feat(media): pagination

internal/infrastructure/useCases/ListMedia.go

@@ -4,13 +4,9 @@ import (
 	"RenewCMS/internal/domain/article"
 	"RenewCMS/internal/domain/image"
 	"RenewCMS/internal/domain/user"
-	"encoding/base64"
-	"strconv"
 	"strings"
 )
 
-const cursorPrefix = "offset:"
-
 type MediaItem struct {
 	Image      image.Image
 	UploadedBy string
@@ -28,9 +24,11 @@ type MediaCounts struct {
 }
 
 type MediaPage struct {
-	Items      []MediaItem
-	NextCursor string
-	Counts     MediaCounts
+	Items  []MediaItem
+	Total  int
+	Page   int
+	Size   int
+	Counts MediaCounts
 }
 
 type ListMediaUseCase struct {
@@ -48,10 +46,6 @@ func (l *ListMediaUseCase) List(query image.ListQuery) (MediaPage, error) {
 	if err := query.Validate(); err != nil {
 		return MediaPage{}, err
 	}
-	offset, err := decodeCursor(query.Cursor)
-	if err != nil {
-		return MediaPage{}, err
-	}
 
 	usage, err := l.usageCounter()
 	if err != nil {
@@ -83,8 +77,9 @@ func (l *ListMediaUseCase) List(query image.ListQuery) (MediaPage, error) {
 		}
 	}
 
-	pageEnd := min(offset+query.Limit, len(matching))
-	pageStart := min(offset, pageEnd)
+	offset := (query.Page - 1) * query.Size
+	pageStart := min(offset, len(matching))
+	pageEnd := min(pageStart+query.Size, len(matching))
 	names := newUploaderNames(l.userRepository)
 	items := []MediaItem{}
 	for _, img := range matching[pageStart:pageEnd] {
@@ -103,11 +98,7 @@ func (l *ListMediaUseCase) List(query image.ListQuery) (MediaPage, error) {
 		})
 	}
 
-	page := MediaPage{Items: items, Counts: counts}
-	if pageEnd < len(matching) {
-		page.NextCursor = encodeCursor(pageEnd)
-	}
-	return page, nil
+	return MediaPage{Items: items, Total: len(matching), Page: query.Page, Size: query.Size, Counts: counts}, nil
 }
 
 func (l *ListMediaUseCase) Describe(img image.Image) (MediaItem, error) {
@@ -217,22 +208,3 @@ func matchesFilter(filter image.Filter, usedIn int, duplicate bool) bool {
 		return true
 	}
 }
-
-func encodeCursor(offset int) string {
-	return base64.RawURLEncoding.EncodeToString([]byte(cursorPrefix + strconv.Itoa(offset)))
-}
-
-func decodeCursor(cursor string) (int, error) {
-	if cursor == "" {
-		return 0, nil
-	}
-	raw, err := base64.RawURLEncoding.DecodeString(cursor)
-	if err != nil || !strings.HasPrefix(string(raw), cursorPrefix) {
-		return 0, image.ErrInvalidQuery
-	}
-	offset, err := strconv.Atoi(strings.TrimPrefix(string(raw), cursorPrefix))
-	if err != nil || offset < 0 {
-		return 0, image.ErrInvalidQuery
-	}
-	return offset, nil
-}