// SPDX-License-Identifier: GPL-3.0-or-later

package apply

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

func write(t *testing.T, path, content string, mode os.FileMode) string {
	t.Helper()
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(content), mode); err != nil {
		t.Fatal(err)
	}
	return path
}

func TestCopyPreservesModeAndModTime(t *testing.T) {
	dir := t.TempDir()
	src := write(t, filepath.Join(dir, "a", "x.pdf"), "content", 0o640)
	old := time.Date(2026, 3, 4, 5, 6, 7, 0, time.UTC)
	if err := os.Chtimes(src, old, old); err != nil {
		t.Fatal(err)
	}
	dst := filepath.Join(dir, "b", "x.pdf")

	if err := copyFile(src, dst); err != nil {
		t.Fatal(err)
	}
	fi, err := os.Stat(dst)
	if err != nil {
		t.Fatal(err)
	}
	if b, _ := os.ReadFile(dst); string(b) != "content" {
		t.Errorf("content = %q", b)
	}
	if fi.Mode().Perm() != 0o640 {
		t.Errorf("mode = %v, want 0640", fi.Mode().Perm())
	}
	if !fi.ModTime().Equal(old) {
		t.Errorf("mtime = %v, want %v", fi.ModTime(), old)
	}
	if si, _ := os.Stat(src); si == nil {
		t.Error("copy removed its source")
	}
}

func TestCopyLeavesNoTempOnFailure(t *testing.T) {
	dir := t.TempDir()
	src := write(t, filepath.Join(dir, "x.pdf"), "content", 0o644)
	// A destination directory that is really a file: the rename must fail.
	blocked := write(t, filepath.Join(dir, "blocked"), "not a directory", 0o644)
	if err := copyFile(src, filepath.Join(blocked, "x.pdf")); err == nil {
		t.Fatal("copy into a non-directory succeeded")
	}
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	for _, e := range entries {
		if len(e.Name()) > 6 && e.Name()[:7] == ".krino-" {
			t.Errorf("a temporary file was left behind: %s", e.Name())
		}
	}
}

// TestMoveAcrossFilesystems exercises the EXDEV fallback. /dev/shm is a
// second filesystem on Linux; the test skips where there is none.
func TestMoveAcrossFilesystems(t *testing.T) {
	other, err := os.MkdirTemp("/dev/shm", "krino-apply-")
	if err != nil {
		t.Skip("no second filesystem available:", err)
	}
	defer os.RemoveAll(other)
	src := write(t, filepath.Join(other, "x.pdf"), "across", 0o644)
	dst := filepath.Join(t.TempDir(), "x.pdf")

	if err := moveFile(src, dst); err != nil {
		t.Fatal(err)
	}
	if b, err := os.ReadFile(dst); err != nil || string(b) != "across" {
		t.Errorf("destination = %q, %v", b, err)
	}
	if _, err := os.Stat(src); !os.IsNotExist(err) {
		t.Error("the source survived a cross-filesystem move")
	}
}