//go:build notmuch
// +build notmuch

package notmuch

import (
	"bufio"
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/url"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"git.sr.ht/~rjarry/aerc/config"
	"git.sr.ht/~rjarry/aerc/log"
	"git.sr.ht/~rjarry/aerc/models"
	"git.sr.ht/~rjarry/aerc/worker/handlers"
	"git.sr.ht/~rjarry/aerc/worker/lib"
	notmuch "git.sr.ht/~rjarry/aerc/worker/notmuch/lib"
	"git.sr.ht/~rjarry/aerc/worker/types"
	"github.com/mitchellh/go-homedir"
)

func init() {
	handlers.RegisterWorkerFactory("notmuch", NewWorker)
}

var errUnsupported = fmt.Errorf("unsupported command")

type worker struct {
	w                   *types.Worker
	nmEvents            chan eventType
	query               string
	currentQueryName    string
	queryMapOrder       []string
	nameQueryMap        map[string]string
	store               *lib.MaildirStore
	db                  *notmuch.DB
	setupErr            error
	currentSortCriteria []*types.SortCriterion
	watcher             types.FSWatcher
	watcherDebounce     *time.Timer
	capabilities        *models.Capabilities
}

// NewWorker creates a new notmuch worker with the provided worker.
func NewWorker(w *types.Worker) (types.Backend, error) {
	events := make(chan eventType, 20)
	watcher, err := handlers.NewWatcher()
	if err != nil {
		return nil, fmt.Errorf("(%s) could not create file system watcher: %w", w.Name, err)
	}
	return &worker{
		w:        w,
		nmEvents: events,
		watcher:  watcher,
		capabilities: &models.Capabilities{
			Sort:   true,
			Thread: true,
		},
	}, nil
}

// Run starts the worker's message handling loop.
func (w *worker) Run() {
	for {
		select {
		case action := <-w.w.Actions:
			msg := w.w.ProcessAction(action)
			if err := w.handleMessage(msg); errors.Is(err, errUnsupported) {
				w.w.PostMessage(&types.Unsupported{
					Message: types.RespondTo(msg),
				}, nil)
				log.Errorf("ProcessAction(%T) unsupported: %v", msg, err)
			} else if err != nil {
				w.w.PostMessage(&types.Error{
					Message: types.RespondTo(msg),
					Error:   err,
				}, nil)
				log.Errorf("ProcessAction(%T) failure: %v", msg, err)
			}
		case nmEvent := <-w.nmEvents:
			err := w.handleNotmuchEvent(nmEvent)
			if err != nil {
				log.Errorf("notmuch event failure: %v", err)
			}
		case <-w.watcher.Events():
			if w.watcherDebounce != nil {
				w.watcherDebounce.Stop()
			}
			// Debounce FS changes
			w.watcherDebounce = time.AfterFunc(50*time.Millisecond, func() {
				defer log.PanicHandler()
				w.nmEvents <- &updateDirCounts{}
			})
		}
	}
}

func (w *worker) Capabilities() *models.Capabilities {
	return w.capabilities
}

func (w *worker) done(msg types.WorkerMessage) {
	w.w.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
}

func (w *worker) err(msg types.WorkerMessage, err error) {
	w.w.PostMessage(&types.Error{
		Message: types.RespondTo(msg),
		Error:   err,
	}, nil)
}

func (w *worker) handleMessage(msg types.WorkerMessage) error {
	if w.setupErr != nil {
		// only configure can recover from a config error, bail for everything else
		_, isConfigure := msg.(*types.Configure)
		if !isConfigure {
			return w.setupErr
		}
	}

	switch msg := msg.(type) {
	case *types.Unsupported:
		// No-op
	case *types.Configure:
		return w.handleConfigure(msg)
	case *types.Connect:
		return w.handleConnect(msg)
	case *types.ListDirectories:
		return w.handleListDirectories(msg)
	case *types.OpenDirectory:
		return w.handleOpenDirectory(msg)
	case *types.FetchDirectoryContents:
		return w.handleFetchDirectoryContents(msg)
	case *types.FetchDirectoryThreaded:
		return w.handleFetchDirectoryThreaded(msg)
	case *types.FetchMessageHeaders:
		return w.handleFetchMessageHeaders(msg)
	case *types.FetchMessageBodyPart:
		return w.handleFetchMessageBodyPart(msg)
	case *types.FetchFullMessages:
		return w.handleFetchFullMessages(msg)
	case *types.FlagMessages:
		return w.handleFlagMessages(msg)
	case *types.AnsweredMessages:
		return w.handleAnsweredMessages(msg)
	case *types.SearchDirectory:
		return w.handleSearchDirectory(msg)
	case *types.ModifyLabels:
		return w.handleModifyLabels(msg)
	case *types.CheckMail:
		go w.handleCheckMail(msg)
		return nil
	case *types.DeleteMessages:
		return w.handleDeleteMessages(msg)
	case *types.CopyMessages:
		return w.handleCopyMessages(msg)
	case *types.MoveMessages:
		return w.handleMoveMessages(msg)
	case *types.AppendMessage:
		return w.handleAppendMessage(msg)
	case *types.CreateDirectory:
		return w.handleCreateDirectory(msg)
	case *types.RemoveDirectory:
		return w.handleRemoveDirectory(msg)
	}
	return errUnsupported
}

func (w *worker) handleConfigure(msg *types.Configure) error {
	var err error
	defer func() {
		if err == nil {
			w.setupErr = nil
			return
		}
		w.setupErr = fmt.Errorf("notmuch: %w", err)
	}()

	u, err := url.Parse(msg.Config.Source)
	if err != nil {
		log.Errorf("error configuring notmuch worker: %v", err)
		return err
	}
	home, err := homedir.Expand(u.Hostname())
	if err != nil {
		return fmt.Errorf("could not resolve home directory: %w", err)
	}
	pathToDB := filepath.Join(home, u.Path)
	err = w.loadQueryMap(msg.Config)
	if err != nil {
		return fmt.Errorf("could not load query map configuration: %w", err)
	}
	excludedTags := w.loadExcludeTags(msg.Config)
	w.db = notmuch.NewDB(pathToDB, excludedTags)

	val, ok := msg.Config.Params["maildir-store"]
	if ok {
		path, err := homedir.Expand(val)
		if err != nil {
			return err
		}
		store, err := lib.NewMaildirStore(path, false)
		if err != nil {
			return fmt.Errorf("Cannot initialize maildir store: %w", err)
		}
		w.store = store
	}

	return nil
}

func (w *worker) handleConnect(msg *types.Connect) error {
	err := w.db.Connect()
	if err != nil {
		return err
	}
	w.done(msg)
	w.emitLabelList()
	// Watch all the files in the xapian folder for changes. We'll debounce
	// changes, so catching multiple is ok
	dbPath := path.Join(w.db.Path(), ".notmuch", "xapian")
	err = w.watcher.Configure(dbPath)
	if err != nil {
		return err
	}
	return nil
}

func (w *worker) handleListDirectories(msg *types.ListDirectories) error {
	if w.store != nil {
		folders, err := w.store.FolderMap()
		if err != nil {
			log.Errorf("failed listing directories: %v", err)
			return err
		}
		for name := range folders {
			w.w.PostMessage(&types.Directory{
				Message: types.RespondTo(msg),
				Dir: &models.Directory{
					Name: name,
				},
			}, nil)
		}
	}

	for _, name := range w.queryMapOrder {
		w.w.PostMessage(&types.Directory{
			Message: types.RespondTo(msg),
			Dir: &models.Directory{
				Name: name,
				Role: models.QueryRole,
			},
		}, nil)
	}
	// Update dir counts when listing directories
	err := w.handleUpdateDirCounts()
	if err != nil {
		return err
	}
	w.done(msg)
	return nil
}

func (w *worker) getDirectoryInfo(name string, query string) *models.DirectoryInfo {
	dirInfo := &models.DirectoryInfo{
		Name: name,
		// total messages
		Exists: 0,
		// new messages since mailbox was last opened
		Recent: 0,
		// total unread
		Unseen: 0,
	}

	count, err := w.db.QueryCountMessages(query)
	if err != nil {
		return dirInfo
	}
	dirInfo.Exists = count.Exists
	dirInfo.Unseen = count.Unread

	return dirInfo
}

func (w *worker) handleOpenDirectory(msg *types.OpenDirectory) error {
	log.Tracef("opening %s", msg.Directory)

	var isDynamicFolder bool
	q := ""
	if w.store != nil {
		folders, _ := w.store.FolderMap()
		dir, ok := folders[msg.Directory]
		if ok {
			q = fmt.Sprintf("folder:%s", strconv.Quote(msg.Directory))
			if err := w.processNewMaildirFiles(string(dir)); err != nil {
				return err
			}
		}
	}
	if q == "" {
		var ok bool
		q, ok = w.nameQueryMap[msg.Directory]
		if !ok {
			q = msg.Directory
			isDynamicFolder = true
			w.w.PostMessage(&types.Directory{
				Message: types.RespondTo(msg),
				Dir: &models.Directory{
					Name: q,
					Role: models.QueryRole,
				},
			}, nil)
		}
	}
	w.query = q
	w.currentQueryName = msg.Directory

	w.w.PostMessage(&types.DirectoryInfo{
		Info:    w.getDirectoryInfo(msg.Directory, w.query),
		Message: types.RespondTo(msg),
	}, nil)
	if isDynamicFolder {
		w.w.PostMessage(&types.DirectoryInfo{
			Info:    w.getDirectoryInfo(msg.Directory, w.query),
			Message: types.RespondTo(msg),
		}, nil)
	}
	w.done(msg)
	return nil
}

func (w *worker) handleFetchDirectoryContents(
	msg *types.FetchDirectoryContents,
) error {
	w.currentSortCriteria = msg.SortCriteria
	err := w.emitDirectoryContents(msg)
	if err != nil {
		return err
	}
	w.done(msg)
	return nil
}

func (w *worker) handleFetchDirectoryThreaded(
	msg *types.FetchDirectoryThreaded,
) error {
	// w.currentSortCriteria = msg.SortCriteria
	err := w.emitDirectoryThreaded(msg)
	if err != nil {
		return err
	}
	w.done(msg)
	return nil
}

func (w *worker) handleFetchMessageHeaders(
	msg *types.FetchMessageHeaders,
) error {
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			w.w.PostMessageInfoError(msg, uid, err)
			continue
		}
		err = w.emitMessageInfo(m, msg)
		if err != nil {
			log.Errorf("could not emit message info: %v", err)
			w.w.PostMessageInfoError(msg, uid, err)
			continue
		}
	}
	w.done(msg)
	return nil
}

func (w *worker) uidsFromQuery(query string) ([]uint32, error) {
	msgIDs, err := w.db.MsgIDsFromQuery(query)
	if err != nil {
		return nil, err
	}
	var uids []uint32
	for _, id := range msgIDs {
		uid := w.db.UidFromKey(id)
		uids = append(uids, uid)

	}
	return uids, nil
}

func (w *worker) msgFromUid(uid uint32) (*Message, error) {
	key, ok := w.db.KeyFromUid(uid)
	if !ok {
		return nil, fmt.Errorf("Invalid uid: %v", uid)
	}
	msg := &Message{
		key: key,
		uid: uid,
		db:  w.db,
	}
	return msg, nil
}

func (w *worker) handleFetchMessageBodyPart(
	msg *types.FetchMessageBodyPart,
) error {
	m, err := w.msgFromUid(msg.Uid)
	if err != nil {
		log.Errorf("could not get message %d: %v", msg.Uid, err)
		return err
	}
	r, err := m.NewBodyPartReader(msg.Part)
	if err != nil {
		log.Errorf(
			"could not get body part reader for message=%d, parts=%#v: %w",
			msg.Uid, msg.Part, err)
		return err
	}
	w.w.PostMessage(&types.MessageBodyPart{
		Message: types.RespondTo(msg),
		Part: &models.MessageBodyPart{
			Reader: r,
			Uid:    msg.Uid,
		},
	}, nil)

	w.done(msg)
	return nil
}

func (w *worker) handleFetchFullMessages(msg *types.FetchFullMessages) error {
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message %d: %v", uid, err)
			return err
		}
		r, err := m.NewReader()
		if err != nil {
			log.Errorf("could not get message reader: %v", err)
			return err
		}
		defer r.Close()
		b, err := io.ReadAll(r)
		if err != nil {
			return err
		}
		w.w.PostMessage(&types.FullMessage{
			Message: types.RespondTo(msg),
			Content: &models.FullMessage{
				Uid:    uid,
				Reader: bytes.NewReader(b),
			},
		}, nil)
	}
	w.done(msg)
	return nil
}

func (w *worker) handleAnsweredMessages(msg *types.AnsweredMessages) error {
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			w.err(msg, err)
			continue
		}
		if err := m.MarkAnswered(msg.Answered); err != nil {
			log.Errorf("could not mark message as answered: %v", err)
			w.err(msg, err)
			continue
		}
		err = w.emitMessageInfo(m, msg)
		if err != nil {
			log.Errorf("could not emit message info: %v", err)
			w.err(msg, err)
			continue
		}
	}
	w.w.PostMessage(&types.DirectoryInfo{
		Info: w.getDirectoryInfo(w.currentQueryName, w.query),
	}, nil)
	w.done(msg)
	return nil
}

func (w *worker) handleFlagMessages(msg *types.FlagMessages) error {
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			w.err(msg, err)
			continue
		}
		if err := m.SetFlag(msg.Flags, msg.Enable); err != nil {
			log.Errorf("could not set flag %v as %t for message: %v",
				msg.Flags, msg.Enable, err)
			w.err(msg, err)
			continue
		}
		err = w.emitMessageInfo(m, msg)
		if err != nil {
			log.Errorf("could not emit message info: %v", err)
			w.err(msg, err)
			continue
		}
	}
	w.w.PostMessage(&types.DirectoryInfo{
		Info: w.getDirectoryInfo(w.currentQueryName, w.query),
	}, nil)
	w.done(msg)
	return nil
}

func (w *worker) handleSearchDirectory(msg *types.SearchDirectory) error {
	// the first item is the command (search / filter)
	s := strings.Join(msg.Argv[1:], " ")
	// we only want to search in the current query, so merge the two together
	search := w.query
	if s != "" {
		search = fmt.Sprintf("(%v) and (%v)", w.query, s)
	}
	uids, err := w.uidsFromQuery(search)
	if err != nil {
		return err
	}
	w.w.PostMessage(&types.SearchResults{
		Message: types.RespondTo(msg),
		Uids:    uids,
	}, nil)
	return nil
}

func (w *worker) handleModifyLabels(msg *types.ModifyLabels) error {
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			return fmt.Errorf("could not get message from uid %d: %w", uid, err)
		}
		err = m.ModifyTags(msg.Add, msg.Remove)
		if err != nil {
			return fmt.Errorf("could not modify message tags: %w", err)
		}
		err = w.emitMessageInfo(m, msg)
		if err != nil {
			return err
		}
	}
	// tags changed, most probably some messages shifted to other folders
	// so we need to re-enumerate the query content
	err := w.emitDirectoryContents(msg)
	if err != nil {
		return err
	}
	// and update the list of possible tags
	w.emitLabelList()
	w.w.PostMessage(&types.DirectoryInfo{
		Info: w.getDirectoryInfo(w.currentQueryName, w.query),
	}, nil)
	w.done(msg)
	return nil
}

func (w *worker) loadQueryMap(acctConfig *config.AccountConfig) error {
	raw, ok := acctConfig.Params["query-map"]
	if !ok {
		// nothing to do
		return nil
	}
	file, err := homedir.Expand(raw)
	if err != nil {
		return err
	}
	f, err := os.Open(file)
	if err != nil {
		return err
	}
	defer f.Close()
	w.nameQueryMap = make(map[string]string)
	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		line := scanner.Text()
		if line == "" || line[0] == '#' {
			continue
		}

		split := strings.SplitN(line, "=", 2)
		if len(split) != 2 {
			return fmt.Errorf("%v: invalid line %q, want name=query", file, line)
		}
		w.nameQueryMap[strings.TrimSpace(split[0])] = split[1]
		w.queryMapOrder = append(w.queryMapOrder, strings.TrimSpace(split[0]))
	}
	return nil
}

func (w *worker) loadExcludeTags(
	acctConfig *config.AccountConfig,
) []string {
	raw, ok := acctConfig.Params["exclude-tags"]
	if !ok {
		// nothing to do
		return nil
	}
	excludedTags := strings.Split(raw, ",")
	for idx, tag := range excludedTags {
		excludedTags[idx] = strings.Trim(tag, " ")
	}
	return excludedTags
}

func (w *worker) emitDirectoryContents(parent types.WorkerMessage) error {
	query := w.query
	if msg, ok := parent.(*types.FetchDirectoryContents); ok {
		s := strings.Join(msg.FilterCriteria[1:], " ")
		if s != "" {
			query = fmt.Sprintf("(%v) and (%v)", query, s)
		}
	}
	uids, err := w.uidsFromQuery(query)
	if err != nil {
		return fmt.Errorf("could not fetch uids: %w", err)
	}
	sortedUids, err := w.sort(uids, w.currentSortCriteria)
	if err != nil {
		log.Errorf("error sorting directory: %v", err)
		return err
	}
	w.w.PostMessage(&types.DirectoryContents{
		Message: types.RespondTo(parent),
		Uids:    sortedUids,
	}, nil)
	return nil
}

func (w *worker) emitDirectoryThreaded(parent types.WorkerMessage) error {
	query := w.query
	if msg, ok := parent.(*types.FetchDirectoryThreaded); ok {
		s := strings.Join(msg.FilterCriteria[1:], " ")
		if s != "" {
			query = fmt.Sprintf("(%v) and (%v)", query, s)
		}
	}
	threads, err := w.db.ThreadsFromQuery(query)
	if err != nil {
		return err
	}
	w.w.PostMessage(&types.DirectoryThreaded{
		Threads: threads,
	}, nil)
	return nil
}

func (w *worker) emitMessageInfo(m *Message,
	parent types.WorkerMessage,
) error {
	info, err := m.MessageInfo()
	if err != nil {
		return fmt.Errorf("could not get MessageInfo: %w", err)
	}
	w.w.PostMessage(&types.MessageInfo{
		Message: types.RespondTo(parent),
		Info:    info,
	}, nil)
	return nil
}

func (w *worker) emitLabelList() {
	tags, err := w.db.ListTags()
	if err != nil {
		log.Errorf("could not load tags: %v", err)
		return
	}
	w.w.PostMessage(&types.LabelList{Labels: tags}, nil)
}

func (w *worker) sort(uids []uint32,
	criteria []*types.SortCriterion,
) ([]uint32, error) {
	if len(criteria) == 0 {
		return uids, nil
	}
	var msgInfos []*models.MessageInfo
	for _, uid := range uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			continue
		}
		info, err := m.MessageInfo()
		if err != nil {
			log.Errorf("could not get message info: %v", err)
			continue
		}
		msgInfos = append(msgInfos, info)
	}
	sortedUids, err := lib.Sort(msgInfos, criteria)
	if err != nil {
		log.Errorf("could not sort the messages: %v", err)
		return nil, err
	}
	return sortedUids, nil
}

func (w *worker) handleCheckMail(msg *types.CheckMail) {
	defer log.PanicHandler()
	if msg.Command == "" {
		w.err(msg, fmt.Errorf("(%s) checkmail: no command specified", w.w.Name))
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), msg.Timeout)
	defer cancel()
	cmd := exec.CommandContext(ctx, "sh", "-c", msg.Command)
	err := cmd.Run()
	switch {
	case ctx.Err() != nil:
		w.err(msg, fmt.Errorf("(%s) checkmail: timed out", w.w.Name))
	case err != nil:
		w.err(msg, fmt.Errorf("(%s) checkmail: error running command: %w", w.w.Name, err))
	default:
		w.done(msg)
	}
}

func (w *worker) handleDeleteMessages(msg *types.DeleteMessages) error {
	if w.store == nil {
		return errUnsupported
	}

	var deleted []uint32

	// With notmuch, two identical files can be referenced under
	// the same index key, even if they exist in two different
	// folders. So in order to remove the message from the right
	// maildir folder we need to pass a hint to Remove() so it
	// can purge the right file.
	folders, _ := w.store.FolderMap()
	path, ok := folders[w.currentQueryName]
	if !ok {
		w.err(msg, fmt.Errorf("Can only delete file from a maildir folder"))
		w.done(msg)
		return nil
	}

	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			w.err(msg, err)
			continue
		}
		if err := m.Remove(path); err != nil {
			log.Errorf("could not remove message: %v", err)
			w.err(msg, err)
			continue
		}
		deleted = append(deleted, uid)
	}
	if len(deleted) > 0 {
		w.w.PostMessage(&types.MessagesDeleted{
			Message: types.RespondTo(msg),
			Uids:    deleted,
		}, nil)
	}
	w.done(msg)
	return nil
}

func (w *worker) handleCopyMessages(msg *types.CopyMessages) error {
	if w.store == nil {
		return errUnsupported
	}

	// Only allow file to be copied to a maildir folder
	folders, _ := w.store.FolderMap()
	dest, ok := folders[msg.Destination]
	if !ok {
		return fmt.Errorf("Can only copy file to a maildir folder")
	}

	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			return err
		}
		if err := m.Copy(dest); err != nil {
			log.Errorf("could not copy message: %v", err)
			return err
		}
	}
	w.w.PostMessage(&types.MessagesCopied{
		Message:     types.RespondTo(msg),
		Destination: msg.Destination,
		Uids:        msg.Uids,
	}, nil)
	w.done(msg)
	return nil
}

func (w *worker) handleMoveMessages(msg *types.MoveMessages) error {
	if w.store == nil {
		return errUnsupported
	}

	var moved []uint32

	folders, _ := w.store.FolderMap()

	// Only allow file to be moved to a maildir folder
	dest, ok := folders[msg.Destination]
	if !ok {
		return fmt.Errorf("Can only move file to a maildir folder")
	}

	var err error
	for _, uid := range msg.Uids {
		m, err := w.msgFromUid(uid)
		if err != nil {
			log.Errorf("could not get message: %v", err)
			break
		}
		filenames, err := m.db.MsgFilenames(m.key)
		if err != nil {
			return err
		}
		// In the future, it'd be nice if we could overload move with
		// the possibility to affect some or all of the files
		// corresponding to a message.
		if len(filenames) > 1 {
			return fmt.Errorf("Cannot move: message %d has multiple files", m.uid)
		}
		source, key := parseFilename(filenames[0])
		if key == "" {
			return fmt.Errorf("failed to parse message filename: %s", filenames[0])
		}
		if err := m.Move(source, dest); err != nil {
			log.Errorf("could not copy message: %v", err)
			break
		}
		moved = append(moved, uid)
	}
	w.w.PostMessage(&types.MessagesDeleted{
		Message: types.RespondTo(msg),
		Uids:    moved,
	}, nil)
	if err == nil {
		w.done(msg)
	}
	return err
}

func (w *worker) handleAppendMessage(msg *types.AppendMessage) error {
	if w.store == nil {
		return errUnsupported
	}

	// Only allow file to be created in a maildir folder
	// since we are the "master" maildir process, we can modify the maildir directly
	folders, _ := w.store.FolderMap()
	dest, ok := folders[msg.Destination]
	if !ok {
		return fmt.Errorf("Can only create file in a maildir folder")
	}
	key, writer, err := dest.Create(lib.ToMaildirFlags(msg.Flags))
	if err != nil {
		log.Errorf("could not create message at %s: %v", msg.Destination, err)
		return err
	}
	filename, err := dest.Filename(key)
	if err != nil {
		writer.Close()
		return err
	}
	if _, err := io.Copy(writer, msg.Reader); err != nil {
		log.Errorf("could not write message to destination: %v", err)
		writer.Close()
		os.Remove(filename)
		return err
	}
	writer.Close()
	if _, err := w.db.IndexFile(filename); err != nil {
		return err
	}
	w.w.PostMessage(&types.DirectoryInfo{
		Info: w.getDirectoryInfo(w.currentQueryName, w.query),
	}, nil)
	w.done(msg)
	return nil
}

func (w *worker) handleCreateDirectory(msg *types.CreateDirectory) error {
	if w.store == nil {
		return errUnsupported
	}

	dir := w.store.Dir(msg.Directory)
	if err := dir.Init(); err != nil {
		log.Errorf("could not create directory %s: %v",
			msg.Directory, err)
		return err
	}
	w.done(msg)
	return nil
}

func (w *worker) handleRemoveDirectory(msg *types.RemoveDirectory) error {
	if w.store == nil {
		return errUnsupported
	}

	dir := w.store.Dir(msg.Directory)
	if err := os.RemoveAll(string(dir)); err != nil {
		log.Errorf("could not remove directory %s: %v",
			msg.Directory, err)
		return err
	}
	w.done(msg)
	return nil
}

// This is a hack that calls MsgModifyTags with an empty list of tags to
// apply on new messages causing notmuch to rename files and effectively
// move them into the cur/ dir.
func (w *worker) processNewMaildirFiles(dir string) error {
	f, err := os.Open(filepath.Join(dir, "new"))
	if err != nil {
		return err
	}
	defer f.Close()
	names, err := f.Readdirnames(0)
	if err != nil {
		return err
	}

	for _, n := range names {
		if n[0] == '.' {
			continue
		}

		key, err := w.db.MsgIDFromFilename(filepath.Join(dir, "new", n))
		if err != nil {
			// Message is not yet indexed, leave it alone
			continue
		}
		// Force message to move from new/ to cur/
		err = w.db.MsgModifyTags(key, nil, nil)
		if err != nil {
			log.Errorf("MsgModifyTags failed: %v", err)
		}
	}

	return nil
}