// Glob returns the names of all files matching pattern or nil
// if there is no matching file. The syntax of patterns is the same
// as in path.Match. The pattern may describe hierarchical names such as
// /usr/*/bin/ed.
//
// Glob ignores file system errors such as I/O errors reading directories.
// The only possible returned error is ErrBadPattern, when pattern
// is malformed.
func Glob(fs vfs.FileSystem, pattern string) (matches []string, err error) {
	if !hasMeta(pattern) {
		if _, err = fs.Lstat(pattern); err != nil {
			return nil, nil
		}
		return []string{pattern}, nil
	}

	dir, file := path.Split(pattern)
	switch dir {
	case "":
		dir = "."
	case string(separator):
		// nothing
	default:
		dir = dir[0 : len(dir)-1] // chop off trailing separator
	}

	if !hasMeta(dir) {
		return glob(fs, dir, file, nil)
	}

	var m []string
	m, err = Glob(fs, dir)
	if err != nil {
		return
	}
	for _, d := range m {
		matches, err = glob(fs, d, file, matches)
		if err != nil {
			return
		}
	}
	return
}

// glob searches for files matching pattern in the directory dir
// and appends them to matches. If the directory cannot be
// opened, it returns the existing matches. New matches are
// added in lexicographical order.
func glob(fs vfs.FileSystem, dir, pattern string, matches []string) (m []string, e error) {
	m = matches
	fi, err := fs.Stat(dir)
	if err != nil {
		return
	}
	if !fi.IsDir() {
		return
	}
	fis, err := fs.ReadDir(dir)
	if err != nil {
		return
	}

	sort.Sort(byName(fis))

	for _, fi := range fis {
		n := fi.Name()
		matched, err := path.Match(path.Clean(pattern), n)
		if err != nil {
			return m, err
		}
		if matched {
			m = append(m, path.Join(dir, n))
		}
	}
	return
}

// Walk walks the filesystem rooted at root, calling walkFn for each file or
// directory in the filesystem, including root. All errors that arise visiting files
// and directories are filtered by walkFn. The files are walked in lexical
// order.
func Walk(fs vfs.FileSystem, root string, walkFn filepath.WalkFunc) error {
	info, err := fs.Lstat(root)
	if err != nil {
		return walkFn(root, nil, err)
	}
	return walk(fs, root, info, walkFn)
}

//VFSStaticServer returns a StaticServer to serve a Godoc virtual file system
//as defined in golang.org/x/tools/godoc/vfs . The Godoc vfs package contains
//implementations for FileSystem, Map and Zip File based virtual file systems
//Use errorHandlers to provide custom http.HandlerFunc to handle http.StatusNotFound
//and http.StatusInternalServerError or provide nil to use default implementation
//If a log.Logger is provided (ie. not nil), StaticServer does verbose logging
func VFSStaticServer(f vfs.FileSystem, errorHandlers map[int]http.HandlerFunc, logger *log.Logger) StaticServer {
	return StaticServer{
		stat: f.Lstat,
		readerfn: func(name string) (io.ReadSeeker, error) {
			rsc, err := f.Open(name)
			return io.ReadSeeker(rsc), err
		},
		errorHandlers: setupErrorHandlers(errorHandlers),
		logger:        logger,
	}
}

// readDirNames reads the directory named by dirname and returns
// a sorted list of directory entries.
func readDirNames(fs vfs.FileSystem, dirname string) ([]string, error) {
	fis, err := fs.ReadDir(dirname)
	if err != nil {
		return nil, err
	}
	names := make([]string, len(fis))
	for i := range fis {
		names[i] = fis[i].Name()
	}
	sort.Strings(names)
	return names, nil
}

func readJSONFileFS(fs vfs.FileSystem, file string, v interface{}) (err error) {
	f, err := fs.Open(file)
	if err != nil {
		return err
	}
	defer func() {
		err2 := f.Close()
		if err == nil {
			err = err2
		}
	}()
	return json.NewDecoder(f).Decode(v)
}

// readDirNames reads the directory named by dirname and returns
// a sorted list of directory entries.
func readDirNames(fs vfs.FileSystem, dirname string) ([]string, error) {
	dirname = filepath.ToSlash(dirname)
	fileInfoList, err := fs.ReadDir(dirname)
	if err != nil {
		return nil, err
	}
	var names []string
	for _, fi := range fileInfoList {
		names = append(names, fi.Name())
	}
	sort.Strings(names)
	return names, nil
}

// ReadCached reads a Tree's configuration from all of its source unit
// definition files (which may either be in a local VFS rooted at a
// .srclib-cache/<COMMITID> dir, or a remote VFS). It does not read
// the Srcfile; the Srcfile's directives are already accounted for in
// the cached source unit definition files.
//
// bdfs should be a VFS obtained from a call to
// (buildstore.RepoBuildStore).Commit.
func ReadCached(bdfs vfs.FileSystem) (*Tree, error) {
	if _, err := bdfs.Lstat("."); os.IsNotExist(err) {
		return nil, fmt.Errorf("build cache dir does not exist (did you run `srclib config` to create it)?")
	} else if err != nil {
		return nil, err
	}

	// Collect all **/*.unit.json files.
	var unitFiles []string
	unitSuffix := buildstore.DataTypeSuffix(unit.SourceUnit{})
	w := fs.WalkFS(".", rwvfs.Walkable(rwvfs.ReadOnly(bdfs)))
	for w.Step() {
		if err := w.Err(); err != nil {
			return nil, err
		}
		if path := w.Path(); strings.HasSuffix(path, unitSuffix) {
			unitFiles = append(unitFiles, path)
		}
	}

	// Parse units
	sort.Strings(unitFiles)
	units := make([]*unit.SourceUnit, len(unitFiles))
	par := parallel.NewRun(runtime.GOMAXPROCS(0))
	for i_, unitFile_ := range unitFiles {
		i, unitFile := i_, unitFile_
		par.Acquire()
		go func() {
			defer par.Release()
			f, err := bdfs.Open(unitFile)
			if err != nil {
				par.Error(err)
				return
			}
			if err := json.NewDecoder(f).Decode(&units[i]); err != nil {
				f.Close()
				par.Error(err)
				return
			}
			if err := f.Close(); err != nil {
				par.Error(err)
				return
			}
		}()
	}
	if err := par.Wait(); err != nil {
		return nil, err
	}
	return &Tree{SourceUnits: units}, nil
}

// GetFileWithOptions gets a file and observes the options specified
// in opt. If fs implements FileGetter, fs.GetFileWithOptions is
// called; otherwise the options are applied on the client side after
// fetching the whole file.
func GetFileWithOptions(fs vfs.FileSystem, path string, opt GetFileOptions) (*FileWithRange, error) {
	if fg, ok := fs.(FileGetter); ok {
		return fg.GetFileWithOptions(path, opt)
	}

	fi, err := fs.Lstat(path)
	if err != nil {
		return nil, err
	}

	e := newTreeEntry(fi)
	fwr := FileWithRange{TreeEntry: e}

	if fi.Mode().IsDir() {
		ee, err := readDir(fs, path, opt.RecurseSingleSubfolder, true)
		if err != nil {
			return nil, err
		}
		sort.Sort(TreeEntriesByTypeByName(ee))
		e.Entries = ee
	} else if fi.Mode().IsRegular() {
		f, err := fs.Open(path)
		if err != nil {
			return nil, err
		}
		defer f.Close()

		contents, err := ioutil.ReadAll(f)
		if err != nil {
			return nil, err
		}

		e.Contents = contents

		if empty := (GetFileOptions{}); opt != empty {
			fr, _, err := ComputeFileRange(contents, opt)
			if err != nil {
				return nil, err
			}

			// Trim to only requested range.
			e.Contents = e.Contents[fr.StartByte:fr.EndByte]
			fwr.FileRange = *fr
		}
	}

	return &fwr, nil
}

// readDir uses the passed vfs.FileSystem to read from starting at the base path.
// If recurseSingleSubfolder is true, it will descend and include sub-folders
// with a single sub-folder inside. first should always be set to true, other values are used internally.
func readDir(fs vfs.FileSystem, base string, recurseSingleSubfolder bool, first bool) ([]*TreeEntry, error) {
	entries, err := fs.ReadDir(base)
	if err != nil {
		return nil, err
	}
	if recurseSingleSubfolder && !first && !singleSubDir(entries) {
		return nil, nil
	}
	te := make([]*TreeEntry, len(entries))
	for i, fi := range entries {
		te[i] = newTreeEntry(fi)
		if fi.Mode().IsDir() && recurseSingleSubfolder {
			ee, err := readDir(fs, path.Join(base, fi.Name()), recurseSingleSubfolder, false)
			if err != nil {
				return nil, err
			}
			te[i].Entries = ee
		}
	}
	return te, nil
}

func uploadFile(local vfs.FileSystem, remote rwvfs.FileSystem, path string, fi os.FileInfo, dryRun bool) error {
	kb := float64(fi.Size()) / 1024
	if GlobalOpt.Verbose || dryRun {
		log.Printf("Uploading %s (%.1fkb)", path, kb)
	}
	if dryRun {
		return nil
	}

	lf, err := local.Open(path)
	if err != nil {
		return err
	}

	if err := rwvfs.MkdirAll(remote, filepath.Dir(path)); err != nil {
		return err
	}
	rf, err := remote.Create(path)
	if err != nil {
		return err
	}
	defer func() {
		if err := rf.Close(); err != nil {
			log.Println("Error closing after error:", err)
		}
	}()

	if _, err := io.Copy(rf, lf); err != nil {
		return err
	}

	if err := rf.Close(); err != nil {
		return err
	}

	if GlobalOpt.Verbose {
		log.Printf("Uploaded %s (%.1fkb)", path, kb)
	}
	return nil
}

func fetchFile(remote vfs.FileSystem, local rwvfs.FileSystem, path string, fi os.FileInfo, dryRun bool) error {
	kb := float64(fi.Size()) / 1024
	if GlobalOpt.Verbose || dryRun {
		log.Printf("Fetching %s (%.1fkb)", path, kb)
	}
	if dryRun {
		return nil
	}

	if err := rwvfs.MkdirAll(local, filepath.Dir(path)); err != nil {
		return err
	}

	rf, err := remote.Open(path)
	if err != nil {
		return fmt.Errorf("remote file: %s", err)
	}
	defer rf.Close()

	lf, err := local.Create(path)
	if err != nil {
		return fmt.Errorf("local file: %s", err)
	}
	defer lf.Close()

	if _, err := io.Copy(lf, rf); err != nil {
		return fmt.Errorf("copy from remote to local: %s", err)
	}

	if GlobalOpt.Verbose {
		log.Printf("Fetched %s (%.1fkb)", path, kb)
	}

	if err := lf.Close(); err != nil {
		return fmt.Errorf("local file: %s", err)
	}
	return nil
}

// walk recursively descends path, calling walkFn.
func walk(fs vfs.FileSystem, path string, info os.FileInfo, walkFn filepath.WalkFunc) error {
	err := walkFn(path, info, nil)
	if err != nil {
		if info.IsDir() && err == filepath.SkipDir {
			return nil
		}
		return err
	}

	if !info.IsDir() {
		return nil
	}

	names, err := readDirNames(fs, path)
	if err != nil {
		return walkFn(path, info, err)
	}

	for _, name := range names {
		filename := pathpkg.Join(path, name)
		fileInfo, err := fs.Lstat(filename)
		if err != nil {
			if err := walkFn(filename, fileInfo, err); err != nil && err != filepath.SkipDir {
				return err
			}
		} else {
			err = walk(fs, filename, fileInfo, walkFn)
			if err != nil {
				if !fileInfo.IsDir() || err != filepath.SkipDir {
					return err
				}
			}
		}
	}
	return nil
}