compose: warn before sending without attachment

Prevent the embarrassing forgotten attachment scenario by warning the
user before sending a message that may need an attachment but does not
have one. Whether a message needs an attachment is determined by testing
a configurable regex against the message body.

Signed-off-by: Jason Cox <dev@jasoncarloscox.com>
Acked-by: Robin Jarry <robin@jarry.cc>

2 files changed, 24 insertions, 0 deletions

diff --git a/widgets/aerc.go b/widgets/aerc.go
index 35c32fe3..81d07474 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -598,6 +598,10 @@ func (aerc *Aerc) BeginExCommand(cmd string) {
 	aerc.focus(exline)
 }
 
+func (aerc *Aerc) PushPrompt(prompt *ExLine) {
+	aerc.prompts.Push(prompt)
+}
+
 func (aerc *Aerc) RegisterPrompt(prompt string, cmd []string) {
 	p := NewPrompt(aerc.conf, prompt, func(text string) {
 		if text != "" {
diff --git a/widgets/compose.go b/widgets/compose.go
index dc0c21aa..6e34365a 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -776,6 +776,26 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 	}
 }
 
+func (c *Composer) ShouldWarnAttachment() (bool, error) {
+	regex := c.config.Compose.NoAttachmentWarning
+
+	if regex == nil || len(c.attachments) > 0 {
+		return false, nil
+	}
+
+	err := c.reloadEmail()
+	if err != nil {
+		return false, errors.Wrap(err, "reloadEmail")
+	}
+
+	body, err := io.ReadAll(c.email)
+	if err != nil {
+		return false, errors.Wrap(err, "io.ReadAll")
+	}
+
+	return regex.Match(body), nil
+}
+
 func writeMsgImpl(c *Composer, header *mail.Header, writer io.Writer) error {
 	if len(c.attachments) == 0 && len(c.textParts) == 0 {
 		// no attachments