feat(API): media library

internal/infrastructure/useCases/MergeMedia.go

@@ -0,0 +1,137 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/article"
+	"RenewCMS/internal/domain/image"
+	"cmp"
+	"errors"
+	"slices"
+	"strings"
+)
+
+type MergeMediaResult struct {
+	ArticlesUpdated int
+	Merged          int
+}
+
+type MergeMediaUseCase struct {
+	imageRepository   image.Repository
+	articleRepository article.Repository
+}
+
+func NewMergeMediaUseCase(imageRepository image.Repository, articleRepository article.Repository) *MergeMediaUseCase {
+	return &MergeMediaUseCase{imageRepository, articleRepository}
+}
+
+type bodyRewrite struct {
+	articleId uint32
+	original  string
+	rewritten string
+}
+
+func (u *MergeMediaUseCase) Merge(keepId uint32, mergeIds []uint32) (MergeMediaResult, error) {
+	if err := validateMergeRequest(keepId, mergeIds); err != nil {
+		return MergeMediaResult{}, err
+	}
+
+	kept, err := u.imageRepository.Get(keepId)
+	if err != nil {
+		return MergeMediaResult{}, err
+	}
+	copies, err := u.loadCopies(kept, mergeIds)
+	if err != nil {
+		return MergeMediaResult{}, err
+	}
+
+	rewrites, err := u.planRewrites(kept, copies)
+	if err != nil {
+		return MergeMediaResult{}, err
+	}
+	if err := u.applyRewrites(rewrites); err != nil {
+		return MergeMediaResult{}, err
+	}
+
+	for _, duplicate := range copies {
+		if err := u.imageRepository.Delete(duplicate.ID); err != nil {
+			return MergeMediaResult{}, err
+		}
+	}
+
+	return MergeMediaResult{ArticlesUpdated: len(rewrites), Merged: len(copies)}, nil
+}
+
+func validateMergeRequest(keepId uint32, mergeIds []uint32) error {
+	if keepId == 0 || len(mergeIds) == 0 {
+		return image.ErrInvalidMergeRequest
+	}
+	seen := map[uint32]bool{keepId: true}
+	for _, id := range mergeIds {
+		if id == 0 || seen[id] {
+			return image.ErrInvalidMergeRequest
+		}
+		seen[id] = true
+	}
+	return nil
+}
+
+func (u *MergeMediaUseCase) loadCopies(kept image.Image, mergeIds []uint32) ([]image.Image, error) {
+	copies := make([]image.Image, 0, len(mergeIds))
+	for _, id := range mergeIds {
+		duplicate, err := u.imageRepository.Get(id)
+		if errors.Is(err, image.ErrImageNotFound) {
+			return nil, image.ErrMergeCopyMissing
+		}
+		if err != nil {
+			return nil, err
+		}
+		if duplicate.SHA256 == "" || duplicate.SHA256 != kept.SHA256 {
+			return nil, image.ErrMergeHashMismatch
+		}
+		copies = append(copies, duplicate)
+	}
+	return copies, nil
+}
+
+func (u *MergeMediaUseCase) planRewrites(kept image.Image, copies []image.Image) ([]bodyRewrite, error) {
+	keptName := image.StoredName(kept.Path)
+	rewritten := map[uint32]*bodyRewrite{}
+
+	for _, duplicate := range copies {
+		copyName := image.StoredName(duplicate.Path)
+		articles, err := u.articleRepository.FindByBodyContaining(copyName)
+		if err != nil {
+			return nil, err
+		}
+		for _, a := range articles {
+			plan, ok := rewritten[a.ID]
+			if !ok {
+				plan = &bodyRewrite{articleId: a.ID, original: a.Body, rewritten: a.Body}
+				rewritten[a.ID] = plan
+			}
+			plan.rewritten = strings.ReplaceAll(plan.rewritten, copyName, keptName)
+		}
+	}
+
+	plans := make([]bodyRewrite, 0, len(rewritten))
+	for _, plan := range rewritten {
+		plans = append(plans, *plan)
+	}
+	slices.SortFunc(plans, func(a, b bodyRewrite) int { return cmp.Compare(a.articleId, b.articleId) })
+	return plans, nil
+}
+
+func (u *MergeMediaUseCase) applyRewrites(rewrites []bodyRewrite) error {
+	for applied, plan := range rewrites {
+		if _, err := u.articleRepository.UpdateBody(plan.articleId, plan.rewritten); err != nil {
+			u.restoreBodies(rewrites[:applied])
+			return err
+		}
+	}
+	return nil
+}
+
+func (u *MergeMediaUseCase) restoreBodies(applied []bodyRewrite) {
+	for _, plan := range applied {
+		_, _ = u.articleRepository.UpdateBody(plan.articleId, plan.original)
+	}
+}