<?php
namespace metagen_go;
use Exception;

function get_twig(array $inc_path = [])
{
  array_unshift($inc_path, __DIR__ . "/../tpl/");
  $loader = new \Twig\Loader\FilesystemLoader($inc_path);

  $twig = new \Twig\Environment($loader, [
    'debug' => true, 
    'autoescape' => false, 
    'strict_variables' => true]
  );
  $twig->addExtension(new \Twig\Extension\DebugExtension());

  _add_twig_support($twig);

  return $twig;
}

function supported_tokens()
{
  return [
    'POD',
    'default',
    'optional',
    'bitfields',
    'cloneable',
    'virtual',

    'table',
    'id',
    'owner',
    'pkey',

    'statist',
    'statist_skip',
  ];
}

function _add_twig_support(\Twig\Environment $twig)
{
  $twig->addTest(new \Twig\TwigTest('instanceof', 
    function($obj, $class) 
    { 
      return (new \ReflectionClass($class))->isInstance($obj);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('Error', 
    function($e) 
    {
      throw new Exception($e);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('has_token', 
    function($o, $token) 
    { 
      return $o->hasToken($token);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('has_token_in_parent', 
    function($o, $token) 
    { 
      return $o->hasTokenInParent($token);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('token', 
    function($o, $name) 
    {
      return $o->getToken($name);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('token_or', 
    function($o, $name, $v) 
    {
      if($o->hasToken($name))
        return $o->getToken($name);
      else
        return $v;
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('get_all_fields', 
    function($meta, $o) 
    {
      return \mtg_get_all_fields($meta, $o);
    }
  ));
  $twig->addFunction(new \Twig\TwigFunction('count_optional', 
    function($units) 
    {
      $opts = 0;
      foreach($units as $u)
        if($u->hasToken('optional'))
          ++$opts;
      return $opts;
    }
  ));
  $twig->addFilter(new \Twig\TwigFilter('go_type', 
    function($type, $tokens) 
    {
      return go_type($type, $tokens);
    }
  ));
  $twig->addFilter(new \Twig\TwigFilter('ucfirst', 
    function($str) 
    {
      return ucfirst($str);
    }
  ));
}

function go_type(\mtgType $type, array $tokens = array())
{
  if($type instanceof \mtgArrType)
  {
    $vtype = $type->getValue();

    $native = go_type($vtype);

    $str = "[]";
    if(array_key_exists("virtual", $tokens))
      $str .= "I";
    else
      $str .= $vtype instanceof mtgMetaStruct ? "*" : "";

    $str .= $native;

    return $str;
  }
  else if($type instanceof \mtgBuiltinType)
  {
    if($type->isFloat())
      return "float32";
    else if($type->isDouble())
      return "float64";
    else if($type->isBlob())
      return "[]byte";
    else
      return $type->getName();
  }
  else if($type instanceof \mtgMetaEnum)
    return $type->getName();
  else if($type instanceof \mtgMetaStruct)
  {
    if(array_key_exists("virtual", $tokens))
      return "I{$type->getName()}";
    else
      return $type->getName();
  }
  else
    throw new Exception("Unknown type '$type'");
}