package backup

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

func TestApplyRetentionByCount(t *testing.T) {
	dir := t.TempDir()
	projDir := filepath.Join(dir, "testapp")
	os.MkdirAll(projDir, 0755)

	for i := 0; i < 5; i++ {
		name := "testapp-20250101-00000" + string(rune('1'+i)) + ".tar.gz"
		f, err := os.Create(filepath.Join(projDir, name))
		if err != nil {
			t.Fatal(err)
		}
		f.Close()
		mt := time.Now().Add(-time.Duration(5-i) * time.Hour)
		os.Chtimes(f.Name(), mt, mt)
	}

	removed, err := ApplyRetention(dir, "testapp", RetentionPolicy{Count: 3})
	if err != nil {
		t.Fatal(err)
	}
	if removed != 2 {
		t.Errorf("expected 2 removed, got %d", removed)
	}

	entries, _ := os.ReadDir(projDir)
	if len(entries) != 3 {
		t.Errorf("expected 3 remaining, got %d", len(entries))
	}
}

func TestApplyRetentionByDays(t *testing.T) {
	dir := t.TempDir()
	projDir := filepath.Join(dir, "testapp")
	os.MkdirAll(projDir, 0755)

	oldTime := time.Now().AddDate(0, 0, -10)
	recentTime := time.Now().Add(-1 * time.Hour)

	f1, _ := os.Create(filepath.Join(projDir, "testapp-old.tar.gz"))
	f1.Close()
	os.Chtimes(f1.Name(), oldTime, oldTime)

	f2, _ := os.Create(filepath.Join(projDir, "testapp-recent.tar.gz"))
	f2.Close()
	os.Chtimes(f2.Name(), recentTime, recentTime)

	removed, err := ApplyRetention(dir, "testapp", RetentionPolicy{Count: 0, Days: 7})
	if err != nil {
		t.Fatal(err)
	}
	if removed != 1 {
		t.Errorf("expected 1 removed, got %d", removed)
	}

	entries, _ := os.ReadDir(projDir)
	if len(entries) != 1 {
		t.Errorf("expected 1 remaining, got %d", len(entries))
	}
}

func TestApplyRetentionIgnoresNonBackupFiles(t *testing.T) {
	dir := t.TempDir()
	projDir := filepath.Join(dir, "testapp")
	os.MkdirAll(projDir, 0755)

	keepNames := []string{"README.txt", "otherapp-20250101.tar.gz", "testapp-note.txt"}
	for _, name := range keepNames {
		f, err := os.Create(filepath.Join(projDir, name))
		if err != nil {
			t.Fatal(err)
		}
		f.Close()
	}

	for i := 0; i < 3; i++ {
		name := "testapp-20250101-00000" + string(rune('1'+i)) + ".tar.gz"
		f, err := os.Create(filepath.Join(projDir, name))
		if err != nil {
			t.Fatal(err)
		}
		f.Close()
		mt := time.Now().Add(-time.Duration(3-i) * time.Hour)
		os.Chtimes(f.Name(), mt, mt)
	}

	removed, err := ApplyRetention(dir, "testapp", RetentionPolicy{Count: 1})
	if err != nil {
		t.Fatal(err)
	}
	if removed != 2 {
		t.Errorf("expected 2 removed, got %d", removed)
	}

	for _, name := range keepNames {
		if _, err := os.Stat(filepath.Join(projDir, name)); err != nil {
			t.Fatalf("non-backup file %s should remain: %v", name, err)
		}
	}
}

func TestApplyRetentionEmptyDir(t *testing.T) {
	dir := t.TempDir()
	removed, err := ApplyRetention(dir, "nonexistent", RetentionPolicy{Count: 7})
	if err != nil {
		t.Fatal(err)
	}
	if removed != 0 {
		t.Errorf("expected 0 removed, got %d", removed)
	}
}

func TestApplyRetentionSortOrder(t *testing.T) {
	dir := t.TempDir()
	projDir := filepath.Join(dir, "testapp")
	os.MkdirAll(projDir, 0755)

	times := []time.Time{
		time.Now().Add(-5 * time.Hour),
		time.Now().Add(-1 * time.Hour),
		time.Now().Add(-3 * time.Hour),
	}

	for i, mt := range times {
		name := "testapp-2025010" + string(rune('1'+i)) + "-000001.tar.gz"
		f, _ := os.Create(filepath.Join(projDir, name))
		f.Close()
		os.Chtimes(f.Name(), mt, mt)
	}

	removed, err := ApplyRetention(dir, "testapp", RetentionPolicy{Count: 2})
	if err != nil {
		t.Fatal(err)
	}
	if removed != 1 {
		t.Fatalf("expected 1 removed, got %d", removed)
	}

	entries, _ := os.ReadDir(projDir)
	names := make([]string, len(entries))
	for i, e := range entries {
		names[i] = e.Name()
	}
	sort.Strings(names)

	expected := []string{"testapp-20250102-000001.tar.gz", "testapp-20250103-000001.tar.gz"}
	if len(names) != len(expected) {
		t.Fatalf("expected %v, got %v", expected, names)
	}
	for i := range expected {
		if expected[i] != names[i] {
			t.Errorf("expected[%d]=%s, got %s", i, expected[i], names[i])
		}
	}
}