From 1b8b6e218c7a70cb61c5449a204e38738b7bd945 Mon Sep 17 00:00:00 2001
From: Ben Burwell <ben@benburwell.com>
Date: Thu, 11 Jul 2019 09:44:51 -0400
Subject: Add maildir backend worker

Add the initial implementation of a backend for Maildir accounts. Much
of the functionality required is implemented in the go-message and
go-maildir libraries, so we use them as much as possible.

The maildir worker hooks into a new maildir:// URL scheme in the
accounts.conf file which points to a container of several maildir
directories. From there, the OpenDirectory, FetchDirectoryContents, etc
messages work on subdirectories. This is implemented as a Container
struct which handles mapping between the symbolic email folder names and
UIDs to the concrete directories and file names.
---
 worker/maildir/worker.go | 353 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 353 insertions(+)
 create mode 100644 worker/maildir/worker.go

(limited to 'worker/maildir/worker.go')

diff --git a/worker/maildir/worker.go b/worker/maildir/worker.go
new file mode 100644
index 0000000..f0c92ed
--- /dev/null
+++ b/worker/maildir/worker.go
@@ -0,0 +1,353 @@
+package maildir
+
+import (
+	"fmt"
+	"io"
+	"net/url"
+	"os"
+	"path/filepath"
+
+	"github.com/emersion/go-maildir"
+
+	"git.sr.ht/~sircmpwn/aerc/models"
+	"git.sr.ht/~sircmpwn/aerc/worker/types"
+)
+
+var errUnsupported = fmt.Errorf("unsupported command")
+
+// A Worker handles interfacing between aerc's UI and a group of maildirs.
+type Worker struct {
+	c        *Container
+	selected *maildir.Dir
+	worker   *types.Worker
+}
+
+// NewWorker creates a new maildir worker with the provided worker.
+func NewWorker(worker *types.Worker) *Worker {
+	return &Worker{worker: worker}
+}
+
+// Run starts the worker's message handling loop.
+func (w *Worker) Run() {
+	for {
+		action := <-w.worker.Actions
+		msg := w.worker.ProcessAction(action)
+		if err := w.handleMessage(msg); err == errUnsupported {
+			w.worker.PostMessage(&types.Unsupported{
+				Message: types.RespondTo(msg),
+			}, nil)
+		} else if err != nil {
+			w.worker.PostMessage(&types.Error{
+				Message: types.RespondTo(msg),
+				Error:   err,
+			}, nil)
+		}
+	}
+}
+
+func (w *Worker) done(msg types.WorkerMessage) {
+	w.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
+}
+
+func (w *Worker) err(msg types.WorkerMessage, err error) {
+	w.worker.PostMessage(&types.Error{
+		Message: types.RespondTo(msg),
+		Error:   err,
+	}, nil)
+}
+
+func (w *Worker) handleMessage(msg types.WorkerMessage) error {
+	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.CreateDirectory:
+		return w.handleCreateDirectory(msg)
+	case *types.FetchMessageHeaders:
+		return w.handleFetchMessageHeaders(msg)
+	case *types.FetchMessageBodyPart:
+		return w.handleFetchMessageBodyPart(msg)
+	case *types.FetchFullMessages:
+		return w.handleFetchFullMessages(msg)
+	case *types.DeleteMessages:
+		return w.handleDeleteMessages(msg)
+	case *types.ReadMessages:
+		return w.handleReadMessages(msg)
+	case *types.CopyMessages:
+		return w.handleCopyMessages(msg)
+	case *types.AppendMessage:
+		return w.handleAppendMessage(msg)
+	case *types.SearchDirectory:
+		return w.handleSearchDirectory(msg)
+	}
+	return errUnsupported
+}
+
+func (w *Worker) handleConfigure(msg *types.Configure) error {
+	defer w.done(msg)
+	u, err := url.Parse(msg.Config.Source)
+	if err != nil {
+		w.worker.Logger.Printf("error configuring maildir worker: %v", err)
+		return err
+	}
+	dir := u.Path
+	if u.Host == "~" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return fmt.Errorf("could not resolve home directory: %v", err)
+		}
+		dir = filepath.Join(home, u.Path)
+	}
+	w.c = NewContainer(dir, w.worker.Logger)
+	w.worker.Logger.Printf("configured base maildir: %s", dir)
+	return nil
+}
+
+func (w *Worker) handleConnect(msg *types.Connect) error {
+	w.done(msg)
+	return nil
+}
+
+func (w *Worker) handleListDirectories(msg *types.ListDirectories) error {
+	defer w.done(msg)
+	dirs, err := w.c.ListFolders()
+	if err != nil {
+		w.worker.Logger.Printf("error listing directories: %v", err)
+		return err
+	}
+	for _, name := range dirs {
+		w.worker.PostMessage(&types.Directory{
+			Message: types.RespondTo(msg),
+			Dir: &models.Directory{
+				Name:       name,
+				Attributes: []string{},
+			},
+		}, nil)
+	}
+	return nil
+}
+
+func (w *Worker) handleOpenDirectory(msg *types.OpenDirectory) error {
+	defer w.done(msg)
+	w.worker.Logger.Printf("opening %s", msg.Directory)
+	dir, err := w.c.OpenDirectory(msg.Directory)
+	if err != nil {
+		return err
+	}
+	w.selected = &dir
+	// TODO: why does this need to be sent twice??
+	info := &types.DirectoryInfo{
+		Info: &models.DirectoryInfo{
+			Name:     msg.Directory,
+			Flags:    []string{},
+			ReadOnly: false,
+			// total messages
+			Exists: 0,
+			// new messages since mailbox was last opened
+			Recent: 0,
+			// total unread
+			Unseen: 0,
+		},
+	}
+	w.worker.PostMessage(info, nil)
+	w.worker.PostMessage(info, nil)
+	return nil
+}
+
+func (w *Worker) handleFetchDirectoryContents(
+	msg *types.FetchDirectoryContents) error {
+	defer w.done(msg)
+	uids, err := w.c.UIDs(*w.selected)
+	if err != nil {
+		w.worker.Logger.Printf("error scanning uids: %v", err)
+		return err
+	}
+	w.worker.PostMessage(&types.DirectoryContents{
+		Message: types.RespondTo(msg),
+		Uids:    uids,
+	}, nil)
+	return nil
+}
+
+func (w *Worker) handleCreateDirectory(msg *types.CreateDirectory) error {
+	dir := w.c.Dir(msg.Directory)
+	defer w.done(msg)
+	if err := dir.Create(); err != nil {
+		w.worker.Logger.Printf("could not create directory %s: %v",
+			msg.Directory, err)
+		return err
+	}
+	return nil
+}
+
+func (w *Worker) handleFetchMessageHeaders(
+	msg *types.FetchMessageHeaders) error {
+	defer w.done(msg)
+	for _, uid := range msg.Uids {
+		m, err := w.c.Message(*w.selected, uid)
+		if err != nil {
+			w.worker.Logger.Printf("could not get message: %v", err)
+			w.err(msg, err)
+			continue
+		}
+		info, err := m.MessageInfo()
+		if err != nil {
+			w.worker.Logger.Printf("could not get message info: %v", err)
+			w.err(msg, err)
+			continue
+		}
+		w.worker.PostMessage(&types.MessageInfo{
+			Message: types.RespondTo(msg),
+			Info:    info,
+		}, nil)
+	}
+	return nil
+}
+
+func (w *Worker) handleFetchMessageBodyPart(
+	msg *types.FetchMessageBodyPart) error {
+	defer w.done(msg)
+
+	// get reader
+	m, err := w.c.Message(*w.selected, msg.Uid)
+	if err != nil {
+		w.worker.Logger.Printf("could not get message %d: %v", msg.Uid, err)
+		return err
+	}
+	r, err := m.NewBodyPartReader(msg.Part)
+	if err != nil {
+		w.worker.Logger.Printf(
+			"could not get body part reader for message=%d, parts=%#v: %v",
+			msg.Uid, msg.Part, err)
+		return err
+	}
+	w.worker.PostMessage(&types.MessageBodyPart{
+		Message: types.RespondTo(msg),
+		Part: &models.MessageBodyPart{
+			Reader: r,
+			Uid:    msg.Uid,
+		},
+	}, nil)
+
+	// mark message as read
+	if err := m.MarkRead(true); err != nil {
+		w.worker.Logger.Printf("could not mark message as read: %v", err)
+		return err
+	}
+
+	// send updated flags to ui
+	info, err := m.MessageInfo()
+	if err != nil {
+		w.worker.Logger.Printf("could not fetch message info: %v", err)
+		return err
+	}
+	w.worker.PostMessage(&types.MessageInfo{
+		Message: types.RespondTo(msg),
+		Info:    info,
+	}, nil)
+
+	return nil
+}
+
+func (w *Worker) handleFetchFullMessages(msg *types.FetchFullMessages) error {
+	defer w.done(msg)
+	for _, uid := range msg.Uids {
+		m, err := w.c.Message(*w.selected, uid)
+		if err != nil {
+			w.worker.Logger.Printf("could not get message %d: %v", uid, err)
+			return err
+		}
+		r, err := m.NewReader()
+		if err != nil {
+			w.worker.Logger.Printf("could not get message reader: %v", err)
+			return err
+		}
+		w.worker.PostMessage(&types.FullMessage{
+			Message: types.RespondTo(msg),
+			Content: &models.FullMessage{
+				Uid:    uid,
+				Reader: r,
+			},
+		}, nil)
+	}
+	return nil
+}
+
+func (w *Worker) handleDeleteMessages(msg *types.DeleteMessages) error {
+	defer w.done(msg)
+	deleted, err := w.c.DeleteAll(*w.selected, msg.Uids)
+	if len(deleted) > 0 {
+		w.worker.PostMessage(&types.MessagesDeleted{
+			Message: types.RespondTo(msg),
+			Uids:    deleted,
+		}, nil)
+	}
+	if err != nil {
+		w.worker.Logger.Printf("error removing some messages: %v", err)
+		return err
+	}
+	return nil
+}
+
+func (w *Worker) handleReadMessages(msg *types.ReadMessages) error {
+	defer w.done(msg)
+	for _, uid := range msg.Uids {
+		m, err := w.c.Message(*w.selected, uid)
+		if err != nil {
+			w.worker.Logger.Printf("could not get message: %v", err)
+			w.err(msg, err)
+			continue
+		}
+		if err := m.MarkRead(msg.Read); err != nil {
+			w.worker.Logger.Printf("could not mark message as read: %v", err)
+			w.err(msg, err)
+			continue
+		}
+		info, err := m.MessageInfo()
+		if err != nil {
+			w.worker.Logger.Printf("could not get message info: %v", err)
+			w.err(msg, err)
+			continue
+		}
+		w.worker.PostMessage(&types.MessageInfo{
+			Message: types.RespondTo(msg),
+			Info:    info,
+		}, nil)
+	}
+	return nil
+}
+
+func (w *Worker) handleCopyMessages(msg *types.CopyMessages) error {
+	// TODO: this.
+	return nil
+}
+
+func (w *Worker) handleAppendMessage(msg *types.AppendMessage) error {
+	defer w.done(msg)
+	dest := w.c.Dir(msg.Destination)
+	delivery, err := dest.NewDelivery()
+	if err != nil {
+		w.worker.Logger.Printf("could not deliver message to %s: %v",
+			msg.Destination, err)
+		return err
+	}
+	defer delivery.Close()
+	if _, err := io.Copy(delivery, msg.Reader); err != nil {
+		w.worker.Logger.Printf("could not write message to destination: %v", err)
+		return err
+	}
+	return nil
+}
+
+func (w *Worker) handleSearchDirectory(msg *types.SearchDirectory) error {
+	return errUnsupported
+}
-- 
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