package store

import (
	"os"
	"path/filepath"
	"testing"
	"time"
)

func TestFailingMigrationReusesBackup(t *testing.T) {
	t.Parallel()
	dir := t.TempDir()

	db, err := Open(dir, "FULL")
	if err != nil {
		t.Fatal(err)
	}
	_ = db.Close()

	w, err := OpenWriter(dir, "FULL")
	if err != nil {
		t.Fatal(err)
	}
	defer func() { _ = w.Close() }()

	pending := []migrationFile{{
		version: 9999,
		name:    "9999_fail.sql",
		body:    "THIS IS NOT VALID SQL",
	}}
	if applyErr := applyPending(w, dir, true, pending); applyErr == nil {
		t.Fatal("expected first failing migration to error")
	}
	backupDir := filepath.Join(dir, "backup")
	first, err := os.ReadDir(backupDir)
	if err != nil {
		t.Fatal(err)
	}
	if len(first) != 1 || first[0].Name() != "pre-migrate-v4-to-v9999.db" {
		t.Fatalf("first backups=%v", dirNames(first))
	}

	if applyErr := applyPending(w, dir, true, pending); applyErr == nil {
		t.Fatal("expected second failing migration to error")
	}
	second, err := os.ReadDir(backupDir)
	if err != nil {
		t.Fatal(err)
	}
	if len(second) != 1 || second[0].Name() != first[0].Name() {
		t.Fatalf("second backups=%v first=%v", dirNames(second), dirNames(first))
	}
	info1, err := first[0].Info()
	if err != nil {
		t.Fatal(err)
	}
	info2, err := second[0].Info()
	if err != nil {
		t.Fatal(err)
	}
	if info2.ModTime().After(info1.ModTime().Add(time.Second)) && info2.Size() != info1.Size() {
		// 复用同一文件即可；时钟精度下允许 mtime 相同。
		t.Logf("mtime first=%s second=%s", info1.ModTime(), info2.ModTime())
	}
}

func dirNames(entries []os.DirEntry) []string {
	out := make([]string, 0, len(entries))
	for _, e := range entries {
		out = append(out, e.Name())
	}
	return out
}