// Package webdav provides an interface to the Webdav
// object storage system.
package webdav

// SetModTime might be possible
// https://stackoverflow.com/questions/3579608/webdav-can-a-client-modify-the-mtime-of-a-file
// ...support for a PROPSET to lastmodified (mind the missing get) which does the utime() call might be an option.
// For example the ownCloud WebDAV server does it that way.

import (
	"bytes"
	"context"
	"encoding/xml"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os/exec"
	"path"
	"strconv"
	"strings"
	"time"

	"github.com/pkg/errors"
	"github.com/rclone/rclone/backend/webdav/api"
	"github.com/rclone/rclone/backend/webdav/odrvcookie"
	"github.com/rclone/rclone/fs"
	"github.com/rclone/rclone/fs/config/configmap"
	"github.com/rclone/rclone/fs/config/configstruct"
	"github.com/rclone/rclone/fs/config/obscure"
	"github.com/rclone/rclone/fs/fserrors"
	"github.com/rclone/rclone/fs/fshttp"
	"github.com/rclone/rclone/fs/hash"
	"github.com/rclone/rclone/lib/pacer"
	"github.com/rclone/rclone/lib/rest"
)

const (
	minSleep      = 10 * time.Millisecond
	maxSleep      = 2 * time.Second
	decayConstant = 2   // bigger for slower decay, exponential
	defaultDepth  = "1" // depth for PROPFIND
)

// Register with Fs
func init() {
	fs.Register(&fs.RegInfo{
		Name:        "webdav",
		Description: "Webdav",
		NewFs:       NewFs,
		Options: []fs.Option{{
			Name:     "url",
			Help:     "URL of http host to connect to",
			Required: true,
			Examples: []fs.OptionExample{{
				Value: "https://example.com",
				Help:  "Connect to example.com",
			}},
		}, {
			Name: "vendor",
			Help: "Name of the Webdav site/service/software you are using",
			Examples: []fs.OptionExample{{
				Value: "nextcloud",
				Help:  "Nextcloud",
			}, {
				Value: "owncloud",
				Help:  "Owncloud",
			}, {
				Value: "sharepoint",
				Help:  "Sharepoint",
			}, {
				Value: "other",
				Help:  "Other site/service or software",
			}},
		}, {
			Name: "user",
			Help: "User name",
		}, {
			Name:       "pass",
			Help:       "Password.",
			IsPassword: true,
		}, {
			Name: "bearer_token",
			Help: "Bearer token instead of user/pass (e.g. a Macaroon)",
		}, {
			Name:     "bearer_token_command",
			Help:     "Command to run to get a bearer token",
			Advanced: true,
		}, {
			Name:    "delete_on_error",
			Default: false,
			Help: `Delete a partially uploaded file on upload failure.

Some webdav backends (eg rclone serve webdav) leave behind half
written files on error.  This flag causes them to be deleted if the
upload fails part of the way through.`,
			Advanced: true,
		}},
	})
}

// Options defines the configuration for this backend
type Options struct {
	URL                string `config:"url"`
	Vendor             string `config:"vendor"`
	User               string `config:"user"`
	Pass               string `config:"pass"`
	BearerToken        string `config:"bearer_token"`
	BearerTokenCommand string `config:"bearer_token_command"`
	DeleteOnError bool   `config:"delete_on_error"`
}

// Fs represents a remote webdav
type Fs struct {
	name               string        // name of this remote
	root               string        // the path we are working on
	opt                Options       // parsed options
	features           *fs.Features  // optional features
	endpoint           *url.URL      // URL of the host
	endpointURL        string        // endpoint as a string
	srv                *rest.Client  // the connection to the one drive server
	pacer              *fs.Pacer     // pacer for API calls
	precision          time.Duration // mod time precision
	canStream          bool          // set if can stream
	useOCMtime         bool          // set if can use X-OC-Mtime
	retryWithZeroDepth bool          // some vendors (sharepoint) won't list files when Depth is 1 (our default)
	hasMD5             bool          // set if can use owncloud style checksums for MD5
	hasSHA1            bool          // set if can use owncloud style checksums for SHA1
}

// Object describes a webdav object
//
// Will definitely have info but maybe not meta
type Object struct {
	fs          *Fs       // what this object is part of
	remote      string    // The remote path
	hasMetaData bool      // whether info below has been set
	size        int64     // size of the object
	modTime     time.Time // modification time of the object
	sha1        string    // SHA-1 of the object content if known
	md5         string    // MD5 of the object content if known
}

// ------------------------------------------------------------

// Name of the remote (as passed into NewFs)
func (f *Fs) Name() string {
	return f.name
}

// Root of the remote (as passed into NewFs)
func (f *Fs) Root() string {
	return f.root
}

// String converts this Fs to a string
func (f *Fs) String() string {
	return fmt.Sprintf("webdav root '%s'", f.root)
}

// Features returns the optional features of this Fs
func (f *Fs) Features() *fs.Features {
	return f.features
}

// retryErrorCodes is a slice of error codes that we will retry
var retryErrorCodes = []int{
	423, // Locked
	429, // Too Many Requests.
	500, // Internal Server Error
	502, // Bad Gateway
	503, // Service Unavailable
	504, // Gateway Timeout
	509, // Bandwidth Limit Exceeded
}

// shouldRetry returns a boolean as to whether this resp and err
// deserve to be retried.  It returns the err as a convenience
func (f *Fs) shouldRetry(resp *http.Response, err error) (bool, error) {
	// If we have a bearer token command and it has expired then refresh it
	if f.opt.BearerTokenCommand != "" && resp != nil && resp.StatusCode == 401 {
		fs.Debugf(f, "Bearer token expired: %v", err)
		authErr := f.fetchAndSetBearerToken()
		if authErr != nil {
			err = authErr
		}
		return true, err
	}
	return fserrors.ShouldRetry(err) || fserrors.ShouldRetryHTTP(resp, retryErrorCodes), err
}

// itemIsDir returns true if the item is a directory
//
// When a client sees a resourcetype it doesn't recognize it should
// assume it is a regular non-collection resource.  [WebDav book by
// Lisa Dusseault ch 7.5.8 p170]
func itemIsDir(item *api.Response) bool {
	if t := item.Props.Type; t != nil {
		if t.Space == "DAV:" && t.Local == "collection" {
			return true
		}
		fs.Debugf(nil, "Unknown resource type %q/%q on %q", t.Space, t.Local, item.Props.Name)
	}
	// the iscollection prop is a Microsoft extension, but if present it is a reliable indicator
	// if the above check failed - see #2716. This can be an integer or a boolean - see #2964
	if t := item.Props.IsCollection; t != nil {
		switch x := strings.ToLower(*t); x {
		case "0", "false":
			return false
		case "1", "true":
			return true
		default:
			fs.Debugf(nil, "Unknown value %q for IsCollection", x)
		}
	}
	return false
}

// readMetaDataForPath reads the metadata from the path
func (f *Fs) readMetaDataForPath(ctx context.Context, path string, depth string) (info *api.Prop, err error) {
	// FIXME how do we read back additional properties?
	opts := rest.Opts{
		Method: "PROPFIND",
		Path:   f.filePath(path),
		ExtraHeaders: map[string]string{
			"Depth": depth,
		},
		NoRedirect: true,
	}
	if f.hasMD5 || f.hasSHA1 {
		opts.Body = bytes.NewBuffer(owncloudProps)
	}
	var result api.Multistatus
	var resp *http.Response
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallXML(ctx, &opts, nil, &result)
		return f.shouldRetry(resp, err)
	})
	if apiErr, ok := err.(*api.Error); ok {
		// does not exist
		switch apiErr.StatusCode {
		case http.StatusNotFound:
			if f.retryWithZeroDepth && depth != "0" {
				return f.readMetaDataForPath(ctx, path, "0")
			}
			return nil, fs.ErrorObjectNotFound
		case http.StatusMovedPermanently, http.StatusFound, http.StatusSeeOther:
			// Some sort of redirect - go doesn't deal with these properly (it resets
			// the method to GET).  However we can assume that if it was redirected the
			// object was not found.
			return nil, fs.ErrorObjectNotFound
		}
	}
	if err != nil {
		return nil, errors.Wrap(err, "read metadata failed")
	}
	if len(result.Responses) < 1 {
		return nil, fs.ErrorObjectNotFound
	}
	item := result.Responses[0]
	if !item.Props.StatusOK() {
		return nil, fs.ErrorObjectNotFound
	}
	if itemIsDir(&item) {
		return nil, fs.ErrorNotAFile
	}
	return &item.Props, nil
}

// errorHandler parses a non 2xx error response into an error
func errorHandler(resp *http.Response) error {
	body, err := rest.ReadBody(resp)
	if err != nil {
		return errors.Wrap(err, "error when trying to read error from body")
	}
	// Decode error response
	errResponse := new(api.Error)
	err = xml.Unmarshal(body, &errResponse)
	if err != nil {
		// set the Message to be the body if can't parse the XML
		errResponse.Message = strings.TrimSpace(string(body))
	}
	errResponse.Status = resp.Status
	errResponse.StatusCode = resp.StatusCode
	return errResponse
}

// addSlash makes sure s is terminated with a / if non empty
func addSlash(s string) string {
	if s != "" && !strings.HasSuffix(s, "/") {
		s += "/"
	}
	return s
}

// filePath returns a file path (f.root, file)
func (f *Fs) filePath(file string) string {
	return rest.URLPathEscape(path.Join(f.root, file))
}

// dirPath returns a directory path (f.root, dir)
func (f *Fs) dirPath(dir string) string {
	return addSlash(f.filePath(dir))
}

// filePath returns a file path (f.root, remote)
func (o *Object) filePath() string {
	return o.fs.filePath(o.remote)
}

// NewFs constructs an Fs from the path, container:path
func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, error) {
	// Parse config into Options struct
	opt := new(Options)
	err := configstruct.Set(m, opt)
	if err != nil {
		return nil, err
	}
	rootIsDir := strings.HasSuffix(root, "/")
	root = strings.Trim(root, "/")

	if !strings.HasSuffix(opt.URL, "/") {
		opt.URL += "/"
	}
	if opt.Pass != "" {
		var err error
		opt.Pass, err = obscure.Reveal(opt.Pass)
		if err != nil {
			return nil, errors.Wrap(err, "couldn't decrypt password")
		}
	}
	if opt.Vendor == "" {
		opt.Vendor = "other"
	}
	root = strings.Trim(root, "/")

	// Parse the endpoint
	u, err := url.Parse(opt.URL)
	if err != nil {
		return nil, err
	}

	f := &Fs{
		name:        name,
		root:        root,
		opt:         *opt,
		endpoint:    u,
		endpointURL: u.String(),
		srv:         rest.NewClient(fshttp.NewClient(ctx)).SetRoot(u.String()),
		pacer:       fs.NewPacer(ctx, pacer.NewDefault(pacer.MinSleep(minSleep), pacer.MaxSleep(maxSleep), pacer.DecayConstant(decayConstant))),
		precision:   fs.ModTimeNotSupported,
	}
	f.features = (&fs.Features{
		CanHaveEmptyDirectories: true,
	}).Fill(ctx, f)
	if opt.User != "" || opt.Pass != "" {
		f.srv.SetUserPass(opt.User, opt.Pass)
	} else if opt.BearerToken != "" {
		f.setBearerToken(opt.BearerToken)
	} else if f.opt.BearerTokenCommand != "" {
		err = f.fetchAndSetBearerToken()
		if err != nil {
			return nil, err
		}
	}
	f.srv.SetErrorHandler(errorHandler)
	err = f.setQuirks(ctx, opt.Vendor)
	if err != nil {
		return nil, err
	}
	f.srv.SetHeader("Referer", u.String())

	if root != "" && !rootIsDir {
		// Check to see if the root actually an existing file
		remote := path.Base(root)
		f.root = path.Dir(root)
		if f.root == "." {
			f.root = ""
		}
		_, err := f.NewObject(ctx, remote)
		if err != nil {
			if errors.Cause(err) == fs.ErrorObjectNotFound || errors.Cause(err) == fs.ErrorNotAFile {
				// File doesn't exist so return old f
				f.root = root
				return f, nil
			}
			return nil, err
		}
		// return an error with an fs which points to the parent
		return f, fs.ErrorIsFile
	}
	return f, nil
}

// sets the BearerToken up
func (f *Fs) setBearerToken(token string) {
	f.opt.BearerToken = token
	f.srv.SetHeader("Authorization", "Bearer "+token)
}

// fetch the bearer token using the command
func (f *Fs) fetchBearerToken(cmd string) (string, error) {
	var (
		args   = strings.Split(cmd, " ")
		stdout bytes.Buffer
		stderr bytes.Buffer
		c      = exec.Command(args[0], args[1:]...)
	)
	c.Stdout = &stdout
	c.Stderr = &stderr
	var (
		err          = c.Run()
		stdoutString = strings.TrimSpace(stdout.String())
		stderrString = strings.TrimSpace(stderr.String())
	)
	if err != nil {
		if stderrString == "" {
			stderrString = stdoutString
		}
		return "", errors.Wrapf(err, "failed to get bearer token using %q: %s", f.opt.BearerTokenCommand, stderrString)
	}
	return stdoutString, nil
}

// fetch the bearer token and set it if successful
func (f *Fs) fetchAndSetBearerToken() error {
	if f.opt.BearerTokenCommand == "" {
		return nil
	}
	token, err := f.fetchBearerToken(f.opt.BearerTokenCommand)
	if err != nil {
		return err
	}
	f.setBearerToken(token)
	return nil
}

// setQuirks adjusts the Fs for the vendor passed in
func (f *Fs) setQuirks(ctx context.Context, vendor string) error {
	switch vendor {
	case "owncloud":
		f.canStream = true
		f.precision = time.Second
		f.useOCMtime = true
		f.hasMD5 = true
		f.hasSHA1 = true
	case "nextcloud":
		f.precision = time.Second
		f.useOCMtime = true
		f.hasSHA1 = true
	case "sharepoint":
		// To mount sharepoint, two Cookies are required
		// They have to be set instead of BasicAuth
		f.srv.RemoveHeader("Authorization") // We don't need this Header if using cookies
		spCk := odrvcookie.New(f.opt.User, f.opt.Pass, f.endpointURL)
		spCookies, err := spCk.Cookies(ctx)
		if err != nil {
			return err
		}

		odrvcookie.NewRenew(12*time.Hour, func() {
			spCookies, err := spCk.Cookies(ctx)
			if err != nil {
				fs.Errorf("could not renew cookies: %s", err.Error())
				return
			}
			f.srv.SetCookie(&spCookies.FedAuth, &spCookies.RtFa)
			fs.Debugf(spCookies, "successfully renewed sharepoint cookies")
		})

		f.srv.SetCookie(&spCookies.FedAuth, &spCookies.RtFa)

		// sharepoint, unlike the other vendors, only lists files if the depth header is set to 0
		// however, rclone defaults to 1 since it provides recursive directory listing
		// to determine if we may have found a file, the request has to be resent
		// with the depth set to 0
		f.retryWithZeroDepth = true
	case "other":
	default:
		fs.Debugf(f, "Unknown vendor %q", vendor)
	}

	// Remove PutStream from optional features
	if !f.canStream {
		f.features.PutStream = nil
	}
	return nil
}

// Return an Object from a path
//
// If it can't be found it returns the error fs.ErrorObjectNotFound.
func (f *Fs) newObjectWithInfo(ctx context.Context, remote string, info *api.Prop) (fs.Object, error) {
	o := &Object{
		fs:     f,
		remote: remote,
	}
	var err error
	if info != nil {
		// Set info
		err = o.setMetaData(info)
	} else {
		err = o.readMetaData(ctx) // reads info and meta, returning an error
	}
	if err != nil {
		return nil, err
	}
	return o, nil
}

// NewObject finds the Object at remote.  If it can't be found
// it returns the error fs.ErrorObjectNotFound.
func (f *Fs) NewObject(ctx context.Context, remote string) (fs.Object, error) {
	return f.newObjectWithInfo(ctx, remote, nil)
}

// Read the normal props, plus the checksums
//
// <oc:checksums><oc:checksum>SHA1:f572d396fae9206628714fb2ce00f72e94f2258f MD5:b1946ac92492d2347c6235b4d2611184 ADLER32:084b021f</oc:checksum></oc:checksums>
var owncloudProps = []byte(`<?xml version="1.0"?>
<d:propfind  xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns" xmlns:nc="http://nextcloud.org/ns">
 <d:prop>
  <d:displayname />
  <d:getlastmodified />
  <d:getcontentlength />
  <d:resourcetype />
  <d:getcontenttype />
  <oc:checksums />
 </d:prop>
</d:propfind>
`)

// list the objects into the function supplied
//
// If directories is set it only sends directories
// User function to process a File item from listAll
//
// Should return true to finish processing
type listAllFn func(string, bool, *api.Prop) bool

// Lists the directory required calling the user function on each item found
//
// If the user fn ever returns true then it early exits with found = true
func (f *Fs) listAll(ctx context.Context, dir string, directoriesOnly bool, filesOnly bool, depth string, fn listAllFn) (found bool, err error) {
	opts := rest.Opts{
		Method: "PROPFIND",
		Path:   f.dirPath(dir), // FIXME Should not start with /
		ExtraHeaders: map[string]string{
			"Depth": depth,
		},
	}
	if f.hasMD5 || f.hasSHA1 {
		opts.Body = bytes.NewBuffer(owncloudProps)
	}
	var result api.Multistatus
	var resp *http.Response
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallXML(ctx, &opts, nil, &result)
		return f.shouldRetry(resp, err)
	})
	if err != nil {
		if apiErr, ok := err.(*api.Error); ok {
			// does not exist
			if apiErr.StatusCode == http.StatusNotFound {
				if f.retryWithZeroDepth && depth != "0" {
					return f.listAll(ctx, dir, directoriesOnly, filesOnly, "0", fn)
				}
				return found, fs.ErrorDirNotFound
			}
		}
		return found, errors.Wrap(err, "couldn't list files")
	}
	//fmt.Printf("result = %#v", &result)
	baseURL, err := rest.URLJoin(f.endpoint, opts.Path)
	if err != nil {
		return false, errors.Wrap(err, "couldn't join URL")
	}
	for i := range result.Responses {
		item := &result.Responses[i]
		isDir := itemIsDir(item)

		// Find name
		u, err := rest.URLJoin(baseURL, item.Href)
		if err != nil {
			fs.Errorf(nil, "URL Join failed for %q and %q: %v", baseURL, item.Href, err)
			continue
		}
		// Make sure directories end with a /
		if isDir {
			u.Path = addSlash(u.Path)
		}
		if !strings.HasPrefix(u.Path, baseURL.Path) {
			fs.Debugf(nil, "Item with unknown path received: %q, %q", u.Path, baseURL.Path)
			continue
		}
		remote := path.Join(dir, u.Path[len(baseURL.Path):])
		if strings.HasSuffix(remote, "/") {
			remote = remote[:len(remote)-1]
		}

		// the listing contains info about itself which we ignore
		if remote == dir {
			continue
		}

		// Check OK
		if !item.Props.StatusOK() {
			fs.Debugf(remote, "Ignoring item with bad status %q", item.Props.Status)
			continue
		}

		if isDir {
			if filesOnly {
				continue
			}
		} else {
			if directoriesOnly {
				continue
			}
		}
		// 	item.Name = restoreReservedChars(item.Name)
		if fn(remote, isDir, &item.Props) {
			found = true
			break
		}
	}
	return
}

// List the objects and directories in dir into entries.  The
// entries can be returned in any order but should be for a
// complete directory.
//
// dir should be "" to list the root, and should not have
// trailing slashes.
//
// This should return ErrDirNotFound if the directory isn't
// found.
func (f *Fs) List(ctx context.Context, dir string) (entries fs.DirEntries, err error) {
	var iErr error
	_, err = f.listAll(ctx, dir, false, false, defaultDepth, func(remote string, isDir bool, info *api.Prop) bool {
		if isDir {
			d := fs.NewDir(remote, time.Time(info.Modified))
			// .SetID(info.ID)
			// FIXME more info from dir? can set size, items?
			entries = append(entries, d)
		} else {
			o, err := f.newObjectWithInfo(ctx, remote, info)
			if err != nil {
				iErr = err
				return true
			}
			entries = append(entries, o)
		}
		return false
	})
	if err != nil {
		return nil, err
	}
	if iErr != nil {
		return nil, iErr
	}
	return entries, nil
}

// Creates from the parameters passed in a half finished Object which
// must have setMetaData called on it
//
// Used to create new objects
func (f *Fs) createObject(remote string, modTime time.Time, size int64) (o *Object) {
	// Temporary Object under construction
	o = &Object{
		fs:      f,
		remote:  remote,
		size:    size,
		modTime: modTime,
	}
	return o
}

// Put the object
//
// Copy the reader in to the new object which is returned
//
// The new object may have been created if an error is returned
func (f *Fs) Put(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
	o := f.createObject(src.Remote(), src.ModTime(ctx), src.Size())
	return o, o.Update(ctx, in, src, options...)
}

// PutStream uploads to the remote path with the modTime given of indeterminate size
func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
	return f.Put(ctx, in, src, options...)
}

// mkParentDir makes the parent of the native path dirPath if
// necessary and any directories above that
func (f *Fs) mkParentDir(ctx context.Context, dirPath string) (err error) {
	// defer log.Trace(dirPath, "")("err=%v", &err)
	// chop off trailing / if it exists
	if strings.HasSuffix(dirPath, "/") {
		dirPath = dirPath[:len(dirPath)-1]
	}
	parent := path.Dir(dirPath)
	if parent == "." {
		parent = ""
	}
	return f.mkdir(ctx, parent)
}

// _dirExists - list dirPath to see if it exists
//
// dirPath should be a native path ending in a /
func (f *Fs) _dirExists(ctx context.Context, dirPath string) (exists bool) {
	opts := rest.Opts{
		Method: "PROPFIND",
		Path:   dirPath,
		ExtraHeaders: map[string]string{
			"Depth": "0",
		},
	}
	var result api.Multistatus
	var resp *http.Response
	var err error
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallXML(ctx, &opts, nil, &result)
		return f.shouldRetry(resp, err)
	})
	return err == nil
}

// low level mkdir, only makes the directory, doesn't attempt to create parents
func (f *Fs) _mkdir(ctx context.Context, dirPath string) error {
	// We assume the root is already created
	if dirPath == "" {
		return nil
	}
	// Collections must end with /
	if !strings.HasSuffix(dirPath, "/") {
		dirPath += "/"
	}
	opts := rest.Opts{
		Method:     "MKCOL",
		Path:       dirPath,
		NoResponse: true,
	}
	err := f.pacer.Call(func() (bool, error) {
		resp, err := f.srv.Call(ctx, &opts)
		return f.shouldRetry(resp, err)
	})
	if apiErr, ok := err.(*api.Error); ok {
		// Check if it already exists. The response code for this isn't
		// defined in the RFC so the implementations vary wildly.
		//
		// owncloud returns 423/StatusLocked if the create is already in progress
		if apiErr.StatusCode == http.StatusMethodNotAllowed || apiErr.StatusCode == http.StatusNotAcceptable || apiErr.StatusCode == http.StatusLocked {
			return nil
		}
		// 4shared returns a 409/StatusConflict here which clashes
		// horribly with the intermediate paths don't exist meaning. So
		// check to see if actually exists. This will correct other
		// error codes too.
		if f._dirExists(ctx, dirPath) {
			return nil
		}

	}
	return err
}

// mkdir makes the directory and parents using native paths
func (f *Fs) mkdir(ctx context.Context, dirPath string) (err error) {
	// defer log.Trace(dirPath, "")("err=%v", &err)
	err = f._mkdir(ctx, dirPath)
	if apiErr, ok := err.(*api.Error); ok {
		// parent does not exist so create it first then try again
		if apiErr.StatusCode == http.StatusConflict {
			err = f.mkParentDir(ctx, dirPath)
			if err == nil {
				err = f._mkdir(ctx, dirPath)
			}
		}
	}
	return err
}

// Mkdir creates the directory if it doesn't exist
func (f *Fs) Mkdir(ctx context.Context, dir string) error {
	dirPath := f.dirPath(dir)
	return f.mkdir(ctx, dirPath)
}

// dirNotEmpty returns true if the directory exists and is not Empty
//
// if the directory does not exist then err will be ErrorDirNotFound
func (f *Fs) dirNotEmpty(ctx context.Context, dir string) (found bool, err error) {
	return f.listAll(ctx, dir, false, false, defaultDepth, func(remote string, isDir bool, info *api.Prop) bool {
		return true
	})
}

// purgeCheck removes the root directory, if check is set then it
// refuses to do so if it has anything in
func (f *Fs) purgeCheck(ctx context.Context, dir string, check bool) error {
	if check {
		notEmpty, err := f.dirNotEmpty(ctx, dir)
		if err != nil {
			return err
		}
		if notEmpty {
			return fs.ErrorDirectoryNotEmpty
		}
	}
	opts := rest.Opts{
		Method:     "DELETE",
		Path:       f.dirPath(dir),
		NoResponse: true,
	}
	var resp *http.Response
	var err error
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallXML(ctx, &opts, nil, nil)
		return f.shouldRetry(resp, err)
	})
	if err != nil {
		return errors.Wrap(err, "rmdir failed")
	}
	// FIXME parse Multistatus response
	return nil
}

// Rmdir deletes the root folder
//
// Returns an error if it isn't empty
func (f *Fs) Rmdir(ctx context.Context, dir string) error {
	return f.purgeCheck(ctx, dir, true)
}

// Precision return the precision of this Fs
func (f *Fs) Precision() time.Duration {
	return f.precision
}

// Copy or Move src to this remote using server-side copy operations.
//
// This is stored with the remote path given
//
// It returns the destination Object and a possible error
//
// Will only be called if src.Fs().Name() == f.Name()
//
// If it isn't possible then return fs.ErrorCantCopy/fs.ErrorCantMove
func (f *Fs) copyOrMove(ctx context.Context, src fs.Object, remote string, method string) (fs.Object, error) {
	srcObj, ok := src.(*Object)
	if !ok {
		fs.Debugf(src, "Can't copy - not same remote type")
		if method == "COPY" {
			return nil, fs.ErrorCantCopy
		}
		return nil, fs.ErrorCantMove
	}
	dstPath := f.filePath(remote)
	err := f.mkParentDir(ctx, dstPath)
	if err != nil {
		return nil, errors.Wrap(err, "Copy mkParentDir failed")
	}
	destinationURL, err := rest.URLJoin(f.endpoint, dstPath)
	if err != nil {
		return nil, errors.Wrap(err, "copyOrMove couldn't join URL")
	}
	var resp *http.Response
	opts := rest.Opts{
		Method:     method,
		Path:       srcObj.filePath(),
		NoResponse: true,
		ExtraHeaders: map[string]string{
			"Destination": destinationURL.String(),
			"Overwrite":   "F",
		},
	}
	if f.useOCMtime {
		opts.ExtraHeaders["X-OC-Mtime"] = fmt.Sprintf("%d", src.ModTime(ctx).Unix())
	}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.Call(ctx, &opts)
		return f.shouldRetry(resp, err)
	})
	if err != nil {
		return nil, errors.Wrap(err, "Copy call failed")
	}
	dstObj, err := f.NewObject(ctx, remote)
	if err != nil {
		return nil, errors.Wrap(err, "Copy NewObject failed")
	}
	return dstObj, nil
}

// Copy src to this remote using server-side copy operations.
//
// This is stored with the remote path given
//
// It returns the destination Object and a possible error
//
// Will only be called if src.Fs().Name() == f.Name()
//
// If it isn't possible then return fs.ErrorCantCopy
func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
	return f.copyOrMove(ctx, src, remote, "COPY")
}

// Purge deletes all the files in the directory
//
// Optional interface: Only implement this if you have a way of
// deleting all the files quicker than just running Remove() on the
// result of List()
func (f *Fs) Purge(ctx context.Context, dir string) error {
	return f.purgeCheck(ctx, dir, false)
}

// Move src to this remote using server-side move operations.
//
// This is stored with the remote path given
//
// It returns the destination Object and a possible error
//
// Will only be called if src.Fs().Name() == f.Name()
//
// If it isn't possible then return fs.ErrorCantMove
func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
	return f.copyOrMove(ctx, src, remote, "MOVE")
}

// DirMove moves src, srcRemote to this remote at dstRemote
// using server-side move operations.
//
// Will only be called if src.Fs().Name() == f.Name()
//
// If it isn't possible then return fs.ErrorCantDirMove
//
// If destination exists then return fs.ErrorDirExists
func (f *Fs) DirMove(ctx context.Context, src fs.Fs, srcRemote, dstRemote string) error {
	srcFs, ok := src.(*Fs)
	if !ok {
		fs.Debugf(srcFs, "Can't move directory - not same remote type")
		return fs.ErrorCantDirMove
	}
	srcPath := srcFs.filePath(srcRemote)
	dstPath := f.filePath(dstRemote)

	// Check if destination exists
	_, err := f.dirNotEmpty(ctx, dstRemote)
	if err == nil {
		return fs.ErrorDirExists
	}
	if err != fs.ErrorDirNotFound {
		return errors.Wrap(err, "DirMove dirExists dst failed")
	}

	// Make sure the parent directory exists
	err = f.mkParentDir(ctx, dstPath)
	if err != nil {
		return errors.Wrap(err, "DirMove mkParentDir dst failed")
	}

	destinationURL, err := rest.URLJoin(f.endpoint, dstPath)
	if err != nil {
		return errors.Wrap(err, "DirMove couldn't join URL")
	}

	var resp *http.Response
	opts := rest.Opts{
		Method:     "MOVE",
		Path:       addSlash(srcPath),
		NoResponse: true,
		ExtraHeaders: map[string]string{
			"Destination": addSlash(destinationURL.String()),
			"Overwrite":   "F",
		},
	}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.Call(ctx, &opts)
		return f.shouldRetry(resp, err)
	})
	if err != nil {
		return errors.Wrap(err, "DirMove MOVE call failed")
	}
	return nil
}

// Hashes returns the supported hash sets.
func (f *Fs) Hashes() hash.Set {
	hashes := hash.Set(hash.None)
	if f.hasMD5 {
		hashes.Add(hash.MD5)
	}
	if f.hasSHA1 {
		hashes.Add(hash.SHA1)
	}
	return hashes
}

// About gets quota information
func (f *Fs) About(ctx context.Context) (*fs.Usage, error) {
	opts := rest.Opts{
		Method: "PROPFIND",
		Path:   "",
		ExtraHeaders: map[string]string{
			"Depth": "0",
		},
	}
	opts.Body = bytes.NewBuffer([]byte(`<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
 <D:prop>
  <D:quota-available-bytes/>
  <D:quota-used-bytes/>
 </D:prop>
</D:propfind>
`))
	var q api.Quota
	var resp *http.Response
	var err error
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallXML(ctx, &opts, nil, &q)
		return f.shouldRetry(resp, err)
	})
	if err != nil {
		return nil, errors.Wrap(err, "about call failed")
	}
	usage := &fs.Usage{}
	if i, err := strconv.ParseInt(q.Used, 10, 64); err == nil && i >= 0 {
		usage.Used = fs.NewUsageValue(i)
	}
	if i, err := strconv.ParseInt(q.Available, 10, 64); err == nil && i >= 0 {
		usage.Free = fs.NewUsageValue(i)
	}
	if usage.Used != nil && usage.Free != nil {
		usage.Total = fs.NewUsageValue(*usage.Used + *usage.Free)
	}
	return usage, nil
}

// ------------------------------------------------------------

// Fs returns the parent Fs
func (o *Object) Fs() fs.Info {
	return o.fs
}

// Return a string version
func (o *Object) String() string {
	if o == nil {
		return "<nil>"
	}
	return o.remote
}

// Remote returns the remote path
func (o *Object) Remote() string {
	return o.remote
}

// Hash returns the SHA1 or MD5 of an object returning a lowercase hex string
func (o *Object) Hash(ctx context.Context, t hash.Type) (string, error) {
	if t == hash.MD5 && o.fs.hasMD5 {
		return o.md5, nil
	}
	if t == hash.SHA1 && o.fs.hasSHA1 {
		return o.sha1, nil
	}
	return "", hash.ErrUnsupported
}

// Size returns the size of an object in bytes
func (o *Object) Size() int64 {
	ctx := context.TODO()
	err := o.readMetaData(ctx)
	if err != nil {
		fs.Logf(o, "Failed to read metadata: %v", err)
		return 0
	}
	return o.size
}

// setMetaData sets the metadata from info
func (o *Object) setMetaData(info *api.Prop) (err error) {
	o.hasMetaData = true
	o.size = info.Size
	o.modTime = time.Time(info.Modified)
	if o.fs.hasMD5 || o.fs.hasSHA1 {
		hashes := info.Hashes()
		if o.fs.hasSHA1 {
			o.sha1 = hashes[hash.SHA1]
		}
		if o.fs.hasMD5 {
			o.md5 = hashes[hash.MD5]
		}
	}
	return nil
}

// readMetaData gets the metadata if it hasn't already been fetched
//
// it also sets the info
func (o *Object) readMetaData(ctx context.Context) (err error) {
	if o.hasMetaData {
		return nil
	}
	info, err := o.fs.readMetaDataForPath(ctx, o.remote, defaultDepth)
	if err != nil {
		return err
	}
	return o.setMetaData(info)
}

// ModTime returns the modification time of the object
//
// It attempts to read the objects mtime and if that isn't present the
// LastModified returned in the http headers
func (o *Object) ModTime(ctx context.Context) time.Time {
	err := o.readMetaData(ctx)
	if err != nil {
		fs.Logf(o, "Failed to read metadata: %v", err)
		return time.Now()
	}
	return o.modTime
}

// SetModTime sets the modification time of the local fs object
func (o *Object) SetModTime(ctx context.Context, modTime time.Time) error {
	return fs.ErrorCantSetModTime
}

// Storable returns a boolean showing whether this object storable
func (o *Object) Storable() bool {
	return true
}

// Open an object for read
func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (in io.ReadCloser, err error) {
	var resp *http.Response
	fs.FixRangeOption(options, o.size)
	opts := rest.Opts{
		Method:  "GET",
		Path:    o.filePath(),
		Options: options,
		ExtraHeaders: map[string]string{
			"Depth": "0",
		},
	}
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.Call(ctx, &opts)
		return o.fs.shouldRetry(resp, err)
	})
	if err != nil {
		return nil, err
	}
	return resp.Body, err
}

// Update the object with the contents of the io.Reader, modTime and size
//
// If existing is set then it updates the object rather than creating a new one
//
// The new object may have been created if an error is returned
func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (err error) {
	err = o.fs.mkParentDir(ctx, o.filePath())
	if err != nil {
		return errors.Wrap(err, "Update mkParentDir failed")
	}

	size := src.Size()
	var resp *http.Response
	opts := rest.Opts{
		Method:        "PUT",
		Path:          o.filePath(),
		Body:          in,
		NoResponse:    true,
		ContentLength: &size, // FIXME this isn't necessary with owncloud - See https://github.com/nextcloud/nextcloud-snap/issues/365
		ContentType:   fs.MimeType(ctx, src),
		Options:       options,
	}
	if o.fs.useOCMtime || o.fs.hasMD5 || o.fs.hasSHA1 {
		opts.ExtraHeaders = map[string]string{}
		if o.fs.useOCMtime {
			opts.ExtraHeaders["X-OC-Mtime"] = fmt.Sprintf("%d", src.ModTime(ctx).Unix())
		}
		// Set one upload checksum
		// Owncloud uses one checksum only to check the upload and stores its own SHA1 and MD5
		// Nextcloud stores the checksum you supply (SHA1 or MD5) but only stores one
		if o.fs.hasSHA1 {
			if sha1, _ := src.Hash(ctx, hash.SHA1); sha1 != "" {
				opts.ExtraHeaders["OC-Checksum"] = "SHA1:" + sha1
			}
		}
		if o.fs.hasMD5 && opts.ExtraHeaders["OC-Checksum"] == "" {
			if md5, _ := src.Hash(ctx, hash.MD5); md5 != "" {
				opts.ExtraHeaders["OC-Checksum"] = "MD5:" + md5
			}
		}
	}
	err = o.fs.pacer.CallNoRetry(func() (bool, error) {
		resp, err = o.fs.srv.Call(ctx, &opts)
		return o.fs.shouldRetry(resp, err)
	})
	if err != nil {
		if o.fs.opt.DeleteOnError {
			// Give the WebDAV server a chance to get its internal state in order after the
			// error.  The error may have been local in which case we closed the connection.
			// The server may still be dealing with it for a moment. A sleep isn't ideal but I
			// haven't been able to think of a better method to find out if the server has
			// finished - ncw
			time.Sleep(1 * time.Second)
			// Remove failed upload
			_ = o.Remove(ctx)
		}
		return err
	}
	// read metadata from remote
	o.hasMetaData = false
	return o.readMetaData(ctx)
}

// Remove an object
func (o *Object) Remove(ctx context.Context) error {
	opts := rest.Opts{
		Method:     "DELETE",
		Path:       o.filePath(),
		NoResponse: true,
	}
	return o.fs.pacer.Call(func() (bool, error) {
		resp, err := o.fs.srv.Call(ctx, &opts)
		return o.fs.shouldRetry(resp, err)
	})
}

// Check the interfaces are satisfied
var (
	_ fs.Fs          = (*Fs)(nil)
	_ fs.Purger      = (*Fs)(nil)
	_ fs.PutStreamer = (*Fs)(nil)
	_ fs.Copier      = (*Fs)(nil)
	_ fs.Mover       = (*Fs)(nil)
	_ fs.DirMover    = (*Fs)(nil)
	_ fs.Abouter     = (*Fs)(nil)
	_ fs.Object      = (*Object)(nil)
)