discord: add /tagme command.

app/logical/discord_api_client.rb

@@ -3,6 +3,10 @@ class DiscordApiClient
 
   BASE_URL = "https://discord.com/api/v8"
 
+  # https://discord.com/developers/docs/resources/webhook#execute-webhook
+  # Actual limit is 2000; use 1950 for headroom.
+  MAX_MESSAGE_LENGTH = 1950
+
   attr_reader :application_id, :bot_token, :http
 
   def initialize(application_id: Danbooru.config.discord_application_client_id, bot_token: Danbooru.config.discord_bot_token, http: Danbooru::Http.new)
@@ -11,6 +15,9 @@ class DiscordApiClient
     @http = http
   end
 
+  # https://discord.com/developers/docs/interactions/slash-commands#registering-a-command
+  # https://discord.com/developers/docs/interactions/slash-commands#create-global-application-command
+  # https://discord.com/developers/docs/interactions/slash-commands#create-guild-application-command
   def register_slash_command(name:, description:, options: [], guild_id: nil)
     json = {
       name: name,
@@ -25,34 +32,55 @@ class DiscordApiClient
     end
   end
 
+  # https://discord.com/developers/docs/interactions/slash-commands#create-followup-message
+  def create_followup_message(interaction_token, allowed_mentions: { parse: [] }, **options)
+    post("/webhooks/#{application_id}/#{interaction_token}", {
+      allowed_mentions: allowed_mentions,
+      **options
+    })
+  end
+
+  # https://discord.com/developers/docs/resources/channel#get-channel
   def get_channel(channel_id, **options)
     get("/channels/#{channel_id}", **options)
   end
 
-  def me(**options)
+  def get_channel_messages(channel_id, limit: 50, **options)
+    get("/channels/#{channel_id}/messages", params: { limit: limit }, **options)
+  end
+
+  # https://discord.com/developers/docs/resources/channel#trigger-typing-indicator
+  def trigger_typing_indicator(channel_id)
+    post("/channels/#{channel_id}/typing")
+  end
+
+  # https://discord.com/developers/docs/resources/user#get-current-user
+  def get_current_user(**options)
     get("/users/@me", **options)
   end
 
   def get(url, cache: nil, **options)
     if cache
-      client.cache(cache).get("#{BASE_URL}/#{url}").parse
+      client.cache(cache).get("#{BASE_URL}/#{url}", **options).parse
     else
-      client.get("#{BASE_URL}/#{url}").parse
+      client.get("#{BASE_URL}/#{url}", **options).parse
     end
   end
 
-  def post(url, data)
+  def post(url, data = {})
     client.post("#{BASE_URL}/#{url}", json: data).parse
   end
 
-  def client
-    headers = {
+  def http_headers
+    {
       "User-Agent": "#{Danbooru.config.canonical_app_name} (#{Danbooru.config.source_code_url}, 1.0)",
       "Authorization": "Bot #{bot_token}"
     }
-
-    http.headers(headers)
   end
 
-  memoize :client
+  def client
+    http.headers(http_headers)
+  end
+
+  memoize :client, :http_headers
 end