feat: cursor implemented

modules/backend/handlers/common.go

@@ -13,6 +13,71 @@ func NewServer(db *sqlc.Queries) Server {
 	return Server{db: db}
 }
 
+// type Cursor interface {
+// 	ParseCursor(sortBy oapi.TitleSort, data oapi.Cursor) (Cursor, error)
+
+// 	Values() map[string]interface{}
+// 	// for logs only
+// 	Type() string
+// }
+
+// type CursorByID struct {
+// 	ID int64
+// }
+
+// func (c CursorByID) ParseCursor(sortBy oapi.TitleSort, data oapi.Cursor) (Cursor, error) {
+//     var cur CursorByID
+//     if err := json.Unmarshal(data, &cur); err != nil {
+//         return nil, fmt.Errorf("invalid cursor (id): %w", err)
+//     }
+//     if cur.ID == 0 {
+//         return nil, errors.New("cursor id must be non-zero")
+//     }
+//     return cur, nil
+// }
+
+// func (c CursorByID) Values() map[string]interface{} {
+//     return map[string]interface{}{
+//         "cursor_id":     c.ID,
+//         "cursor_year":   nil,
+//         "cursor_rating": nil,
+//     }
+// }
+
+// func (c CursorByID) Type() string { return "id" }
+
+// func NewCursor(sortBy string) (Cursor, error) {
+// 	switch Type(sortBy) {
+// 	case TypeID:
+// 		return CursorByID{}, nil
+// 	case TypeYear:
+// 		return CursorByYear{}, nil
+// 	case TypeRating:
+// 		return CursorByRating{}, nil
+// 	default:
+// 		return nil, fmt.Errorf("unsupported sort_by: %q", sortBy)
+// 	}
+// }
+
+// decodes a base64-encoded JSON string into a CursorObj
+// Returns the parsed CursorObj and an error
+// func parseCursor(encoded oapi.Cursor) (*oapi.CursorObj, error) {
+
+// 	// Decode base64
+// 	decoded, err := base64.StdEncoding.DecodeString(encoded)
+// 	if err != nil {
+// 		return nil, fmt.Errorf("parseCursor: %v", err)
+// 	}
+
+// 	// Parse JSON
+// 	var cursor oapi.CursorObj
+// 	if err := json.Unmarshal(decoded, &cursor); err != nil {
+// 		return nil, fmt.Errorf("parseCursor: %v", err)
+// 	}
+
+// 	return &cursor, nil
+// }
+
 func parseInt64(s string) (int32, error) {
 	i, err := strconv.ParseInt(s, 10, 64)
 	return int32(i), err