016, "image_asset_create_failed", "failed to create image asset")
	}

	if err := tx.Commit(ctx); err != nil {
		return nil, response.ErrInternal(50017, "image_upload_tx_commit_failed", "failed to finalize upload transaction")
	}

	if err := s.objectStorage.PutBytes(ctx, objectKey, webpBytes, "image/webp"); err != nil {
		s.logError("image upload to object storage failed", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.String("object_key", objectKey), zap.Error(err))
		s.rollbackUpload(ctx, tenantID, assetID, sizeBytes)
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return nil, response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return nil, response.ErrInternal(50018, "image_upload_failed", "failed to upload image")
	}

	imageRepo := repository.NewImageRepository(s.pool)
	if err := imageRepo.UpdateStatus(ctx, tenantID, assetID, "active"); err != nil {
		s.logError("failed to mark image active after upload", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
		if queueErr := s.enqueueFinalizeUploadTask(tenantID, assetID); queueErr == nil {
			return &ImageUploadResult{
				ID:        assetID,
				URL:       buildURL(objectKey),
				Name:      displayName,
				SizeBytes: sizeBytes,
			}, nil
		} else {
			s.logError("failed to enqueue upload finalization compensation", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(queueErr))
		}
		if deleteErr := s.objectStorage.Delete(ctx, objectKey); deleteErr != nil {
			s.logError("failed to clean up uploaded object after finalize error", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.String("object_key", objectKey), zap.Error(deleteErr))
		}
		s.rollbackUpload(ctx, tenantID, assetID, sizeBytes)
		return nil, response.ErrInternal(50019, "image_upload_finalize_failed", "failed to finalize image upload")
	}

	return &ImageUploadResult{
		ID:        assetID,
		URL:       buildURL(objectKey),
		Name:      displayName,
		SizeBytes: sizeBytes,
	}, nil
}

func (s *ImageService) List(ctx context.Context, folderID *int64, query *string, page, pageSize int, buildURL func(string) string) (*ImageListResult, error) {
	if page < 1 {
		page = 1
	}
	if pageSize < 1 || pageSize > 100 {
		pageSize = 20
	}

	searchQuery := normalizeSearchQuery(query)
	if searchQuery != nil {
		folderID = nil
	}

	tenantID := middleware.TenantIDFromCtx(ctx)
	repo := repository.NewImageRepository(s.pool)
	assets, total, err := repo.List(ctx, repository.ImageAssetListParams{
		TenantID:    tenantID,
		FolderID:    folderID,
		SearchQuery: searchQuery,
		PageSize:    pageSize,
		PageOffset:  (page - 1) * pageSize,
	})
	if err != nil {
		return nil, err
	}

	items := make([]ImageListItem, len(assets))
	for i, asset := range assets {
		items[i] = ImageListItem{
			ID:        asset.ID,
			FolderID:  asset.FolderID,
			Name:      asset.Name,
			URL:       buildURL(asset.ObjectKey),
			SizeBytes: asset.SizeBytes,
			CreatedAt: asset.CreatedAt.Format(timeLayoutRFC3339),
		}
	}
	if items == nil {
		items = []ImageListItem{}
	}

	return &ImageListResult{
		Items:    items,
		Total:    total,
		Page:     page,
		PageSize: pageSize,
	}, nil
}

func (s *ImageService) Update(ctx context.Context, id int64, req ImageUpdateRequest) error {
	if req.Name == nil && !req.FolderID.Set {
		return response.ErrBadRequest(40000, "invalid_request", "at least one field is required")
	}

	tenantID := middleware.TenantIDFromCtx(ctx)
	repo := repository.NewImageRepository(s.pool)

	asset, err := repo.Get(ctx, tenantID, id)
	if err != nil {
		return mapImageNotFound(err)
	}
	if asset.Status != "active" {
		return response.ErrNotFound(40401, "image_not_found", "image not found")
	}

	if req.Name != nil {
		name := strings.TrimSpace(*req.Name)
		if name == "" {
			return response.ErrBadRequest(40001, "invalid_name", "name is required")
		}
		if len(name) > 255 {
			return response.ErrBadRequest(40002, "invalid_name", "name must be at most 255 characters")
		}
		if err := repo.UpdateName(ctx, tenantID, id, name); err != nil {
			return err
		}
	}

	if req.FolderID.Set {
		folderID, err := normalizeAssignableFolderID(req.FolderID.Value)
		if err != nil {
			return err
		}
		if folderID != nil {
			if err := s.ensureFolderExists(ctx, tenantID, *folderID); err != nil {
				return err
			}
		}
		if err := repo.UpdateFolder(ctx, tenantID, id, folderID); err != nil {
			if isConstraintError(err, "fk_image_assets_folder") {
				return response.ErrNotFound(40402, "image_folder_not_found", "folder not found")
			}
			return err
		}
	}

	return nil
}

type existingImageAsset struct {
	ID        int64
	ObjectKey string
	Name      string
	SizeBytes int64
}

func (s *ImageService) findActiveImageAssetByContentHash(ctx context.Context, tenantID int64, contentHash string) (*existingImageAsset, error) {
	if strings.TrimSpace(contentHash) == "" {
		return nil, nil
	}

	var asset existingImageAsset
	err := s.pool.QueryRow(ctx, `
SELECT id, object_key, name, size_bytes
FROM image_assets
WHERE tenant_id = $1
  AND content_hash = $2
  AND status = 'active'
  AND deleted_at IS NULL
ORDER BY created_at DESC
LIMIT 1
`, tenantID, contentHash).Scan(&asset.ID, &asset.ObjectKey, &asset.Name, &asset.SizeBytes)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, nil
		}
		return nil, err
	}

	return &asset, nil
}

func (s *ImageService) insertPendingImageAsset(
	ctx context.Context,
	tx pgx.Tx,
	tenantID int64,
	folderID *int64,
	objectKey string,
	name string,
	sizeBytes int64,
	contentHash string,
	createdBy int64,
) (int64, error) {
	row := tx.QueryRow(ctx, `
INSERT INTO image_assets (tenant_id, folder_id, object_key, name, size_bytes, status, content_hash, created_by)
VALUES ($1, $2, $3, $4, $5, 'pending_upload', $6, $7)
RETURNING id
`, tenantID, nullableImageFolderValue(folderID), objectKey, name, sizeBytes, contentHash, createdBy)

	var assetID int64
	if err := row.Scan(&assetID); err != nil {
		return 0, err
	}
	return assetID, nil
}

func (s *ImageService) GetReferences(ctx context.Context, imageID int64) (*ImageReferenceDetail, error) {
	tenantID := middleware.TenantIDFromCtx(ctx)
	imageRepo := repository.NewImageRepository(s.pool)
	refRepo := repository.NewImageReferenceRepository(s.pool)

	asset, err := imageRepo.Get(ctx, tenantID, imageID)
	if err != nil {
		return nil, mapImageNotFound(err)
	}
	if asset.Status != "active" {
		return nil, response.ErrNotFound(40401, "image_not_found", "image not found")
	}

	articles, err := refRepo.ListArticles(ctx, tenantID, imageID)
	if err != nil {
		return nil, err
	}

	articleMap := make(map[int64]map[string]struct{})
	bodyCount := 0
	coverCount := 0
	for _, article := range articles {
		if articleMap[article.ArticleID] == nil {
			articleMap[article.ArticleID] = make(map[string]struct{})
		}
		articleMap[article.ArticleID][article.RefScope] = struct{}{}
		switch article.RefScope {
		case "article_body":
			bodyCount++
		case "article_cover":
			coverCount++
		}
	}

	briefs := make([]ImageReferenceArticleBrief, 0, len(articleMap))
	for articleID, scopeSet := range articleMap {
		scopes := make([]string, 0, len(scopeSet))
		for scope := range scopeSet {
			scopes = append(scopes, scope)
		}
		slices.Sort(scopes)
		briefs = append(briefs, ImageReferenceArticleBrief{
			ArticleID: articleID,
			Scopes:    scopes,
		})
	}
	sort.Slice(briefs, func(i, j int) bool {
		return briefs[i].ArticleID < briefs[j].ArticleID
	})
	if briefs == nil {
		briefs = []ImageReferenceArticleBrief{}
	}

	return &ImageReferenceDetail{
		Total:        len(articles),
		ArticleBody:  bodyCount,
		ArticleCover: coverCount,
		Articles:     briefs,
	}, nil
}

func (s *ImageService) Delete(ctx context.Context, id int64, force bool) error {
	if err := s.objectStorage.Validate(); err != nil {
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return response.ErrInternal(50019, "image_storage_validation_failed", "failed to validate object storage")
	}

	tenantID := middleware.TenantIDFromCtx(ctx)
	imageRepo := repository.NewImageRepository(s.pool)
	refRepo := repository.NewImageReferenceRepository(s.pool)

	asset, err := imageRepo.Get(ctx, tenantID, id)
	if err != nil {
		return mapImageNotFound(err)
	}
	if asset.Status != "active" {
		return response.ErrNotFound(40401, "image_not_found", "image not found")
	}

	if !force {
		count, err := refRepo.Count(ctx, tenantID, id)
		if err != nil {
			return err
		}
		if count > 0 {
			return response.ErrConflict(40904, "image_asset_in_use", "image is referenced by articles")
		}
	}

	if err := imageRepo.UpdateStatus(ctx, tenantID, id, "pending_delete"); err != nil {
		return err
	}

	return s.finalizeDeleteNowOrEnqueue(ctx, tenantID, id)
}

func (s *ImageService) GetStorageUsage(ctx context.Context) (*StorageUsageResponse, error) {
	tenantID := middleware.TenantIDFromCtx(ctx)
	usageRepo := repository.NewImageUsageRepository(s.pool)

	if err := usageRepo.EnsureRow(ctx, tenantID); err != nil {
		return nil, response.ErrInternal(50025, "image_usage_init_failed", "failed to initialize image storage usage")
	}

	usage, err := usageRepo.Get(ctx, tenantID)
	if err != nil {
		return nil, response.ErrInternal(50026, "image_usage_query_failed", "failed to query image storage usage")
	}

	quotaBytes, err := s.lookupImageQuotaBytes(ctx, tenantID)
	if err != nil {
		return nil, response.ErrInternal(50027, "image_quota_query_failed", "failed to query image storage quota")
	}

	usedPct := 0.0
	if quotaBytes > 0 {
		usedPct = float64(usage.UsedBytes) / float64(quotaBytes) * 100
	}

	return &StorageUsageResponse{
		UsedBytes:  usage.UsedBytes,
		QuotaBytes: quotaBytes,
		UsedPct:    usedPct,
	}, nil
}

func (s *ImageService) rollbackUpload(ctx context.Context, tenantID, assetID, sizeBytes int64) {
	imageRepo := repository.NewImageRepository(s.pool)
	usageRepo := repository.NewImageUsageRepository(s.pool)

	if err := imageRepo.UpdateStatus(ctx, tenantID, assetID, "upload_failed"); err != nil {
		s.logError("failed to mark image upload as failed", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
	}
	if err := usageRepo.Release(ctx, tenantID, sizeBytes); err != nil {
		s.logError("failed to release image storage quota after upload rollback", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
	}
}

func (s *ImageService) ProcessFinalizeUpload(ctx context.Context, tenantID, assetID int64) error {
	asset, err := s.loadImageAsset(ctx, tenantID, assetID)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil
		}
		return response.ErrInternal(50028, "image_upload_lookup_failed", "failed to load image upload state")
	}
	if asset.Status != "pending_upload" {
		return nil
	}

	exists, err := s.objectStorage.Exists(ctx, asset.ObjectKey)
	if err != nil {
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return response.ErrInternal(50029, "image_upload_finalize_failed", "failed to check image upload state")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return response.ErrInternal(50030, "image_upload_tx_begin_failed", "failed to finalize image upload")
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	lockedAsset, found, err := s.lockImageAsset(ctx, tx, tenantID, assetID)
	if err != nil {
		return response.ErrInternal(50031, "image_upload_lock_failed", "failed to lock image upload state")
	}
	if !found || lockedAsset.Status != "pending_upload" {
		if err := tx.Commit(ctx); err != nil {
			return response.ErrInternal(50032, "image_upload_tx_commit_failed", "failed to finalize image upload")
		}
		return nil
	}

	imageRepoTx := repository.NewImageRepository(tx)
	if exists {
		if err := imageRepoTx.UpdateStatus(ctx, tenantID, assetID, "active"); err != nil {
			return response.ErrInternal(50033, "image_upload_finalize_failed", "failed to activate uploaded image")
		}
	} else {
		if err := imageRepoTx.UpdateStatus(ctx, tenantID, assetID, "upload_failed"); err != nil {
			return response.ErrInternal(50034, "image_upload_finalize_failed", "failed to mark image upload as failed")
		}
		usageRepoTx := repository.NewImageUsageRepository(tx)
		if err := usageRepoTx.Release(ctx, tenantID, lockedAsset.SizeBytes); err != nil {
			return response.ErrInternal(50035, "image_quota_release_failed", "failed to release image storage quota")
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return response.ErrInternal(50036, "image_upload_tx_commit_failed", "failed to finalize image upload")
	}
	return nil
}

func (s *ImageService) ProcessFinalizeDelete(ctx context.Context, tenantID, assetID int64) error {
	asset, err := s.loadImageAsset(ctx, tenantID, assetID)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil
		}
		return response.ErrInternal(50037, "image_delete_lookup_failed", "failed to load image delete state")
	}
	if asset.Status != "pending_delete" {
		return nil
	}

	exists, err := s.objectStorage.Exists(ctx, asset.ObjectKey)
	if err != nil {
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return response.ErrInternal(50038, "image_delete_finalize_failed", "failed to check image object state")
	}
	if exists {
		if err := s.objectStorage.Delete(ctx, asset.ObjectKey); err != nil {
			if errors.Is(err, objectstorage.ErrNotConfigured) {
				return response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
			}
			return response.ErrInternal(50039, "image_delete_failed", "failed to delete image from storage")
		}
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return response.ErrInternal(50040, "image_delete_tx_begin_failed", "failed to finalize image deletion")
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	lockedAsset, found, err := s.lockImageAsset(ctx, tx, tenantID, assetID)
	if err != nil {
		return response.ErrInternal(50041, "image_delete_lock_failed", "failed to lock image delete state")
	}
	if !found || lockedAsset.Status != "pending_delete" {
		if err := tx.Commit(ctx); err != nil {
			return response.ErrInternal(50042, "image_delete_tx_commit_failed", "failed to finalize image deletion")
		}
		return nil
	}

	if _, err := tx.Exec(ctx, `
DELETE FROM image_asset_references
WHERE tenant_id = $1 AND image_asset_id = $2
`, tenantID, assetID); err != nil {
		return response.ErrInternal(50043, "image_delete_reference_cleanup_failed", "failed to clean image references")
	}

	imageRepoTx := repository.NewImageRepository(tx)
	usageRepoTx := repository.NewImageUsageRepository(tx)
	if err := imageRepoTx.MarkDeleted(ctx, tenantID, assetID); err != nil {
		return response.ErrInternal(50044, "image_delete_finalize_failed", "failed to finalize image deletion")
	}
	if err := usageRepoTx.Release(ctx, tenantID, lockedAsset.SizeBytes); err != nil {
		return response.ErrInternal(50045, "image_quota_release_failed", "failed to release image storage quota")
	}
	if err := tx.Commit(ctx); err != nil {
		return response.ErrInternal(50046, "image_delete_tx_commit_failed", "failed to finalize image deletion")
	}

	return nil
}

func (s *ImageService) finalizeDeleteNowOrEnqueue(ctx context.Context, tenantID, assetID int64) error {
	if err := s.ProcessFinalizeDelete(ctx, tenantID, assetID); err != nil {
		s.logError("failed to finalize image delete synchronously", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
		if queueErr := s.enqueueFinalizeDeleteTask(tenantID, assetID); queueErr != nil {
			s.logError("failed to enqueue image delete compensation", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(queueErr))
			return err
		}
	}
	return nil
}

func (s *ImageService) enqueueFinalizeUploadTask(tenantID, assetID int64) error {
	ctx, cancel := context.WithTimeout(context.Background(), imageAssetQueueIOTimeout)
	defer cancel()
	return publishImageAssetTask(ctx, s.rabbitMQ, imageAssetTaskEnvelope{
		Kind:     imageAssetTaskKindFinalizeUpload,
		TenantID: tenantID,
		AssetID:  assetID,
	})
}

func (s *ImageService) enqueueFinalizeDeleteTask(tenantID, assetID int64) error {
	ctx, cancel := context.WithTimeout(context.Background(), imageAssetQueueIOTimeout)
	defer cancel()
	return publishImageAssetTask(ctx, s.rabbitMQ, imageAssetTaskEnvelope{
		Kind:     imageAssetTaskKindFinalizeDelete,
		TenantID: tenantID,
		AssetID:  assetID,
	})
}

func (s *ImageService) loadImageAsset(ctx context.Context, tenantID, assetID int64) (*repository.ImageAsset, error) {
	return repository.NewImageRepository(s.pool).Get(ctx, tenantID, assetID)
}

type lockedImageAsset struct {
	ObjectKey string
	SizeBytes int64
	Status    string
	Deleted   bool
}

func (s *ImageService) lockImageAsset(ctx context.Context, tx pgx.Tx, tenantID, assetID int64) (*lockedImageAsset, bool, error) {
	var asset lockedImageAsset
	var deletedAt *time.Time
	err := tx.QueryRow(ctx, `
SELECT object_key, size_bytes, status, deleted_at
FROM image_assets
WHERE tenant_id = $1 AND id = $2
FOR UPDATE
`, tenantID, assetID).Scan(&asset.ObjectKey, &asset.SizeBytes, &asset.Status, &deletedAt)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, false, nil
		}
		return nil, false, err
	}
	asset.Deleted = deletedAt != nil
	return &asset, true, nil
}

func (s *ImageService) ensureFolderExists(ctx context.Context, tenantID, folderID int64) error {
	folderRepo := repository.NewImageFolderRepository(s.pool)
	if _, err := folderRepo.Get(ctx, tenantID, folderID); err != nil {
		return mapImageFolderNotFound(err)
	}
	return nil
}

func (s *ImageService) lookupImageQuotaBytes(ctx context.Context, tenantID int64) (int64, error) {
	var quotaBytes int64
	err := s.pool.QueryRow(ctx, `
SELECT COALESCE((p.quota_policy_json ->> 'image_storage_bytes')::BIGINT, $2) AS quota_bytes
FROM tenant_plan_subscriptions s
JOIN plans p ON p.id = s.plan_id
WHERE s.tenant_id = $1
	AND s.status = 'active'
	AND s.deleted_at IS NULL
	AND s.end_at > NOW()
LIMIT 1
`, tenantID, defaultImageQuotaBytes).Scan(&quotaBytes)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return defaultImageQuotaBytes, nil
		}
		return 0, err
	}
	return quotaBytes, nil
}

func mapImageNotFound(err error) error {
	if errors.Is(err, pgx.ErrNoRows) {
		return response.ErrNotFound(40401, "image_not_found", "image not found")
	}
	return err
}

func normalizeSearchQuery(query *string) *string {
	if query == nil {
		return nil
	}
	trimmed := strings.TrimSpace(*query)
	if trimmed == "" {
		return nil
	}
	return &trimmed
}

func normalizeAssignableFolderID(folderID *int64) (*int64, error) {
	if folderID == nil {
		return nil, nil
	}
	if *folderID <= 0 {
		return nil, response.ErrBadRequest(40003, "invalid_folder_id", "folder_id must be a positive integer or null")
	}
	return folderID, nil
}

func buildImageObjectKey(tenantID int64) string {
	return fmt.Sprintf("tenants/%d/images/%s.webp", tenantID, uuid.NewString())
}

func hashImageContent(content []byte) string {
	if len(content) == 0 {
		return ""
	}
	digest := sha256.Sum256(content)
	return hex.EncodeToString(digest[:])
}

func nullableImageFolderValue(value *int64) interface{} {
	if value == nil {
		return nil
	}
	return *value
}

func deriveImageName(fileName string) string {
	name := strings.TrimSpace(filepath.Base(fileName))
	if name == "" {
		return "untitled"
	}
	if ext := filepath.Ext(name); ext != "" {
		name = strings.TrimSuffix(name, ext)
	}
	name = strings.TrimSpace(name)
	if name == "" {
		return "untitled"
	}
	if len(name) > 255 {
		name = name[:255]
	}
	return name
}

func (s *ImageService) logError(msg string, fields ...zap.Field) {
	if s.logger != nil {
		s.logger.Error(msg, fields...)
	}
}