feat: add jikan cache cleanup worker

internal/database/database_test.go

@@ -3,6 +3,8 @@ package database
 import (
 	"context"
 	"database/sql"
+	"mal/internal/db"
+	"mal/internal/observability"
 	"testing"
 
 	_ "github.com/mattn/go-sqlite3"
@@ -43,3 +45,81 @@ func TestRunMigrationsCreatesHotPathIndexes(t *testing.T) {
 		})
 	}
 }
+
+func TestCleanupExpiredJikanCache(t *testing.T) {
+	sqlDB := newMigratedTestDB(t)
+	defer closeTestDB(t, sqlDB)
+
+	ctx := context.Background()
+	for _, row := range []struct {
+		key       string
+		expiresAt string
+	}{
+		{key: "expired", expiresAt: "2000-01-01T00:00:00Z"},
+		{key: "fresh", expiresAt: "2999-01-01T00:00:00Z"},
+	} {
+		_, err := sqlDB.ExecContext(ctx, `INSERT INTO jikan_cache (key, data, expires_at) VALUES (?, ?, ?)`, row.key, "{}", row.expiresAt)
+		if err != nil {
+			t.Fatalf("insert %s cache row: %v", row.key, err)
+		}
+	}
+
+	cleanupExpiredJikanCache(ctx, db.New(sqlDB), observability.NewMetrics())
+
+	keys := jikanCacheKeys(ctx, t, sqlDB)
+	if len(keys) != 1 || keys[0] != "fresh" {
+		t.Fatalf("remaining cache keys = %v, want [fresh]", keys)
+	}
+}
+
+func newMigratedTestDB(t *testing.T) *sql.DB {
+	t.Helper()
+
+	sqlDB, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	sqlDB.SetMaxOpenConns(1)
+
+	if err := RunMigrations(sqlDB); err != nil {
+		closeTestDB(t, sqlDB)
+		t.Fatalf("RunMigrations: %v", err)
+	}
+
+	return sqlDB
+}
+
+func closeTestDB(t *testing.T, sqlDB *sql.DB) {
+	t.Helper()
+
+	if err := sqlDB.Close(); err != nil {
+		t.Errorf("close sqlite: %v", err)
+	}
+}
+
+func jikanCacheKeys(ctx context.Context, t *testing.T, sqlDB *sql.DB) []string {
+	t.Helper()
+
+	var keys []string
+	rows, err := sqlDB.QueryContext(ctx, `SELECT key FROM jikan_cache ORDER BY key`)
+	if err != nil {
+		t.Fatalf("query cache keys: %v", err)
+	}
+	defer func() {
+		if err := rows.Close(); err != nil {
+			t.Errorf("close rows: %v", err)
+		}
+	}()
+	for rows.Next() {
+		var key string
+		if err := rows.Scan(&key); err != nil {
+			t.Fatalf("scan key: %v", err)
+		}
+		keys = append(keys, key)
+	}
+	if err := rows.Err(); err != nil {
+		t.Fatalf("iterate keys: %v", err)
+	}
+
+	return keys
+}