<?php

/**
 * @file
 * Advanced aggregation font module.
 */

// Define default variables.
/**
 * Default value to use font face observer for asynchronous font loading.
 */
define('ADVAGG_FONT_FONTFACEOBSERVER', 0);

/**
 * Default value to use a cookie in order to prevent the FOUT.
 */
define('ADVAGG_FONT_COOKIE', 1);

/**
 * Default value to only replace the font if it's been downloaded.
 */
define('ADVAGG_FONT_NO_FOUT', 0);

// Core hook implementations.
/**
 * Implements hook_page_build().
 */
function advagg_font_page_build(&$page) {
  // The $page variable is not an array; or the content key does not exist.
  if (!is_array($page) || !isset($page['content'])) {
    return;
  }
  $advagg_font_ffo = variable_get('advagg_font_fontfaceobserver', ADVAGG_FONT_FONTFACEOBSERVER);
  // Fontface Observer is disabled.
  if (empty($advagg_font_ffo)) {
    return;
  }

  $page['content']['#attached']['js'][] = array(
    'type' => 'setting',
    'data' => array(
      'advagg_font_cookie' => variable_get('advagg_font_cookie', ADVAGG_FONT_COOKIE),
      'advagg_font_no_fout' => variable_get('advagg_font_no_fout', ADVAGG_FONT_NO_FOUT),
    ),
  );

  // Add inline script for reading the cookies and adding the fonts already
  // loaded to the html class.
  if (variable_get('advagg_font_cookie', ADVAGG_FONT_COOKIE)) {
    $inline_script_min = 'var fonts=document.cookie.split("advagg");for(var key in fonts){var font=fonts[key].split("="),pos=font[0].indexOf("font_");-1!==pos&&(window.document.documentElement.className+=" "+font[0].substr(5).replace(/[^a-zA-Z0-9\-]/g,""))}';
    $page['content']['#attached']['js']['advagg_font.inline.js'] = array(
      'type' => 'inline',
      'group' => JS_LIBRARY - 1,
      'weight' => -50000,
      'scope_lock' => TRUE,
      'movable' => FALSE,
      'no_defer' => TRUE,
      'data' => $inline_script_min,
    );
  }

  // Add advagg_font.js; sets cookie and changes the class of the top level
  // element once a font has been downloaded.
  $file_path = drupal_get_path('module', 'advagg_font') . '/advagg_font.js';
  $page['content']['#attached']['js'][$file_path] = array(
    'async' => TRUE,
    'defer' => TRUE,
  );

  // Add fontfaceobserver.js async.
  if ($advagg_font_ffo != 6) {
    // Libraries module is not installed.
    if (!function_exists('libraries_info')) {
      $advagg_font_ffo = 6;
    }
    if ($advagg_font_ffo != 6) {
      // The fontfaceobserver library is not installed.
      $lib_info = libraries_detect('fontfaceobserver');
      if (empty($lib_info['installed'])) {
        $advagg_font_ffo = 6;
      }
    }
  }
  if ($advagg_font_ffo == 6) {
    $page['content']['#attached']['js']['https://cdn.rawgit.com/bramstein/fontfaceobserver/master/fontfaceobserver.js'] = array(
      'type' => 'external',
      'async' => TRUE,
      'defer' => TRUE,
    );
  }
  else {
    // Load the fontfaceobserver library.
    libraries_load('fontfaceobserver');
  }
}

/**
 * Implements hook_js_alter().
 */
function advagg_font_js_alter(&$js) {
  // Convert to the inline version.
  $advagg_font_ffo = variable_get('advagg_font_fontfaceobserver', ADVAGG_FONT_FONTFACEOBSERVER);
  if ($advagg_font_ffo == 2) {
    foreach ($js as $name => &$values) {
      if ($values['type'] === 'file' && strpos($name, '/fontfaceobserver.js') !== FALSE) {
        $values['type'] = 'inline';
        $values['data'] = file_get_contents($values['data']);
      }
    }
  }
}

/**
 * Implements hook_menu().
 */
function advagg_font_menu() {
  $file_path = drupal_get_path('module', 'advagg_font');
  $config_path = advagg_admin_config_root_path();

  $items[$config_path . '/advagg/font'] = array(
    'title' => 'Async Font Loader',
    'description' => 'Load external fonts in a non blocking manner.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('advagg_font_admin_settings_form'),
    'type' => MENU_LOCAL_TASK,
    'access arguments' => array('administer site configuration'),
    'file path' => $file_path,
    'file' => 'advagg_font.admin.inc',
    'weight' => 10,
  );

  return $items;
}

// Contrib hook implementations.
/**
 * Implements hook_libraries_info().
 */
function advagg_font_libraries_info() {
  $libraries['fontfaceobserver'] = array(
    // Only used in administrative UI of Libraries API.
    'name' => 'fontfaceobserver',
    'vendor url' => 'https://github.com/bramstein/fontfaceobserver',
    'download url' => 'https://github.com/bramstein/fontfaceobserver/archive/master.zip',
    // 1.50. : "version": "1.5.0",
    'version arguments' => array(
      'file' => 'package.json',
      'pattern' => '/"version":\\s+"([0-9\.]+)"/',
      'lines' => 10,
    ),
    'files' => array(
      'js' => array(
        'fontfaceobserver.js' => array(
          'type' => 'file',
          'group' => JS_LIBRARY,
          'async' => TRUE,
          'defer' => TRUE,
        ),
      ),
    ),
  );

  return $libraries;
}

/**
 * Implements hook_advagg_current_hooks_hash_array_alter().
 */
function advagg_font_advagg_current_hooks_hash_array_alter(&$aggregate_settings) {
  $aggregate_settings['variables']['advagg_font_fontfaceobserver'] = variable_get('advagg_font_fontfaceobserver', ADVAGG_FONT_FONTFACEOBSERVER);
}

// Helper functions.
/**
 * Get the replacements array for the css.
 *
 * @param string $css_string
 *   String of CSS.
 *
 * @return array
 *   An array containing the replacemnts and the font class name.
 */
function advagg_font_get_replacements_array($css_string) {
  // Get the CSS that contains a font-family rule.
  $length = strlen($css_string);
  $property = 'font-family';
  $property_position = 0;
  $replacements = array();

  while (($property_position = strpos($css_string, $property, $property_position)) !== FALSE) {
    // Get position of the last closing bracket plus 1 (start of this section).
    $start = strrpos($css_string, '}', -($length - $property_position));
    if ($start === FALSE) {
      // Property is in the first selector and a declaration block (full rule
      // set).
      $start = 0;
    }
    else {
      // Add one to start after the }.
      $start++;
    }

    // Get closing bracket (end of this section).
    $end = strpos($css_string, '}', $property_position);
    if ($end === FALSE) {
      // The end is the end of this file.
      $end = $length;
    }

    // Get closing ; in order to get the end of the declaration of the property.
    $declaration_end = strpos($css_string, ';', $property_position);
    if ($declaration_end > $end) {
      $declaration_end = $end;
    }
    // Add one in order to capture the } when we ge the full rule set.
    $end++;

    // Get values assigned to this property.
    $start_of_values = strpos($css_string, ':', $property_position);
    $values_string = substr($css_string, $start_of_values + 1, $declaration_end - ($start_of_values + 1));
    // Parse values string into an array of values.
    $values_array = explode(',', $values_string);

    // Values array has more than 1 value and first element is a quoted string.
    if (count($values_array) > 1 && (strpos($values_array[0], '"') !== FALSE || strpos($values_array[0], "'") !== FALSE)) {
      // Save the first value to a variable and trim it.
      $removed_value_original = trim($values_array[0]);
      // Get value as a classname. Remove quotes, trim, lowercase, and replace
      // spaces with dashes.
      $removed_value_classname = strtolower(trim(str_replace(array('"', "'"), '', $removed_value_original)));
      $removed_value_classname = str_replace(' ', '-', $removed_value_classname);
      // Remove value if it contains a quote.
      foreach ($values_array as $key => $value) {
        if (strpos($value, '"') !== FALSE || strpos($value, "'") !== FALSE) {
          unset($values_array[$key]);
        }
        else {
          break;
        }
      }
      if (empty($values_array)) {
        // No unquoted values left; do not modify the css.
        continue;
      }
      // Rezero the keys.
      $values_array = array_values($values_array);
      // Save next value.
      $next_value_original = trim($values_array[0]);
      // Create the values string.
      $new_values_string = implode(',', $values_array);

      // Get all selectors.
      $end_of_selectors = strpos($css_string, '{', $start);
      $selectors = substr($css_string, $start, $end_of_selectors - $start);
      // Ensure selectors is not a media query
      if (strpos($selectors,"@media") !== FALSE) {
        // Move the start to the end of the media query.
        $start = $end_of_selectors + 1;
        // Get the selectors again.
        $end_of_selectors = strpos($css_string, '{', $start);
        $selectors = substr($css_string, $start, $end_of_selectors - $start);
      }

      // From advagg_load_stylesheet_content().
      // Perform some safe CSS optimizations.
      // Regexp to match comment blocks.
      $comment     = '/\*[^*]*\*+(?:[^/*][^*]*\*+)*/';
      // Regexp to match double quoted strings.
      $double_quot = '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"';
      // Regexp to match single quoted strings.
      $single_quot = "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'";
      // Strip all comment blocks, but keep double/single quoted strings.
      $selectors_stripped = preg_replace(
        "<($double_quot|$single_quot)|$comment>Ss",
        "$1",
        $selectors
      );

      // Add css class to all the selectors.
      $selectors_array = explode(',', $selectors_stripped);
      foreach ($selectors_array as &$selector) {
        $selector = ' .' . $removed_value_classname . ' ' . $selector;
      }
      $new_selectors = implode(',', $selectors_array);

      // Get full rule set.
      $full_rule_set = substr($css_string, $start, $end - $start);
      // Replace values.
      $new_values_full_rule_set = str_replace($values_string, $new_values_string, $full_rule_set);
      // Add in old rule set with new selectors.
      $new_selectors_full_rule_set = $new_selectors . '{' . $property . ': ' . $values_string . ';}';

      // Record info.
      $replacements[] = array(
        $full_rule_set,
        $new_values_full_rule_set,
        $new_selectors_full_rule_set,
        $removed_value_original,
        $removed_value_classname,
        $next_value_original,
      );
    }

    // Advance position.
    $property_position = $end;
  }
  return $replacements;
}