<?php
class http
{
  /** Choose the best choice from user choices.
      Can be used for languages (HTTP_ACCEPT_LANGUAGE), type of pages 
      (HTTP_ACCEPT)...
      Ex. fr, en-gb;q=0.8, en;q=0.7
      Ex. text/html,application/xhtml+xml,application/xml;q=0.9,* /*;q=0.8
      If available is empty, then return the best priority defined by user,
      and throw an exception if nothing is provided for by the user.
      If nothing match, return $default
    */
  function bestChoice ($uservar, $available=array(), $default=FALSE)
  {
    $uservar = str_replace (" ", "", $uservar);
    $userchoices = explode (",", $uservar);
    if (!isset ($userchoices[0]))
    {
      if ($default === FALSE)
        throw new Exception ("No user choice provided to bestChoice", 500);
      return $default;
    }
    // Remove weights (provided by the order of the user)
    // TODO : Reorganise the order if the weights are not in the right order
    foreach ($userchoices as $key=>$val)
    {
      $vals = @explode (";q", $val);
      $userchoices[$key] = $vals[0];
    }

    if (count ($available) === 0)
      return $userchoices[0];

    // Look at the best existing solution
    foreach ($userchoices as $choice)
    {
      foreach ($available as $avail)
      {
        if (strtolower ($avail) === strtolower ($choice))
          return $avail;
        // Case en_US
        $availTmp = str_replace ("_", "-", $avail);
        if (strtolower ($availTmp) === strtolower ($choice))
          return $avail;
        // Case text/xml, application/csv (just compare xml or csv)
        $mimes = explode ("/", $choice);
        if (isset ($mimes[1]) && strtolower ($availTmp) === $mimes[1])
          return $avail;
      }
    }

    // No best solution found. Use the default available solution
    return $default;
  }
}