require 'cgi'
require 'open-uri'
require 'json/pure'

class SoundCloud
  include Observable
  LIMIT = 100

  def initialize(client_id)
    @cid = client_id
    @playlist_pos = -1
    @download_queue = []
    @dthread = Thread.new do downloader end
  end

  def load_playlist(search = nil, offset = 0)
    search = "" unless search && !search.empty?
    if search =~ /\s*http(s)?:\/\/(www.)?soundcloud.com.*/
      url = "http://api.soundcloud.com/resolve.json?url=%s&client_id=%s" % [CGI.escape(search), @cid]
    else
      url = "http://api.soundcloud.com/tracks.json?client_id=%s&filter=streamable&limit=%d&offset=%d&q=%s" \
        % [@cid, LIMIT, offset, CGI.escape(search)]
    end
    c = open(url) do |io|
      io.readlines
    end.join
    @tracks = JSON.parse c
    @tracks = [@tracks] if @tracks.is_a? Hash
    @tracks.map! do |t|
      t["mpg123url"] = client_url t['stream_url']
      t["download"] = client_url t['download_url']
      t["duration"] = t["duration"].nil? ? 0 : t["duration"].to_i/1000
      t["bpm"] = t["bpm"].nil? ? 0 : t["bpm"].to_i
      t[:error] = "Not streamable" if t["stream_url"].nil?
      t
    end
    changed
    notify_observers :state =>:load, :tracks => @tracks
    rescue => e
      @error = {:error => e}
  end

  def shufflePlaylist
    return unless @tracks.respond_to? "shuffle!"
    @tracks.shuffle!
    changed
    notify_observers :state => :shuffle, :tracks => @tracks
  end

  def nextTrack
    return @error unless @tracks
    return if @tracks.empty? || @tracks.nil?
    if @tracks.is_a? Hash
      t = @tracks
    else 
      @playlist_pos += 1
      @playlist_pos -= @tracks.size if @playlist_pos >= @tracks.size
      t = @tracks[@playlist_pos]
      changed
      notify_observers :state => :next, :position => @playlist_pos
    end
    t
  end

  def prevTrack
    return @error unless @tracks
    return if @tracks.empty?
    if @tracks.is_a? Hash
      t = @tracks
    else 
      @playlist_pos -= 1
      @playlist_pos += @tracks.size if @playlist_pos < 0
      t = @tracks[@playlist_pos]
      changed
      notify_observers :state => :previous, :position => @playlist_pos
    end
    t
  end

  def download(target_dir)
    return @error unless @tracks
    return if @tracks.empty?
    if @tracks.is_a? Hash
      t = @tracks
    else 
      t = @tracks[@playlist_pos]
    end
    unless t["download"].nil? || t["download"].size == 0
      filename = "#{t["permalink"]}.#{t["original_format"]}"
      path = File.join(target_dir, filename)
      pair = [path, t['download']]
      @download_queue << pair unless @download_queue.include? pair
      @dthread.run

      changed
      notify_observers :state => :download, :count => @download_queue.size
    else
      changed
      notify_observers :state => :download, :error => "Not downloadable"
    end
  end

  # download thread
  def downloader
    loop do
      size = @download_queue.size
      while d = @download_queue.shift
        path = d[0]
        uri = d[1]
        changed
        notify_observers :state => :download, :name => path, :count => size
        size = @download_queue.size
        begin
          path = File.expand_path path
          file = File.new(path, "wb")
          File.open(path, "wb") do |file|
            file.print open(uri).read
          end
          changed
          notify_observers :state => :download, :name => path, :count => size
        rescue OpenURI::HTTPError => e
          changed
          notify_observers :state => :error, :error => e
        ensure
          file.close
        end
      end
      sleep 5
    end
  rescue => e
    changed
    notify_observers :state => "error", :error => e
  end

  private

  def client_url(url)
    "#{url}?client_id=%s" % [@cid] if url
  end
end