package backup

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

// fakeSnap writes a tiny file so backup files exist on disk for the tests, and
// records how many times it ran.
type fakeSnap struct{ calls int }

func (f *fakeSnap) SnapshotTo(dest string, includeBlobs bool) error {
	f.calls++
	return os.WriteFile(dest, []byte("snap"), 0o600)
}

func TestWriteBackup_NamesAndSameDayNoOp(t *testing.T) {
	dir := t.TempDir()
	s := &fakeSnap{}
	now := time.Date(2026, 6, 10, 9, 0, 0, 0, time.UTC)

	if err := writeBackup(s, dir, now); err != nil {
		t.Fatal(err)
	}
	files := backupFiles(dir)
	if len(files) != 1 || files[0] != "hsa_sqlite_backup_2026_06_10.db" {
		t.Fatalf("files = %v", files)
	}

	// A same-day second call is a no-op: no error, still one file, no re-snapshot.
	if err := writeBackup(s, dir, now.Add(time.Hour)); err != nil {
		t.Fatal(err)
	}
	if files := backupFiles(dir); len(files) != 1 {
		t.Errorf("same-day re-run produced %v, want 1 file", files)
	}
	if s.calls != 1 {
		t.Errorf("SnapshotTo called %d times, want 1 (second was a no-op)", s.calls)
	}
}

func TestPruneKeepsMostRecent(t *testing.T) {
	dir := t.TempDir()
	s := &fakeSnap{}
	base := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	for i := 0; i < 5; i++ {
		_ = writeBackup(s, dir, base.AddDate(0, 0, i))
	}
	if err := prune(dir, 2); err != nil {
		t.Fatal(err)
	}
	files := backupFiles(dir)
	if len(files) != 2 {
		t.Fatalf("after prune: %v", files)
	}
	// The two newest (Jan 04, Jan 05) survive.
	if !strings.Contains(files[0], "2026_01_04") || !strings.Contains(files[1], "2026_01_05") {
		t.Errorf("wrong files kept: %v", files)
	}
}

func TestScheduleRunsOnceThenStops(t *testing.T) {
	dir := t.TempDir()
	s := &fakeSnap{}
	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)
	// A real store would be passed in production; here the fake is enough.
	go Schedule(ctx, s, dir, time.Hour, 4, func() time.Time {
		return time.Date(2026, 6, 10, 9, 0, 0, 0, time.UTC)
	})
	// Wait for the immediate first backup to land.
	deadline := time.Now().Add(2 * time.Second)
	for time.Now().Before(deadline) {
		if _, err := os.Stat(filepath.Join(dir, "hsa_sqlite_backup_2026_06_10.db")); err == nil {
			return
		}
		time.Sleep(10 * time.Millisecond)
	}
	t.Fatal("Schedule did not write an initial backup")
}