discord: add /wiki command.

app/logical/discord_slash_command.rb

@@ -5,6 +5,7 @@ class DiscordSlashCommand
     count: DiscordSlashCommand::CountCommand,
     posts: DiscordSlashCommand::PostsCommand,
     random: DiscordSlashCommand::RandomCommand,
+    wiki: DiscordSlashCommand::WikiCommand,
   }
 
   # https://discord.com/developers/docs/interactions/slash-commands#interaction-interactiontype

app/logical/discord_slash_command/post_embed.rb

@@ -17,12 +17,12 @@ class DiscordSlashCommand
         image: {
           width: post.image_width,
           height: post.image_height,
-          url: embed_image,
+          url: embed_image_url,
         },
       }
     end
 
-    def embed_image
+    def embed_image_url
       if is_censored?
         nil
       elsif post.file_ext.match?(/jpe?g|png|gif/)

app/logical/discord_slash_command/wiki_command.rb

@@ -0,0 +1,83 @@
+class DiscordSlashCommand
+  class WikiCommand < DiscordSlashCommand
+    extend Memoist
+
+    def name
+      "wiki"
+    end
+
+    def description
+      "Show a wiki page"
+    end
+
+    def options
+      [
+        {
+          name: "name",
+          description: "The name of the wiki page",
+          required: true,
+          type: ApplicationCommandOptionType::String
+        },
+      ]
+    end
+
+    def call
+      if wiki_page.nil?
+        respond_with("`#{params[:name]}` doesn't have a wiki.")
+      else
+        respond_with(
+          embeds: [{
+            description: DText.to_markdown(wiki_page.body).truncate(500),
+            title: wiki_page.pretty_title,
+            url: Routes.url_for(wiki_page),
+            **example_embed,
+          }]
+        )
+      end
+    end
+
+    def wiki_page
+      WikiPage.titled(params[:name]).first
+    end
+
+    def tag
+      wiki_page&.tag
+    end
+
+    def example_post
+      return nil if tag.nil? || tag.empty?
+
+      if tag.artist?
+        search = "#{tag.name} rating:safe"
+      elsif tag.copyright?
+        search = "#{tag.name} rating:safe everyone copytags:<5 -parody -crossover"
+      elsif tag.character?
+        search = "#{tag.name} rating:safe solo chartags:<5"
+      else # meta or general
+        search = "#{tag.name} rating:safe -animated -6+girls -comic"
+      end
+
+      Post.system_tag_match(search).limit(500).sort_by(&:score).last
+    end
+
+    def example_embed
+      return {} if example_post.nil? || example_image_url.nil?
+
+      {
+        image: {
+          url: example_image_url,
+        },
+        author: {
+          name: example_post.dtext_shortlink,
+          url: Routes.url_for(example_post),
+        }
+      }
+    end
+
+    def example_image_url
+      DiscordSlashCommand::PostEmbed.new(example_post, self).embed_image_url
+    end
+
+    memoize :wiki_page, :tag, :example_post, :example_embed, :example_image_url
+  end
+end