# Discord backend.
module Backend_Discord
   require 'discordrb'

   # Helper for channel permissions handling.
   class ChannelPerms
      def initialize() @cprm = {} end

      # @param chan [Bot_Discord::Channel] the channel for this permission
      # @return [Boolean] true if the channel is enabled, false otherwise.
      def [](chan) @cprm[chan.name] or @cprm[chan.real.id] end

      # Sets a channel's permission on/off.
      # @param chan [Bot_Discord::Channel] the channel for this permission
      # @param set [Boolean] if this permission should be set
      # @return [void]
      def []=(chan, set) @cprm[chan] = set end
   end

   # A Discord user.
   class User < Vrobot4::Server::User
      attr_reader :real # @return [Discordrb::User] the instance

      # @param user [Discordrb::User] the discord user
      # @param ops [Array] list of operator role IDs
      # @param hop [Array] list of half-operator role IDs
      def initialize user, ops, hop
         @real  = user
         @name  = user.name
         @id    = user.id
         @roles = "v"
         if user.is_a? Discordrb::Member
            if user.owner?
               @roles += "Ooh"
            elsif ops and ops.any? do |role| user.role? role end
               @roles += "oh"
            elsif hop and hop.any? do |role| user.role? role end
               @roles += "h"
            end
         end
      end
   end

   # A Discord channel.
   class Channel < Vrobot4::Server::Channel
      attr_reader :real # @return [Discordrb::Channel] the instance

      # @param chan [Discordrb::Channel] the discord channel
      def initialize chan
         @real = chan
         @name = ?# + chan.name
         @id   = chan.id
      end
   end

   # A Discord server.
   class Server < Vrobot4::Server::AudioServer
      # The server type name.
      def self.type() "Discord" end

      attr_reader :real # @return [Discordrb::Server] the instance

      # (see Vrobot4::Server::Server#initialize)
      # @param real [Discordrb::Server] the instance
      def initialize info, bot, real
         super info, bot

         @real = real
         @id = real.id

         @ops = info[:admins] || []
         @hop = info[:halfop] || []

         if mods = info[:modules]
            for mod in mods
               load_mod mod
            end
         end
      end

      # (see Vrobot4::Server::AudioServer#voice_quit)
      def voice_quit m
         @bot.real.voice_destroy m.chan.real.server.id
      end

      # (see Vrobot4::Server::AudioServer#voice_play)
      def voice_play m, fname
         vc = @bot.real.voice m.chan.real
         raise RuntimeError, "I'm not in a voice channel" unless vc
         vc.play_file fname
      end

      # (see Vrobot4::Server::AudioServer#voice_play_io)
      def voice_play_io m, io
         vc = @bot.real.voice m.chan.real
         raise ArgumentError, "Invalid IO stream" unless io
         raise RuntimeError, "I'm not in a voice channel" unless vc
         Thread.new do
            vc.play_io io
         end

         # HACK
         sleep 1
         oldst = nil
         while vc.stream_time != oldst
            oldst = vc.stream_time
            sleep 5
         end
      end

      # (see Vrobot4::Server::Server#flags)
      def flags
         ?A
      end

      protected

      # (see Vrobot4::Server::Server#load_permissions)
      def load_permissions pinf
         @mprm = {chan: {}, role: {}, glob: {}}
         return unless pinf
         pinf.each do |pr|
            mod = Vrobot4::Module.get_module_type(pr[:module])[:type]
            if pr.key? :channel
               @mprm[:chan][mod] = ChannelPerms.new unless @mprm[:chan][mod]
               @mprm[:chan][mod][pr[:channel]] = true
            elsif pr.key? :roles
               @mprm[:role][mod] = pr[:roles]
            elsif pr.key? :enable
               @mprm[:glob][mod] = pr[:enable]
            end
         end
      end
   end

   # A bot implementation for Discord using discordrb.
   class Bot < Vrobot4::Robots::Bot
      # The bot type name.
      def self.type() "Discord" end
      Vrobot4::Robots.add_bot_type self

      attr_reader :real

      def initialize info
         super
         @servers = {}

         @real = Discordrb::Bot.new \
            token:     info[:apikey],
            client_id: info[:client]

         @real.ready do |evt|
            for _, serv in evt.bot.servers
               add_server serv
            end
         end

         @real.message do |evt|
            if evt.server
               serv = get_server evt.server

               m = Vrobot4::Server::Message.new \
                  msg:  evt.message.content,
                  user: User.new(evt.user, @ops, @hop),
                  chan: Channel.new(evt.channel),
                  serv: serv,
                  bot:  self,
                  reply:   -> (text) {evt.channel.send text},
                  reply_b: -> (text) {evt.channel.send "```\n#{text}```"}

               serv.handle_text_cmd m
            end
         end
      end

      # (see Vrobot4::Robots::Bot#connect)
      def connect
         @real.run
      end

      protected

      # Adds a server to the hash.
      # @param serv [Discordrb::Server] server instance
      # @return [Server]
      def add_server serv
         Vrobot4.log :DEBUG, "initializing server #{serv.id}"
         @servers[serv.id] = Server.new @info[serv.id] || {}, self, serv
      end

      # Finds a server in the hash, potentially adding it.
      # @param serv [Discordrb::Server] server instance
      # @return [Server]
      def get_server serv
         @servers[serv.id] || add_server(serv)
      end
   end
end

## EOF