Adds support of multipart/related for inline attachments

mail/attachment.go

@@ -4,13 +4,8 @@ import (
 	"github.com/emersion/go-message"
 )
 
-// An AttachmentHeader represents an attachment's header.
-type AttachmentHeader struct {
-	message.Header
-}
-
-// Filename parses the attachment's filename.
-func (h *AttachmentHeader) Filename() (string, error) {
+// parseFilename parses the filename from the header.
+func parseFilename(h message.Header) (string, error) {
 	_, params, err := h.ContentDisposition()
 
 	filename, ok := params["filename"]
@@ -23,8 +18,34 @@ func (h *AttachmentHeader) Filename() (string, error) {
 	return filename, err
 }
 
+// An AttachmentHeader represents an attachment's header.
+type AttachmentHeader struct {
+	message.Header
+}
+
+// Filename parses the attachment's filename.
+func (h *AttachmentHeader) Filename() (string, error) {
+	return parseFilename(h.Header)
+}
+
 // SetFilename formats the attachment's filename.
 func (h *AttachmentHeader) SetFilename(filename string) {
 	dispParams := map[string]string{"filename": filename}
 	h.SetContentDisposition("attachment", dispParams)
 }
+
+// An InlineAttachmentHeader represents an inlined attachment's header.
+type InlineAttachmentHeader struct {
+	message.Header
+}
+
+// Filename parses the attachment's filename.
+func (h *InlineAttachmentHeader) Filename() (string, error) {
+	return parseFilename(h.Header)
+}
+
+// SetFilename formats the attachment's filename.
+func (h *InlineAttachmentHeader) SetFilename(filename string) {
+	dispParams := map[string]string{"filename": filename}
+	h.SetContentDisposition("inline", dispParams)
+}

mail/attachment_test.go

@@ -49,3 +49,14 @@ func TestAttachmentHeader_Filename_encoded(t *testing.T) {
 		t.Errorf("Expected filename to be %q but got %q", "", filename)
 	}
 }
+
+func TestInlineAttachmentHeader_Filename(t *testing.T) {
+	var h mail.InlineAttachmentHeader
+	h.Set("Content-Disposition", "inline; filename=note.txt")
+
+	if filename, err := h.Filename(); err != nil {
+		t.Error("Expected no error while parsing filename, got:", err)
+	} else if filename != "note.txt" {
+		t.Errorf("Expected filename to be %q but got %q", "note.txt", filename)
+	}
+}

mail/writer.go

@@ -33,6 +33,16 @@ func initAttachmentHeader(h *AttachmentHeader) {
 	}
 }
 
+func initInlineAttachmentHeader(h *InlineAttachmentHeader) {
+	disp, _, _ := h.ContentDisposition()
+	if disp != "inline" {
+		h.Set("Content-Disposition", "inline")
+	}
+	if !h.Has("Content-Transfer-Encoding") {
+		h.Set("Content-Transfer-Encoding", "base64")
+	}
+}
+
 // A Writer writes a mail message. A mail message contains one or more text
 // parts and zero or more attachments.
 type Writer struct {
@@ -52,9 +62,25 @@ func CreateWriter(w io.Writer, header Header) (*Writer, error) {
 	return &Writer{mw}, nil
 }
 
+// CreateAlternativeWriter writes a mail header to w. The mail will contain an
+// inline part, allowing to represent the same text in different formats.
+// Attachments cannot be included.
+func CreateAlternativeWriter(w io.Writer, header Header) (*AlternativeWriter, error) {
+	header = header.Copy() // don't modify the caller's view
+	header.Set("Content-Type", "multipart/alternative")
+
+	mw, err := message.CreateWriter(w, header.Header)
+	if err != nil {
+		return nil, err
+	}
+
+	return &AlternativeWriter{mw}, nil
+}
+
 // CreateInlineWriter writes a mail header to w. The mail will contain an
 // inline part, allowing to represent the same text in different formats.
 // Attachments cannot be included.
+// Deprecated: Use CreateAlternativeWriter and the returned AlternativeWriter instead.
 func CreateInlineWriter(w io.Writer, header Header) (*InlineWriter, error) {
 	header = header.Copy() // don't modify the caller's view
 	header.Set("Content-Type", "multipart/alternative")
@@ -67,6 +93,20 @@ func CreateInlineWriter(w io.Writer, header Header) (*InlineWriter, error) {
 	return &InlineWriter{mw}, nil
 }
 
+// CreateRelatedWriter writes a mail header to w. The mail will contain an
+// inline part and any inline attachments. Non-inline attachments cannot be added.
+func CreateRelatedWriter(w io.Writer, header Header) (*RelatedWriter, error) {
+	header = header.Copy() // don't modify the caller's view
+	header.Set("Content-Type", "multipart/related")
+
+	mw, err := message.CreateWriter(w, header.Header)
+	if err != nil {
+		return nil, err
+	}
+
+	return &RelatedWriter{mw}, nil
+}
+
 // CreateSingleInlineWriter writes a mail header to w. The mail will contain a
 // single inline part. The body of the part should be written to the returned
 // io.WriteCloser. Only one single inline part should be written, use
@@ -77,8 +117,24 @@ func CreateSingleInlineWriter(w io.Writer, header Header) (io.WriteCloser, error
 	return message.CreateWriter(w, header.Header)
 }
 
+// ------------------------------------------------------------------------------------------------------------------ //
+
+// CreateAlternative creates an AlternativeWriter. One or more parts representing the same
+// text in different formats can be written to an AlternativeWriter.
+func (w *Writer) CreateAlternative() (*AlternativeWriter, error) {
+	var h message.Header
+	h.Set("Content-Type", "multipart/alternative")
+
+	mw, err := w.mw.CreatePart(h)
+	if err != nil {
+		return nil, err
+	}
+	return &AlternativeWriter{mw}, nil
+}
+
 // CreateInline creates a InlineWriter. One or more parts representing the same
 // text in different formats can be written to a InlineWriter.
+// Deprecated: Use CreateAlternative() and the AlternativeWriter instead.
 func (w *Writer) CreateInline() (*InlineWriter, error) {
 	var h message.Header
 	h.Set("Content-Type", "multipart/alternative")
@@ -90,10 +146,24 @@ func (w *Writer) CreateInline() (*InlineWriter, error) {
 	return &InlineWriter{mw}, nil
 }
 
+// CreateRelated created a RelatedWriter. Inline attachments and one or more
+// parts representing the same text in different format can be written to a
+// RelatedWriter.
+func (w *Writer) CreateRelated() (*RelatedWriter, error) {
+	var h message.Header
+	h.Set("Content-Type", "multipart/related")
+
+	mw, err := w.mw.CreatePart(h)
+	if err != nil {
+		return nil, err
+	}
+	return &RelatedWriter{mw}, nil
+}
+
 // CreateSingleInline creates a new single text part with the provided header.
 // The body of the part should be written to the returned io.WriteCloser. Only
-// one single text part should be written, use CreateInline if you want multiple
-// text parts.
+// one single text part should be written, use CreateAlternative if you want
+// multiple text parts.
 func (w *Writer) CreateSingleInline(h InlineHeader) (io.WriteCloser, error) {
 	h = InlineHeader{h.Header.Copy()} // don't modify the caller's view
 	initInlineHeader(&h)
@@ -113,13 +183,33 @@ func (w *Writer) Close() error {
 	return w.mw.Close()
 }
 
+// AlternativeWriter writes a mail message's text.
+type AlternativeWriter struct {
+	mw *message.Writer
+}
+
+// CreatePart creates a new text part with the provided header. The body of the
+// part should be written to the returned io.WriteCloser.
+func (w *AlternativeWriter) CreatePart(h InlineHeader) (io.WriteCloser, error) {
+	h = InlineHeader{h.Header.Copy()} // don't modify the caller's view
+	initInlineHeader(&h)
+	return w.mw.CreatePart(h.Header)
+}
+
+// Close finishes the AlternativeWriter.
+func (w *AlternativeWriter) Close() error {
+	return w.mw.Close()
+}
+
 // InlineWriter writes a mail message's text.
+// Deprecated: Use AlternativeWriter instead.
 type InlineWriter struct {
 	mw *message.Writer
 }
 
 // CreatePart creates a new text part with the provided header. The body of the
 // part should be written to the returned io.WriteCloser.
+// Deprecated: Use AlternativeWriter and its CreatePart instead.
 func (w *InlineWriter) CreatePart(h InlineHeader) (io.WriteCloser, error) {
 	h = InlineHeader{h.Header.Copy()} // don't modify the caller's view
 	initInlineHeader(&h)
@@ -130,3 +220,44 @@ func (w *InlineWriter) CreatePart(h InlineHeader) (io.WriteCloser, error) {
 func (w *InlineWriter) Close() error {
 	return w.mw.Close()
 }
+
+// RelatedWriter write a mail message with inline attachments and text parts.
+type RelatedWriter struct {
+	mw *message.Writer
+}
+
+// CreateAlternative creates an AlternativeWriter. One or more parts representing the same
+// text in different formats can be written to the AlternativeWriter.
+func (w *RelatedWriter) CreateAlternative() (*AlternativeWriter, error) {
+	var h message.Header
+	h.Set("Content-Type", "multipart/alternative")
+
+	mw, err := w.mw.CreatePart(h)
+	if err != nil {
+		return nil, err
+	}
+	return &AlternativeWriter{mw}, nil
+}
+
+// CreateSingleInline creates a new single text part with the provided header.
+// The body of the part should be written to the returned io.WriteCloser. Only
+// one single text part should be written, use CreateAlternative if you want multiple
+// text parts.
+func (w *RelatedWriter) CreateSingleInline(h InlineHeader) (io.WriteCloser, error) {
+	h = InlineHeader{h.Header.Copy()} // don't modify the caller's view
+	initInlineHeader(&h)
+	return w.mw.CreatePart(h.Header)
+}
+
+// CreateInlineAttachment creates a new inline attachment with the provided header.
+// The body of the part should be written to the returned io.WriteCloser.
+func (w *RelatedWriter) CreateInlineAttachment(h InlineAttachmentHeader) (io.WriteCloser, error) {
+	h = InlineAttachmentHeader{h.Header.Copy()} // don't modify the caller's view
+	initInlineAttachmentHeader(&h)
+	return w.mw.CreatePart(h.Header)
+}
+
+// Close finishes the RelatedWriter.
+func (w *RelatedWriter) Close() error {
+	return w.mw.Close()
+}

mail/writer_test.go

@@ -29,7 +29,7 @@ func ExampleWriter() {
 	}
 
 	// Create a text part
-	tw, err := mw.CreateInline()
+	tw, err := mw.CreateAlternative()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -70,7 +70,7 @@ func TestWriter(t *testing.T) {
 	}
 
 	// Create a text part
-	tw, err := mw.CreateInline()
+	tw, err := mw.CreateAlternative()
 	if err != nil {
 		t.Fatal(err)
 	}