<?php

/**
 * Implements hook_theme().
 */
function highcharts_theme() {
  return array(
    'highcharts_chart' => array(
      'arguments' => array('attributes' => array()),
    ),
  );
}

/**
 * Returns HTML for a highcharts container.
 * 
 * @param $attributes
 *   An associative array containing valid HTML attributes to be applied to the
 *   highchart container:
 *   - id: Required. Must match the 'renderTo' option in the 'Highcharts.Chart'
 *     object.
 *   - style: Default: 'margin 0 auto' is appended to any existing style.
 *   - class: Default: 'highcharts-chart' is appended to any existing class.
 *
 * @ingroup themeable
 *
 * @return
 *   The chart div, ready for the highchart JS to render to.
 */
function theme_highcharts_chart($attributes = array()) {
  if ($attributes['id']) {
    $attributes['style'] = isset($attributes['style'])
      ? $attributes['style']  . 'margin: 0 auto'
      : 'margin: 0 auto';

    $attributes['class'] = isset($attributes['class'])
      ? $attributes['class'] . ' highcharts-chart'
      : 'highcharts-chart';

    $output  = '<div ' . drupal_attributes($attributes) . '></div>';
  }

  return $output;
}

/**
 * Render a highchart.
 *
 * @param object $options
 *   By reference. A highcharts options object.
 *
 *   Any callbacks are specially handled as Drupal.settings only stores strings.
 *
 *   Also includes:
 *   - chart_id: added by reference.
 *
 *   @see the highcharts API http://www.highcharts.com/ref/
 */
function highcharts_render(&$options) {
  // Load common JS only once.
  static $js_added = false;
  if (!$js_added) {
    // Add highcharts library JS.
    module_load_include('module', 'libraries', 'libraries');
    $path = libraries_get_path('highcharts');
    if (!empty($path)) {
      drupal_add_js($path . '/js/highcharts.js');
    }
    // Add highcharts behavior. This allows us to leverage the entire highcharts
    // API without needing to define each type separately.
    drupal_add_js(drupal_get_path('module', 'highcharts') . '/js/highcharts.js', 'module', 'footer');
    // Flag common JS loaded status.
    $js_added = TRUE;
  }

  // Generate a unique chart ID.
  $chart_id = 'highcharts_' . uniqid();

  // Pass this chart ID by reference to the options object.
  $options->chart->renderTo = $chart_id;
  // Add Drupal.settings for this chart.
  drupal_add_js(array('highcharts' => array($chart_id => $options)), 'setting');

  // Add highchart options object methods, which can't be passed through
  // Drupal.settings.
  // @todo check for all possible highchart options object callbacks.
  $formatter = $options->tooltip->formatter;
  if ($formatter) {
    drupal_add_js("Drupal.settings.highcharts.{$chart_id}.tooltip.formatter = $formatter", 'inline', 'header', 'FALSE', 'FALSE', FALSE);
  }
}