core: use local watch-order store

internal/watchorder/store.go

@@ -0,0 +1,72 @@
+package watchorder
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strconv"
+)
+
+type Store struct {
+	byID map[int][]WatchOrderEntry
+}
+
+func EmptyStore() *Store {
+	return &Store{byID: make(map[int][]WatchOrderEntry)}
+}
+
+func (s *Store) Len() int {
+	if s == nil {
+		return 0
+	}
+
+	return len(s.byID)
+}
+
+func (s *Store) Get(id int) ([]WatchOrderEntry, bool) {
+	if s == nil {
+		return nil, false
+	}
+
+	entries, ok := s.byID[id]
+	if !ok {
+		return nil, false
+	}
+
+	return entries, true
+}
+
+func LoadFromFile(path string) (*Store, error) {
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read watch-order file %q: %w", path, err)
+	}
+
+	rawMessages := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(content, &rawMessages); err != nil {
+		return nil, fmt.Errorf("failed to parse watch-order file %q: %w", path, err)
+	}
+
+	raw := make(map[string][]WatchOrderEntry)
+	if wrappedData, ok := rawMessages["data"]; ok && len(rawMessages) == 1 {
+		if err := json.Unmarshal(wrappedData, &raw); err != nil {
+			return nil, fmt.Errorf("failed to parse watch-order data in file %q: %w", path, err)
+		}
+	} else {
+		if err := json.Unmarshal(content, &raw); err != nil {
+			return nil, fmt.Errorf("failed to parse watch-order file %q: %w", path, err)
+		}
+	}
+
+	byID := make(map[int][]WatchOrderEntry, len(raw))
+	for key, entries := range raw {
+		id, err := strconv.Atoi(key)
+		if err != nil {
+			return nil, fmt.Errorf("invalid anime id key %q in watch-order file %q: %w", key, path, err)
+		}
+
+		byID[id] = entries
+	}
+
+	return &Store{byID: byID}, nil
+}