forum: automatically post new forum posts to Discord.

app/logical/d_text.rb

@@ -250,6 +250,29 @@ class DText
     text.gsub(/\A[[:space:]]+|[[:space:]]+\z/, "")
   end
 
+  def self.to_markdown(dtext)
+    html_to_markdown(format_text(dtext))
+  end
+
+  def self.html_to_markdown(html)
+    html = Nokogiri::HTML.fragment(html)
+
+    html.children.map do |node|
+      case node.name
+      when "div", "blockquote", "table"
+        "" # strip [expand], [quote], and [table] tags
+      when "br"
+        "\n"
+      when "text"
+        node.text.gsub(/_/, '\_').gsub(/\*/, '\*')
+      when "p", "h1", "h2", "h3", "h4", "h5", "h6"
+        html_to_markdown(node.inner_html) + "\n\n"
+      else
+        html_to_markdown(node.inner_html)
+      end
+    end.join
+  end
+
   def self.from_html(text, inline: false, &block)
     html = Nokogiri::HTML.fragment(text)
 

app/logical/discord_api_client.rb

@@ -0,0 +1,56 @@
+class DiscordApiClient
+  attr_reader :webhook_id, :webhook_secret, :http
+
+  def initialize(webhook_id: Danbooru.config.discord_webhook_id, webhook_secret: Danbooru.config.discord_webhook_secret, http: Danbooru::Http.new)
+    @webhook_id = webhook_id
+    @webhook_secret = webhook_secret
+    @http = http
+  end
+
+  def enabled?
+    webhook_id.present? && webhook_secret.present?
+  end
+
+  # https://discord.com/developers/docs/resources/webhook#execute-webhook
+  def post_message(forum_post)
+    return unless enabled?
+
+    http.post(webhook_url, params: { wait: true }, json: build_message(forum_post))
+  end
+
+  # https://discord.com/developers/docs/resources/channel#embed-object
+  def build_message(forum_post)
+    {
+      embeds: [{
+        title: forum_post.topic.title,
+        description: convert_dtext(forum_post.body),
+        timestamp: forum_post.created_at.iso8601,
+        url: Routes.url_for(forum_post),
+        author: {
+          name: forum_post.creator.name,
+          url: Routes.url_for(forum_post.creator)
+        },
+        fields: [
+          {
+            name: "Replies",
+            value: forum_post.topic.response_count,
+            inline: true
+          },
+          {
+            name: "Users",
+            value: forum_post.topic.forum_posts.distinct.count(:creator_id),
+            inline: true
+          }
+        ]
+      }]
+    }
+  end
+
+  def convert_dtext(dtext)
+    DText.to_markdown(dtext).truncate(2000)
+  end
+
+  def webhook_url
+    "https://discord.com/api/webhooks/#{webhook_id}/#{webhook_secret}"
+  end
+end