minor changes to table.go

internal/database/table.go

@@ -5,7 +5,7 @@ import (
 	"sync"
 )
 
-type DbStatus int
+type DbStatus uint8
 
 const (
 	New DbStatus = iota
@@ -80,27 +80,56 @@ func (d *DbTable[K, T]) Map() map[K]T {
 	return res
 }
 
+func (d *DbTable[K, T]) First(filter func(match T) bool) (key K, value T, ok bool) {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	for k, manga := range d.items {
+		if filter(manga) {
+			return k, manga, true
+		}
+	}
+
+	return *new(K), *new(T), false
+}
+
+func (d *DbTable[K, T]) Where(filter func(match T) bool) map[K]T {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+	res := make(map[K]T, len(d.items))
+	for k, manga := range d.items {
+		if filter(manga) {
+			res[k] = manga
+		}
+	}
+	return res
+}
+
 func (d *DbTable[K, T]) Delete(db *sql.DB, key K) error {
 	d.mutex.Lock()
 	defer d.mutex.Unlock()
-	delete(d.items, key)
-	return d.deleteFunc(db, key)
+	err := d.deleteFunc(db, key)
+	if err == nil {
+		delete(d.items, key)
+	}
+	return err
 }
 
 func (d *DbTable[K, T]) Save(db *sql.DB) error {
 	d.mutex.Lock()
 	defer d.mutex.Unlock()
 	for k, status := range d.updated {
-		if status == Loaded {
+		switch status {
+		case Loaded:
 			continue
-		} else if status == Updated {
+		case Updated:
 			item := d.items[k]
 			err := d.updateFunc(db, &item)
 			if err != nil {
 				return err
 			}
 			d.updated[k] = Loaded
-		} else {
+		case New:
 			item := d.items[k]
 			err := d.insertFunc(db, &item)
 			if err != nil {