<?php

/**
 * @file
 * Enables assigning menus to content types through the menu edit page.
 *
 * In Drupal 7, site builders must assign menus to content types before they
 * will appear on the node edit page. This module makes it possible to assign
 * multiple content types to a menu through the menu edit form.
 */

/**
 * Implements hook_help().
 */
function ct_per_menu_help($path, $arg) {
  if ($path == 'admin/help#ct_per_menu'){
    $output = '';
    $output .= '<h3>' . t('About') . '</h3>';
    $output .= '<p>' . t('This module makes it possible to assign multiple content types to a menu through the menu edit form.') . '</p>';
    $output .= '<h3>' . t('Uses') . '</h3>';
    $output .= '<p>' . t('With this module installed, go to Structure > Menus (admin/structure/menu) in your site and click the \'edit menu\' link for the menu you want to assign.');
    $output .= t(' At the bottom of the screen, you will see a list of all content types on you site.');
    $output .= t(' Click a content type\'s checkbox to enable or disable it for this menu.') . '</p>';
    return $output;
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function ct_per_menu_form_menu_edit_menu_alter(&$form, &$form_state) {
  $defaults = ct_per_menu_get_defaults();
  $form['types'] = array(
    '#type' => 'checkboxes',
    '#title' => t('Content type assignments to this menu'),
    '#description' => t('Enable or disable this menu for a content type using the checkbox beside its name.'),
    '#options' => node_type_get_names(),
    '#default_value' => $defaults,
  );
  $form['#submit'][] = 'ct_per_menu_menu_edit_menu_form_submit';
}

/**
 * Helper function to find already enabled content types.
 */
function ct_per_menu_get_defaults() {
  //Get machine name of current menu.
  $menu = menu_get_object('menu', 4);
  $menu_name = $menu['menu_name'];
  //Get list of content types.
  $node_types = node_type_get_names();
  $defaults = array();
  if ($menu_name == 'main-menu') {
    //Find content types without 'menu_options' variable. These will have main
    //menu enabled by default.
    foreach ($node_types as $type => $name) {
      if (is_null(variable_get('menu_options_' . $type))) {
        array_push($defaults, $type);
      }
      //Add content types to main-menu for any user saved settings.
      if (variable_get('menu_options_' . $type)) {
        $options = variable_get('menu_options_' . $type);
        foreach ($options as $o) {
          if ($o == $menu_name) {
            array_push($defaults, $type);
          }
        }
      }
    }
  } else {
    //Get all other 'menu_options' variable settings.
    foreach ($node_types as $type => $name) {
      if (variable_get('menu_options_' . $type)) {
        $options = variable_get('menu_options_' . $type);
        foreach ($options as $o) {
          if ($o == $menu_name) {
            array_push($defaults, $type);
          }
        }
      }
    }
  }
  return $defaults;
}

/**
 * Custom submit function.
 *
 * This function first looks for a persistent variable assigned to the relevant
 * content type and creates one if none is present. It then cycles through the
 * existing variables to add the chosen menus if not included. Finally, it
 * cycles through the variables to identify deleted menus and remove them.
 */
function ct_per_menu_menu_edit_menu_form_submit($form, $form_state) {
  //Get the machine name of the current menu from the URL.
  $menu = menu_get_object('menu', 4);
  $menu_name = $menu['menu_name'];
  //If no variable has been set, must retain default main menu.
  $menu_name_main = array('main-menu', $menu_name);
  //Or simply include it if it is $menu_name.
  $main = array('main-menu');
  //Eliminate the unchecked options.
  $values = array_filter($form_state['values']['types']);

  foreach ($values as $v) {
    //No persistent variable set. Create one, add menu and include main menu.
    if (is_null(variable_get('menu_options_' . $v))) {
      //If main, create with only main in the array.
      if ($menu_name == 'main-menu'){
        variable_set('menu_options_' . $v, $main);
      }
      //Otherwise, create with main and the new menu.
      else {
      variable_set('menu_options_' . $v, $menu_name_main);
      }
    }
    //Find existing persistent variables. If no entry for this menu, add it.
    //variable_get alone won't detect empty arrays (for content types with
    //no menus assigned).
    if (!is_null(variable_get('menu_options_' . $v))) {
      $options = variable_get('menu_options_' . $v);
      if (!in_array($menu_name, $options)) {
        array_push($options, $menu_name);
        variable_set('menu_options_' . $v, $options);
      }
    }
  }

  //Now delete unchecked content types that were previously set.
  //First get an array of types not assigned this menu.
  $non_values = array_diff($form_state['values']['types'], $values);
  //If the type has a variable, check it for this menu. If there, delete and
  //reset variable.
  foreach ($non_values as $type => $value) {
    if (variable_get('menu_options_' . $type)) {
      $options = variable_get('menu_options_' . $type);
      if (in_array($menu_name, $options)) {
        $key = array_search($menu_name, $options);
        unset($options[$key]);
        variable_set('menu_options_' . $type, $options);
      }
    }
    //If variable doesn't exist, create it with empty array as value to delete
    //main menu, otherwise with main menu as default.
    if (is_null(variable_get('menu_options_' . $type))) {
      $empty = array();
      if ($menu_name == 'main-menu') {
        variable_set('menu_options_' . $type, $empty);
      } else {
        variable_set('menu_options_' . $type, $main);
      }
    }
  }
}