<?php

/**
 * Check if the password given at login is correct.
 *
 * @param $password :string
 *   the plaintext password as typed by the user
 * @param $password_in_db_serialized :string
 *   the serialized string that is stored in the database
 * @return :bool
 *   true, if the pw is correct.
 */
function check_pass($password, $password_in_db_serialized) {
  $password_in_db = unserialize($password_in_db_serialized);
  $salt = $password_in_db['salt'];
  $password_hashed = custom_password_hash($salt . $password, $password_in_db['hash_function']);
  return ($password_hashed == $password_in_db['password_hashed']);
}

/**
 * Generate the serialized string that is stored in the database.
 * This is called whenever someone changes the password.
 * 
 * @param password :string
 *   the password as typed by the user.
 * @return :string
 *   the serialized string to be stored in the database.
 */
function generate_db_pass($password) {
  $salt = _mesportmod_band_generate_random_salt();
  return serialize(array(
    'salt' => $salt,
    'password_hashed' => custom_password_hash($salt . $password),
  ));
}

/**
 * utility function to generate random strings
 */
function generate_random_salt($length = 32, $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890') {
  
  // Length of character list
  $rand_max = strlen($chars) - 1;
  
  // Start our string
  $salt = $chars{rand(0, $chars_length)}; 
  
  // Generate random string
  for ($i = 1; $i < $length; $i = strlen($salt)) {
    
    // Grab a random character from our list
    $r = $chars{mt_rand(0, $rand_max)};
    
    // Make sure the same two characters don't appear next to each other
    if ($r != $salt{$i - 1}) {
      $salt .= $r;
    }
  }
  
  return $salt;
}


/**
 * this can be defined in sites/%/settings.php
 */
function custom_password_hash($unhashed, $hash_function = NULL) {
  static $system_salt = 'l0ajcpoaioaöjp897zvqn7';
  switch ($hash_function) {
    // case 'myhashfunction':
    //   ... (implement your own hashing)
    default:
      // TODO: add key strengthening with blowfish, if available.
      return sha256($unhashed . $system_salt);
  }
}