<?php
// $Id$

/**
 * @file
 * The core of the SEO Checker.
 *
 * This file contains the hook_menu implementation such as the different
 * functions that hook into the process of node creation and modification
 * in order to perform the checks based on the implemented rules.
 *
 * The SEO Checker requires at least one submodule that defines SEO rules and
 * implements the checks for them. The core module comes along with two
 * submodules that implement some basic checks.
 *
 * In order to implement your own rules, implement hook_register_seo_rules().
 */

require_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'seo_checker') . '/inc/seo_checker.admin.inc';
require_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'seo_checker') . '/inc/seo_checker.theme.inc';

/**
 * Implements hook_menu().
 *
 * @return array
 */
function seo_checker_menu() {
  $items['admin/config/content/seo_checker'] = array(
    'title' => 'SEO Checker',
    'description' => 'Manage SEO Checker',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('seo_checker_settings'),
    'access arguments' => array('administer seo_checker configuration'),
    'type' => MENU_NORMAL_ITEM,
  );
  $items['admin/config/content/seo_checker/thresholds'] = array(
    'title' => 'SEO Rule Thresholds',
    'description' => 'Set the tresholds for the different SEO rules.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('seo_checker_settings'),
    'access arguments' => array('administer seo_checker configuration'),
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -1,
  );
  return $items;
}

function seo_checker_node_validate($node, $form, &$form_state) {
  if (variable_get('seo_checker_' . $form['type']['#value'], 0) != 0) {
    seo_checker_perform_checks($node, $form);
  }
}

/**
 * Get the threshold of a rule. Pass the rule array and the ID.
 */
function seo_checker_get_rule_threshold($rule, $rid) {
  $threshold = variable_get('seo_threshold_' . $rid, !empty($rule['default threshold'])?$rule['default threshold']:array(1000, 100));
  if (!is_array($threshold)) {
    $threshold = array($threshold, 100);
  }
  return $threshold;
}

/**
 * This is the main seo checker function. It checks the submitted node
 * by applying all the rules and includes the summary to the node form.
 */
function seo_checker_perform_checks($node, $form) {
  global $user;

  /* overall status */
  $checks_passed = TRUE;

  /* the results will be prepended to the node_preview block */
  $results = array();

  /* loop over all the rules and apply them to the form_values */
  $rules = module_invoke_all('register_seo_rules');
  foreach ($rules as $rid => $rule) {
    if (!function_exists($rule['callback'])) {
      drupal_set_message(sprintf(t('The function <i>%s()</i> for seo_checker rule <b>%s</b> was not found.'), $rule['callback'], check_plain($rule['name'])), 'error');
      continue;
    }

    /* threshold == 0 implies that this rule is disabled. */
    if (($threshold = seo_checker_get_rule_threshold($rule, $rid)) == array(0, 100)) {
      continue;
    }
    $threshold_text = '';
    if ($threshold[1] == 100) {
      $threshold_text = '&ge;&nbsp;' . $threshold[0] . '%';
    }
    else {
      $threshold_text = '&#8712;&nbsp;[' . $threshold[0] . '%,' . $threshold[1] . '%]';
    }

    /* here we apply the rules to the values. It should return an integer result or FALSE if not applicable. */
    $arguments = isset($rule['callback arguments']) ? $rule['callback arguments'] : array();
    array_unshift($arguments, $form);
    $check_result = call_user_func_array($rule['callback'], $arguments);
    if ($check_result === FALSE) {
      /* skip this rule */
      continue;
    }
    $check_result = round($check_result);

    /* check if the submitted node has passed the test. */
    $passed = $check_result >= $threshold[0] && $check_result <= $threshold[1] ? 'passed' : 'failed';
    $data = array(
      'rule' => check_plain($rule['name']),
      'message' => $rule[$passed . ' feedback'],
      'achieved' => $check_result . '%',
      'required' => $threshold_text,
      'passed' => '<img src="' . file_create_url(drupal_get_path('module', 'seo_checker') . '/img/' . $passed) . '.gif" alt="' . $passed . '" />',
    );

    /* append the results to the array and update the overall status variable */
    $results[] = array(
      'data' => $data,
      'class' => array('seo_checker_result_' . $passed),
    );
    $checks_passed &= ($check_result >= $threshold[0] && $check_result <= $threshold[1]);
  }

  /* append the check results just before the title field */
  $seo_check_results = array(
    '#type' => 'seo_check_results',
    '#title' => t('SEO Check Results'),
    '#results' => $results,
  );

  $message = drupal_render($seo_check_results);

  if (!$checks_passed && (!user_access('allow seo check failures', $user))) {
    form_set_error('check_results', t('The SEO compliance check was not successful. Check the table and modify your content as required.'));
    drupal_set_message($message);
  }
  else {
    /* throw an error if failures are not allowed */
    $check_policy = variable_get('seo_checker_allow_failures', 'show-preview-only');
    switch ($check_policy) {
      case 'show-always':
        drupal_set_message($message);
        break;
      case 'show-preview-only':
        if ($node->op == 'Preview') {
          drupal_set_message($message);
        }
    }
  }
}

/**
 * The SEO Checker has to be enabled per content type
 */
function seo_checker_form_node_type_form_alter(&$form, $form_status) {
  if (!isset($form['seo_checker'])) {
    $form['seo_checker'] = array(
      '#type' => 'fieldset',
      '#title' => t('SEO Complicance Checker'),
      '#collapsible' => TRUE,
      '#collapsed' => TRUE,
      '#weight' => 1,
      "#group" => "additional_settings",
    );
  }
  $form['seo_checker']['seo_checker'] = array(
    '#type' => 'checkbox',
    '#title' => t('Enable SEO checking'),
    '#default_value' => variable_get('seo_checker_' . $form['#node_type']->type, 0),
    '#description' => t('Check this box to enable SEO checking for this node type.'),
  );
}


/********************************** HELPERS **********************************/

/**
 * Find position of first occurrence of a case-insensitive WORD
 * @return int
 * @param array $haystack
 * @param string $needle
 */
function seo_checker_wordipos($haystack, $needle, $offset=0) {
  $pos = -1;
  $found = FALSE;
  while ($found === FALSE) {
    $pos = stripos($haystack, $needle, $offset);
    if ($pos === FALSE) {
      return FALSE;
    }

    /* check if the characters before and after the found tag are non-word characters */
    $expanded_string = (isset($haystack[$pos-1]) ? $haystack[$pos-1] :' ') . (isset($haystack[$pos+strlen($needle)]) ? $haystack[$pos+strlen($needle)] : ' ');
    if (preg_match_all('/[\W_]/', $expanded_string, $null) == 2) {
      $found = TRUE;
    }
    $offset = $pos+1;
  }
  return $pos;
}
