// Package pcloud provides an interface to the Pcloud
// object storage system.
package pcloud

// FIXME implement ListR? /listfolder can do recursive lists

// FIXME cleanup returns login required?

// FIXME mime type? Fix overview if implement.

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

	"github.com/pkg/errors"
	"github.com/rclone/rclone/backend/pcloud/api"
	"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/hash"
	"github.com/rclone/rclone/lib/dircache"
	"github.com/rclone/rclone/lib/encoder"
	"github.com/rclone/rclone/lib/oauthutil"
	"github.com/rclone/rclone/lib/pacer"
	"github.com/rclone/rclone/lib/rest"
	"golang.org/x/oauth2"
)

const (
	rcloneClientID              = "DnONSzyJXpm"
	rcloneEncryptedClientSecret = "ej1OIF39VOQQ0PXaSdK9ztkLw3tdLNscW2157TKNQdQKkICR4uU7aFg4eFM"
	minSleep                    = 10 * time.Millisecond
	maxSleep                    = 2 * time.Second
	decayConstant               = 2 // bigger for slower decay, exponential
	defaultHostname             = "api.pcloud.com"
)

// Globals
var (
	// Description of how to auth for this app
	oauthConfig = &oauth2.Config{
		Scopes: nil,
		Endpoint: oauth2.Endpoint{
			AuthURL: "https://my.pcloud.com/oauth2/authorize",
			// TokenURL: "https://api.pcloud.com/oauth2_token", set by updateTokenURL
		},
		ClientID:     rcloneClientID,
		ClientSecret: obscure.MustReveal(rcloneEncryptedClientSecret),
		RedirectURL:  oauthutil.RedirectLocalhostURL,
	}
)

// Update the TokenURL with the actual hostname
func updateTokenURL(oauthConfig *oauth2.Config, hostname string) {
	oauthConfig.Endpoint.TokenURL = "https://" + hostname + "/oauth2_token"
}

// Register with Fs
func init() {
	updateTokenURL(oauthConfig, defaultHostname)
	fs.Register(&fs.RegInfo{
		Name:        "pcloud",
		Description: "Pcloud",
		NewFs:       NewFs,
		Config: func(name string, m configmap.Mapper) {
			optc := new(Options)
			err := configstruct.Set(m, optc)
			if err != nil {
				fs.Errorf(nil, "Failed to read config: %v", err)
			}
			updateTokenURL(oauthConfig, optc.Hostname)
			checkAuth := func(oauthConfig *oauth2.Config, auth *oauthutil.AuthResult) error {
				if auth == nil || auth.Form == nil {
					return errors.New("form not found in response")
				}
				hostname := auth.Form.Get("hostname")
				if hostname == "" {
					hostname = defaultHostname
				}
				// Save the hostname in the config
				m.Set("hostname", hostname)
				// Update the token URL
				updateTokenURL(oauthConfig, hostname)
				fs.Debugf(nil, "pcloud: got hostname %q", hostname)
				return nil
			}
			opt := oauthutil.Options{
				CheckAuth:    checkAuth,
				StateBlankOK: true, // pCloud seems to drop the state parameter now - see #4210
			}
			err = oauthutil.Config("pcloud", name, m, oauthConfig, &opt)
			if err != nil {
				log.Fatalf("Failed to configure token: %v", err)
			}
		},
		Options: append(oauthutil.SharedOptions, []fs.Option{{
			Name:     config.ConfigEncoding,
			Help:     config.ConfigEncodingHelp,
			Advanced: true,
			// Encode invalid UTF-8 bytes as json doesn't handle them properly.
			//
			// TODO: Investigate Unicode simplification (＼ gets converted to \ server-side)
			Default: (encoder.Display |
				encoder.EncodeBackSlash |
				encoder.EncodeInvalidUtf8),
		}, {
			Name:     "root_folder_id",
			Help:     "Fill in for rclone to use a non root folder as its starting point.",
			Default:  "d0",
			Advanced: true,
		}, {
			Name: "hostname",
			Help: `Hostname to connect to.

This is normally set when rclone initially does the oauth connection.`,
			Default:  defaultHostname,
			Advanced: true,
		}}...),
	})
}

// Options defines the configuration for this backend
type Options struct {
	Enc          encoder.MultiEncoder `config:"encoding"`
	RootFolderID string               `config:"root_folder_id"`
	Hostname     string               `config:"hostname"`
}

// Fs represents a remote pcloud
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
	dirCache     *dircache.DirCache // Map of directory path to directory id
	pacer        *fs.Pacer          // pacer for API calls
	tokenRenewer *oauthutil.Renew   // renew the token on expiry
}

// Object describes a pcloud 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
	id          string    // ID of the object
	md5         string    // MD5 if known
	sha1        string    // SHA1 if known
	link        *api.GetFileLinkResult
}

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

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

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

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

// retryErrorCodes is a slice of error codes that we will retry
var retryErrorCodes = []int{
	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 shouldRetry(resp *http.Response, err error) (bool, error) {
	doRetry := false

	// Check if it is an api.Error
	if apiErr, ok := err.(*api.Error); ok {
		// See https://docs.pcloud.com/errors/ for error treatment
		// Errors are classified as 1xxx, 2xxx etc
		switch apiErr.Result / 1000 {
		case 4: // 4xxx: rate limiting
			doRetry = true
		case 5: // 5xxx: internal errors
			doRetry = true
		}
	}

	if resp != nil && resp.StatusCode == 401 && len(resp.Header["Www-Authenticate"]) == 1 && strings.Index(resp.Header["Www-Authenticate"][0], "expired_token") >= 0 {
		doRetry = true
		fs.Debugf(nil, "Should retry: %v", err)
	}
	return doRetry || fserrors.ShouldRetry(err) || fserrors.ShouldRetryHTTP(resp, retryErrorCodes), err
}

// readMetaDataForPath reads the metadata from the path
func (f *Fs) readMetaDataForPath(ctx context.Context, path string) (info *api.Item, err error) {
	// defer fs.Trace(f, "path=%q", path)("info=%+v, err=%v", &info, &err)
	leaf, directoryID, err := f.dirCache.FindPath(ctx, path, false)
	if err != nil {
		if err == fs.ErrorDirNotFound {
			return nil, fs.ErrorObjectNotFound
		}
		return nil, err
	}

	found, err := f.listAll(ctx, directoryID, false, true, func(item *api.Item) bool {
		if item.Name == leaf {
			info = item
			return true
		}
		return false
	})
	if err != nil {
		return nil, err
	}
	if !found {
		return nil, fs.ErrorObjectNotFound
	}
	return info, nil
}

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

// NewFs constructs an Fs from the path, container:path
func NewFs(name, root string, m configmap.Mapper) (fs.Fs, error) {
	ctx := context.Background()
	// Parse config into Options struct
	opt := new(Options)
	err := configstruct.Set(m, opt)
	if err != nil {
		return nil, err
	}
	root = parsePath(root)
	oAuthClient, ts, err := oauthutil.NewClient(name, m, oauthConfig)
	if err != nil {
		return nil, errors.Wrap(err, "failed to configure Pcloud")
	}
	updateTokenURL(oauthConfig, opt.Hostname)

	f := &Fs{
		name:  name,
		root:  root,
		opt:   *opt,
		srv:   rest.NewClient(oAuthClient).SetRoot("https://" + opt.Hostname),
		pacer: fs.NewPacer(pacer.NewDefault(pacer.MinSleep(minSleep), pacer.MaxSleep(maxSleep), pacer.DecayConstant(decayConstant))),
	}
	f.features = (&fs.Features{
		CaseInsensitive:         false,
		CanHaveEmptyDirectories: true,
	}).Fill(f)
	f.srv.SetErrorHandler(errorHandler)

	// Renew the token in the background
	f.tokenRenewer = oauthutil.NewRenew(f.String(), ts, func() error {
		_, err := f.readMetaDataForPath(ctx, "")
		return err
	})

	// Get rootFolderID
	rootID := f.opt.RootFolderID
	f.dirCache = dircache.New(root, rootID, 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, rootID, &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
}

// 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.Item) (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)
}

// 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) {
	// Find the leaf in pathID
	found, err = f.listAll(ctx, pathID, true, false, func(item *api.Item) bool {
		if item.Name == leaf {
			pathIDOut = item.ID
			return true
		}
		return false
	})
	return pathIDOut, found, err
}

// 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, leaf)
	var resp *http.Response
	var result api.ItemResult
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/createfolder",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("name", f.opt.Enc.FromStandardName(leaf))
	opts.Parameters.Set("folderid", dirIDtoNumber(pathID))
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		//fmt.Printf("...Error %v\n", err)
		return "", err
	}
	// fmt.Printf("...Id %q\n", *info.Id)
	return result.Metadata.ID, nil
}

// Converts a dirID which is usually 'd' followed by digits into just
// the digits
func dirIDtoNumber(dirID string) string {
	if len(dirID) > 0 && dirID[0] == 'd' {
		return dirID[1:]
	}
	fs.Debugf(nil, "Invalid directory id %q", dirID)
	return dirID
}

// Converts a fileID which is usually 'f' followed by digits into just
// the digits
func fileIDtoNumber(fileID string) string {
	if len(fileID) > 0 && fileID[0] == 'f' {
		return fileID[1:]
	}
	fs.Debugf(nil, "Invalid file id %q", fileID)
	return fileID
}

// 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(*api.Item) 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, dirID string, directoriesOnly bool, filesOnly bool, fn listAllFn) (found bool, err error) {
	opts := rest.Opts{
		Method:     "GET",
		Path:       "/listfolder",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("folderid", dirIDtoNumber(dirID))
	// FIXME can do recursive

	var result api.ItemResult
	var resp *http.Response
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return found, errors.Wrap(err, "couldn't list files")
	}
	for i := range result.Metadata.Contents {
		item := &result.Metadata.Contents[i]
		if item.IsFolder {
			if filesOnly {
				continue
			}
		} else {
			if directoriesOnly {
				continue
			}
		}
		item.Name = f.opt.Enc.ToStandardName(item.Name)
		if fn(item) {
			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) {
	directoryID, err := f.dirCache.FindDir(ctx, dir, false)
	if err != nil {
		return nil, err
	}
	var iErr error
	_, err = f.listAll(ctx, directoryID, false, false, func(info *api.Item) bool {
		remote := path.Join(dir, info.Name)
		if info.IsFolder {
			// cache the directory ID for later lookups
			f.dirCache.Put(remote, info.ID)
			d := fs.NewDir(remote, info.ModTime()).SetID(info.ID)
			// FIXME more info from dir?
			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
//
// 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
	}
	// Temporary Object under construction
	o = &Object{
		fs:     f,
		remote: remote,
	}
	return o, leaf, directoryID, nil
}

// Put the object into the container
//
// 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)

	o, _, _, err := f.createObject(ctx, remote, modTime, size)
	if err != nil {
		return nil, err
	}
	return o, o.Update(ctx, in, src, options...)
}

// Mkdir creates the container if it doesn't exist
func (f *Fs) Mkdir(ctx context.Context, dir string) error {
	_, err := f.dirCache.FindDir(ctx, dir, true)
	return err
}

// 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 {
	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
	}

	opts := rest.Opts{
		Method:     "POST",
		Path:       "/deletefolder",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("folderid", dirIDtoNumber(rootID))
	if !check {
		opts.Path = "/deletefolderrecursive"
	}
	var resp *http.Response
	var result api.ItemResult
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return errors.Wrap(err, "rmdir failed")
	}
	f.dirCache.FlushDir(dir)
	if err != nil {
		return err
	}
	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 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) {
	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
	}

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

	// Copy the object
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/copyfile",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("fileid", fileIDtoNumber(srcObj.id))
	opts.Parameters.Set("toname", f.opt.Enc.FromStandardName(leaf))
	opts.Parameters.Set("tofolderid", dirIDtoNumber(directoryID))
	opts.Parameters.Set("mtime", fmt.Sprintf("%d", srcObj.modTime.Unix()))
	var resp *http.Response
	var result api.ItemResult
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return nil, err
	}
	err = dstObj.setMetaData(&result.Metadata)
	if err != nil {
		return nil, err
	}
	return dstObj, 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)
}

// CleanUp empties the trash
func (f *Fs) CleanUp(ctx context.Context) error {
	rootID, err := f.dirCache.RootID(ctx, false)
	if err != nil {
		return err
	}
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/trash_clear",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("folderid", dirIDtoNumber(rootID))
	var resp *http.Response
	var result api.Error
	return f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Update(err)
		return shouldRetry(resp, err)
	})
}

// 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) {
	srcObj, ok := src.(*Object)
	if !ok {
		fs.Debugf(src, "Can't move - not same remote type")
		return nil, fs.ErrorCantMove
	}

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

	// Do the move
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/renamefile",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("fileid", fileIDtoNumber(srcObj.id))
	opts.Parameters.Set("toname", f.opt.Enc.FromStandardName(leaf))
	opts.Parameters.Set("tofolderid", dirIDtoNumber(directoryID))
	var resp *http.Response
	var result api.ItemResult
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return nil, err
	}

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

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

	// Do the move
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/renamefolder",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("folderid", dirIDtoNumber(srcID))
	opts.Parameters.Set("toname", f.opt.Enc.FromStandardName(dstLeaf))
	opts.Parameters.Set("tofolderid", dirIDtoNumber(dstDirectoryID))
	var resp *http.Response
	var result api.ItemResult
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return err
	}

	srcFs.dirCache.FlushDir(srcRemote)
	return nil
}

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

func (f *Fs) linkDir(ctx context.Context, dirID string, expire fs.Duration) (string, error) {
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/getfolderpublink",
		Parameters: url.Values{},
	}
	var result api.PubLinkResult
	opts.Parameters.Set("folderid", dirIDtoNumber(dirID))
	err := f.pacer.Call(func() (bool, error) {
		resp, err := f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return "", err
	}
	return result.Link, err
}

func (f *Fs) linkFile(ctx context.Context, path string, expire fs.Duration) (string, error) {
	obj, err := f.NewObject(ctx, path)
	if err != nil {
		return "", err
	}
	o := obj.(*Object)
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/getfilepublink",
		Parameters: url.Values{},
	}
	var result api.PubLinkResult
	opts.Parameters.Set("fileid", fileIDtoNumber(o.id))
	err = f.pacer.Call(func() (bool, error) {
		resp, err := f.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return "", err
	}
	return result.Link, nil
}

// PublicLink adds a "readable by anyone with link" permission on the given file or folder.
func (f *Fs) PublicLink(ctx context.Context, remote string, expire fs.Duration, unlink bool) (string, error) {
	dirID, err := f.dirCache.FindDir(ctx, remote, false)
	if err == fs.ErrorDirNotFound {
		return f.linkFile(ctx, remote, expire)
	}
	if err != nil {
		return "", err
	}
	return f.linkDir(ctx, dirID, expire)
}

// About gets quota information
func (f *Fs) About(ctx context.Context) (usage *fs.Usage, err error) {
	opts := rest.Opts{
		Method: "POST",
		Path:   "/userinfo",
	}
	var resp *http.Response
	var q api.UserInfo
	err = f.pacer.Call(func() (bool, error) {
		resp, err = f.srv.CallJSON(ctx, &opts, nil, &q)
		err = q.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return nil, errors.Wrap(err, "about failed")
	}
	usage = &fs.Usage{
		Total: fs.NewUsageValue(q.Quota),               // quota of bytes that can be used
		Used:  fs.NewUsageValue(q.UsedQuota),           // bytes in use
		Free:  fs.NewUsageValue(q.Quota - q.UsedQuota), // bytes which can be uploaded before reaching the quota
	}
	return usage, nil
}

// Hashes returns the supported hash sets.
func (f *Fs) Hashes() hash.Set {
	return hash.Set(hash.MD5 | hash.SHA1)
}

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

// 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
}

// getHashes fetches the hashes into the object
func (o *Object) getHashes(ctx context.Context) (err error) {
	var resp *http.Response
	var result api.ChecksumFileResult
	opts := rest.Opts{
		Method:     "GET",
		Path:       "/checksumfile",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("fileid", fileIDtoNumber(o.id))
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return err
	}
	o.setHashes(&result.Hashes)
	return o.setMetaData(&result.Metadata)
}

// Hash returns the SHA-1 of an object returning a lowercase hex string
func (o *Object) Hash(ctx context.Context, t hash.Type) (string, error) {
	if t != hash.MD5 && t != hash.SHA1 {
		return "", hash.ErrUnsupported
	}
	if o.md5 == "" && o.sha1 == "" {
		err := o.getHashes(ctx)
		if err != nil {
			return "", errors.Wrap(err, "failed to get hash")
		}
	}
	if t == hash.MD5 {
		return o.md5, nil
	}
	return o.sha1, nil
}

// Size returns the size of an object in bytes
func (o *Object) Size() int64 {
	err := o.readMetaData(context.TODO())
	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.Item) (err error) {
	if info.IsFolder {
		return errors.Wrapf(fs.ErrorNotAFile, "%q is a folder", o.remote)
	}
	o.hasMetaData = true
	o.size = info.Size
	o.modTime = info.ModTime()
	o.id = info.ID
	return nil
}

// setHashes sets the hashes from that passed in
func (o *Object) setHashes(hashes *api.Hashes) {
	o.sha1 = hashes.SHA1
	o.md5 = hashes.MD5
}

// 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)
	if err != nil {
		//if apiErr, ok := err.(*api.Error); ok {
		// FIXME
		// if apiErr.Code == "not_found" || apiErr.Code == "trashed" {
		// 	return fs.ErrorObjectNotFound
		// }
		//}
		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 {
	// Pcloud doesn't have a way of doing this so returning this
	// error will cause the file to be re-uploaded to set the time.
	return fs.ErrorCantSetModTime
}

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

// downloadURL fetches the download link
func (o *Object) downloadURL(ctx context.Context) (URL string, err error) {
	if o.id == "" {
		return "", errors.New("can't download - no id")
	}
	if o.link.IsValid() {
		return o.link.URL(), nil
	}
	var resp *http.Response
	var result api.GetFileLinkResult
	opts := rest.Opts{
		Method:     "GET",
		Path:       "/getfilelink",
		Parameters: url.Values{},
	}
	opts.Parameters.Set("fileid", fileIDtoNumber(o.id))
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		return "", err
	}
	if !result.IsValid() {
		return "", errors.Errorf("fetched invalid link %+v", result)
	}
	o.link = &result
	return o.link.URL(), nil
}

// Open an object for read
func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (in io.ReadCloser, err error) {
	url, err := o.downloadURL(ctx)
	if err != nil {
		return nil, err
	}
	var resp *http.Response
	opts := rest.Opts{
		Method:  "GET",
		RootURL: url,
		Options: options,
	}
	err = o.fs.pacer.Call(func() (bool, error) {
		resp, err = o.fs.srv.Call(ctx, &opts)
		return 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) {
	o.fs.tokenRenewer.Start()
	defer o.fs.tokenRenewer.Stop()

	size := src.Size() // NB can upload without size
	modTime := src.ModTime(ctx)
	remote := o.Remote()

	// Create the directory for the object if it doesn't exist
	leaf, directoryID, err := o.fs.dirCache.FindPath(ctx, remote, true)
	if err != nil {
		return err
	}

	// Experiments with pcloud indicate that it doesn't like any
	// form of request which doesn't have a Content-Length.
	// According to the docs if you close the connection at the
	// end then it should work without Content-Length, but I
	// couldn't get this to work using opts.Close (which sets
	// http.Request.Close).
	//
	// This means that chunked transfer encoding needs to be
	// disabled and a Content-Length needs to be supplied.  This
	// also rules out streaming.
	//
	// Docs: https://docs.pcloud.com/methods/file/uploadfile.html
	var resp *http.Response
	var result api.UploadFileResponse
	opts := rest.Opts{
		Method:           "PUT",
		Path:             "/uploadfile",
		Body:             in,
		ContentType:      fs.MimeType(ctx, o),
		ContentLength:    &size,
		Parameters:       url.Values{},
		TransferEncoding: []string{"identity"}, // pcloud doesn't like chunked encoding
		Options:          options,
	}
	leaf = o.fs.opt.Enc.FromStandardName(leaf)
	opts.Parameters.Set("filename", leaf)
	opts.Parameters.Set("folderid", dirIDtoNumber(directoryID))
	opts.Parameters.Set("nopartial", "1")
	opts.Parameters.Set("mtime", fmt.Sprintf("%d", modTime.Unix()))

	// Special treatment for a 0 length upload.  This doesn't work
	// with PUT even with Content-Length set (by setting
	// opts.Body=0), so upload it as a multpart form POST with
	// Content-Length set.
	if size == 0 {
		formReader, contentType, overhead, err := rest.MultipartUpload(in, opts.Parameters, "content", leaf)
		if err != nil {
			return errors.Wrap(err, "failed to make multipart upload for 0 length file")
		}

		contentLength := overhead + size

		opts.ContentType = contentType
		opts.Body = formReader
		opts.Method = "POST"
		opts.Parameters = nil
		opts.ContentLength = &contentLength
	}

	err = o.fs.pacer.CallNoRetry(func() (bool, error) {
		resp, err = o.fs.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
	if err != nil {
		// sometimes pcloud leaves a half complete file on
		// error, so delete it if it exists
		delObj, delErr := o.fs.NewObject(ctx, o.remote)
		if delErr == nil && delObj != nil {
			_ = delObj.Remove(ctx)
		}
		return err
	}
	if len(result.Items) != 1 {
		return errors.Errorf("failed to upload %v - not sure why", o)
	}
	o.setHashes(&result.Checksums[0])
	return o.setMetaData(&result.Items[0])
}

// Remove an object
func (o *Object) Remove(ctx context.Context) error {
	opts := rest.Opts{
		Method:     "POST",
		Path:       "/deletefile",
		Parameters: url.Values{},
	}
	var result api.ItemResult
	opts.Parameters.Set("fileid", fileIDtoNumber(o.id))
	return o.fs.pacer.Call(func() (bool, error) {
		resp, err := o.fs.srv.CallJSON(ctx, &opts, nil, &result)
		err = result.Error.Update(err)
		return shouldRetry(resp, err)
	})
}

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

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