compose: ensure signature uses standard delimiter

Since it has recently been a topic on IRC, and to guide users new to
"raw" email, add a note on how signatures are detected and what they
should look like.

Prepend signature-file and signature-cmd with the standard delimiter if
missing.

Signed-off-by: Moritz Poldrack <git@moritz.sh>
Signed-off-by: Robin Jarry <robin@jarry.cc>

1 files changed, 17 insertions, 0 deletions

diff --git a/widgets/compose.go b/widgets/compose.go
index 94fd79d5..7311de7a 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -1,6 +1,7 @@
 package widgets
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"io"
@@ -550,6 +551,7 @@ func (c *Composer) AddSignature() {
 	} else {
 		signature = c.readSignatureFromFile()
 	}
+	signature = ensureSignatureDelimiter(signature)
 	c.AppendContents(bytes.NewReader(signature))
 }
 
@@ -581,6 +583,21 @@ func (c *Composer) readSignatureFromFile() []byte {
 	return signature
 }
 
+func ensureSignatureDelimiter(signature []byte) []byte {
+	buf := bytes.NewBuffer(signature)
+	scanner := bufio.NewScanner(buf)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "-- " {
+			// signature contains standard delimiter, we're good
+			return signature
+		}
+	}
+	// signature does not contain standard delimiter, prepend one
+	sig := "\n\n-- \n" + strings.TrimLeft(string(signature), " \t\r\n")
+	return []byte(sig)
+}
+
 func (c *Composer) FocusTerminal() *Composer {
 	c.Lock()
 	defer c.Unlock()