/**

 * AJAX functions

 * 

 * Greyhound - real web management for Amarok

 * Copyright (C) 2008 Dan Fuhry

 *

 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied

 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.

 */

var ajax;

var is_playing = false, current_track = -1, current_track_length, current_track_pos, ct_advance_timeout = false, ct_counter = false, playlist_md5 = false, first_load = true;

function ajaxGet(uri, f)

{

  if (window.XMLHttpRequest)

  {

    ajax = new XMLHttpRequest();

  }

  else

  {

    if (window.ActiveXObject) {           

      ajax = new ActiveXObject("Microsoft.XMLHTTP");

    }

    else

    {

      alert('AmaroK client-side runtime error: No AJAX support, unable to continue');

      return;

    }

  }

  ajax.onreadystatechange = f;

  ajax.open('GET', uri, true);

  ajax.setRequestHeader( "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT" );

  ajax.send(null);

}

function ajaxPost(uri, parms, f)

{

  if (window.XMLHttpRequest)

  {

    ajax = new XMLHttpRequest();

  }

  else

  {

    if (window.ActiveXObject)

    {           

      ajax = new ActiveXObject("Microsoft.XMLHTTP");

    }

    else

    {

      alert('AmaroK client-side runtime error: No AJAX support, unable to continue');

      return;

    }

  }

  ajax.onreadystatechange = f;

  ajax.open('POST', uri, true);

  ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

  // Setting Content-length in Safari triggers a warning

  if ( !is_Safari )

  {

    ajax.setRequestHeader("Content-length", parms.length);

  }

  ajax.setRequestHeader("Connection", "close");

  ajax.send(parms);

}

function setAjaxLoading()

{

  $('ajax_status').object.src = img_ajax;

  $('ajax_status').object.style.display = 'block';

}

function unsetAjaxLoading()

{

  $('ajax_status').object.src = 'about:blank';

  $('ajax_status').object.style.display = 'none';

}

var refresh_playlist = function()

{

  setAjaxLoading();

  ajaxGet('/action.json/refresh', function()

    {

      if ( ajax.readyState == 4 && ajax.status == 200 )

      {

        unsetAjaxLoading();

        var response = (' ' + ajax.responseText).substr(1);

        // quickie JSON parser :)

        response = eval('(' + response + ')');

        // has the playlist been modified?

        if ( playlist_md5 )

        {

          if ( response.playlist_hash != playlist_md5 )

          {

            // playlist has changed, reload

            window.location.reload();

            return false;

          }

        }

        playlist_md5 = response.playlist_hash;

        // update track number

        if ( response.current_track != current_track )

        {

          var ot_id = 'track_' + current_track;

          var nt_id = 'track_' + response.current_track;

          current_track = response.current_track;

          if ( $(ot_id).hasClass('current') )

          {

            $(ot_id).rmClass('current');

          }

          if ( ! $(nt_id).hasClass('current') )

          {

            $(nt_id).addClass('current');

          }

        }

        // update playing status

        is_playing = response.is_playing;

        if ( allow_control )

        {

          var img = $('btn_playpause').object.getElementsByTagName('img')[0];

          if ( is_playing )

          {

            img.src = img_pause;

          }

          else

          {

            img.src = img_play;

          }

        }

        // update volume

        if ( response.volume != current_volume )

        {

          set_volume_fill(response.volume);

          current_volume = response.volume;

        }

        // auto-refresh on track advance

        if ( ct_advance_timeout )

        {

          clearTimeout(ct_advance_timeout);

        }

        var time_remaining = response.current_track_length - response.current_track_pos;

        current_track_length = response.current_track_length;

        current_track_pos = response.current_track_pos;

        if ( ct_counter )

          clearInterval(ct_counter);

        update_clock();

        {

          ct_advance_timeout = setTimeout(refresh_playlist, ( 1000 * time_remaining ));

          ct_counter = setInterval(update_clock, 1000);

        }

        if ( first_load )

        {

          first_load = false;

          var top = $('track_' + current_track).Top() - 138;

          window.scroll(0, top);

        }

      }

    });

}

function player_action(action)

{

  var act2 = action;

  setAjaxLoading();

  ajaxGet('/action.json/' + action, function()

    {

      if ( ajax.readyState == 4 && ajax.status == 200 )

      {

        unsetAjaxLoading();

        refresh_playlist();

      }

    });

}

function jump_to_song(tid)

{

  setAjaxLoading();

  if ( tid == current_track )

    return false;

  if ( !allow_control )

    return false;

  ajaxGet('/action.json/jump/' + tid, function()

    {

      if ( ajax.readyState == 4 && ajax.status == 200 )

      {

        unsetAjaxLoading();

        var response = (' ' + ajax.responseText).substr(1);

        // quickie JSON parser :)

        response = eval('(' + response + ')');

        // update track number

        var ot_id = 'track_' + current_track;

        var nt_id = 'track_' + tid;

        current_track = tid;

        if ( $(ot_id).hasClass('current') )

        {

          $(ot_id).rmClass('current');

        }

        if ( ! $(nt_id).hasClass('current') )

        {

          $(nt_id).addClass('current');

        }

        // update playing status

        var img = $('btn_playpause').object.getElementsByTagName('img')[0];

        is_playing = true;

        img.src = img_play;

        // auto-refresh on track advance

        if ( ct_advance_timeout )

        {

          clearTimeout(ct_advance_timeout);

        }

        if ( ct_counter )

          clearInterval(ct_counter);

        var time_remaining = response.current_track_length - response.current_track_pos;

        current_track_length = response.current_track_length;

        current_track_pos = response.current_track_pos;

        if ( is_playing )

        {

          ct_advance_timeout = setTimeout(refresh_playlist, ( 1000 * time_remaining ));

          update_clock();

          ct_counter = setInterval(update_clock, 1000);

        }

      }

    });

}

function update_clock()

{

  var str = secs_to_string(current_track_pos) + '/' + secs_to_string(current_track_length);

  $('playmeter').object.innerHTML = str;

  current_track_pos++;

}

function secs_to_string(time)

{

  var count_seconds = time % 60;

  var count_minutes = ( time - count_seconds ) / 60;

  return fill_zeroes(count_minutes) + ':' + fill_zeroes(count_seconds);

}

function fill_zeroes(str, len)

{

  if ( !len )

    len = 2;

  if ( typeof(str) == 'number' && str == 0 )

    str = '0';

  str = String(str);

  while ( str.length < len )

  {

    str = '0' + str;

  }

  return str;

}

setInterval(refresh_playlist, 10000);