feat: media duplicate purge, part 1 of 3: persisted purge settings and the purge API

internal/infrastructure/useCases/RunPurge.go

@@ -0,0 +1,91 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/article"
+	"RenewCMS/internal/domain/image"
+	"RenewCMS/internal/domain/purge"
+	"log"
+	"slices"
+	"sync"
+	"time"
+)
+
+type RunPurgeResult struct {
+	GroupsTotal     int
+	GroupsPurged    int
+	Merged          int
+	ArticlesUpdated int
+	FailedGroups    int
+}
+
+type RunPurgeUseCase struct {
+	planner    *purgePlanner
+	merge      *MergeMediaUseCase
+	repository purge.Repository
+	now        func() time.Time
+	logger     *log.Logger
+	guard      sync.Mutex
+}
+
+func NewRunPurgeUseCase(imageRepository image.Repository, articleRepository article.Repository, merge *MergeMediaUseCase, repository purge.Repository, now func() time.Time, logger *log.Logger) *RunPurgeUseCase {
+	return &RunPurgeUseCase{
+		planner:    &purgePlanner{imageRepository, articleRepository},
+		merge:      merge,
+		repository: repository,
+		now:        now,
+		logger:     logger,
+	}
+}
+
+func (u *RunPurgeUseCase) Run(fingerprint *string) (RunPurgeResult, error) {
+	if !u.guard.TryLock() {
+		return RunPurgeResult{}, purge.ErrPurgeBusy
+	}
+	defer u.guard.Unlock()
+
+	plan, err := u.planner.plan()
+	if err != nil {
+		return RunPurgeResult{}, err
+	}
+	if fingerprint != nil && *fingerprint != plan.fingerprint {
+		return RunPurgeResult{}, purge.ErrPurgeConflict
+	}
+
+	result := u.mergeGroups(plan)
+	if err := u.recordRun(result); err != nil {
+		u.logger.Printf("purge: could not record the run result: %v", err)
+		return RunPurgeResult{}, err
+	}
+	return result, nil
+}
+
+func (u *RunPurgeUseCase) mergeGroups(plan purgePlan) RunPurgeResult {
+	result := RunPurgeResult{GroupsTotal: len(plan.groups)}
+	updated := map[uint32]bool{}
+	for _, group := range plan.groups {
+		merged, err := u.merge.Merge(group.kept.ID, slices.Clone(group.mergedIds))
+		if err != nil {
+			result.FailedGroups++
+			continue
+		}
+		result.GroupsPurged++
+		result.Merged += merged.Merged
+		for _, id := range merged.UpdatedArticleIDs {
+			updated[id] = true
+		}
+	}
+	result.ArticlesUpdated = len(updated)
+	return result
+}
+
+func (u *RunPurgeUseCase) recordRun(result RunPurgeResult) error {
+	settings, err := u.repository.Get()
+	if err != nil {
+		return err
+	}
+	at := u.now().UTC()
+	settings.LastPurgeAt = &at
+	settings.LastPurgeMerged = result.Merged
+	settings.LastPurgeArticlesUpdated = result.ArticlesUpdated
+	return u.repository.Save(settings)
+}