discord: add /time command.

app/logical/discord_slash_command.rb

@@ -5,6 +5,7 @@ class DiscordSlashCommand
     count: DiscordSlashCommand::CountCommand,
     posts: DiscordSlashCommand::PostsCommand,
     random: DiscordSlashCommand::RandomCommand,
+    time: DiscordSlashCommand::TimeCommand,
     wiki: DiscordSlashCommand::WikiCommand,
   }
 

app/logical/discord_slash_command/time_command.rb

@@ -0,0 +1,57 @@
+class DiscordSlashCommand
+  class TimeCommand < DiscordSlashCommand
+    def name
+      "time"
+    end
+
+    def description
+      "Show the current time around the world"
+    end
+
+    def options
+      [{
+        name: "name",
+        description: "The name of the country to show",
+        required: false,
+        type: ApplicationCommandOptionType::String
+      }]
+    end
+
+    def call
+      name = params[:name]
+
+      if name.present?
+        msg = times_for_country(name)
+        msg = "Timezone not found: #{name}" if msg.blank?
+      else
+        msg = <<~EOS
+          `US (west): #{time("US/Pacific")}`
+          `US (east): #{time("US/Eastern")}`
+          `Europe:    #{time("Europe/Berlin")}`
+          `Japan:     #{time("Asia/Tokyo")}`
+          `Australia: #{time("Australia/Sydney")}`
+        EOS
+      end
+
+      respond_with(msg)
+    end
+
+    def times_for_country(country_name)
+      country = TZInfo::Country.all.find do |country|
+        country.name.downcase == country_name.downcase
+      end
+
+      return nil if country.nil?
+
+      zones = country.zones.group_by(&:abbr).transform_values(&:first).values
+      zones.map do |zone|
+        "`#{zone.friendly_identifier}: #{time(zone.identifier)}`"
+      end.join("\n")
+    end
+
+    # format: Thu, Nov 02 2017  6:11 PM CDT
+    def time(zone, format: "%a, %b %d %Y %l:%M %p %Z")
+      Time.use_zone(zone) { Time.current.strftime(format) }
+    end
+  end
+end