From 3bf722c5fe27d624313af15aa82c1ef0f1c13f06 Mon Sep 17 00:00:00 2001
From: Harvey Tindall <hrfee@protonmail.ch>
Date: Fri, 21 May 2021 21:59:50 +0100
Subject: [PATCH] Discord: send links as embeds

Kind of janky but works. This kind of messes up the layout if you write
links in-line.
---
 discord.go | 54 ++++++++++++++++++++++++++++++++++++++++++------------
 stripmd.go | 25 ++++++++++++++++++++-----
 2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/discord.go b/discord.go
index f80d216..4f49354 100644
--- a/discord.go
+++ b/discord.go
@@ -232,19 +232,49 @@ func (d *DiscordDaemon) commandPIN(s *dg.Session, m *dg.MessageCreate, sects []s
 }
 
 func (d *DiscordDaemon) Send(message *Message, channelID ...string) error {
-	for _, id := range channelID {
-		msg := ""
-		if message.Markdown == "" {
-			msg = message.Text
-		} else {
-			msg = message.Markdown
+	msg := ""
+	var embeds []*dg.MessageEmbed
+	if message.Markdown != "" {
+		var links []Link
+		msg, links = StripAltText(message.Markdown, true)
+		embeds = make([]*dg.MessageEmbed, len(links))
+		for i := range links {
+			embeds[i] = &dg.MessageEmbed{
+				URL:   links[i].URL,
+				Title: links[i].Alt,
+				Type:  dg.EmbedTypeLink,
+			}
 		}
-		_, err := d.bot.ChannelMessageSend(
-			id,
-			msg,
-		)
-		if err != nil {
-			return err
+	} else {
+		msg = message.Text
+	}
+	for _, id := range channelID {
+		var err error
+		if len(embeds) != 0 {
+			_, err = d.bot.ChannelMessageSendComplex(
+				id,
+				&dg.MessageSend{
+					Content: msg,
+					Embed:   embeds[0],
+				},
+			)
+			if err != nil {
+				return err
+			}
+			for i := 1; i < len(embeds); i++ {
+				_, err := d.bot.ChannelMessageSendEmbed(id, embeds[i])
+				if err != nil {
+					return err
+				}
+			}
+		} else {
+			_, err := d.bot.ChannelMessageSend(
+				id,
+				msg,
+			)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	return nil
diff --git a/stripmd.go b/stripmd.go
index 0568067..2a5ea4d 100644
--- a/stripmd.go
+++ b/stripmd.go
@@ -6,18 +6,32 @@ import (
 	stripmd "github.com/writeas/go-strip-markdown"
 )
 
+type Link struct {
+	Alt, URL string
+}
+
 // StripAltText removes Markdown alt text from links and images and replaces them with just the URL.
 // Currently uses the deepest alt text when links/images are nested.
-func StripAltText(md string) string {
+// If links = true, links are completely removed, and a list of URLs and their alt text is also returned.
+func StripAltText(md string, links bool) (string, []Link) {
 	altTextStart := -1 // Start of alt text (between '[' & ']')
 	URLStart := -1     // Start of url (between '(' & ')')
 	URLEnd := -1
 	previousURLEnd := -2
 	out := ""
+	embeds := []Link{}
 	for i := range md {
 		if altTextStart != -1 && URLStart != -1 && md[i] == ')' {
 			URLEnd = i - 1
-			out += md[previousURLEnd+2:altTextStart-1] + md[URLStart:URLEnd+1]
+			out += md[previousURLEnd+2 : altTextStart-1]
+			if links {
+				embeds = append(embeds, Link{
+					URL: md[URLStart : URLEnd+1],
+					Alt: md[altTextStart : URLStart-2],
+				})
+			} else {
+				out += md[URLStart : URLEnd+1]
+			}
 			previousURLEnd = URLEnd
 			altTextStart, URLStart, URLEnd = -1, -1, -1
 			continue
@@ -36,11 +50,12 @@ func StripAltText(md string) string {
 		out += md[previousURLEnd+2:]
 	}
 	if out == "" {
-		return md
+		return md, embeds
 	}
-	return out
+	return out, embeds
 }
 
 func stripMarkdown(md string) string {
-	return strings.TrimPrefix(strings.TrimSuffix(stripmd.Strip(StripAltText(md)), "</p>"), "<p>")
+	stripped, _ := StripAltText(md, false)
+	return strings.TrimPrefix(strings.TrimSuffix(stripmd.Strip(stripped), "</p>"), "<p>")
 }