// Package opendrive provides an interface to the OpenDrive storage system.
package opendrive

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

	"github.com/rclone/rclone/fs"
	"github.com/rclone/rclone/fs/config"
	"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/dircache"
	"github.com/rclone/rclone/lib/encoder"
	"github.com/rclone/rclone/lib/pacer"
	"github.com/rclone/rclone/lib/readers"
	"github.com/rclone/rclone/lib/rest"
)

const (
	defaultEndpoint = "https://dev.opendrive.com/api/v1"
	minSleep        = 10 * time.Millisecond
	maxSleep        = 5 * time.Minute
	decayConstant   = 1 // bigger for slower decay, exponential
)

// Register with Fs
func init() {
	fs.Register(&fs.RegInfo{
		Name:        "opendrive",
		Description: "OpenDrive",
		NewFs:       NewFs,
		Options: []fs.Option{{
			Name:      "username",
			Help:      "Username.",
			Required:  true,
			Sensitive: true,
		}, {
			Name:       "password",
			Help:       "Password.",
			IsPassword: true,
			Required:   true,
		}, {
			Name:     config.ConfigEncoding,
			Help:     config.ConfigEncodingHelp,
			Advanced: true,
			// List of replaced characters:
			//   < (less than)     -> '＜' // FULLWIDTH LESS-THAN SIGN
			//   > (greater than)  -> '＞' // FULLWIDTH GREATER-THAN SIGN
			//   : (colon)         -> '：' // FULLWIDTH COLON
			//   " (double quote)  -> '＂' // FULLWIDTH QUOTATION MARK
			//   \ (backslash)     -> '＼' // FULLWIDTH REVERSE SOLIDUS
			//   | (vertical line) -> '｜' // FULLWIDTH VERTICAL LINE
			//   ? (question mark) -> '？' // FULLWIDTH QUESTION MARK
			//   * (asterisk)      -> '＊' // FULLWIDTH ASTERISK
			//
			// Additionally names can't begin or end with an ASCII whitespace.
			// List of replaced characters:
			//     (space)           -> '␠'  // SYMBOL FOR SPACE
			//     (horizontal tab)  -> '␉'  // SYMBOL FOR HORIZONTAL TABULATION
			//     (line feed)       -> '␊'  // SYMBOL FOR LINE FEED
			//     (vertical tab)    -> '␋'  // SYMBOL FOR VERTICAL TABULATION
			//     (carriage return) -> '␍'  // SYMBOL FOR CARRIAGE RETURN
			//
			// Also encode invalid UTF-8 bytes as json doesn't handle them properly.
			//
			// https://www.opendrive.com/wp-content/uploads/guides/OpenDrive_API_guide.pdf
			Default: (encoder.Base |
				encoder.EncodeWin |
				encoder.EncodeLeftCrLfHtVt |
				encoder.EncodeRightCrLfHtVt |
				encoder.EncodeBackSlash |
				encoder.EncodeLeftSpace |
				encoder.EncodeRightSpace |
				encoder.EncodeInvalidUtf8),
		}, {
			Name: "chunk_size",
			Help: `Files will be uploaded in chunks this size.

Note that these chunks are buffered in memory so increasing them will
increase memory use.`,
			Default:  10 * fs.Mebi,
			Advanced: true,
		}, {
			Name:     "access",
			Help:     "Files and folders will be uploaded with this access permission (default private)",
			Default:  "private",
			Advanced: true,
			Examples: []fs.OptionExample{{
				Value: "private",
				Help:  "The file or folder access can be granted in a way that will allow select users to view, read or write what is absolutely essential for them.",
			}, {
				Value: "public",
				Help:  "The file or folder can be downloaded by anyone from a web browser. The link can be shared in any way,",
			}, {
				Value: "hidden",
				Help:  "The file or folder can be accessed has the same restrictions as  Public if the user knows the URL of the file or folder link in order to access the contents",
			}},
		}},
	})
}

// Options defines the configuration for this backend
type Options struct {
	UserName  string               `config:"username"`
	Password  string               `config:"password"`
	Enc       encoder.MultiEncoder `config:"encoding"`
	ChunkSize fs.SizeSuffix        `config:"chunk_size"`
	Access    string               `config:"access"`
}

// Fs represents a remote server
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
	srv      *rest.Client       // the connection to the server
	pacer    *fs.Pacer          // To pace and retry the API calls
	session  UserSessionInfo    // contains the session data
	dirCache *dircache.DirCache // Map of directory path to directory id
}

// Object describes an object
type Object struct {
	fs      *Fs       // what this object is part of
	remote  string    // The remote path
	id      string    // ID of the file
	parent  string    // ID of the parent directory
	modTime time.Time // The modified time of the object if known
	md5     string    // MD5 hash if known
	size    int64     // Size of the object
}

// parsePath parses an incoming 'url'
func parsePath(path string) (root string) {
	root = strings.Trim(path, "/")
	return
}

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

// 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("OpenDrive root '%s'", f.root)
}

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

// Hashes returns the supported hash sets.
func (f *Fs) Hashes() hash.Set {
	return hash.Set(hash.MD5)
}

// DirCacheFlush resets the directory cache - used in testing as an
// optional interface
func (f *Fs) DirCacheFlush() {
	f.dirCache.ResetRoot()
}

// NewFs constructs an Fs from the path, bucket: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
	}
	root = parsePath(root)
	if opt.UserName == "" {
		return nil, errors.New("username not found")
	}
	opt.Password, err = obscure.Reveal(opt.Password)
	if err != nil {
		return nil, errors.New("password could not revealed")
	}
	if opt.Password == "" {
		return nil, errors.New("password not found")
	}

	f := &Fs{
		name:  name,
		root:  root,
		opt:   *opt,
		srv:   rest.NewClient(fshttp.NewClient(ctx)).SetErrorHandler(errorHandler),
		pacer: fs.NewPacer(ctx, pacer.NewDefault(pacer.MinSleep(minSleep), pacer.MaxSleep(maxSleep), pacer.DecayConstant(decayConstant))),
	}

	f.dirCache = dircache.New(root, "0", f)

	// set the rootURL for the REST client
	f.srv.SetRoot(defaultEndpoint)

	// get sessionID
	var resp *http.Response
	err = f.pacer.Call(func() (bool, error) {
		account := Account{Username: opt.UserName, Password: opt.Password}

		opts := rest.Opts{
			Method: "POST",
			Path:   "/session/login.json",
		}
		resp, err = f.srv.CallJSON(ctx, &opts, &account, &f.session)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return nil, fmt.Errorf("failed to create session: %w", err)
	}
	fs.Debugf(nil, "Starting OpenDrive session with ID: %s", f.session.SessionID)

	f.features = (&fs.Features{
		CaseInsensitive:         true,
		CanHaveEmptyDirectories: true,
	}).Fill(ctx, f)

	// Find the current root
	err = f.dirCache.FindRoot(ctx, false)
	if err != nil {
		// Assume it is a file
		newRoot, remote := dircache.SplitPath(root)
		tempF := *f
		tempF.dirCache = dircache.New(newRoot, "0", &tempF)
		tempF.root = newRoot

		// Make new Fs which is the parent
		err = tempF.dirCache.FindRoot(ctx, false)
		if err != nil {
			// No root so return old f
			return f, nil
		}
		_, err := tempF.newObjectWithInfo(ctx, remote, nil, "")
		if err != nil {
			if err == fs.ErrorObjectNotFound {
				// File doesn't exist so return old f
				return f, nil
			}
			return nil, err
		}
		// XXX: update the old f here instead of returning tempF, since
		// `features` were already filled with functions having *f as a receiver.
		// See https://github.com/rclone/rclone/issues/2182
		f.dirCache = tempF.dirCache
		f.root = tempF.root
		// return an error with an fs which points to the parent
		return f, fs.ErrorIsFile
	}
	return f, nil
}

// rootSlash returns root with a slash on if it is empty, otherwise empty string
func (f *Fs) rootSlash() string {
	if f.root == "" {
		return f.root
	}
	return f.root + "/"
}

// errorHandler parses a non 2xx error response into an error
func errorHandler(resp *http.Response) error {
	errResponse := new(Error)
	err := rest.DecodeJSON(resp, &errResponse)
	if err != nil {
		fs.Debugf(nil, "Couldn't decode error response: %v", err)
	}
	if errResponse.Info.Code == 0 {
		errResponse.Info.Code = resp.StatusCode
	}
	if errResponse.Info.Message == "" {
		errResponse.Info.Message = "Unknown " + resp.Status
	}
	return errResponse
}

// Mkdir creates the folder if it doesn't exist
func (f *Fs) Mkdir(ctx context.Context, dir string) error {
	// fs.Debugf(nil, "Mkdir(\"%s\")", dir)
	_, err := f.dirCache.FindDir(ctx, dir, true)
	return err
}

// deleteObject removes an object by ID
func (f *Fs) deleteObject(ctx context.Context, id string) error {
	return f.pacer.Call(func() (bool, error) {
		removeDirData := removeFolder{SessionID: f.session.SessionID, FolderID: id}
		opts := rest.Opts{
			Method:     "POST",
			NoResponse: true,
			Path:       "/folder/remove.json",
		}
		resp, err := f.srv.CallJSON(ctx, &opts, &removeDirData, nil)
		return f.shouldRetry(ctx, resp, err)
	})
}

// purgeCheck remotes 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 {
	root := path.Join(f.root, dir)
	if root == "" {
		return errors.New("can't purge root directory")
	}
	dc := f.dirCache
	rootID, err := dc.FindDir(ctx, dir, false)
	if err != nil {
		return err
	}
	item, err := f.readMetaDataForFolderID(ctx, rootID)
	if err != nil {
		return err
	}
	if check && len(item.Files) != 0 {
		return errors.New("folder not empty")
	}
	err = f.deleteObject(ctx, rootID)
	if err != nil {
		return err
	}
	f.dirCache.FlushDir(dir)
	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 {
	// fs.Debugf(nil, "Rmdir(\"%s\")", path.Join(f.root, dir))
	return f.purgeCheck(ctx, dir, true)
}

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

// 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) {
	// fs.Debugf(nil, "Copy(%v)", remote)
	srcObj, ok := src.(*Object)
	if !ok {
		fs.Debugf(src, "Can't copy - not same remote type")
		return nil, fs.ErrorCantCopy
	}
	err := srcObj.readMetaData(ctx)
	if err != nil {
		return nil, err
	}

	srcPath := srcObj.fs.rootSlash() + srcObj.remote
	dstPath := f.rootSlash() + remote
	if strings.EqualFold(srcPath, dstPath) {
		return nil, fmt.Errorf("can't copy %q -> %q as are same name when lowercase", srcPath, dstPath)
	}

	// Create temporary object
	dstObj, leaf, directoryID, err := f.createObject(ctx, remote, srcObj.modTime, srcObj.size)
	if err != nil {
		return nil, err
	}
	// fs.Debugf(nil, "...%#v\n...%#v", remote, directoryID)

	// Copy the object
	var resp *http.Response
	response := moveCopyFileResponse{}
	err = f.pacer.Call(func() (bool, error) {
		copyFileData := moveCopyFile{
			SessionID:         f.session.SessionID,
			SrcFileID:         srcObj.id,
			DstFolderID:       directoryID,
			Move:              "false",
			OverwriteIfExists: "true",
			NewFileName:       leaf,
		}
		opts := rest.Opts{
			Method: "POST",
			Path:   "/file/move_copy.json",
		}
		resp, err = f.srv.CallJSON(ctx, &opts, &copyFileData, &response)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return nil, err
	}

	size, _ := strconv.ParseInt(response.Size, 10, 64)
	dstObj.id = response.FileID
	dstObj.size = size

	return dstObj, nil
}

// About gets quota information
func (f *Fs) About(ctx context.Context) (usage *fs.Usage, err error) {
	var uInfo usersInfoResponse
	var resp *http.Response

	err = f.pacer.Call(func() (bool, error) {
		opts := rest.Opts{
			Method: "GET",
			Path:   "/users/info.json/" + f.session.SessionID,
		}
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &uInfo)
		return f.shouldRetry(ctx, resp, err)
	})

	if err != nil {
		return nil, err
	}

	usage = &fs.Usage{
		Used:  fs.NewUsageValue(uInfo.StorageUsed),
		Total: fs.NewUsageValue(uInfo.MaxStorage * 1024 * 1024), // MaxStorage appears to be in MB
		Free:  fs.NewUsageValue(uInfo.MaxStorage*1024*1024 - uInfo.StorageUsed),
	}
	return usage, nil
}

// 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) {
	// fs.Debugf(nil, "Move(%v)", remote)
	srcObj, ok := src.(*Object)
	if !ok {
		fs.Debugf(src, "Can't move - not same remote type")
		return nil, fs.ErrorCantCopy
	}
	err := srcObj.readMetaData(ctx)
	if err != nil {
		return nil, err
	}

	// Create temporary object
	dstObj, leaf, directoryID, err := f.createObject(ctx, remote, srcObj.modTime, srcObj.size)
	if err != nil {
		return nil, err
	}

	// move_copy will silently truncate new filenames
	if len(leaf) > 255 {
		fs.Debugf(src, "Can't move file: name (%q) exceeds 255 char", leaf)
		return nil, fs.ErrorFileNameTooLong
	}

	moveCopyFileData := moveCopyFile{
		SessionID:         f.session.SessionID,
		SrcFileID:         srcObj.id,
		DstFolderID:       directoryID,
		Move:              "true",
		OverwriteIfExists: "true",
		NewFileName:       leaf,
	}
	opts := rest.Opts{
		Method: "POST",
		Path:   "/file/move_copy.json",
	}
	var request interface{} = moveCopyFileData

	// use /file/rename.json if moving within the same directory
	_, srcDirID, err := srcObj.fs.dirCache.FindPath(ctx, srcObj.remote, false)
	if err != nil {
		return nil, err
	}
	if srcDirID == directoryID {
		fs.Debugf(src, "same parent dir (%v) - using file/rename instead of move_copy for %s", directoryID, remote)
		renameFileData := renameFile{
			SessionID:   f.session.SessionID,
			FileID:      srcObj.id,
			NewFileName: leaf,
		}
		opts.Path = "/file/rename.json"
		request = renameFileData
	}

	// Move the object
	var resp *http.Response
	response := moveCopyFileResponse{}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, &request, &response)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return nil, err
	}

	size, _ := strconv.ParseInt(response.Size, 10, 64)
	dstObj.id = response.FileID
	dstObj.size = size

	return dstObj, nil
}

// 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) (err error) {
	srcFs, ok := src.(*Fs)
	if !ok {
		fs.Debugf(srcFs, "Can't move directory - not same remote type")
		return fs.ErrorCantDirMove
	}

	srcID, srcDirectoryID, _, dstDirectoryID, dstLeaf, err := f.dirCache.DirMove(ctx, srcFs.dirCache, srcFs.root, srcRemote, f.root, dstRemote)
	if err != nil {
		return err
	}

	// move_copy will silently truncate new filenames
	if len(dstLeaf) > 255 {
		fs.Debugf(src, "Can't move folder: name (%q) exceeds 255 char", dstLeaf)
		return fs.ErrorFileNameTooLong
	}

	moveFolderData := moveCopyFolder{
		SessionID:     f.session.SessionID,
		FolderID:      srcID,
		DstFolderID:   dstDirectoryID,
		Move:          "true",
		NewFolderName: dstLeaf,
	}
	opts := rest.Opts{
		Method: "POST",
		Path:   "/folder/move_copy.json",
	}
	var request interface{} = moveFolderData

	// use /folder/rename.json if moving within the same parent directory
	if srcDirectoryID == dstDirectoryID {
		fs.Debugf(dstRemote, "same parent dir (%v) - using folder/rename instead of move_copy", srcDirectoryID)
		renameFolderData := renameFolder{
			SessionID:  f.session.SessionID,
			FolderID:   srcID,
			FolderName: dstLeaf,
		}
		opts.Path = "/folder/rename.json"
		request = renameFolderData
	}

	// Do the move
	var resp *http.Response
	response := moveCopyFolderResponse{}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, &request, &response)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		fs.Debugf(src, "DirMove error %v", err)
		return err
	}

	srcFs.dirCache.FlushDir(srcRemote)
	return nil
}

// 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)
}

// 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, file *File, parent string) (fs.Object, error) {
	// fs.Debugf(nil, "newObjectWithInfo(%s, %v)", remote, file)

	var o *Object
	if nil != file {
		o = &Object{
			fs:      f,
			remote:  remote,
			id:      file.FileID,
			parent:  parent,
			modTime: time.Unix(file.DateModified, 0),
			size:    file.Size,
			md5:     file.FileHash,
		}
	} else {
		o = &Object{
			fs:     f,
			remote: remote,
		}

		err := o.readMetaData(ctx)
		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) {
	// fs.Debugf(nil, "NewObject(\"%s\")", remote)
	return f.newObjectWithInfo(ctx, remote, nil, "")
}

// Creates from the parameters passed in a half finished Object which
// must have setMetaData called on it
//
// Returns the object, leaf, directoryID and error.
//
// Used to create new objects
func (f *Fs) createObject(ctx context.Context, remote string, modTime time.Time, size int64) (o *Object, leaf string, directoryID string, err error) {
	// Create the directory for the object if it doesn't exist
	leaf, directoryID, err = f.dirCache.FindPath(ctx, remote, true)
	if err != nil {
		return nil, leaf, directoryID, err
	}
	// fs.Debugf(nil, "\n...leaf %#v\n...id %#v", leaf, directoryID)
	// Temporary Object under construction
	o = &Object{
		fs:     f,
		remote: remote,
	}
	return o, f.opt.Enc.FromStandardName(leaf), directoryID, nil
}

// readMetaDataForPath reads the metadata from the path
func (f *Fs) readMetaDataForFolderID(ctx context.Context, id string) (info *FolderList, err error) {
	var resp *http.Response
	opts := rest.Opts{
		Method: "GET",
		Path:   "/folder/list.json/" + f.session.SessionID + "/" + id,
	}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &info)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return nil, err
	}
	return info, err
}

// Put the object into the bucket
//
// 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) {
	remote := src.Remote()
	size := src.Size()
	modTime := src.ModTime(ctx)

	// fs.Debugf(nil, "Put(%s)", remote)

	o, leaf, directoryID, err := f.createObject(ctx, remote, modTime, size)
	if err != nil {
		return nil, err
	}

	if o.id == "" {
		// Attempt to read ID, ignore error
		// FIXME is this correct?
		_ = o.readMetaData(ctx)
	}

	if o.id == "" {
		// We need to create an ID for this file
		var resp *http.Response
		response := createFileResponse{}
		err := o.fs.pacer.Call(func() (bool, error) {
			createFileData := createFile{
				SessionID: o.fs.session.SessionID,
				FolderID:  directoryID,
				Name:      leaf,
			}
			opts := rest.Opts{
				Method:  "POST",
				Options: options,
				Path:    "/upload/create_file.json",
			}
			resp, err = o.fs.srv.CallJSON(ctx, &opts, &createFileData, &response)
			return o.fs.shouldRetry(ctx, resp, err)
		})
		if err != nil {
			return nil, fmt.Errorf("failed to create file: %w", err)
		}

		o.id = response.FileID
	}

	return o, o.Update(ctx, in, src, options...)
}

// retryErrorCodes is a slice of error codes that we will retry
var retryErrorCodes = []int{
	401, // Unauthorized (seen in "Token has expired")
	408, // Request Timeout
	423, // Locked - get this on folders sometimes
	429, // Rate exceeded.
	500, // Get occasional 500 Internal Server Error
	502, // Bad Gateway when doing big listings
	503, // Service Unavailable
	504, // Gateway Time-out
}

// 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(ctx context.Context, resp *http.Response, err error) (bool, error) {
	if fserrors.ContextError(ctx, &err) {
		return false, err
	}
	return fserrors.ShouldRetry(err) || fserrors.ShouldRetryHTTP(resp, retryErrorCodes), err
}

// getAccessLevel is a helper function to determine access level integer
func getAccessLevel(access string) int64 {
	var accessLevel int64
	switch access {
	case "private":
		accessLevel = 0
	case "public":
		accessLevel = 1
	case "hidden":
		accessLevel = 2
	default:
		accessLevel = 0
		fs.Errorf(nil, "Invalid access: %s, defaulting to private", access)
	}
	return accessLevel
}

// DirCacher methods

// CreateDir makes a directory with pathID as parent and name leaf
func (f *Fs) CreateDir(ctx context.Context, pathID, leaf string) (newID string, err error) {
	// fs.Debugf(f, "CreateDir(%q, %q)\n", pathID, replaceReservedChars(leaf))
	var resp *http.Response
	response := createFolderResponse{}
	err = f.pacer.Call(func() (bool, error) {
		createDirData := createFolder{
			SessionID:           f.session.SessionID,
			FolderName:          f.opt.Enc.FromStandardName(leaf),
			FolderSubParent:     pathID,
			FolderIsPublic:      getAccessLevel(f.opt.Access),
			FolderPublicUpl:     0,
			FolderPublicDisplay: 0,
			FolderPublicDnl:     0,
		}
		opts := rest.Opts{
			Method: "POST",
			Path:   "/folder.json",
		}
		resp, err = f.srv.CallJSON(ctx, &opts, &createDirData, &response)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return "", err
	}

	return response.FolderID, nil
}

// FindLeaf finds a directory of name leaf in the folder with ID pathID
func (f *Fs) FindLeaf(ctx context.Context, pathID, leaf string) (pathIDOut string, found bool, err error) {
	// fs.Debugf(nil, "FindLeaf(\"%s\", \"%s\")", pathID, leaf)

	if pathID == "0" && leaf == "" {
		// fs.Debugf(nil, "Found OpenDrive root")
		// that's the root directory
		return pathID, true, nil
	}

	// get the folderIDs
	var resp *http.Response
	folderList := FolderList{}
	err = f.pacer.Call(func() (bool, error) {
		opts := rest.Opts{
			Method: "GET",
			Path:   "/folder/list.json/" + f.session.SessionID + "/" + pathID,
		}
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &folderList)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return "", false, fmt.Errorf("failed to get folder list: %w", err)
	}

	leaf = f.opt.Enc.FromStandardName(leaf)
	for _, folder := range folderList.Folders {
		// fs.Debugf(nil, "Folder: %s (%s)", folder.Name, folder.FolderID)

		if strings.EqualFold(leaf, folder.Name) {
			// found
			return folder.FolderID, true, nil
		}
	}

	return "", false, nil
}

// 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) {
	// fs.Debugf(nil, "List(%v)", dir)
	directoryID, err := f.dirCache.FindDir(ctx, dir, false)
	if err != nil {
		return nil, err
	}

	var resp *http.Response
	opts := rest.Opts{
		Method: "GET",
		Path:   "/folder/list.json/" + f.session.SessionID + "/" + directoryID,
	}
	folderList := FolderList{}
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &folderList)
		return f.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		if apiError, ok := err.(*Error); ok {
			// Work around a bug maybe in opendrive or maybe in rclone.
			//
			// We should know whether the folder exists or not by the call to
			// FindDir above so exactly why it is not found here is a mystery.
			//
			// This manifests as a failure in fs/sync TestSyncOverlapWithFilter
			if apiError.Info.Message == "Folder is already deleted" {
				return fs.DirEntries{}, nil
			}
		}
		return nil, fmt.Errorf("failed to get folder list: %w", err)
	}

	for _, folder := range folderList.Folders {
		folder.Name = f.opt.Enc.ToStandardName(folder.Name)
		// fs.Debugf(nil, "Folder: %s (%s)", folder.Name, folder.FolderID)
		remote := path.Join(dir, folder.Name)
		// cache the directory ID for later lookups
		f.dirCache.Put(remote, folder.FolderID)
		d := fs.NewDir(remote, time.Unix(folder.DateModified, 0)).SetID(folder.FolderID)
		d.SetItems(int64(folder.ChildFolders))
		d.SetParentID(directoryID)
		entries = append(entries, d)
	}

	for _, file := range folderList.Files {
		file.Name = f.opt.Enc.ToStandardName(file.Name)
		// fs.Debugf(nil, "File: %s (%s)", file.Name, file.FileID)
		remote := path.Join(dir, file.Name)
		o, err := f.newObjectWithInfo(ctx, remote, &file, directoryID)
		if err != nil {
			return nil, err
		}
		entries = append(entries, o)
	}

	return entries, 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 Md5sum of an object returning a lowercase hex string
func (o *Object) Hash(ctx context.Context, t hash.Type) (string, error) {
	if t != hash.MD5 {
		return "", hash.ErrUnsupported
	}
	return o.md5, nil
}

// Size returns the size of an object in bytes
func (o *Object) Size() int64 {
	return o.size // Object is likely PENDING
}

// 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 {
	return o.modTime
}

// SetModTime sets the modification time of the local fs object
func (o *Object) SetModTime(ctx context.Context, modTime time.Time) error {
	// fs.Debugf(nil, "SetModTime(%v)", modTime.String())
	opts := rest.Opts{
		Method:     "PUT",
		NoResponse: true,
		Path:       "/file/filesettings.json",
	}
	update := modTimeFile{
		SessionID:            o.fs.session.SessionID,
		FileID:               o.id,
		FileModificationTime: strconv.FormatInt(modTime.Unix(), 10),
	}
	err := o.fs.pacer.Call(func() (bool, error) {
		resp, err := o.fs.srv.CallJSON(ctx, &opts, &update, nil)
		return o.fs.shouldRetry(ctx, resp, err)
	})

	o.modTime = modTime

	return err
}

// Open an object for read
func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (in io.ReadCloser, err error) {
	// fs.Debugf(nil, "Open(\"%v\")", o.remote)
	fs.FixRangeOption(options, o.size)
	opts := rest.Opts{
		Method:  "GET",
		Path:    "/download/file.json/" + o.id + "?session_id=" + o.fs.session.SessionID,
		Options: options,
	}
	var resp *http.Response
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.Call(ctx, &opts)
		return o.fs.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return nil, fmt.Errorf("failed to open file): %w", err)
	}

	return resp.Body, nil
}

// Remove an object
func (o *Object) Remove(ctx context.Context) error {
	// fs.Debugf(nil, "Remove(\"%s\")", o.id)
	return o.fs.pacer.Call(func() (bool, error) {
		opts := rest.Opts{
			Method:     "DELETE",
			NoResponse: true,
			Path:       "/file.json/" + o.fs.session.SessionID + "/" + o.id,
		}
		resp, err := o.fs.srv.Call(ctx, &opts)
		return o.fs.shouldRetry(ctx, resp, err)
	})
}

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

// Update the object with the contents of the io.Reader, modTime and size
//
// 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) error {
	size := src.Size()
	modTime := src.ModTime(ctx)
	// fs.Debugf(nil, "Update(\"%s\", \"%s\")", o.id, o.remote)

	// Open file for upload
	var resp *http.Response
	openResponse := openUploadResponse{}
	err := o.fs.pacer.Call(func() (bool, error) {
		openUploadData := openUpload{SessionID: o.fs.session.SessionID, FileID: o.id, Size: size}
		// fs.Debugf(nil, "PreOpen: %#v", openUploadData)
		opts := rest.Opts{
			Method:  "POST",
			Options: options,
			Path:    "/upload/open_file_upload.json",
		}
		resp, err := o.fs.srv.CallJSON(ctx, &opts, &openUploadData, &openResponse)
		return o.fs.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return fmt.Errorf("failed to create file: %w", err)
	}
	// resp.Body.Close()
	// fs.Debugf(nil, "PostOpen: %#v", openResponse)

	buf := make([]byte, o.fs.opt.ChunkSize)
	chunkOffset := int64(0)
	remainingBytes := size
	chunkCounter := 0

	for remainingBytes > 0 {
		currentChunkSize := int64(o.fs.opt.ChunkSize)
		if currentChunkSize > remainingBytes {
			currentChunkSize = remainingBytes
		}
		remainingBytes -= currentChunkSize
		fs.Debugf(o, "Uploading chunk %d, size=%d, remain=%d", chunkCounter, currentChunkSize, remainingBytes)

		chunk := readers.NewRepeatableLimitReaderBuffer(in, buf, currentChunkSize)
		var reply uploadFileChunkReply
		err = o.fs.pacer.Call(func() (bool, error) {
			// seek to the start in case this is a retry
			if _, err = chunk.Seek(0, io.SeekStart); err != nil {
				return false, err
			}
			opts := rest.Opts{
				Method: "POST",
				Path:   "/upload/upload_file_chunk.json",
				Body:   chunk,
				MultipartParams: url.Values{
					"session_id":    []string{o.fs.session.SessionID},
					"file_id":       []string{o.id},
					"temp_location": []string{openResponse.TempLocation},
					"chunk_offset":  []string{strconv.FormatInt(chunkOffset, 10)},
					"chunk_size":    []string{strconv.FormatInt(currentChunkSize, 10)},
				},
				MultipartContentName: "file_data", // ..name of the parameter which is the attached file
				MultipartFileName:    o.remote,    // ..name of the file for the attached file

			}
			resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &reply)
			return o.fs.shouldRetry(ctx, resp, err)
		})
		if err != nil {
			return fmt.Errorf("failed to create file: %w", err)
		}
		if reply.TotalWritten != currentChunkSize {
			return fmt.Errorf("failed to create file: incomplete write of %d/%d bytes", reply.TotalWritten, currentChunkSize)
		}

		chunkCounter++
		chunkOffset += currentChunkSize
	}

	// Close file for upload
	closeResponse := closeUploadResponse{}
	err = o.fs.pacer.Call(func() (bool, error) {
		closeUploadData := closeUpload{SessionID: o.fs.session.SessionID, FileID: o.id, Size: size, TempLocation: openResponse.TempLocation}
		// fs.Debugf(nil, "PreClose: %#v", closeUploadData)
		opts := rest.Opts{
			Method: "POST",
			Path:   "/upload/close_file_upload.json",
		}
		resp, err = o.fs.srv.CallJSON(ctx, &opts, &closeUploadData, &closeResponse)
		return o.fs.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return fmt.Errorf("failed to create file: %w", err)
	}
	// fs.Debugf(nil, "PostClose: %#v", closeResponse)

	o.id = closeResponse.FileID
	o.size = closeResponse.Size

	// Set the mod time now
	err = o.SetModTime(ctx, modTime)
	if err != nil {
		return err
	}

	// Set permissions
	err = o.fs.pacer.Call(func() (bool, error) {
		update := permissions{SessionID: o.fs.session.SessionID, FileID: o.id, FileIsPublic: getAccessLevel(o.fs.opt.Access)}
		// fs.Debugf(nil, "Permissions : %#v", update)
		opts := rest.Opts{
			Method:     "POST",
			NoResponse: true,
			Path:       "/file/access.json",
		}
		resp, err = o.fs.srv.CallJSON(ctx, &opts, &update, nil)
		return o.fs.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return err
	}

	return o.readMetaData(ctx)
}

func (o *Object) readMetaData(ctx context.Context) (err error) {
	leaf, directoryID, err := o.fs.dirCache.FindPath(ctx, o.remote, false)
	if err != nil {
		if err == fs.ErrorDirNotFound {
			return fs.ErrorObjectNotFound
		}
		return err
	}
	var resp *http.Response
	fileInfo := File{}

	// If we know the object id perform a direct lookup
	// because the /folder/itembyname.json endpoint is unreliable:
	// newly created objects take an arbitrary amount of time to show up
	if o.id != "" {
		opts := rest.Opts{
			Method: "GET",
			Path: fmt.Sprintf("/file/info.json/%s?session_id=%s",
				o.id, o.fs.session.SessionID),
		}
		err = o.fs.pacer.Call(func() (bool, error) {
			resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &fileInfo)
			return o.fs.shouldRetry(ctx, resp, err)
		})
		if err != nil {
			return fmt.Errorf("failed to get fileinfo: %w", err)
		}

		o.id = fileInfo.FileID
		o.modTime = time.Unix(fileInfo.DateModified, 0)
		o.md5 = fileInfo.FileHash
		o.size = fileInfo.Size
		return nil
	}
	folderList := FolderList{}
	opts := rest.Opts{
		Method: "GET",
		Path: fmt.Sprintf("/folder/itembyname.json/%s/%s?name=%s",
			o.fs.session.SessionID, directoryID, url.QueryEscape(o.fs.opt.Enc.FromStandardName(leaf))),
	}
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &folderList)
		return o.fs.shouldRetry(ctx, resp, err)
	})
	if err != nil {
		return fmt.Errorf("failed to get folder list: %w", err)
	}
	if len(folderList.Files) == 0 {
		return fs.ErrorObjectNotFound
	}
	fileInfo = folderList.Files[0]
	o.id = fileInfo.FileID
	o.modTime = time.Unix(fileInfo.DateModified, 0)
	o.md5 = fileInfo.FileHash
	o.size = fileInfo.Size
	return nil
}

// ID returns the ID of the Object if known, or "" if not
func (o *Object) ID() string {
	return o.id
}

// ParentID returns the ID of the Object parent directory if known, or "" if not
func (o *Object) ParentID() string {
	return o.parent
}

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