<?php

/**
 * @file
 * Test module for Drupal which get a page.
 */

/**
 * Implements hook_menu().
 */
function pv_test_cache_menu() {
  $items = array();
  $items['testcache'] = array(
    'title' => 'Test cache',
    'description' => 'Test Cache',
    'page callback' => 'pv_test_cache_content',
    'access callback' => TRUE,
    'type' => MENU_NORMAL_ITEM,
    'menu_name' => 'main-menu',
  );
  return $items;
}

/**
 * Provide data to template.
 */
function pv_test_cache_content() {
  $content = "<h1> User First Name: " . pv_test_cache_check_cache() . "</h1>";
  return $content;
}

/**
 * Function which look at cache.
 */
function pv_test_cache_check_cache() {
  $user_first_name_from_cache = cache_get('pv_test_cache');
  $user_first_name_from_db = get_user_first_name();
  if ($user_first_name_from_cache && $user_first_name_from_cache->data == $user_first_name_from_db) {
    return $user_first_name_from_cache->data;
  }
  else {
    cache_clear_all('pv_test_cache', 'cache', TRUE);
    cache_set('pv_test_cache', $user_first_name_from_db, 'cache');
    return $user_first_name_from_db;
  }
}

/**
 * Function which take User First Name from db.
 */
function get_user_first_name() {
  global $user;
  $query = db_select('field_data_field_account_first_name', 'fdfafn');
  $query->fields('fdfafn', array('field_account_first_name_value'));
  $query->condition('fdfafn.entity_id', $user->uid);
  $first_name = $query->execute()->fetchAll();
  return $first_name[0]->field_account_first_name_value;
}