package sysfs

import (
	"io/fs"
	"os"
	"runtime"
	"syscall"
	"testing"

	"github.com/tetratelabs/wazero/internal/fsapi"
	"github.com/tetratelabs/wazero/internal/fstest"
	"github.com/tetratelabs/wazero/internal/testing/require"
)

func TestNewReadFS(t *testing.T) {
	tmpDir := t.TempDir()

	// Doesn't double-wrap file systems that are already read-only
	require.Equal(t, fsapi.UnimplementedFS{}, NewReadFS(fsapi.UnimplementedFS{}))

	// Wraps a fsapi.FS because it allows access to Write
	adapted := Adapt(os.DirFS(tmpDir))
	require.NotEqual(t, adapted, NewReadFS(adapted))

	// Wraps a writeable file system
	writeable := NewDirFS(tmpDir)
	readFS := NewReadFS(writeable)
	require.NotEqual(t, writeable, readFS)
}

func TestReadFS_String(t *testing.T) {
	writeable := NewDirFS("/tmp")

	readFS := NewReadFS(writeable)
	require.NotEqual(t, writeable, readFS)
	require.Equal(t, "/tmp", readFS.String())
}

func TestReadFS_Lstat(t *testing.T) {
	tmpDir := t.TempDir()
	require.NoError(t, fstest.WriteTestFiles(tmpDir))

	writeable := NewDirFS(tmpDir)
	for _, path := range []string{"animals.txt", "sub", "sub-link"} {
		require.EqualErrno(t, 0, writeable.Symlink(path, path+"-link"))
	}

	testFS := NewReadFS(writeable)

	testLstat(t, testFS)
}

func TestReadFS_MkDir(t *testing.T) {
	writeable := NewDirFS(t.TempDir())
	testFS := NewReadFS(writeable)

	err := testFS.Mkdir("mkdir", fs.ModeDir)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_Chmod(t *testing.T) {
	writeable := NewDirFS(t.TempDir())
	testFS := NewReadFS(writeable)

	err := testFS.Chmod("chmod", fs.ModeDir)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_Rename(t *testing.T) {
	tmpDir := t.TempDir()
	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)

	file1 := "file1"
	file1Path := joinPath(tmpDir, file1)
	file1Contents := []byte{1}
	err := os.WriteFile(file1Path, file1Contents, 0o600)
	require.NoError(t, err)

	file2 := "file2"
	file2Path := joinPath(tmpDir, file2)
	file2Contents := []byte{2}
	err = os.WriteFile(file2Path, file2Contents, 0o600)
	require.NoError(t, err)

	err = testFS.Rename(file1, file2)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_Rmdir(t *testing.T) {
	tmpDir := t.TempDir()
	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)

	path := "rmdir"
	realPath := joinPath(tmpDir, path)
	require.NoError(t, os.Mkdir(realPath, 0o700))

	err := testFS.Rmdir(path)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_Unlink(t *testing.T) {
	tmpDir := t.TempDir()
	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)

	path := "unlink"
	realPath := joinPath(tmpDir, path)
	require.NoError(t, os.WriteFile(realPath, []byte{}, 0o600))

	err := testFS.Unlink(path)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_UtimesNano(t *testing.T) {
	tmpDir := t.TempDir()
	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)

	path := "utimes"
	realPath := joinPath(tmpDir, path)
	require.NoError(t, os.WriteFile(realPath, []byte{}, 0o600))

	err := testFS.Utimens(path, nil, true)
	require.EqualErrno(t, syscall.EROFS, err)
}

func TestReadFS_Open_Read(t *testing.T) {
	t.Parallel()

	tmpDir := t.TempDir()
	require.NoError(t, fstest.WriteTestFiles(tmpDir))

	type test struct {
		name          string
		fs            fsapi.FS
		expectFileIno bool
		expectDirIno  bool
	}

	tests := []test{
		{
			name:          "DirFS",
			fs:            NewReadFS(NewDirFS(tmpDir)),
			expectFileIno: true,
			expectDirIno:  true,
		},
		{
			name:          "fstest.MapFS",
			fs:            NewReadFS(Adapt(fstest.FS)),
			expectFileIno: false,
			expectDirIno:  false,
		},
		{
			name:          "os.DirFS",
			fs:            NewReadFS(Adapt(os.DirFS(tmpDir))),
			expectFileIno: statSetsIno(),
			expectDirIno:  runtime.GOOS != "windows",
		},
		{
			name:          "mask(os.DirFS)",
			fs:            NewReadFS(Adapt(&MaskOsFS{os.DirFS(tmpDir)})),
			expectFileIno: statSetsIno(),
			expectDirIno:  runtime.GOOS != "windows",
		},
	}

	for _, tc := range tests {
		tc := tc

		t.Run(tc.name, func(t *testing.T) {
			testOpen_Read(t, tc.fs, tc.expectFileIno, tc.expectDirIno)
		})
	}
}

func TestReadFS_Stat(t *testing.T) {
	tmpDir := t.TempDir()
	require.NoError(t, fstest.WriteTestFiles(tmpDir))

	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)
	testStat(t, testFS)
}

func TestReadFS_Readlink(t *testing.T) {
	tmpDir := t.TempDir()
	require.NoError(t, fstest.WriteTestFiles(tmpDir))

	writeable := NewDirFS(tmpDir)
	testFS := NewReadFS(writeable)
	testReadlink(t, testFS, writeable)
}