package files

import (
	"errors"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
)

type failingReader struct {
	sent bool
}

func (r *failingReader) Read(buffer []byte) (int, error) {
	if !r.sent {
		r.sent = true
		return copy(buffer, "partial"), nil
	}
	return 0, errors.New("copy failed")
}

type closeFailingFile struct {
	*os.File
}

func (f *closeFailingFile) Close() error {
	_ = f.File.Close()
	return errors.New("close failed")
}

func TestSaveStoresFileUnderProjectDirectory(t *testing.T) {
	service := NewService(t.TempDir())

	stored, err := service.Save(12, "brief.md", strings.NewReader("hello"))

	require.NoError(t, err)
	require.Equal(t, "brief.md", stored.OriginalName)
	require.Contains(t, stored.RelativePath, "projects/12/")
	require.FileExists(t, stored.AbsolutePath)
}

func TestSaveNeutralizesPathTraversal(t *testing.T) {
	service := NewService(t.TempDir())

	stored, err := service.Save(12, "..\\..\\secret.txt", strings.NewReader("hello"))

	require.NoError(t, err)
	require.Equal(t, "secret.txt", stored.OriginalName)
	require.Contains(t, stored.RelativePath, "projects/12/")
}

func TestSaveRemovesTemporaryAndPartialFilesWhenCopyFails(t *testing.T) {
	storageRoot := t.TempDir()
	service := NewService(storageRoot)

	_, err := service.Save(12, "broken.bin", &failingReader{})

	require.ErrorContains(t, err, "copy failed")
	requireNoStoredFiles(t, storageRoot)
}

func TestSaveRemovesTemporaryFileWhenCloseFails(t *testing.T) {
	storageRoot := t.TempDir()
	service := NewService(storageRoot)
	service.createTemp = func(directory, pattern string) (stagedFile, error) {
		file, err := os.CreateTemp(directory, pattern)
		if err != nil {
			return nil, err
		}
		return &closeFailingFile{File: file}, nil
	}

	_, err := service.Save(12, "broken.bin", strings.NewReader("content"))

	require.ErrorContains(t, err, "close failed")
	requireNoStoredFiles(t, storageRoot)
}

func TestSaveRemovesTemporaryAndPartialFilesWhenRenameFails(t *testing.T) {
	storageRoot := t.TempDir()
	service := NewService(storageRoot)
	service.rename = func(oldPath, newPath string) error {
		require.NoError(t, os.WriteFile(newPath, []byte("partial final"), 0o600))
		return errors.New("rename failed")
	}

	_, err := service.Save(12, "broken.bin", strings.NewReader("content"))

	require.ErrorContains(t, err, "rename failed")
	requireNoStoredFiles(t, storageRoot)
}

func requireNoStoredFiles(t *testing.T, storageRoot string) {
	t.Helper()
	require.NoError(t, filepath.WalkDir(storageRoot, func(path string, entry fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if path != storageRoot && !entry.IsDir() {
			t.Fatalf("unexpected stored file after failure: %s", path)
		}
		return nil
	}))
}