<?php

/**
 * Implements hook_field_info().
 */
function tmgmt_language_combination_field_info() {
  $info['tmgmt_language_combination'] = array(
    'label' => t('Language combination'),
    'description' => t('Allows the definition of language combinations (e.g. "From english to german").'),
    'default_widget' => 'tmgmt_language_combination_default',
    'default_formatter' => 'tmgmt_language_combination_default',
    'settings' => array(
      'user_register_form' => 1,
    ),
  );

  return $info;
}

/**
 * Implements hook_field_schema().
 */
function tmgmt_language_combination_field_schema($field) {
  $schema = array(
    'columns' => array(
      'language_from' => array(
        'description' => 'The langcode of the language from which the user is able to translate.',
        'type' => 'varchar',
        'length' => 10,
      ),
      'language_to' => array(
        'description' => 'The langcode of the language to which the user is able to translate.',
        'type' => 'varchar',
        'length' => 10,
      ),
    ),
    'indexes' => array(
      'language' => array('language_from', 'language_to'),
    ),
  );

  return $schema;
}

/**
 * Implements hook_field_widget_info().
 */
function tmgmt_language_combination_field_widget_info() {
  $info['tmgmt_language_combination_default'] = array(
    'label' => t('Select list'),
    'description' => t('Default widget for allowing users to define translation combination.'),
    'field types' => array('tmgmt_language_combination'),
    'behaviors' => array(
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
      'default value' => FIELD_BEHAVIOR_DEFAULT,
    ),
  );

  return $info;
}

/**
 * Implements hook_field_widget_form().
 */
function tmgmt_language_combination_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
  if (isset($form_state['list_all_languages'])) {
    $languages_options = tmgmt_language_combination_languages_predefined_list();
  }
  else {
    $languages_options = array();
    foreach (language_list() as $code => $language) {
      $languages_options[$code] = $language->name;
    }
  }

  $options = array('_none' => t('- None -')) + $languages_options;

  $element['language_from'] = array(
    '#type' => 'select',
    '#title' => t('From'),
    '#options' => $options,
    '#default_value' => isset($items[$delta]) ? $items[$delta]['language_from'] : '',
    '#attributes' => array('class' => array('from-language')),
  );

  $element['language_to'] = array(
    '#type' => 'select',
    '#title' => t('To'),
    '#options' => $options,
    '#default_value' => isset($items[$delta]) ? $items[$delta]['language_to'] : '',
    '#attributes' => array('class' => array('to-language')),
  );

  return $element;
}

/**
 * Implements hook_field_validate().
 */
function tmgmt_language_combination_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
  $existing = array();

  foreach ($items as $delta => $item) {
    $key = $item['language_from'] . ':' . $item['language_to'];

    if (!tmgmt_language_combination_field_is_empty($item, 'tmgmt_language_combination')) {
      if ($item['language_from'] == $item['language_to']) {
        $errors[$field['field_name']][$langcode][$delta][] = array(
          'error' => 'tmgmt_language_combination_equal',
          'message' => t("%name: The 'from' and 'to' language fields can't have the same value.", array('%name' => $instance['label'])),
        );
      }

      if (isset($existing[$key])) {
        $errors[$field['field_name']][$langcode][$delta][] = array(
          'error' => 'tmgmt_language_combination_equal',
          'message' => t('%name: The language combination has to be unique.', array('%name' => $instance['label'])),
        );
      }
    }

    $existing[$key] = TRUE;
  }
}

/**
 * Implements hook_field_widget_error().
 */
function tmgmt_language_combination_field_widget_error($element, $error, $form, &$form_state) {
  form_error($element, $error['message']);
}

/**
 * Implements hook_field_is_empty().
 */
function tmgmt_language_combination_field_is_empty($item, $field) {
  if (empty($item['language_from']) || empty($item['language_to']) || $item['language_from'] == '_none' || $item['language_to'] == '_none') {
    return TRUE;
  }

  return FALSE;
}

/**
 * Implements hook_field_formatter_info().
 */
function tmgmt_language_combination_field_formatter_info() {
  $info['tmgmt_language_combination_default'] = array(
    'label' => t('Default'),
    'description' => t('Default formatter for displaying the translation combination of a user.'),
    'field types' => array('tmgmt_language_combination'),
  );

  $info['tmgmt_language_combination_table'] = array(
    'label' => t('Table'),
    'description' => t('Formatter for displaying the translation combination of a user in a table.'),
    'field types' => array('tmgmt_language_combination'),
  );

  return $info;
}

/**
 * Implements hook_field_formatter_view().
 */
function tmgmt_language_combination_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
  $element = array();

  switch ($display['type']) {
    case 'tmgmt_language_combination_default':
      $element['#theme'] = 'item_list';
      $element['#items'] = array();

      foreach ($items as $delta => $item) {
        $from = tmgmt_language_combination_language_label($item['language_from']);
        $to = tmgmt_language_combination_language_label($item['language_to']);
        $element['#items'][$delta]['data'] = t('From @from to @to', array('@from' => $from, '@to' => $to));
        $element['#items'][$delta]['class'][] = drupal_html_class($from . '-' . $to) . '">';
      }
      break;

    case 'tmgmt_language_combination_table':
      $rows = array();

      foreach ($items as $item) {
        $to = tmgmt_language_combination_language_label($item['language_to']);
        $from = tmgmt_language_combination_language_label($item['language_from']);
        $row[] = array(
          'data' => $from,
          'class' => array('from-language', drupal_html_class('language-' . $from)),
        );

        $row[] = array(
          'data' => $to,
          'class' => array('to-language', drupal_html_class('language-' . $to)),
        );

        $rows[] = array(
          'data' => $row,
          'class' => array(drupal_html_class($from . '-' . $to)),
        );
      }

      $element = array(
        '#theme' => 'table',
        '#header' => array(t('From'), t('To')),
        '#rows' => $rows,
      );
      break;
  }

  return $element;
}

/**
 * Implements hook_field_update().
 */
function tmgmt_language_combination_field_update($entity_type, $entity, $field, $instance, $langcode, &$items) {
  $languages = language_list();
  $added_languages = array();

  // In case the skill languages is not know to the system, install them.
  foreach ($items as $item) {
    if (!isset($languages[$item['language_to']]) && !isset($added_languages[$item['language_to']])) {
      locale_add_language($item['language_to']);
      $added_languages[$item['language_to']] = $item['language_to'];
    }
    if (!isset($languages[$item['language_from']]) && !isset($added_languages[$item['language_from']])) {
      locale_add_language($item['language_from']);
      $added_languages[$item['language_from']] = $item['language_from'];
    }
  }
}

/**
 * Returns the label of a language.
 *
 * @todo Remove this once the core language label function is fixed.
 *
 * @param $language
 *   A language in ISO format.
 * @return string
 *   The label of the language or an empty string if the language or its label
 *   are not defined.
 */
function tmgmt_language_combination_language_label($language) {
  $languages = tmgmt_language_combination_languages_predefined_list();
  if (!empty($languages[$language])) {
    return $languages[$language];
  }
  return '';
}

/**
 * Prepares a language code list for a select form item with all languages.
 */
function tmgmt_language_combination_languages_predefined_list() {
  $predefined = &drupal_static(__FUNCTION__);

  if (!isset($predefined)) {
    include_once DRUPAL_ROOT . '/includes/iso.inc';
    $predefined = _locale_get_predefined_list();

    foreach ($predefined as $key => $value) {

      // Include native name in output, if possible
      if (count($value) > 1) {
        $tname = t($value[0]);
        $predefined[$key] = ($tname == $value[1]) ? $tname : "$tname ($value[1])";
      }
      else {
        $predefined[$key] = t($value[0]);
      }
    }

    // Add custom languages that are not part of the iso.inc definition.
    $installed_languages = language_list();
    foreach ($installed_languages as $lang => $info) {
      if (!isset($predefined[$lang])) {
        $predefined[$lang] = $info->name;
      }
    }

    asort($predefined);
  }

  return $predefined;
}