Add postpone command

This command uses the Postpone folder from the account config to save
messages to. Messages are saved as though they were sent so have a valid
'to' recipient address and should be able to be read back in for later
editing.

commands/account/compose.go

@@ -31,7 +31,7 @@ func (Compose) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 	acct := aerc.SelectedAccount()
 
-	composer, err := widgets.NewComposer(aerc,
+	composer, err := widgets.NewComposer(aerc, acct
 		aerc.Config(), acct.AccountConfig(), acct.Worker(),
 		template, nil, models.OriginalMail{})
 	if err != nil {

commands/compose/postpone.go

@@ -0,0 +1,119 @@
+package compose
+
+import (
+	"io"
+	"io/ioutil"
+	"time"
+
+	"github.com/emersion/go-imap"
+	"github.com/miolini/datacounter"
+	"github.com/pkg/errors"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"git.sr.ht/~sircmpwn/aerc/worker/types"
+)
+
+type Postpone struct{}
+
+func init() {
+	register(Postpone{})
+}
+
+func (Postpone) Aliases() []string {
+	return []string{"postpone"}
+}
+
+func (Postpone) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (Postpone) Execute(aerc *widgets.Aerc, args []string) error {
+	if len(args) != 1 {
+		return errors.New("Usage: postpone")
+	}
+	composer, _ := aerc.SelectedTab().(*widgets.Composer)
+	config := composer.Config()
+
+	if config.Postpone == "" {
+		return errors.New("No Postpone location configured")
+	}
+
+	aerc.Logger().Println("Postponing mail")
+
+	header, _, err := composer.PrepareHeader()
+	if err != nil {
+		return errors.Wrap(err, "PrepareHeader")
+	}
+	header.SetContentType("text/plain", map[string]string{"charset": "UTF-8"})
+	header.Set("Content-Transfer-Encoding", "quoted-printable")
+	worker := composer.Worker()
+	dirs := aerc.SelectedAccount().Directories().List()
+	alreadyCreated := false
+	for _, dir := range dirs {
+		if dir == config.Postpone {
+			alreadyCreated = true
+			break
+		}
+	}
+
+	errChan := make(chan string)
+
+	// run this as a goroutine so we can make other progress. The message
+	// will be saved once the directory is created.
+	go func() {
+		errStr := <-errChan
+		if errStr != "" {
+			aerc.PushError(" " + errStr)
+			return
+		}
+
+		aerc.RemoveTab(composer)
+		ctr := datacounter.NewWriterCounter(ioutil.Discard)
+		err = composer.WriteMessage(header, ctr)
+		if err != nil {
+			aerc.PushError(errors.Wrap(err, "WriteMessage").Error())
+			composer.Close()
+			return
+		}
+		nbytes := int(ctr.Count())
+		r, w := io.Pipe()
+		worker.PostAction(&types.AppendMessage{
+			Destination: config.Postpone,
+			Flags:       []string{imap.SeenFlag},
+			Date:        time.Now(),
+			Reader:      r,
+			Length:      int(nbytes),
+		}, func(msg types.WorkerMessage) {
+			switch msg := msg.(type) {
+			case *types.Done:
+				aerc.PushStatus("Message postponed.", 10*time.Second)
+				r.Close()
+				composer.Close()
+			case *types.Error:
+				aerc.PushError(" " + msg.Error.Error())
+				r.Close()
+				composer.Close()
+			}
+		})
+		composer.WriteMessage(header, w)
+		w.Close()
+	}()
+
+	if !alreadyCreated {
+		// to synchronise the creating of the directory
+		worker.PostAction(&types.CreateDirectory{
+			Directory: config.Postpone,
+		}, func(msg types.WorkerMessage) {
+			switch msg := msg.(type) {
+			case *types.Done:
+				errChan <- ""
+			case *types.Error:
+				errChan <- msg.Error.Error()
+			}
+		})
+	} else {
+		errChan <- ""
+	}
+
+	return nil
+}

commands/msg/forward.go

@@ -70,7 +70,6 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 		"To":      to,
 		"Subject": subject,
 	}
-
 	original := models.OriginalMail{}
 
 	addTab := func() (*widgets.Composer, error) {

commands/msg/reply.go

@@ -124,7 +124,7 @@ func (reply) Execute(aerc *widgets.Aerc, args []string) error {
 			original.Date = msg.Envelope.Date.Format("Mon Jan 2, 2006 at 3:04 PM")
 		}
 
-		composer, err := widgets.NewComposer(aerc, aerc.Config(),
+		composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
 			acct.AccountConfig(), acct.Worker(), template, defaults, original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())

commands/msg/unsubscribe.go

@@ -90,6 +90,7 @@ func unsubscribeMailto(aerc *widgets.Aerc, u *url.URL) error {
 	}
 	composer, err := widgets.NewComposer(
 		aerc,
+		acct,
 		aerc.Config(),
 		acct.AccountConfig(),
 		acct.Worker(),