thodg/mpd_client/lib/mpd_client.rb

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• Author : Anton Maminov
  Date : 2018-07-31 17:31:06
  Hash : 141cc085
  Message : Rename MPDClient to MPD::Client (#6) * Rename MPDClient to MPD::Client * remove redundants return * Avoid single-line method definitions * nothing special * update readme * add idle example * add rubocop * add .hound.yml * add travis config * add badges to readme * remove rakefile * add rake * revert rakefile * ichange gemspec * add rspec * change travis config * remove rakefile * remove rack-test * add spec * add test * fix rubocop * update badges

• lib/mpd_client.rb

• # frozen_string_literal: true
  
  require 'socket'
  require 'mpd_client/version'
  
  module MPD
    HELLO_PREFIX = 'OK MPD '
    ERROR_PREFIX = 'ACK '
    SUCCESS = 'OK'
    NEXT = 'list_OK'
  
    # MPD changelog: http://git.musicpd.org/cgit/master/mpd.git/plain/NEWS
    # http://www.musicpd.org/doc/protocol/command_reference.html
    # http://git.musicpd.org/cgit/cirrus/mpd.git/plain/doc/protocol.xml
    COMMANDS = {
      # Status Commands
      'clearerror'         => 'fetch_nothing',
      'currentsong'        => 'fetch_object',
      'idle'               => 'fetch_list',
      'noidle'             => '',
      'status'             => 'fetch_object',
      'stats'              => 'fetch_object',
      # Playback Option Commands
      'consume'            => 'fetch_nothing',
      'crossfade'          => 'fetch_nothing',
      'mixrampdb'          => 'fetch_nothing',
      'mixrampdelay'       => 'fetch_nothing',
      'random'             => 'fetch_nothing',
      'repeat'             => 'fetch_nothing',
      'setvol'             => 'fetch_nothing',
      'single'             => 'fetch_nothing',
      'replay_gain_mode'   => 'fetch_nothing',
      'replay_gain_status' => 'fetch_item',
      'volume'             => 'fetch_nothing',
      # Playback Control Commands
      'next'               => 'fetch_nothing',
      'pause'              => 'fetch_nothing',
      'play'               => 'fetch_nothing',
      'playid'             => 'fetch_nothing',
      'previous'           => 'fetch_nothing',
      'seek'               => 'fetch_nothing',
      'seekid'             => 'fetch_nothing',
      'seekcur'            => 'fetch_nothing',
      'stop'               => 'fetch_nothing',
      # Playlist Commands
      'add'                => 'fetch_nothing',
      'addid'              => 'fetch_item',
      'addtagid'           => 'fetch_nothing',
      'cleartagid'         => 'fetch_nothing',
      'clear'              => 'fetch_nothing',
      'delete'             => 'fetch_nothing',
      'deleteid'           => 'fetch_nothing',
      'move'               => 'fetch_nothing',
      'moveid'             => 'fetch_nothing',
      'playlist'           => 'fetch_playlist',
      'playlistfind'       => 'fetch_songs',
      'playlistid'         => 'fetch_songs',
      'playlistinfo'       => 'fetch_songs',
      'playlistsearch'     => 'fetch_songs',
      'plchanges'          => 'fetch_songs',
      'plchangesposid'     => 'fetch_changes',
      'prio'               => 'fetch_nothing',
      'prioid'             => 'fetch_nothing',
      'rangeid'            => 'fetch_nothing',
      'shuffle'            => 'fetch_nothing',
      'swap'               => 'fetch_nothing',
      'swapid'             => 'fetch_nothing',
      # Stored Playlist Commands
      'listplaylist'       => 'fetch_list',
      'listplaylistinfo'   => 'fetch_songs',
      'listplaylists'      => 'fetch_playlists',
      'load'               => 'fetch_nothing',
      'playlistadd'        => 'fetch_nothing',
      'playlistclear'      => 'fetch_nothing',
      'playlistdelete'     => 'fetch_nothing',
      'playlistmove'       => 'fetch_nothing',
      'rename'             => 'fetch_nothing',
      'rm'                 => 'fetch_nothing',
      'save'               => 'fetch_nothing',
      # Database Commands
      'count'              => 'fetch_object',
      'find'               => 'fetch_songs',
      'findadd'            => 'fetch_nothing',
      'list'               => 'fetch_list',
      'listall'            => 'fetch_database',
      'listallinfo'        => 'fetch_database',
      'listfiles'          => 'fetch_database',
      'lsinfo'             => 'fetch_database',
      'search'             => 'fetch_songs',
      'searchadd'          => 'fetch_nothing',
      'searchaddp1'        => 'fetch_nothing',
      'update'             => 'fetch_item',
      'rescan'             => 'fetch_item',
      'readcomments'       => 'fetch_object',
      # Mounts and neighbors
      'mount'              => 'fetch_nothing',
      'unmount'            => 'fetch_nothing',
      'listmounts'         => 'fetch_mounts',
      'listneighbors'      => 'fetch_neighbors',
      # Sticker Commands
      'sticker get'        => 'fetch_sticker',
      'sticker set'        => 'fetch_nothing',
      'sticker delete'     => 'fetch_nothing',
      'sticker list'       => 'fetch_stickers',
      'sticker find'       => 'fetch_songs',
      # Connection Commands
      'close'              => '',
      'kill'               => '',
      'password'           => 'fetch_nothing',
      'ping'               => 'fetch_nothing',
      # Audio Output Commands
      'disableoutput'      => 'fetch_nothing',
      'enableoutput'       => 'fetch_nothing',
      'outputs'            => 'fetch_outputs',
      'toggleoutput'       => 'fetch_nothing',
      # Reflection Commands
      'config'             => 'fetch_item',
      'commands'           => 'fetch_list',
      'notcommands'        => 'fetch_list',
      'tagtypes'           => 'fetch_list',
      'urlhandlers'        => 'fetch_list',
      'decoders'           => 'fetch_plugins',
      # Client To Client
      'subscribe'          => 'fetch_nothing',
      'unsubscribe'        => 'fetch_nothing',
      'channels'           => 'fetch_list',
      'readmessages'       => 'fetch_messages',
      'sendmessage'        => 'fetch_nothing'
    }.freeze
  
    # The `MPD::Client` is used for interactions with a MPD server.
    #
    # Example:
    #
    # ```ruby
    # require 'mpd_client'
    # require 'logger'
    #
    # client = MPD::Client.new
    # client.log = Logger.new($stderr)
    # client.connect('/var/run/mpd/socket')
    # ```
    class Client
      attr_reader :mpd_version
  
      class << self
        # Default logger for all `MPD::Client`` instances
        #
        # ```ruby
        # MPD::Client.log = Logger.new($stderr)
        # ```
        attr_accessor :log
  
        def connect(host = 'localhost', port = 6600)
          client = MPD::Client.new
          client.connect(host, port)
  
          client
        end
  
        def add_command(name, retval)
          escaped_name = name.tr(' ', '_')
          define_method escaped_name.to_sym do |*args|
            ensure_connected
  
            execute(name, *args, retval)
          end
        end
  
        def remove_command(name)
          raise "Can't remove not existent '#{name}' command" unless method_defined? name.to_sym
          remove_method name.to_sym
        end
      end
  
      def initialize
        @mutex = Mutex.new
        reset
      end
  
      def connect(host = 'localhost', port = 6600)
        @host = host
        @port = port
  
        reconnect
      end
  
      def reconnect
        log&.info("MPD (re)connect #{@host}, #{@port}")
  
        @socket = if @host.start_with?('/')
                    UNIXSocket.new(@host)
                  else
                    TCPSocket.new(@host, @port)
                  end
  
        hello
        @connected = true
      end
  
      def disconnect
        log&.info('MPD disconnect')
        @socket.close
        reset
      end
  
      def reset
        @mpd_version = nil
        @command_list = nil
        @socket = nil
        @log = nil
        @connected = false
      end
  
      def connected?
        @connected
      end
  
      # http://www.musicpd.org/doc/protocol/ch01s04.html
      def command_list_ok_begin
        raise 'Already in command list' unless @command_list.nil?
        write_command('command_list_ok_begin')
        @command_list = []
      end
  
      def command_list_end
        raise 'Not in command list' if @command_list.nil?
        write_command('command_list_end')
  
        fetch_command_list
      end
  
      # The current logger. If no logger has been set MPD::Client.log is used
      def log
        @log || MPD::Client.log
      end
  
      # Sets the +logger+ used by this instance of MPD::Client
      attr_writer :log
  
      private
  
      def ensure_connected
        raise 'Please connect to MPD server' unless connected?
      end
  
      def execute(command, *args, retval)
        @mutex.synchronize do
          write_command(command, *args)
  
          if !@command_list.nil?
            @command_list << retval
          else
            eval retval
          end
        end
      end
  
      def write_line(line)
        begin
          @socket.puts line
        rescue Errno::EPIPE
          reconnect
          @socket.puts line
        end
        @socket.flush
      end
  
      def write_command(command, *args)
        parts = [command]
        args.each do |arg|
          line = if arg.is_a?(Array)
                   arg.size == 1 ? "\"#{arg[0].to_i}:\"" : "\"#{arg[0].to_i}:#{arg[1].to_i}\""
                 else
                   "\"#{escape(arg)}\""
                 end
  
          parts << line
        end
        # log.debug("Calling MPD: #{command}#{args}") if log
        log&.debug("Calling MPD: #{parts.join(' ')}")
        write_line(parts.join(' '))
      end
  
      def read_line
        line = @socket.gets.force_encoding('utf-8')
        raise 'Connection lost while reading line' unless line.end_with?("\n")
        line.chomp!
        if line.start_with?(ERROR_PREFIX)
          error = line[/#{ERROR_PREFIX}(.*)/, 1].strip
          raise error
        end
  
        if !@command_list.nil?
          return if line == NEXT
          raise "Got unexpected '#{SUCCESS}'" if line == SUCCESS
        elsif line == SUCCESS
          return
        end
  
        line
      end
  
      def read_pair(separator)
        line = read_line
        return if line.nil?
        pair = line.split(separator, 2)
        raise "Could now parse pair: '#{line}'" if pair.size < 2
  
        pair # Array
      end
  
      def read_pairs(separator = ': ')
        result = []
        pair = read_pair(separator)
        while pair
          result << pair
          pair = read_pair(separator)
        end
  
        result
      end
  
      def fetch_item
        pairs = read_pairs
        return nil if pairs.size != 1
  
        pairs[0][1]
      end
  
      def fetch_nothing
        line = read_line
        raise "Got unexpected value: #{line}" unless line.nil?
      end
  
      def fetch_list
        result = []
        seen = nil
  
        read_pairs.each do |key, value|
          if key != seen
            raise "Expected key '#{seen}', got '#{key}'" unless seen.nil?
            seen = key
          end
  
          result << value
        end
  
        result
      end
  
      def fetch_objects(delimeters = [])
        result = []
        obj = {}
        read_pairs.each do |key, value|
          key = key.downcase
          if delimeters.include?(key)
            result << obj unless obj.empty?
            obj = {}
          elsif obj.include?(key)
            obj[key] << value
          end
          obj[key] = value
        end
  
        result << obj unless obj.empty?
  
        result
      end
  
      def fetch_object
        objs = fetch_objects
  
        objs ? objs[0] : {}
      end
  
      def fetch_changes
        fetch_objects(['cpos'])
      end
  
      def fetch_songs
        fetch_objects(['file'])
      end
  
      def fetch_mounts
        fetch_objects(['mount'])
      end
  
      def fetch_neighbors
        fetch_objects(['neighbor'])
      end
  
      def fetch_messages
        fetch_objects('channel')
      end
  
      def fetch_outputs
        fetch_objects(['outputid'])
      end
  
      def fetch_plugins
        fetch_objects(['plugin'])
      end
  
      def fetch_database
        fetch_objects(%w[file directory playlist])
      end
  
      def fetch_playlists
        fetch_objects(['playlist'])
      end
  
      def fetch_playlist
        result = []
        read_pairs(':').each do |_key, value|
          result << value
        end
  
        result
      end
  
      def fetch_stickers
        result = []
        read_pairs.each do |_key, sticker|
          value = sticker.split('=', 2)
          raise "Could now parse sticker: #{sticker}" if value.size < 2
          result << Hash[*value]
        end
  
        result
      end
  
      def fetch_sticker
        fetch_stickers[0]
      end
  
      def fetch_command_list
        result = []
        begin
          @command_list.each do |retval|
            result << (eval retval)
          end
        ensure
          @command_list = nil
        end
  
        result
      end
  
      def hello
        line = @socket.gets
        raise 'Connection lost while reading MPD hello' unless line.end_with?("\n")
        line.chomp!
        raise "Got invalid MPD hello: #{line}" unless line.start_with?(HELLO_PREFIX)
        @mpd_version = line[/#{HELLO_PREFIX}(.*)/, 1]
      end
  
      def escape(text)
        text.to_s.gsub('\\', '\\\\').gsub('"', '\\"')
      end
    end
  end
  
  MPD::COMMANDS.each_pair do |name, callback|
    MPD::Client.add_command(name, callback)
  end