// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package webdav provides a WebDAV server implementation.
package webdav // import "golang.org/x/net/webdav"

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/http/httputil"
	"net/url"
	"path"
	"strconv"
	"strings"
	"sync"
	"time"

	model "github.com/cloudreve/Cloudreve/v3/models"
	"github.com/cloudreve/Cloudreve/v3/pkg/filesystem"
	"github.com/cloudreve/Cloudreve/v3/pkg/filesystem/fsctx"
	"github.com/cloudreve/Cloudreve/v3/pkg/util"
)

type Handler struct {
	// Prefix is the URL path prefix to strip from WebDAV resource paths.
	Prefix string
	// LockSystem is the lock management system.
	LockSystem map[uint]LockSystem
	// Logger is an optional error logger. If non-nil, it will be called
	// for all HTTP requests.
	Logger func(*http.Request, error)
	Mutex  *sync.Mutex
}

func (h *Handler) stripPrefix(p string, uid uint) (string, int, error) {
	if h.Prefix == "" {
		return p, http.StatusOK, nil
	}
	prefix := h.Prefix
	if r := strings.TrimPrefix(p, prefix); len(r) < len(p) {
		if len(r) == 0 {
			r = "/"
		}
		return util.RemoveSlash(r), http.StatusOK, nil
	}
	return p, http.StatusNotFound, errPrefixMismatch
}

// isPathExist 路径是否存在
func isPathExist(ctx context.Context, fs *filesystem.FileSystem, path string) (bool, FileInfo) {
	// 尝试目录
	if ok, folder := fs.IsPathExist(path); ok {
		return ok, folder
	}
	if ok, file := fs.IsFileExist(path); ok {
		return ok, file
	}
	return false, nil
}

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) {
	status, err := http.StatusBadRequest, errUnsupportedMethod
	h.Mutex.Lock()
	if h.LockSystem == nil {
		h.Mutex.Unlock()
		status, err = http.StatusInternalServerError, errNoLockSystem
	} else {
		// 检查并新建 LockSystem
		ls, ok := h.LockSystem[fs.User.ID]
		if !ok {
			h.LockSystem[fs.User.ID] = NewMemLS()
			ls = h.LockSystem[fs.User.ID]
		}
		h.Mutex.Unlock()

		switch r.Method {
		case "OPTIONS":
			status, err = h.handleOptions(w, r, fs)
		case "GET", "HEAD", "POST":
			status, err = h.handleGetHeadPost(w, r, fs)
		case "DELETE":
			status, err = h.handleDelete(w, r, fs)
		case "PUT":
			status, err = h.handlePut(w, r, fs)
		case "MKCOL":
			status, err = h.handleMkcol(w, r, fs)
		case "COPY", "MOVE":
			status, err = h.handleCopyMove(w, r, fs)
		case "LOCK":
			status, err = h.handleLock(w, r, fs, ls)
		case "UNLOCK":
			status, err = h.handleUnlock(w, r, fs, ls)
		case "PROPFIND":
			status, err = h.handlePropfind(w, r, fs, ls)
		case "PROPPATCH":
			status, err = h.handleProppatch(w, r, fs, ls)
		}
	}

	if status != 0 {
		w.WriteHeader(status)
		if status != http.StatusNoContent {
			w.Write([]byte(StatusText(status)))
		}
	}
	if h.Logger != nil {
		h.Logger(r, err)
	}
}

// OK
func (h *Handler) lock(now time.Time, root string, fs *filesystem.FileSystem, ls LockSystem) (token string, status int, err error) {
	//token, err = ls.Create(now, LockDetails{
	//	Root:      root,
	//	Duration:  infiniteTimeout,
	//	ZeroDepth: true,
	//})
	//if err != nil {
	//	if err == ErrLocked {
	//		return "", StatusLocked, err
	//	}
	//	return "", http.StatusInternalServerError, err
	//}

	return fmt.Sprintf("%d", time.Now().Unix()), 0, nil
}

// ok
func (h *Handler) confirmLocks(r *http.Request, src, dst string, fs *filesystem.FileSystem) (release func(), status int, err error) {

	//hdr := r.Header.Get("If")
	//h.Mutex.Lock()
	//ls,ok := h.LockSystem[fs.User.ID]
	//h.Mutex.Unlock()
	//if !ok{
	//	return nil, http.StatusInternalServerError, errNoLockSystem
	//}
	//
	//if hdr == "" {
	//	// An empty If header means that the client hasn't previously created locks.
	//	// Even if this client doesn't care about locks, we still need to check that
	//	// the resources aren't locked by another client, so we create temporary
	//	// locks that would conflict with another client's locks. These temporary
	//	// locks are unlocked at the end of the HTTP request.
	//	now, srcToken, dstToken := time.Now(), "", ""
	//	if src != "" {
	//		srcToken, status, err = h.lock(now, src, fs,ls)
	//		if err != nil {
	//			return nil, status, err
	//		}
	//	}
	//	if dst != "" {
	//		dstToken, status, err = h.lock(now, dst, fs,ls)
	//		if err != nil {
	//			if srcToken != "" {
	//				ls.Unlock(now, srcToken)
	//			}
	//			return nil, status, err
	//		}
	//	}
	//
	//	return func() {
	//		if dstToken != "" {
	//			ls.Unlock(now, dstToken)
	//		}
	//		if srcToken != "" {
	//			ls.Unlock(now, srcToken)
	//		}
	//	}, 0, nil
	//}
	//
	//ih, ok := parseIfHeader(hdr)
	//if !ok {
	//	return nil, http.StatusBadRequest, errInvalidIfHeader
	//}
	//// ih is a disjunction (OR) of ifLists, so any ifList will do.
	//for _, l := range ih.lists {
	//	lsrc := l.resourceTag
	//	if lsrc == "" {
	//		lsrc = src
	//	} else {
	//		u, err := url.Parse(lsrc)
	//		if err != nil {
	//			continue
	//		}
	//		//if u.Host != r.Host {
	//		//	continue
	//		//}
	//		lsrc, status, err = h.stripPrefix(u.Path, fs.User.ID)
	//		if err != nil {
	//			return nil, status, err
	//		}
	//	}
	//	release, err = ls.Confirm(
	//		time.Now(),
	//		lsrc,
	//		dst,
	//		l.conditions...,
	//	)
	//	if err == ErrConfirmationFailed {
	//		continue
	//	}
	//	if err != nil {
	//		return nil, http.StatusInternalServerError, err
	//	}
	//	return release, 0, nil
	//}
	//// Section 10.4.1 says that "If this header is evaluated and all state lists
	//// fail, then the request must fail with a 412 (Precondition Failed) status."
	//// We follow the spec even though the cond_put_corrupt_token test case from
	//// the litmus test warns on seeing a 412 instead of a 423 (Locked).
	//return nil, http.StatusPreconditionFailed, ErrLocked

	return func() {

	}, 0, nil
}

// OK
func (h *Handler) handleOptions(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}
	ctx := r.Context()
	allow := "OPTIONS, LOCK, PUT, MKCOL"
	if exist, fi := isPathExist(ctx, fs, reqPath); exist {
		if fi.IsDir() {
			allow = "OPTIONS, LOCK, DELETE, PROPPATCH, COPY, MOVE, UNLOCK, PROPFIND"
		} else {
			allow = "OPTIONS, LOCK, GET, HEAD, POST, DELETE, PROPPATCH, COPY, MOVE, UNLOCK, PROPFIND, PUT"
		}
	}
	w.Header().Set("Allow", allow)
	// http://www.webdav.org/specs/rfc4918.html#dav.compliance.classes
	w.Header().Set("DAV", "1, 2")
	// http://msdn.microsoft.com/en-au/library/cc250217.aspx
	w.Header().Set("MS-Author-Via", "DAV")
	return 0, nil
}

var proxy = &httputil.ReverseProxy{
	Director: func(request *http.Request) {
		if target, ok := request.Context().Value(fsctx.WebDAVProxyUrlCtx).(*url.URL); ok {
			request.URL.Scheme = target.Scheme
			request.URL.Host = target.Host
			request.URL.Path = target.Path
			request.URL.RawPath = target.RawPath
			request.URL.RawQuery = target.RawQuery
			request.Host = target.Host
			request.Header.Del("Authorization")
		}
	},
	ErrorHandler: func(writer http.ResponseWriter, request *http.Request, err error) {
		writer.WriteHeader(http.StatusInternalServerError)
	},
}

// OK
func (h *Handler) handleGetHeadPost(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	defer fs.Recycle()

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}

	ctx := r.Context()

	exist, file := fs.IsFileExist(reqPath)
	if !exist {
		return http.StatusNotFound, nil
	}
	fs.SetTargetFile(&[]model.File{*file})

	rs, err := fs.Preview(ctx, 0, false)
	if err != nil {
		if err == filesystem.ErrObjectNotExist {
			return http.StatusNotFound, err
		}
		return http.StatusInternalServerError, err
	}

	etag, err := findETag(ctx, fs, nil, reqPath, &fs.FileTarget[0])
	if err != nil {
		return http.StatusInternalServerError, err
	}
	w.Header().Set("ETag", etag)

	if !rs.Redirect {
		defer rs.Content.Close()
		// 获取文件内容
		http.ServeContent(w, r, reqPath, fs.FileTarget[0].UpdatedAt, rs.Content)
		return 0, nil
	}

	if application, ok := r.Context().Value(fsctx.WebDAVCtx).(*model.Webdav); ok && application.UseProxy {
		target, err := url.Parse(rs.URL)
		if err != nil {
			return http.StatusInternalServerError, err
		}

		r = r.Clone(context.WithValue(r.Context(), fsctx.WebDAVProxyUrlCtx, target))
		// 忽略反向代理在传输错误时报错
		defer func() {
			if err := recover(); err != nil && err != http.ErrAbortHandler {
				panic(err)
			}
		}()
		proxy.ServeHTTP(w, r)
	} else {
		http.Redirect(w, r, rs.URL, 301)
	}

	return 0, nil
}

// OK
func (h *Handler) handleDelete(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	defer fs.Recycle()

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}

	release, status, err := h.confirmLocks(r, reqPath, "", fs)
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	// 尝试作为文件删除
	if ok, file := fs.IsFileExist(reqPath); ok {
		if err := fs.Delete(ctx, []uint{}, []uint{file.ID}, false, false); err != nil {
			return http.StatusMethodNotAllowed, err
		}
		return http.StatusNoContent, nil
	}

	// 尝试作为目录删除
	if ok, folder := fs.IsPathExist(reqPath); ok {
		if err := fs.Delete(ctx, []uint{folder.ID}, []uint{}, false, false); err != nil {
			return http.StatusMethodNotAllowed, err
		}
		return http.StatusNoContent, nil
	}

	return http.StatusNotFound, nil
}

// OK
func (h *Handler) handlePut(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "", fs)
	if err != nil {
		return status, err
	}
	defer release()
	// TODO(rost): Support the If-Match, If-None-Match headers? See bradfitz'
	// comments in http.checkEtag.
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	ctx = context.WithValue(ctx, fsctx.HTTPCtx, r.Context())
	ctx = context.WithValue(ctx, fsctx.CancelFuncCtx, cancel)

	fileSize, err := strconv.ParseUint(r.Header.Get("Content-Length"), 10, 64)
	if err != nil {
		return http.StatusMethodNotAllowed, err
	}
	fileName := path.Base(reqPath)
	filePath := path.Dir(reqPath)
	fileData := fsctx.FileStream{
		MimeType:    r.Header.Get("Content-Type"),
		File:        r.Body,
		Size:        fileSize,
		Name:        fileName,
		VirtualPath: filePath,
	}

	// 判断文件是否已存在
	exist, originFile := fs.IsFileExist(reqPath)
	if exist {
		// 已存在，为更新操作

		// 检查此文件是否有软链接
		fileList, err := model.RemoveFilesWithSoftLinks([]model.File{*originFile})
		if err == nil && len(fileList) == 0 {
			// 如果包含软连接，应重新生成新文件副本，并更新source_name
			originFile.SourceName = fs.GenerateSavePath(ctx, &fileData)
			fileData.Mode &= ^fsctx.Overwrite
			fs.Use("AfterUpload", filesystem.HookUpdateSourceName)
			fs.Use("AfterUploadCanceled", filesystem.HookUpdateSourceName)
			fs.Use("AfterValidateFailed", filesystem.HookUpdateSourceName)
		}

		fs.Use("BeforeUpload", filesystem.HookResetPolicy)
		fs.Use("BeforeUpload", filesystem.HookValidateFile)
		fs.Use("BeforeUpload", filesystem.HookValidateCapacityDiff)
		fs.Use("AfterUploadCanceled", filesystem.HookCleanFileContent)
		fs.Use("AfterUploadCanceled", filesystem.HookClearFileSize)
		fs.Use("AfterUploadCanceled", filesystem.HookCancelContext)
		fs.Use("AfterUpload", filesystem.GenericAfterUpdate)
		fs.Use("AfterValidateFailed", filesystem.HookCleanFileContent)
		fs.Use("AfterValidateFailed", filesystem.HookClearFileSize)
		ctx = context.WithValue(ctx, fsctx.FileModelCtx, *originFile)
		fileData.Mode |= fsctx.Overwrite
	} else {
		// 尝试获取并重设存储策略
		fs.SetPolicyFromPath(filePath)

		// 给文件系统分配钩子
		fs.Use("BeforeUpload", filesystem.HookValidateFile)
		fs.Use("BeforeUpload", filesystem.HookValidateCapacity)
		fs.Use("AfterUploadCanceled", filesystem.HookDeleteTempFile)
		fs.Use("AfterUploadCanceled", filesystem.HookCancelContext)
		fs.Use("AfterUpload", filesystem.GenericAfterUpload)
		fs.Use("AfterValidateFailed", filesystem.HookDeleteTempFile)
	}

	// rclone 请求
	fs.Use("AfterUpload", filesystem.NewWebdavAfterUploadHook(r))

	// 执行上传
	err = fs.Upload(ctx, &fileData)
	if err != nil {
		return http.StatusMethodNotAllowed, err
	}

	etag, err := findETag(ctx, fs, nil, reqPath, fileData.Model.(*model.File))
	if err != nil {
		return http.StatusInternalServerError, err
	}
	w.Header().Set("ETag", etag)
	return http.StatusCreated, nil
}

// OK
func (h *Handler) handleMkcol(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	defer fs.Recycle()

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "", fs)
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	if r.ContentLength > 0 {
		return http.StatusUnsupportedMediaType, nil
	}

	if _, err := fs.CreateDirectory(ctx, reqPath); err != nil {
		return http.StatusConflict, err
	}
	return http.StatusCreated, nil
}

// OK
func (h *Handler) handleCopyMove(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
	defer fs.Recycle()

	hdr := r.Header.Get("Destination")
	if hdr == "" {
		return http.StatusBadRequest, errInvalidDestination
	}
	u, err := url.Parse(hdr)
	if err != nil {
		return http.StatusBadRequest, errInvalidDestination
	}
	//if u.Host != "" && u.Host != r.Host {
	//	return http.StatusBadGateway, errInvalidDestination
	//}

	src, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}

	dst, status, err := h.stripPrefix(u.Path, fs.User.ID)
	if err != nil {
		return status, err
	}

	if dst == "" {
		return http.StatusBadGateway, errInvalidDestination
	}
	if dst == src {
		return http.StatusForbidden, errDestinationEqualsSource
	}

	ctx := r.Context()

	isExist, target := isPathExist(ctx, fs, src)

	if !isExist {
		return http.StatusNotFound, nil
	}

	if r.Method == "COPY" {
		// Section 7.5.1 says that a COPY only needs to lock the destination,
		// not both destination and source. Strictly speaking, this is racy,
		// even though a COPY doesn't modify the source, if a concurrent
		// operation modifies the source. However, the litmus test explicitly
		// checks that COPYing a locked-by-another source is OK.
		release, status, err := h.confirmLocks(r, "", dst, fs)
		if err != nil {
			return status, err
		}
		defer release()

		// Section 9.8.3 says that "The COPY method on a collection without a Depth
		// header must act as if a Depth header with value "infinity" was included".
		depth := infiniteDepth
		if hdr := r.Header.Get("Depth"); hdr != "" {
			depth = parseDepth(hdr)
			if depth != 0 && depth != infiniteDepth {
				// Section 9.8.3 says that "A client may submit a Depth header on a
				// COPY on a collection with a value of "0" or "infinity"."
				return http.StatusBadRequest, errInvalidDepth
			}
		}
		status, err = copyFiles(ctx, fs, target, dst, r.Header.Get("Overwrite") != "F", depth, 0)
		if err != nil {
			return status, err
		}

		err = updateCopyMoveModtime(r, fs, dst)
		if err != nil {
			return http.StatusInternalServerError, err
		}
		return status, nil
	}

	// windows下，某些情况下（网盘根目录下）Office保存文件时附带的锁token只包含源文件，
	// 此处暂时去除了对dst锁的检查
	release, status, err := h.confirmLocks(r, src, "", fs)
	if err != nil {
		return status, err
	}
	defer release()

	// Section 9.9.2 says that "The MOVE method on a collection must act as if
	// a "Depth: infinity" header was used on it. A client must not submit a
	// Depth header on a MOVE on a collection with any value but "infinity"."
	if hdr := r.Header.Get("Depth"); hdr != "" {
		if parseDepth(hdr) != infiniteDepth {
			return http.StatusBadRequest, errInvalidDepth
		}
	}
	status, err = moveFiles(ctx, fs, target, dst, r.Header.Get("Overwrite") == "T")
	if err != nil {
		return status, err
	}

	err = updateCopyMoveModtime(r, fs, dst)
	if err != nil {
		return http.StatusInternalServerError, err
	}
	return status, nil
}

// OK
func (h *Handler) handleLock(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem, ls LockSystem) (retStatus int, retErr error) {
	defer fs.Recycle()

	duration, err := parseTimeout(r.Header.Get("Timeout"))
	if err != nil {
		return http.StatusBadRequest, err
	}

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}

	////ctx := r.Context()
	//token, ld, now, created := "", LockDetails{}, time.Now(), false
	//if li == (lockInfo{}) {
	//	// An empty lockInfo means to refresh the lock.
	//	ih, ok := parseIfHeader(r.Header.Get("If"))
	//	if !ok {
	//		return http.StatusBadRequest, errInvalidIfHeader
	//	}
	//	if len(ih.lists) == 1 && len(ih.lists[0].conditions) == 1 {
	//		token = ih.lists[0].conditions[0].Token
	//	}
	//	if token == "" {
	//		return http.StatusBadRequest, errInvalidLockToken
	//	}
	//	ld, err = ls.Refresh(now, token, duration)
	//	if err != nil {
	//		if err == ErrNoSuchLock {
	//			return http.StatusPreconditionFailed, err
	//		}
	//		return http.StatusInternalServerError, err
	//	}
	//
	//} else {
	//	// Section 9.10.3 says that "If no Depth header is submitted on a LOCK request,
	//	// then the request MUST act as if a "Depth:infinity" had been submitted."
	//	depth := infiniteDepth
	//	if hdr := r.Header.Get("Depth"); hdr != "" {
	//		depth = parseDepth(hdr)
	//		if depth != 0 && depth != infiniteDepth {
	//			// Section 9.10.3 says that "Values other than 0 or infinity must not be
	//			// used with the Depth header on a LOCK method".
	//			return http.StatusBadRequest, errInvalidDepth
	//		}
	//	}
	//	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	//	if err != nil {
	//		return status, err
	//	}
	//	ld = LockDetails{
	//		Root:      reqPath,
	//		Duration:  duration,
	//		OwnerXML:  li.Owner.InnerXML,
	//		ZeroDepth: depth == 0,
	//	}
	//	token, err = ls.Create(now, ld)
	//	if err != nil {
	//		if err == ErrLocked {
	//			return StatusLocked, err
	//		}
	//		return http.StatusInternalServerError, err
	//	}
	//	defer func() {
	//		if retErr != nil {
	//			ls.Unlock(now, token)
	//		}
	//	}()
	//
	//	// Create the resource if it didn't previously exist.
	//	//if _, err := h.FileSystem.Stat(ctx, reqPath); err != nil {
	//	//	f, err := h.FileSystem.OpenFile(ctx, reqPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
	//	//	if err != nil {
	//	//		// TODO: detect missing intermediate dirs and return http.StatusConflict?
	//	//		return http.StatusInternalServerError, err
	//	//	}
	//	//	f.Close()
	//	//	created = true
	//	//}
	//
	//	// http://www.webdav.org/specs/rfc4918.html#HEADER_Lock-Token says that the
	//	// Lock-Token value is a Coded-URL. We add angle brackets.
	//	w.Header().Set("Lock-Token", "<"+token+">")
	//}
	//
	//w.Header().Set("Content-Type", "application/xml; charset=utf-8")
	//if created {
	//	// This is "w.WriteHeader(http.StatusCreated)" and not "return
	//	// http.StatusCreated, nil" because we write our own (XML) response to w
	//	// and Handler.ServeHTTP would otherwise write "Created".
	//	w.WriteHeader(http.StatusCreated)
	//}

	writeLockInfo(w, fmt.Sprintf("%d", time.Now().UnixNano()), LockDetails{
		Duration: duration,
		OwnerXML: fs.User.Email,
		Root:     reqPath,
	})
	return 0, nil
}

// OK
func (h *Handler) handleUnlock(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem, ls LockSystem) (status int, err error) {
	defer fs.Recycle()
	return http.StatusNoContent, err

	//// http://www.webdav.org/specs/rfc4918.html#HEADER_Lock-Token says that the
	//// Lock-Token value is a Coded-URL. We strip its angle brackets.
	//t := r.Header.Get("Lock-Token")
	//if len(t) < 2 || t[0] != '<' || t[len(t)-1] != '>' {
	//	return http.StatusBadRequest, errInvalidLockToken
	//}
	//t = t[1 : len(t)-1]
	//
	//switch err = ls.Unlock(time.Now(), t); err {
	//case nil:
	//	return http.StatusNoContent, err
	//case ErrForbidden:
	//	return http.StatusForbidden, err
	//case ErrLocked:
	//	return StatusLocked, err
	//case ErrNoSuchLock:
	//	return http.StatusConflict, err
	//default:
	//	return http.StatusInternalServerError, err
	//}
}

// OK
func (h *Handler) handlePropfind(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem, ls LockSystem) (status int, err error) {
	defer fs.Recycle()

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}
	ctx := r.Context()
	ok, fi := isPathExist(ctx, fs, reqPath)
	if !ok {
		return http.StatusNotFound, err
	}

	depth := infiniteDepth
	if hdr := r.Header.Get("Depth"); hdr != "" {
		depth = parseDepth(hdr)
		if depth == invalidDepth {
			return http.StatusBadRequest, errInvalidDepth
		}
	}
	pf, status, err := readPropfind(r.Body)
	if err != nil {
		return status, err
	}

	mw := multistatusWriter{w: w}

	walkFn := func(reqPath string, info FileInfo, err error) error {

		if err != nil {
			return err
		}
		var pstats []Propstat
		if pf.Propname != nil {
			pnames, err := propnames(ctx, fs, ls, info)
			if err != nil {
				return err
			}
			pstat := Propstat{Status: http.StatusOK}
			for _, xmlname := range pnames {
				pstat.Props = append(pstat.Props, Property{XMLName: xmlname})
			}
			pstats = append(pstats, pstat)
		} else if pf.Allprop != nil {
			pstats, err = allprop(ctx, fs, ls, info, pf.Prop)
		} else {
			pstats, err = props(ctx, fs, ls, info, pf.Prop)
		}
		if err != nil {
			return err
		}
		href := path.Join(h.Prefix, reqPath)
		if href != "/" && info.IsDir() {
			href += "/"
		}
		return mw.write(makePropstatResponse(href, pstats))
	}

	walkErr := walkFS(ctx, fs, depth, reqPath, fi, walkFn)
	closeErr := mw.close()
	if walkErr != nil {
		return http.StatusInternalServerError, walkErr
	}
	if closeErr != nil {
		return http.StatusInternalServerError, closeErr
	}
	return 0, nil
}

func (h *Handler) handleProppatch(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem, ls LockSystem) (status int, err error) {
	defer fs.Recycle()

	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "", fs)
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	if exist, _ := isPathExist(ctx, fs, reqPath); !exist {
		return http.StatusNotFound, nil
	}
	patches, status, err := readProppatch(r.Body)
	if err != nil {
		return status, err
	}
	pstats, err := patch(ctx, fs, ls, reqPath, patches)
	if err != nil {
		return http.StatusInternalServerError, err
	}
	mw := multistatusWriter{w: w}
	writeErr := mw.write(makePropstatResponse(r.URL.Path, pstats))
	closeErr := mw.close()
	if writeErr != nil {
		return http.StatusInternalServerError, writeErr
	}
	if closeErr != nil {
		return http.StatusInternalServerError, closeErr
	}
	return 0, nil
}

func makePropstatResponse(href string, pstats []Propstat) *response {
	resp := response{
		Href:     []string{(&url.URL{Path: href}).EscapedPath()},
		Propstat: make([]propstat, 0, len(pstats)),
	}
	for _, p := range pstats {
		var xmlErr *xmlError
		if p.XMLError != "" {
			xmlErr = &xmlError{InnerXML: []byte(p.XMLError)}
		}
		resp.Propstat = append(resp.Propstat, propstat{
			Status:              fmt.Sprintf("HTTP/1.1 %d %s", p.Status, StatusText(p.Status)),
			Prop:                p.Props,
			ResponseDescription: p.ResponseDescription,
			Error:               xmlErr,
		})
	}
	return &resp
}

const (
	infiniteDepth = -1
	invalidDepth  = -2
)

// parseDepth maps the strings "0", "1" and "infinity" to 0, 1 and
// infiniteDepth. Parsing any other string returns invalidDepth.
//
// Different WebDAV methods have further constraints on valid depths:
//   - PROPFIND has no further restrictions, as per section 9.1.
//   - COPY accepts only "0" or "infinity", as per section 9.8.3.
//   - MOVE accepts only "infinity", as per section 9.9.2.
//   - LOCK accepts only "0" or "infinity", as per section 9.10.3.
//
// These constraints are enforced by the handleXxx methods.
func parseDepth(s string) int {
	switch s {
	case "0":
		return 0
	case "1":
		return 1
	case "infinity":
		return infiniteDepth
	}
	return invalidDepth
}

// http://www.webdav.org/specs/rfc4918.html#status.code.extensions.to.http11
const (
	StatusMulti               = 207
	StatusUnprocessableEntity = 422
	StatusLocked              = 423
	StatusFailedDependency    = 424
	StatusInsufficientStorage = 507
)

func StatusText(code int) string {
	switch code {
	case StatusMulti:
		return "Multi-Status"
	case StatusUnprocessableEntity:
		return "Unprocessable Entity"
	case StatusLocked:
		return "Locked"
	case StatusFailedDependency:
		return "Failed Dependency"
	case StatusInsufficientStorage:
		return "Insufficient Storage"
	}
	return http.StatusText(code)
}

var (
	errDestinationEqualsSource = errors.New("webdav: destination equals source")
	errDirectoryNotEmpty       = errors.New("webdav: directory not empty")
	errInvalidDepth            = errors.New("webdav: invalid depth")
	errInvalidDestination      = errors.New("webdav: invalid destination")
	errInvalidIfHeader         = errors.New("webdav: invalid If header")
	errInvalidLockInfo         = errors.New("webdav: invalid lock info")
	errInvalidLockToken        = errors.New("webdav: invalid lock token")
	errInvalidPropfind         = errors.New("webdav: invalid propfind")
	errInvalidProppatch        = errors.New("webdav: invalid proppatch")
	errInvalidResponse         = errors.New("webdav: invalid response")
	errInvalidTimeout          = errors.New("webdav: invalid timeout")
	errNoFileSystem            = errors.New("webdav: no file system")
	errNoLockSystem            = errors.New("webdav: no lock system")
	errNotADirectory           = errors.New("webdav: not a directory")
	errPrefixMismatch          = errors.New("webdav: prefix mismatch")
	errRecursionTooDeep        = errors.New("webdav: recursion too deep")
	errUnsupportedLockInfo     = errors.New("webdav: unsupported lock info")
	errUnsupportedMethod       = errors.New("webdav: unsupported method")
)
