From c832ea4645c4770ee641c062d8cb3fdc0592b87d Mon Sep 17 00:00:00 2001
From: Bastien Riviere <me@babariviere.com>
Date: Sun, 3 Sep 2023 16:46:02 +0200
Subject: [PATCH] feat: add discord_embed handler

---
 bridge/discord.go   | 74 +++++++++++++++++++++++++++++++++++++++++++++
 config.example.scfg |  9 ++++++
 config/config.go    |  5 +++
 k8s/bridge.yaml     |  5 +++
 main.go             |  2 ++
 5 files changed, 95 insertions(+)
 create mode 100644 bridge/discord.go

diff --git a/bridge/discord.go b/bridge/discord.go
new file mode 100644
index 0000000..f2d423f
--- /dev/null
+++ b/bridge/discord.go
@@ -0,0 +1,74 @@
+package bridge
+
+import (
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"strings"
+)
+
+type DiscordMessage struct {
+	Content string `json:"content"`
+	Embeds  []struct {
+		Title       string `json:"title"`
+		Description string `json:"description"`
+		URL         string `json:"url"`
+		Footer      struct {
+			Text string `json:"text"`
+		} `json:"footer"`
+		Author struct {
+			Name string `json:"name"`
+			URL  string `json:"url"`
+		} `json:"author"`
+	} `json:"embeds"`
+}
+
+type DiscordEmbedHandler struct{}
+
+func NewDiscordEmbedHandler() DiscordEmbedHandler {
+	return DiscordEmbedHandler{}
+}
+
+func (d DiscordEmbedHandler) ProduceNotifications(r *http.Request) ([]Notification, error) {
+	l := slog.With(slog.String("handler", "discord_embed"))
+
+	dec := json.NewDecoder(r.Body)
+	defer r.Body.Close()
+
+	var not DiscordMessage
+	if err := dec.Decode(&not); err != nil {
+		l.Error("invalid message format", "error", err)
+		return nil, err
+	}
+
+	notifications := make([]Notification, len(not.Embeds))
+	for i, embed := range not.Embeds {
+		not := notifications[i]
+		not.Title = embed.Title
+		not.IsMarkdown = true
+		if embed.URL != "" {
+			not.Actions = []NotificationAction{NewViewAction("Open in Browser", embed.URL)}
+		}
+
+		var body strings.Builder
+		body.WriteString(embed.Description)
+
+		if embed.Author.Name != "" {
+			body.WriteString("\n\n**Author**\n")
+			body.WriteString(embed.Author.Name)
+			if embed.Author.URL != "" {
+				body.WriteString(" (" + embed.Author.URL + ")")
+			}
+		}
+
+		if embed.Footer.Text != "" {
+			body.WriteString("\n\n" + embed.Footer.Text)
+		}
+
+		not.Body = body.String()
+
+		notifications[i] = not
+	}
+
+	return notifications, nil
+}
diff --git a/config.example.scfg b/config.example.scfg
index 9437d2a..78dff6f 100644
--- a/config.example.scfg
+++ b/config.example.scfg
@@ -23,3 +23,12 @@ handler "/flux" {
 #   type "alertmanager"
 #   topic "/infra"
 # }
+
+# Handle discord type messages. This is meant for
+# webhook that doesn't support generic one's.
+# Instead, we convert discord messages to ntfy message.
+# See: https://discord.com/developers/docs/resources/channel#message-object
+handler "/discord-like" {
+  type "discord_embed" # handle message with `embeds` content
+  topic "discord-like"
+}
diff --git a/config/config.go b/config/config.go
index 2b832f4..a02188c 100644
--- a/config/config.go
+++ b/config/config.go
@@ -11,12 +11,15 @@ type HandlerType int
 
 const (
 	HandlerFlux HandlerType = iota + 1
+	HandlerDiscordEmbed
 )
 
 func (h HandlerType) String() string {
 	switch h {
 	case HandlerFlux:
 		return "flux"
+	case HandlerDiscordEmbed:
+		return "discord_embed"
 	}
 	panic("unreachable")
 }
@@ -148,6 +151,8 @@ func readHandlerType(d *scfg.Directive) (HandlerType, error) {
 	switch ty {
 	case "flux":
 		return HandlerFlux, nil
+	case "discord_embed":
+		return HandlerDiscordEmbed, nil
 	default:
 		return 0, fmt.Errorf("invalid handler type %q", ty)
 	}
diff --git a/k8s/bridge.yaml b/k8s/bridge.yaml
index 5f393b7..490c21b 100644
--- a/k8s/bridge.yaml
+++ b/k8s/bridge.yaml
@@ -17,6 +17,11 @@ data:
         type "flux"
         topic "flux"
     }
+
+    handler "/forgejo" {
+        type "discord_embed"
+        topic "forgejo"
+    }
 ---
 apiVersion: apps/v1
 kind: Deployment
diff --git a/main.go b/main.go
index 8ea1926..252371e 100644
--- a/main.go
+++ b/main.go
@@ -74,6 +74,8 @@ func main() {
 		switch handler.Type {
 		case config.HandlerFlux:
 			h = bridge.NewFluxHandler()
+		case config.HandlerDiscordEmbed:
+			h = bridge.NewDiscordEmbedHandler()
 		}
 
 		slog.Debug("Registering bridge", "route", route, "handler", handler.Type)