<?php
define('CITETHISPAGE_DEFAULT_WARN_LOGGED', 'Please note that you are currently logged in. The snapshot will use the <em>anonymous</em> version of the page.');

/**
 * Implements hook_menu().
 */
function citethispage_menu(){
  $items = array();
  // Admin items
  $items['admin/config/services/citethispage'] = array(
    'title' => 'Cite this page',
    'description' => 'Configure the services available to cite pages',
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'citethispage_settings_form'
    ),
    'file' => 'citethispage.admin.inc',
    'access callback' => 'user_access',
    'access arguments' => array(
      'citethispage_admin'
    )
  );
  // Also provide this as a local task, so other modules can easily provide their own
  // settings pages.
  $items['admin/config/services/citethispage/main'] = $items['admin/config/services/citethispage'];
  $items['admin/config/services/citethispage/main']['type'] = MENU_DEFAULT_LOCAL_TASK;
  return $items;
}

/**
 * Implements hook_permission
 */
function citethispage_permission(){
  return array(
    'citethispage_admin' => array(
      'title' => t('Administer Cite this Page module')
    ),
    'citethispage_cite' => array(
      'title' => t('Use the Cite this Page module')
    )
  );
}

/**
 * Implements hook_theme()
 */
function citethispage_theme($existing, $type, $theme, $path){
  $items = array();
  $items['citethispage_info'] = array(
    'variables' => array(
      'results' => array()
    ),
    'function' => 'theme_citethispage_info',
    'path' => drupal_get_path('module', 'citethispage') . '/theme',
    'file' => 'citethispage.theme.inc'
  );
  $items['citethispage_table_drag'] = array(
    'render element' => 'element',
    'file' => 'citethispage.theme.inc',
    'path' => drupal_get_path('module', 'citethispage') . '/theme',
    'function' => 'theme_citethispage_table_drag'
  );
  return $items;
}

/**
 * Implements hook_block_info
 */
function citethispage_block_info(){
  $items = array();
  $items['citethispage_block'] = array(
    'info' => t('Cite this page block'),
    'cache' => DRUPAL_NO_CACHE
  );
  return $items;
}

/**
 * Implements hook_block_view
 *
 * This only adds a stub - the actual rendering
 * is done in hook_page_alter because parsers
 * may need to wait for other blocks to be rendered
 * in order to gather data (eg. gathering authors
 * from views using hook_views_post_execute)
 * and we can't control block rendering order.
 */
function citethispage_block_view($delta = ''){
  // Permission check
  if(!user_access('citethispage_cite')){return;}

  // Check that anonymous users have access to the node
  $node = menu_get_object();
  if (isset($node->nid)) {
    if (!node_access('view', $node, drupal_anonymous_user())) {
      return;
    }
  }

  return array(
    'subject' => t('Cite this page'),
    'content' => array(
      'citethispage_info' => array(
        '#markup' => 'Stub. If altered, ensure key citethispage_info remains so it can be replaced'
      ),
      'form' => drupal_get_form('citethispage_backend_selection_form')
    )
  );
}

/**
 * Implement hook_page_alter
 *
 * We do the final block rendering here so that we are sure to run after all other
 * elements have been rendered
 */
function citethispage_page_alter(&$page){
  foreach(element_children($page) as $region){
    if(is_array($page[$region]) && isset($page[$region]['citethispage_citethispage_block'])){
      $results = _citethispage_parse_path(current_path(), $page);
      citethispage_store_parse_result(current_path(), $results);
      if($results === FALSE && !variable_get('citethispage_showall', 0)){
        unset($page[$region]['citethispage_citethispage_block']);
      }else{
        $content = array(
          '#theme' => 'citethispage_info',
          '#results' => $results
        );
        // We allow other modules to alter the block's structure, just as long as
        // we can replace the stub it's fine.
        $parents = _citethispage_find_nested_parents('citethispage_info', $page[$region]['citethispage_citethispage_block']);
        if(is_array($parents)){
          $parents[] = 'citethispage_info';
          array_unshift($parents, 'citethispage_citethispage_block');
          array_unshift($parents, $region);
          drupal_array_set_nested_value($page, $parents, $content);
        }
      }
    }
  }
}

/**
 * _citethispage_find_nested_parents
 *
 * Helper function to find nested parents in an array
 *
 */
function _citethispage_find_nested_parents($key, $array){
  if(isset($array[$key])){
    return array();
  }else{
    foreach($array as $k => $v){
      if(is_array($v)){
        $f = _citethispage_find_nested_parents($key, $v);
        if(is_array($f)){
          array_unshift($f, $k);
          return $f;
        }
      }
    }
    return FALSE;
  }
}

/**
 * citethispage_backend_selection_form
 * 
 * Form to select a backend
 */
function citethispage_backend_selection_form($form, &$form_state){
  $handlers = _citethispage_get_archive_handlers();
  $backends = array();
  foreach($handlers as $module => $module_info){
    $backends[$module] = $module_info['title'];
  }
  $backend_modules = array_keys($backends);
  $default = isset($form_state['values']['backend']) ? $form_state['values']['backend'] : reset($backend_modules);
  if(count($backend_modules) == 0){
    return;
  }else if(count($backend_modules) == 1){
    $form['backend'] = array(
      '#type' => 'value',
      '#value' => $default
    );
  }else{
    $form['backend'] = array(
      '#type' => 'select',
      '#title' => t('Service to create citation'),
      '#description' => t('Select which service to use to create a permanent snapshot of the page that can be used for citations.'),
      '#options' => $backends,
      '#required' => TRUE,
      '#default_value' => $default,
      '#ajax' => array(
        'callback' => 'citethispage_backend_selection_form_ajax',
        'wrapper' => 'citethispage_subform',
        'method' => 'replace',
        'effect' => 'fade'
      )
    );
    $form['info'] = array(
      '#prefix' => '<div id="citethispage_subform">',
      '#suffix' => '</div>',
      '#markup' => '<span class="citethispage_select_info_title">' . $handlers[$default]['title'] . '</span>: ' . $handlers[$default]['description']
    );
  }
  $form_state['citethispage_backend_handler'] = $default;
  $form['cite'] = array(
    '#type' => 'submit',
    '#value' => t('Create Citation')
  );
  global $user;
  $warn_default = variable_get('citethispage_warn_logged', array(
    'value' => CITETHISPAGE_DEFAULT_WARN_LOGGED,
    'format' => 'filtered_html'
  ));
  if($user->uid > 0 && $warn_default['value']){
    $form['warn'] = array(
      '#type' => 'markup',
      '#markup' => '<div>' . check_markup($warn_default['value'], $warn_default['format']) . '</div>'
    );
  }
  $form['path'] = array(
    '#type' => 'value',
    '#value' => isset($form_state['values']['path']) ? $form_state['values']['path'] : current_path()
  );
  $form['requested_path'] = array(
    '#type' => 'value',
    '#value' => isset($form_state['values']['requested_path']) ? $form_state['values']['requested_path'] : $_SERVER['REQUEST_URI']
  );
  $form['#attached']['css'] = array(
    drupal_get_path('module', 'citethispage') . '/theme/citethispage.css'
  );
  return $form;
}

/**
 * citethispage_backend_selection_form_ajax
 */
function citethispage_backend_selection_form_ajax($form, &$form_state){
  return $form['info'];
}

/**
 * citethispage_backend_selection_form_validate
 */
function citethispage_backend_selection_form_validate($form, &$form_state){
  $backend = $form_state['values']['backend'];
  $info = module_invoke($backend, 'citethispage_info');
  if(!$info || empty($info[$backend]['archive']['callback'])){
    form_set_error('backend', t('This service does not define archiving facilities'));
  }
  $form_state['citethispage_info'] = $info[$backend]['archive'];
}

/**
 * citethispage_backend_selection_form_submit
 */
function citethispage_backend_selection_form_submit($form, &$form_state){
  $path = $form_state['values']['path'];
  $results = citethispage_get_parse_result($path);
  $context = array(
    'results' => $results,
    'form_state' => $form_state
  );
  $function = $form_state['citethispage_info']['callback'];
  $function($path, $context);
  global $user;
  if($user->uid == 0){
    // Add a query string to ensure the result page is not cached.
    $form_state['redirect'] = array(
      $_GET['q'],
      array(
        'query' => array(
          'citethispage' => substr(md5(rand()), 0, 5)
        )
      )
    );
  }
}

/**
 * citethispage_store_parse_result
 *
 * Store the result of the parsing of the given path, for the give user
 * (or the current one if none is given).
 *
 * This will overwrite any previous value.
 */
function citethispage_store_parse_result($path, $results, $uid = NULL){
  global $user;
  if($uid === NULL){
    $uid = $user->uid;
  }
  $data = array(
    'path' => $path,
    'uid' => $uid,
    'results' => serialize($results)
  );
  $q = db_select('citethispage', 'c');
  $q->addField('c', 'sid', 's');
  $sid = $q->condition('path', $path)->condition('uid', $uid)->execute()->fetchField();
  if ($sid){
    db_update('citethispage')->condition('sid', $sid)->fields($data)->execute();
  } else {
    db_insert('citethispage')->fields(array_keys($data), array_values($data))->execute();
  }
}

/**
 * citethispage_get_parse_result
 *
 * Get the result of the last parse for the given path and user (or current
 * user if none is given).
 *
 * Returns an empty array if no parse was run for that path/user.
 */
function citethispage_get_parse_result($path, $uid = NULL){
  global $user;
  if($uid === NULL){
    $uid = $user->uid;
  }
  $q = db_select('citethispage', 'c');
  $q->addField('c', 'results', 'r');
  $r = $q->condition('c.uid', $uid)->condition('c.path', $path)->execute()->fetchField();
  if(!$r){
    return array();
  }else{
    return unserialize($r);
  }
}

/**
 * function _citethispage_find_parsers
 * 
 * Return an array of description of parsers
 * that can handle the given path.
 * 
 * This is ordered such that default parsers are last.
 */
function _citethispage_find_parsers($path){
  $parsers = array();
  $default_parsers = array();
  $handlers = _citethispage_get_parse_handlers();
  foreach($handlers as $path_pattern => $modules){
    $re = '^' . preg_replace('/%\w*/', '[^\/\?]+', preg_quote($path_pattern, '/')) . '$';
    if(preg_match("/$re/", $path)){
      foreach($modules as $module => $module_info){
        if($module_info['default']){
          $default_parsers[] = $module_info;
        }else{
          $parsers[] = $module_info;
        }
      }
    }
  }
  return array_merge($parsers, $default_parsers);
}

/**
 * _citethispage_parse_path
 *
 * Returns the result provided by the parsers that
 * can parse the given path
 */
function _citethispage_parse_path($path, $page){
  // Find all the parsers than can handle this page
  $parsers = _citethispage_find_parsers($path);
  // Get the parsed info
  $results = FALSE;
  foreach($parsers as $parser_info){
    if(empty($parser_info['callback'])){
      continue;
    }
    if($results !== FALSE && !empty($parser_info['default'])){
      break;
    }
    $function = $parser_info['callback'];
    $r = $function($path, $page);
    if($r !== FALSE){
      if($results === FALSE){
        $results = $r;
      }else{
        $results = array_merge_recursive($results, $r);
      }
    }
  }
  drupal_alter('citethispage_parse', $results);
  return $results;
}

/**
 * _citethispage_get_archive_handlers
 *
 * Returns the list of module implement archiving backends
 * as an array of module name to archive definition.
 *
 * If $all is TRUE, then this also returns the handlers
 * that have been disabled in the configuration.
 *
 * The handlers are ordered as per the configuration, and
 * the status items 'enabled' and 'weight' are added to the
 * returned definitions
 */
function _citethispage_get_archive_handlers($all = FALSE){
  $handlers = module_invoke_all('citethispage_info');
  $archive_handlers = array();
  $archive_handlers_status = variable_get('citethispage_archive_handlers', array());
  foreach($handlers as $module => $module_info){
    if(empty($module_info['archive'])){
      continue;
    }
    if(isset($archive_handlers_status[$module])){
      $status = $archive_handlers_status[$module];
    }else{
      $status = array(
        'enabled' => TRUE,
        'weight' => 0
      );
    }
    if(!$all && !$status['enabled']){
      continue;
    }
    $archive_handlers[$module] = $status['weight'];
  }
  asort($archive_handlers);
  $result = array();
  foreach(array_keys($archive_handlers) as $module){
    $result[$module] = $handlers[$module]['archive'];
    if(isset($archive_handlers_status[$module])){
      $result[$module]['enabled'] = $archive_handlers_status[$module]['enabled'];
      $result[$module]['weight'] = $archive_handlers_status[$module]['weight'];
    }else{
      $result[$module]['enabled'] = TRUE;
      $result[$module]['weight'] = 0;
    }
  }
  return $result;
}

/**
 * _citethispage_get_archive_handlers
 *
 * Returns the list of module implement parse handlers
 * as an array of path patterns to an array of module name 
 * to parse definition.
 *
 * If $all is TRUE, then this also returns the handlers
 * that have been disabled in the configuration.
 *
 * The handlers are ordered as per the configuration, and
 * the status items 'enabled', 'weight' and 'default'
 * are added to the returned definitions
 */
function _citethispage_get_parse_handlers($all = FALSE){
  $handlers = module_invoke_all('citethispage_info');
  $parse_handlers = array();
  $handler_status = variable_get('citethispage_parse_handlers', array());
  foreach($handlers as $module => $module_info){
    if(empty($module_info['parse'])){
      continue;
    }
    foreach($module_info['parse'] as $path => $parse_info){
      if(isset($handler_status[$path][$module])){
        $status = $handler_status[$path][$module];
      }else{
        $status = array(
          'enabled' => TRUE,
          'default' => FALSE,
          'weight' => 0
        );
      }
      if(!$all && !$status['enabled']){
        continue;
      }
      $parse_handlers[$path][$module] = $status['weight'];
    }
  }
  foreach($parse_handlers as $path => $modules){
    asort($modules);
    $parse_handlers[$path] = $modules;
  }
  $result = array();
  foreach($parse_handlers as $path => $modules){
    foreach(array_keys($modules) as $module){
      $result[$path][$module] = $handlers[$module]['parse'][$path];
      if(isset($handler_status[$path][$module])){
        $result[$path][$module]['enabled'] = $handler_status[$path][$module]['enabled'];
        $result[$path][$module]['weight'] = $handler_status[$path][$module]['weight'];
        $result[$path][$module]['default'] = $handler_status[$path][$module]['default'];
      }else{
        $result[$path][$module]['enabled'] = TRUE;
        $result[$path][$module]['weight'] = 0;
        $result[$path][$module]['default'] = FALSE;
      }
    }
  }
  return $result;
}