compose: refactor attachment handling

Refactor the attachment handling process in the composer. The composer
can currently only handle attachments that are stored as files (or pgp
keys). This patch removes this limitation so that any message part can
be handled as an attachment. With this we can treat files, pgp keys and
message parts on an equal footing and it will enable us also to easily
forward attachments.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Tested-by: Tim Culverhouse <tim@timculverhouse.com>

3 files changed, 220 insertions, 151 deletions

diff --git a/commands/compose/attach-key.go b/commands/compose/attach-key.go
index c12df44..c9212e3 100644
--- a/commands/compose/attach-key.go
+++ b/commands/compose/attach-key.go
@@ -27,6 +27,5 @@ func (AttachKey) Execute(aerc *widgets.Aerc, args []string) error {
 
 	composer, _ := aerc.SelectedTab().(*widgets.Composer)
 
-	composer.SetAttachKey(!composer.AttachKey())
-	return nil
+	return composer.SetAttachKey(!composer.AttachKey())
 }
diff --git a/lib/attachment.go b/lib/attachment.go
new file mode 100644
index 0000000..d7cbf3f
--- /dev/null
+++ b/lib/attachment.go
@@ -0,0 +1,136 @@
+package lib
+
+import (
+	"bufio"
+	"io"
+	"mime"
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"github.com/emersion/go-message/mail"
+	"github.com/pkg/errors"
+)
+
+type Part struct {
+	MimeType string
+	Params   map[string]string
+	Body     io.Reader
+}
+
+func NewPart(mimetype string, params map[string]string, body io.Reader) *Part {
+	return &Part{
+		MimeType: mimetype,
+		Params:   params,
+		Body:     body,
+	}
+}
+
+type Attachment interface {
+	Name() string
+	WriteTo(w *mail.Writer) error
+}
+
+type FileAttachment struct {
+	path string
+}
+
+func NewFileAttachment(path string) *FileAttachment {
+	return &FileAttachment{
+		path,
+	}
+}
+
+func (fa *FileAttachment) Name() string {
+	return fa.path
+}
+
+func (fa *FileAttachment) WriteTo(w *mail.Writer) error {
+	f, err := os.Open(fa.path)
+	if err != nil {
+		return errors.Wrap(err, "os.Open")
+	}
+	defer f.Close()
+
+	reader := bufio.NewReader(f)
+
+	// if we have an extension, prefer that instead of trying to sniff the header.
+	// That's generally more accurate than sniffing as lots of things are zip files
+	// under the hood, e.g. most office file types
+	ext := filepath.Ext(fa.path)
+	var mimeString string
+	if mimeString = mime.TypeByExtension(ext); mimeString != "" {
+		// found it in the DB
+	} else {
+		// Sniff the mime type instead
+		// http.DetectContentType only cares about the first 512 bytes
+		head, err := reader.Peek(512)
+		if err != nil && err != io.EOF {
+			return errors.Wrap(err, "Peek")
+		}
+		mimeString = http.DetectContentType(head)
+	}
+
+	// mimeString can contain type and params (like text encoding),
+	// so we need to break them apart before passing them to the headers
+	mimeType, params, err := mime.ParseMediaType(mimeString)
+	if err != nil {
+		return errors.Wrap(err, "ParseMediaType")
+	}
+	filename := filepath.Base(fa.path)
+	params["name"] = filename
+
+	// set header fields
+	ah := mail.AttachmentHeader{}
+	ah.SetContentType(mimeType, params)
+	// setting the filename auto sets the content disposition
+	ah.SetFilename(filename)
+
+	aw, err := w.CreateAttachment(ah)
+	if err != nil {
+		return errors.Wrap(err, "CreateAttachment")
+	}
+	defer aw.Close()
+
+	if _, err := reader.WriteTo(aw); err != nil {
+		return errors.Wrap(err, "reader.WriteTo")
+	}
+
+	return nil
+}
+
+type PartAttachment struct {
+	part *Part
+	name string
+}
+
+func NewPartAttachment(part *Part, name string) *PartAttachment {
+	return &PartAttachment{
+		part,
+		name,
+	}
+}
+
+func (pa *PartAttachment) Name() string {
+	return pa.name
+}
+
+func (pa *PartAttachment) WriteTo(w *mail.Writer) error {
+	// set header fields
+	ah := mail.AttachmentHeader{}
+	ah.SetContentType(pa.part.MimeType, pa.part.Params)
+
+	// setting the filename auto sets the content disposition
+	ah.SetFilename(pa.Name())
+
+	aw, err := w.CreateAttachment(ah)
+	if err != nil {
+		return errors.Wrap(err, "CreateAttachment")
+	}
+	defer aw.Close()
+
+	if _, err := io.Copy(aw, pa.part.Body); err != nil {
+		return errors.Wrap(err, "io.Copy")
+	}
+	return nil
+}
diff --git a/widgets/compose.go b/widgets/compose.go
index 2016abb..cbd4266 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -1,17 +1,13 @@
 package widgets
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"io"
 	"io/ioutil"
-	"mime"
-	"net/http"
 	"net/textproto"
 	"os"
 	"os/exec"
-	"path/filepath"
 	"strings"
 	"time"
 
@@ -23,6 +19,7 @@ import (
 
 	"git.sr.ht/~rjarry/aerc/completer"
 	"git.sr.ht/~rjarry/aerc/config"
+	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/lib/format"
 	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
@@ -30,12 +27,6 @@ import (
 	"git.sr.ht/~rjarry/aerc/worker/types"
 )
 
-type Part struct {
-	MimeType string
-	Params   map[string]string
-	Body     io.Reader
-}
-
 type Composer struct {
 	editors map[string]*headerEditor // indexes in lower case (from / cc / bcc)
 	header  *mail.Header
@@ -46,7 +37,7 @@ type Composer struct {
 	acct       *AccountView
 	aerc       *Aerc
 
-	attachments []string
+	attachments []lib.Attachment
 	editor      *Terminal
 	email       *os.File
 	grid        *ui.Grid
@@ -68,7 +59,7 @@ type Composer struct {
 
 	width int
 
-	textParts []*Part
+	textParts []*lib.Part
 }
 
 func NewComposer(aerc *Aerc, acct *AccountView, conf *config.AercConfig,
@@ -193,7 +184,58 @@ func (c *Composer) Sent() bool {
 }
 
 func (c *Composer) SetAttachKey(attach bool) error {
+	if !attach {
+		name := c.crypto.signKey + ".asc"
+		found := false
+		for _, a := range c.attachments {
+			if a.Name() == name {
+				found = true
+			}
+		}
+		if found {
+			c.DeleteAttachment(name)
+		} else {
+			attach = !attach
+		}
+	}
+	if attach {
+		var s string
+		var err error
+		if c.crypto.signKey == "" {
+			if c.acctConfig.PgpKeyId != "" {
+				s = c.acctConfig.PgpKeyId
+			} else {
+				s, err = getSenderEmail(c)
+				if err != nil {
+					return err
+				}
+			}
+			c.crypto.signKey, err = c.aerc.Crypto.GetSignerKeyId(s)
+			if err != nil {
+				return err
+			}
+		}
+
+		r, err := c.aerc.Crypto.ExportKey(c.crypto.signKey)
+		if err != nil {
+			return err
+		}
+
+		c.attachments = append(c.attachments,
+			lib.NewPartAttachment(
+				lib.NewPart(
+					"application/pgp-keys",
+					map[string]string{"charset": "UTF-8"},
+					r,
+				),
+				c.crypto.signKey+".asc",
+			),
+		)
+
+	}
+
 	c.attachKey = attach
+
 	c.resetReview()
 	return nil
 }
@@ -309,7 +351,8 @@ func (c *Composer) AppendPart(mimetype string, params map[string]string, body io
 	if !strings.HasPrefix(mimetype, "text") {
 		return fmt.Errorf("can only append text mimetypes")
 	}
-	c.textParts = append(c.textParts, &Part{MimeType: mimetype, Params: params, Body: body})
+	c.textParts = append(c.textParts, lib.NewPart(mimetype, params, body))
+	c.resetReview()
 	return nil
 }
 
@@ -611,36 +654,30 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 }
 
 func writeMsgImpl(c *Composer, header *mail.Header, writer io.Writer) error {
-	if len(c.attachments) == 0 && !c.attachKey && len(c.textParts) == 0 {
-		// no attachements
+	if len(c.attachments) == 0 && len(c.textParts) == 0 {
+		// no attachments
 		return writeInlineBody(header, c.email, writer)
 	} else {
-		// with attachements
+		// with attachments
 		w, err := mail.CreateWriter(writer, *header)
 		if err != nil {
 			return errors.Wrap(err, "CreateWriter")
 		}
-		parts := []*Part{
-			&Part{
-				MimeType: "text/plain",
-				Params:   map[string]string{"Charset": "UTF-8"},
-				Body:     c.email,
-			},
+		parts := []*lib.Part{
+			lib.NewPart(
+				"text/plain",
+				map[string]string{"Charset": "UTF-8"},
+				c.email,
+			),
 		}
 		if err := writeMultipartBody(append(parts, c.textParts...), w); err != nil {
 			return errors.Wrap(err, "writeMultipartBody")
 		}
 		for _, a := range c.attachments {
-			if err := writeAttachment(a, w); err != nil {
+			if err := a.WriteTo(w); err != nil {
 				return errors.Wrap(err, "writeAttachment")
 			}
 		}
-		if c.attachKey {
-			err := c.writeKeyAttachment(w)
-			if err != nil {
-				return err
-			}
-		}
 		w.Close()
 	}
 	return nil
@@ -660,7 +697,7 @@ func writeInlineBody(header *mail.Header, body io.Reader, writer io.Writer) erro
 }
 
 // write the message body to the multipart message
-func writeMultipartBody(parts []*Part, w *mail.Writer) error {
+func writeMultipartBody(parts []*lib.Part, w *mail.Writer) error {
 	bi, err := w.CreateInline()
 	if err != nil {
 		return errors.Wrap(err, "CreateInline")
@@ -683,73 +720,29 @@ func writeMultipartBody(parts []*Part, w *mail.Writer) error {
 	return nil
 }
 
-// write the attachment specified by path to the message
-func writeAttachment(path string, writer *mail.Writer) error {
-	f, err := os.Open(path)
-	if err != nil {
-		return errors.Wrap(err, "os.Open")
-	}
-	defer f.Close()
-
-	reader := bufio.NewReader(f)
-
-	// if we have an extension, prefer that instead of trying to sniff the header.
-	// That's generally more accurate than sniffing as lots of things are zip files
-	// under the hood, e.g. most office file types
-	ext := filepath.Ext(path)
-	var mimeString string
-	if mimeString = mime.TypeByExtension(ext); mimeString != "" {
-		// found it in the DB
-	} else {
-		// Sniff the mime type instead
-		// http.DetectContentType only cares about the first 512 bytes
-		head, err := reader.Peek(512)
-		if err != nil && err != io.EOF {
-			return errors.Wrap(err, "Peek")
-		}
-		mimeString = http.DetectContentType(head)
-	}
-
-	// mimeString can contain type and params (like text encoding),
-	// so we need to break them apart before passing them to the headers
-	mimeType, params, err := mime.ParseMediaType(mimeString)
-	if err != nil {
-		return errors.Wrap(err, "ParseMediaType")
-	}
-	filename := filepath.Base(path)
-	params["name"] = filename
-
-	// set header fields
-	ah := mail.AttachmentHeader{}
-	ah.SetContentType(mimeType, params)
-	// setting the filename auto sets the content disposition
-	ah.SetFilename(filename)
-
-	aw, err := writer.CreateAttachment(ah)
-	if err != nil {
-		return errors.Wrap(err, "CreateAttachment")
-	}
-	defer aw.Close()
-
-	if _, err := reader.WriteTo(aw); err != nil {
-		return errors.Wrap(err, "reader.WriteTo")
+func (c *Composer) GetAttachments() []string {
+	var names []string
+	for _, a := range c.attachments {
+		names = append(names, a.Name())
 	}
-
-	return nil
+	return names
 }
 
-func (c *Composer) GetAttachments() []string {
-	return c.attachments
+func (c *Composer) AddAttachment(path string) {
+	c.attachments = append(c.attachments, lib.NewFileAttachment(path))
+	c.resetReview()
 }
 
-func (c *Composer) AddAttachment(path string) {
-	c.attachments = append(c.attachments, path)
+func (c *Composer) AddPartAttachment(name string, mimetype string, params map[string]string, body io.Reader) {
+	c.attachments = append(c.attachments, lib.NewPartAttachment(
+		lib.NewPart(mimetype, params, body), name,
+	))
 	c.resetReview()
 }
 
-func (c *Composer) DeleteAttachment(path string) error {
+func (c *Composer) DeleteAttachment(name string) error {
 	for i, a := range c.attachments {
-		if a == path {
+		if a.Name() == name {
 			c.attachments = append(c.attachments[:i], c.attachments[i+1:]...)
 			c.resetReview()
 			return nil
@@ -1109,9 +1102,6 @@ func newReviewMessage(composer *Composer, err error) *reviewMessage {
 	for i := 0; i < len(composer.attachments)-1; i++ {
 		spec = append(spec, ui.GridSpec{Strategy: ui.SIZE_EXACT, Size: ui.Const(1)})
 	}
-	if composer.attachKey {
-		spec = append(spec, ui.GridSpec{Strategy: ui.SIZE_EXACT, Size: ui.Const(1)})
-	}
 	if len(composer.textParts) > 0 {
 		spec = append(spec, ui.GridSpec{Strategy: ui.SIZE_EXACT, Size: ui.Const(1)})
 		spec = append(spec, ui.GridSpec{Strategy: ui.SIZE_EXACT, Size: ui.Const(1)})
@@ -1144,18 +1134,13 @@ func newReviewMessage(composer *Composer, err error) *reviewMessage {
 		grid.AddChild(ui.NewText("Attachments:",
 			uiConfig.GetStyle(config.STYLE_TITLE))).At(i, 0)
 		i += 1
-		if composer.attachKey {
-			grid.AddChild(ui.NewText(composer.crypto.signKey+".asc",
-				uiConfig.GetStyle(config.STYLE_DEFAULT))).At(i, 0)
-			i += 1
-		}
-		if len(composer.attachments) == 0 && !composer.attachKey {
+		if len(composer.attachments) == 0 {
 			grid.AddChild(ui.NewText("(none)",
 				uiConfig.GetStyle(config.STYLE_DEFAULT))).At(i, 0)
 			i += 1
 		} else {
 			for _, a := range composer.attachments {
-				grid.AddChild(ui.NewText(a, uiConfig.GetStyle(config.STYLE_DEFAULT))).
+				grid.AddChild(ui.NewText(a.Name(), uiConfig.GetStyle(config.STYLE_DEFAULT))).
 					At(i, 0)
 				i += 1
 			}
@@ -1262,54 +1247,3 @@ func (c *Composer) checkEncryptionKeys(_ string) bool {
 	c.updateCrypto()
 	return true
 }
-
-func (c *Composer) writeKeyAttachment(w *mail.Writer) error {
-	// Verify key exists and get keyid
-	cp := c.aerc.Crypto
-	var (
-		err error
-		s   string
-	)
-	if c.crypto.signKey == "" {
-		if c.acctConfig.PgpKeyId != "" {
-			s = c.acctConfig.PgpKeyId
-		} else {
-			s, err = getSenderEmail(c)
-			if err != nil {
-				return err
-			}
-		}
-		c.crypto.signKey, err = cp.GetSignerKeyId(s)
-		if err != nil {
-			return err
-		}
-	}
-	// Get the key in armor format
-	r, err := cp.ExportKey(c.crypto.signKey)
-	if err != nil {
-		c.aerc.PushError(err.Error())
-		return err
-	}
-	filename := c.crypto.signKey + ".asc"
-	mimeType := "application/pgp-keys"
-	params := map[string]string{
-		"charset": "UTF-8",
-		"name":    filename,
-	}
-	// set header fields
-	ah := mail.AttachmentHeader{}
-	ah.SetContentType(mimeType, params)
-	// setting the filename auto sets the content disposition
-	ah.SetFilename(filename)
-
-	aw, err := w.CreateAttachment(ah)
-	if err != nil {
-		return errors.Wrap(err, "CreateKeyAttachment")
-	}
-	defer aw.Close()
-
-	if _, err := io.Copy(aw, r); err != nil {
-		return errors.Wrap(err, "io.Copy")
-	}
-	return nil
-}