<?php
namespace metagen_go;

use Exception;
use Twig\{TwigTest, TwigFilter, TwigFunction};

function get_twig(array $inc_path = []): \Twig\Environment
{
  array_unshift($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_tests($twig);
  add_twig_filters($twig);
  add_twig_functions($twig);

  return $twig;
}

function supported_tokens()
{
  return [
    'table',
    'table_pkey',
    'table_json_kv',
    'db_skip',

    'data_root',
    'bitfields',
    'diffable',
    'diff_removed',

    'alias',
    'default',
    'virtual',

    'statist',
    'statist_skip',
    'statist_alias',
  ];
}

function add_twig_tests(\Twig\Environment $twig)
{
  $twig->addTest(new TwigTest(
    'metaenum',
    fn(\mtgMetaInfoUnit $u): bool => $u->object instanceof \mtgMetaEnum,
  ));
  $twig->addTest(new TwigTest(
    'metastruct',
    fn(\mtgMetaInfoUnit $u): bool => $u->object instanceof \mtgMetaStruct,
  ));
  $twig->addTest(new TwigTest(
    'metarpc',
    fn(\mtgMetaInfoUnit $u): bool => $u->object instanceof \mtgMetaRPC,
  ));
  $twig->addTest(new TwigTest(
    'enum',
    fn(\mtgType $t): bool => $t instanceof \mtgMetaEnum,
  ));
  $twig->addTest(new TwigTest(
    'struct',
    fn(\mtgType $t): bool => $t instanceof \mtgMetaStruct,
  ));
  $twig->addTest(new TwigTest(
    'array',
    fn(\mtgType $t): bool => $t instanceof \mtgArrType,
  ));
  $twig->addTest(new TwigTest(
    'builtin',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType,
  ));
  $twig->addTest(new TwigTest(
    'numeric',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isNumeric(),
  ));
  $twig->addTest(new TwigTest(
    'int',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isInt(),
  ));
  $twig->addTest(new TwigTest(
    'uint',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isUint(),
  ));
  $twig->addTest(new TwigTest(
    'bool',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isBool(),
  ));
  $twig->addTest(new TwigTest(
    'float',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isFloat(),
  ));
  $twig->addTest(new TwigTest(
    'double',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isDouble(),
  ));
  $twig->addTest(new TwigTest(
    'string',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isString(),
  ));
  $twig->addTest(new TwigTest(
    'blob',
    fn(\mtgType $t): bool => $t instanceof \mtgBuiltinType && $t->isBlob(),
  ));

  $twig->addTest(new TwigTest(
    'instanceof',
    fn($obj, $class): bool => (new \ReflectionClass($class))->isInstance($obj),
  ));
}

function add_twig_filters(\Twig\Environment $twig)
{
  $twig->addFilter(new TwigFilter(
    'go_type',
    fn(\mtgType $t): string => go_type($t),
  ));
  $twig->addFilter(new TwigFilter(
    'ucfirst',
    fn(string $str): string => ucfirst($str),
  ));
  $twig->addFilter(new TwigFilter(
    'lcfirst',
    fn(string $str): string => lcfirst($str),
  ));
  $twig->addFilter(new TwigFilter(
    'camel',
    fn(string $str): string => snake2camel($str),
  ));
  $twig->addFilter(new TwigFilter(
    'quote',
    fn(string $str, string $char = '`'): string => "{$char}{$str}{$char}"
  ));
  $twig->addFilter(new TwigFilter(
    'sql_where',
    function(array $fields): string {
      $exprs = [];
      foreach ($fields as $field) {
        $fieldName = $field->getName();
        $exprs[] = "`{$fieldName}` = ?";
      }
      return implode(' AND ', $exprs);
    }
  ));
  $twig->addFilter(new TwigFilter(
    'alias', 
    function(\mtgMetaField $field): string {
      if ($field->hasToken('alias')) {
        return $field->getToken('alias');
      }
      return $field->getName();
    }
  ));
  $twig->addFilter(new TwigFilter(
    'fname', 
    fn(\mtgMetaField $field): string => snake2camel($field->getName())
  ));
  $twig->addFilter(new TwigFilter(
    'varname', 
    fn(\mtgMetaField $field): string => lcfirst(snake2camel($field->getName()))
  ));  
  $twig->addFilter(new TwigFilter(
    'tname', 
    fn(\mtgMetaField $field): string => $field->getType() instanceof \mtgArrType ? $field->getType()->getValue()->getName() : $field->getType()->getName()
  ));
  $twig->addFilter(new TwigFilter(
    'builtin_type_suffix', 
    fn (\mtgBuiltinType $type): string => builtin_type_method_suffix($type),
  ));
  $twig->addFilter(new TwigFilter(
    'default_val', 
    fn(\mtgMetaField $field) => default_value($field)
  ));
  $twig->addFilter(new TwigFilter(
    'fields', 
    function (\mtgMetaField $field): array {
      $type = $field->getType();
      if($type instanceof \mtgArrType)
      {
        $type = $type->getValue();
      }
      return $type->getFields();
    }
  ));
  $twig->addFilter(new TwigFilter(
    'pk_fields', 
    function (\mtgMetaField $field): array {
      $type = $field->getType();
      if($type instanceof \mtgArrType)
      {
        $type = $type->getValue();
      }
      $pkey = explode(',', $type->getToken('table_pkey'));
      $fields = [];
      foreach ($pkey as $fieldName) {
        $fields[] = $type->getField($fieldName);
      }
      return $fields;
    }
  ));

  $twig->addFilter(new TwigFilter(
    'rpc_invert',
    fn(string $name): string => rpc_invert($name),
  ));
}

function add_twig_functions(\Twig\Environment $twig)
{
  $twig->addFunction(new TwigFunction(
    'Error',
    function(string $e) {
      throw new Exception($e);
    }
  ));
  $twig->addFunction(new TwigFunction(
    'has_token',
    fn($o, string $token): bool => $o->hasToken($token),
  ));
  $twig->addFunction(new TwigFunction(
    'has_token_in_parent',
    fn(\mtgMetaStruct $s, string $token): bool => $s->hasTokenInParent($token),
  ));
  $twig->addFunction(new TwigFunction(
    'token',
    fn($o, string $name) => $o->getToken($name),
  ));
  $twig->addFunction(new TwigFunction(
    'token_or',
    fn($o, string $name, $v) => $o->hasToken($name) ? $o->getToken($name) : $v,
  ));
  $twig->addFunction(new TwigFunction(
    'get_all_fields',
    fn(\mtgMetaStruct $s): array => \mtg_get_all_fields($s),
  ));
  $twig->addFunction(new TwigFunction(
    'arr_fill', 
    fn($value, int $count): array => array_fill(0, $count, $value)
  ));
  $twig->addFunction(new TwigFunction(
    'table_pkey', 
    function(\mtgMetaStruct $struct): array {
      $pkey = explode(',', $struct->getToken('table_pkey'));
      $fields = [];
      foreach ($pkey as $fieldName) {
        $fields[] = $struct->getField($fieldName);
      }
      return $fields;
    }
  ));
  $twig->addFunction(new TwigFunction(
    'table_fields', 
    function(\mtgMetaStruct $struct): array {
      $pkey = explode(',', $struct->getToken('table_pkey'));
      return array_filter(
        $struct->getFields(),
        fn(\mtgMetaField $field): bool => !in_array($field->getName(), $pkey),
      );
    }
  ));
  $twig->addFunction(new TwigFunction(
    'meta_field', 
    function (string $str) use ($twig): \mtgMetaField {
      $meta = $twig->getGlobals()['meta'];
      return parse_meta_field($str, $meta);
    }
  ));

  $twig->addFunction(new TwigFunction('field_reset', 
    function($name, $type, $tokens)
    {
      return field_reset($name, $type, $tokens);
    }
  ));
  $twig->addFunction(new TwigFunction('buf2var', 
    function($name, $fname, $type, $buf, $tokens, $is_ptr)
    {
      return buf2var($name, $fname, $type, $buf, $tokens, $is_ptr);
    }
  ));
  $twig->addFunction(new TwigFunction('var2buf', 
    function($name, $fname, $type, $buf, $tokens, $is_ptr)
    {
      return var2buf($name, $fname, $type, $buf, $tokens, $is_ptr);
    }
  ));
}

function snake2camel(string $str): string
{
  return str_replace('_', '', ucwords($str, '_'));
}

function go_type(\mtgType $type, array $tokens = []): string
{
  if($type instanceof \mtgMetaEnum)
    return $type->getName();
  else if($type instanceof \mtgMetaStruct)
    return $type->getName();
  else if($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 \mtgArrType) 
  {
    $native = go_type($type->getValue());
    return "[]$native";
  } 
  else
    throw new Exception("Unknown type '{$type->getName()}'");
}

function builtin_type_method_suffix(\mtgBuiltinType $type): string
{
  if($type->isBlob())
    return 'Bytes';
  
  return ucfirst(go_type($type));
}

function default_value(\mtgMetaField $field)
{
  $type = $field->getType();
  $tokens = $field->getTokens();
  $default = $field->getToken('default');

  if($type instanceof \mtgBuiltinType) 
  {
    if($type->isNumeric())
      return $default ?? 0;
    else if($type->isString())
      return $default ?? '""';
    else if($type->isBool())
      return $default ?? 'false';
    else if($type->isBlob())
    {
      if($default == 'null')
        $default = 'nil';
      
      return $default ?? 'nil';
    } 
    else
      throw new Exception("Unknown type '$type'");
    
  } 
  else if($type instanceof \mtgMetaEnum)
    return $default ? go_type($type, $tokens)."_".trim($tokens['default'], '"') : 0;
  else
    throw new Exception("Unknown type '$type'");
}

function parse_meta_field(string $str, \mtgMetaInfo $meta): \mtgMetaField
{
  list($name, $type) = explode('|', $str);
  return new \mtgMetaField($name, new \mtgTypeRef(new \mtgBuiltinType($type)));
}

function builtin_type_prefix(\mtgBuiltinType $type)
{
  switch($type->getName())
  {
  case "string":
    return "String";
  case "bool":
    return "Bool";
  case "blob":
    return "Blob";
  case "float":
    return "Float";
  case "double":
    return "Double";
  case "uint64":
    return "U64";
  case "int64":
    return "I64";
  case "uint":
  case "uint32":
    return "U32";
  case "uint16":
    return "U16";
  case "uint8":
    return "U8";
  case "int":
  case "int32":
    return "I32";
  case "int16":
    return "I16";
  case "int8":
    return "I8";
  default:
    throw new Exception("Unknown type '{$type}'");
  }
}

function field_reset($name, \mtgType $type, array $tokens)
{
  $str = '';

  if($type instanceof \mtgBuiltinType)
  {
    if($type->isNumeric())
    {
      if(array_key_exists('default', $tokens) && is_numeric($tokens['default']))
        $str .= "self.$name = ".$tokens['default'];
      else
        $str .= " self.$name = 0";
    }
    else if($type->isString())
    {
      if(array_key_exists('default', $tokens))
        $str .= "self.$name = ".$tokens['default'];
      else
        $str .= "self.$name = \"\"";
    }
    else if($type->isBool())
    {
      if(array_key_exists('default', $tokens))
        $str .= "self.$name = ".$tokens['default'];
      else
        $str .= "self.$name = false";
    }
    else if($type->isBlob())
    {
      if(array_key_exists('default', $tokens))
        $str .= "self.$name = ".$tokens['default'];
      else
        $str .= "self.$name = nil";
    }
    else
      throw new Exception("Unknown type '$type'");
  }
  else if($type instanceof \mtgArrType)
  {
    $str = "if self.$name == nil { \nself.$name = make(".go_type($type, $tokens).",0) \n}\n ";
    $str .= "self.$name = self.{$name}[0:0]";
  }
  else if($type instanceof \mtgMetaEnum)
  {
    if(array_key_exists('default', $tokens))
      $str = "self.$name = ".go_type($type, $tokens)."_".trim($tokens['default'], '"');
    else
      $str = "self.$name = 0";
  }
  else if($type instanceof \mtgMetaStruct)
  {
    $is_virtual = array_key_exists("virtual", $tokens);
    if($is_virtual)
      $str .= "self.$name = New".ltrim(go_type($type, $tokens),'I')."() ";
    else
      $str .= "self.$name.Reset()";
  }
  else
    throw new Exception("Unknown type '{$type->getName()}'");
  return $str;
}

function buf2var($name, $fname, \mtgType $type, $buf, array $tokens = array(), $is_ptr = false)
{
  $str = '';

  if($type instanceof \mtgBuiltinType)
  {
    $str .= _read_op($tokens, $buf.'.Read'.builtin_type_prefix($type).'(&'.$fname.', "'.$name.'")');
  }
  else if($type instanceof \mtgMetaEnum)
  {
    $str .= _read_op($tokens, "{$buf}.ReadI32((*int32)(&{$fname}), \"$name\")");
    $str .= "\n  if !{$fname}.IsValid() { return errors.Errorf(\"Bad enum value %d for $name\", $fname) }";
  }
  else if($type instanceof \mtgMetaStruct)
  {
    if(array_key_exists('virtual', $tokens))
      $str .= "if v, err := meta.ReadStructGeneric($buf, CreateById, \"{$name}\"); err != nil { return err } else { {$fname} = v.(I{$type}) }";
    else
      $str .= _read_op($tokens, "meta.ReadStruct($buf, ".($is_ptr?"":"&")."$fname, \"$name\")");
  }
  else if($type instanceof \mtgArrType)
  {
    $is_virtual = array_key_exists("virtual", $tokens);
    $native_type = go_type($type->getValue(), $tokens);
    $offset = "\n  ";
    $str .= "/*[]{$name}*/";
    $str .= $offset . _read_op($tokens, "{$buf}.BeginContainer(\"$name\")");
    $str .= $offset . "_{$name}_size, err := {$buf}.GetContainerSize()";
    $str .= $offset . "if err != nil { return err }";

    $need_new = !$is_virtual && $type->getValue() instanceof \mtgMetaStruct;

    $str .= $offset . "for ; _{$name}_size > 0; _{$name}_size-- {";
    $offset = "\n    ";
    $str .= $offset . "var tmp_{$name} {$native_type}";

    $str .= $offset . buf2var("", "tmp_{$name}", $type->getValue(), $buf, $tokens, $is_virtual);
    $str .= $offset . "{$fname} = append({$fname}, tmp_{$name})";

    $offset = "\n  ";
    $str .= $offset . "}";
    $str .= $offset .  _read_op($tokens, "{$buf}.EndContainer()");
    $str .= "\n";
  }
  else
    throw new Exception("Unknown type '{$type->getName()}'");

  return $str;
}

function var2buf($name, $fname, \mtgType $type, $buf, array $tokens = array(), $is_ptr = false)
{
  $str = '';

  if($type instanceof \mtgBuiltinType)
  {
    $str .= _write_op("{$buf}.Write".builtin_type_prefix($type)."($fname, \"$name\")")."\n";
  }
  else if($type instanceof \mtgMetaEnum)
  {
    $str .= _write_op("{$buf}.WriteI32(int32($fname), \"$name\")");
  }
  else if($type instanceof \mtgMetaStruct)
  {
    if(array_key_exists('virtual', $tokens))
      $str .= _write_op("meta.WriteStructGeneric($buf, ".($is_ptr?"":"&")."$fname, \"$name\")");
    else
      $str .= _write_op("meta.WriteStruct($buf, &$fname, \"$name\")");
  }
  else if($type instanceof \mtgArrType)
  {
    $str .= "{$buf}.BeginContainer(\"{$name}\")\n";
    $str .= "  for _, v := range({$fname}) {\n";
    $str .= "    ".var2buf("", "v", $type->getValue(), $buf, $tokens, true)."\n";
    $str .= "  }\n";
    $str .= "  "._write_op("{$buf}.EndContainer()")."\n";
  }
  else
    throw new Exception("Unknown type '{$type->getName()}'");

  return $str;
}

function _write_op($op)
{
  return "if err := $op; err != nil { return err }";
}

function _read_op(array $tokens, $op)
{
  return "if err := $op; err != nil { return err }";
}

function rpc_invert($name)
{
 if(strpos($name, '_RSP_') !== false)
   return str_replace('_RSP_', '_REQ_', $name);
 else
   return str_replace('_REQ_', '_RSP_', $name);
}