compose: use a proper header instead of a string map

Prior to this commit, the composer was based on a map[string]string.
While this approach was very versatile, it lead to a constant encoding / decoding
of addresses and other headers.

This commit switches to a different model, where the composer is based on a header.
Commands which want to interact with it can simply set some defaults they would
like to have. Users can overwrite them however they like.

In order to get access to the functions generating / getting the msgid go-message
was upgraded.

commands/msg/forward.go

@@ -15,6 +15,7 @@ import (
 	"git.sr.ht/~sircmpwn/aerc/models"
 	"git.sr.ht/~sircmpwn/aerc/widgets"
 	"git.sr.ht/~sircmpwn/aerc/worker/types"
+	"github.com/emersion/go-message/mail"
 
 	"git.sr.ht/~sircmpwn/getopt"
 )
@@ -49,11 +50,6 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 		}
 	}
 
-	to := ""
-	if len(args) != 1 {
-		to = strings.Join(args[optind:], ", ")
-	}
-
 	widget := aerc.SelectedTab().(widgets.ProvidesMessage)
 	acct := widget.SelectedAccount()
 	if acct == nil {
@@ -69,11 +65,19 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 	acct.Logger().Println("Forwarding email " + msg.Envelope.MessageId)
 
+	h := &mail.Header{}
 	subject := "Fwd: " + msg.Envelope.Subject
-	defaults := map[string]string{
-		"To":      to,
-		"Subject": subject,
+	h.SetSubject(subject)
+
+	if len(args) != 1 {
+		to := strings.Join(args[optind:], ", ")
+		tolist, err := mail.ParseAddressList(to)
+		if err != nil {
+			return fmt.Errorf("invalid to address(es): %v", err)
+		}
+		h.SetAddressList("to", tolist)
 	}
+
 	original := models.OriginalMail{
 		From:          format.FormatAddresses(msg.Envelope.From),
 		Date:          msg.Envelope.Date,
@@ -81,15 +85,15 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 
 	addTab := func() (*widgets.Composer, error) {
-		composer, err := widgets.NewComposer(aerc, acct, aerc.Config(), acct.AccountConfig(),
-			acct.Worker(), template, defaults, original)
+		composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
+			acct.AccountConfig(), acct.Worker(), template, h, original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())
 			return nil, err
 		}
 
 		tab := aerc.NewTab(composer, subject)
-		if to == "" {
+		if !h.Has("to") {
 			composer.FocusRecipient()
 		} else {
 			composer.FocusTerminal()

commands/msg/recall.go

@@ -53,15 +53,9 @@ func (Recall) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 	acct.Logger().Println("Recalling message " + msgInfo.Envelope.MessageId)
 
-	// copy the headers to the defaults map for addition to the composition
-	defaults := make(map[string]string)
-	headerFields := msgInfo.RFC822Headers.Fields()
-	for headerFields.Next() {
-		defaults[headerFields.Key()] = headerFields.Value()
-	}
-
 	composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
-		acct.AccountConfig(), acct.Worker(), "", defaults, models.OriginalMail{})
+		acct.AccountConfig(), acct.Worker(), "", msgInfo.RFC822Headers,
+		models.OriginalMail{})
 	if err != nil {
 		return errors.Wrap(err, "Cannot open a new composer")
 	}

commands/msg/reply.go

@@ -145,22 +145,22 @@ func (reply) Execute(aerc *widgets.Aerc, args []string) error {
 		subject = msg.Envelope.Subject
 	}
 
-	defaults := map[string]string{
-		"To":          format.FormatAddresses(to),
-		"Cc":          format.FormatAddresses(cc),
-		"From":        format.AddressForHumans(from),
-		"Subject":     subject,
-		"In-Reply-To": msg.Envelope.MessageId,
-	}
+	h := &mail.Header{}
+	h.SetAddressList("to", to)
+	h.SetAddressList("cc", cc)
+	h.SetAddressList("from", []*mail.Address{from})
+	h.SetSubject(subject)
+	h.SetMsgIDList("in-reply-to", []string{msg.Envelope.MessageId})
+	//TODO: references header
 	original := models.OriginalMail{
-		From: format.FormatAddresses(msg.Envelope.From),
-		Date: msg.Envelope.Date,
+		From:          format.FormatAddresses(msg.Envelope.From),
+		Date:          msg.Envelope.Date,
 		RFC822Headers: msg.RFC822Headers,
 	}
 
 	addTab := func() error {
 		composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
-			acct.AccountConfig(), acct.Worker(), template, defaults, original)
+			acct.AccountConfig(), acct.Worker(), template, h, original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())
 			return err

commands/msg/unsubscribe.go

@@ -9,6 +9,7 @@ import (
 	"git.sr.ht/~sircmpwn/aerc/lib"
 	"git.sr.ht/~sircmpwn/aerc/models"
 	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"github.com/emersion/go-message/mail"
 )
 
 // Unsubscribe helps people unsubscribe from mailing lists by way of the
@@ -84,10 +85,13 @@ func parseUnsubscribeMethods(header string) (methods []*url.URL) {
 func unsubscribeMailto(aerc *widgets.Aerc, u *url.URL) error {
 	widget := aerc.SelectedTab().(widgets.ProvidesMessage)
 	acct := widget.SelectedAccount()
-	defaults := map[string]string{
-		"To":      u.Opaque,
-		"Subject": u.Query().Get("subject"),
+
+	h := &mail.Header{}
+	h.SetSubject(u.Query().Get("subject"))
+	if to, err := mail.ParseAddressList(u.Opaque); err == nil {
+		h.SetAddressList("to", to)
 	}
+
 	composer, err := widgets.NewComposer(
 		aerc,
 		acct,
@@ -95,7 +99,7 @@ func unsubscribeMailto(aerc *widgets.Aerc, u *url.URL) error {
 		acct.AccountConfig(),
 		acct.Worker(),
 		"",
-		defaults,
+		h,
 		models.OriginalMail{},
 	)
 	if err != nil {