<?php

/*
 * This file is part of Twig.
 *
 * (c) Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Twig\TokenParser;

use Twig\Error\SyntaxError;
use Twig\Node\BodyNode;
use Twig\Node\EmptyNode;
use Twig\Node\Expression\ArrayExpression;
use Twig\Node\Expression\ConstantExpression;
use Twig\Node\Expression\Unary\NegUnary;
use Twig\Node\Expression\Unary\PosUnary;
use Twig\Node\Expression\Variable\LocalVariable;
use Twig\Node\MacroNode;
use Twig\Node\Node;
use Twig\Token;

/**
 * Defines a macro.
 *
 *   {% macro input(name, value, type, size) %}
 *      <input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
 *   {% endmacro %}
 *
 * @internal
 */
final class MacroTokenParser extends AbstractTokenParser
{
    public function parse(Token $token): Node
    {
        $lineno = $token->getLine();
        $stream = $this->parser->getStream();
        $name = $stream->expect(Token::NAME_TYPE)->getValue();
        $arguments = $this->parseDefinition();

        $stream->expect(Token::BLOCK_END_TYPE);
        $this->parser->pushLocalScope();
        $body = $this->parser->subparse($this->decideBlockEnd(...), true);
        if ($token = $stream->nextIf(Token::NAME_TYPE)) {
            $value = $token->getValue();

            if ($value != $name) {
                throw new SyntaxError(\sprintf('Expected endmacro for macro "%s" (but "%s" given).', $name, $value), $stream->getCurrent()->getLine(), $stream->getSourceContext());
            }
        }
        $this->parser->popLocalScope();
        $stream->expect(Token::BLOCK_END_TYPE);

        $this->parser->setMacro($name, new MacroNode($name, new BodyNode([$body]), $arguments, $lineno));

        return new EmptyNode($lineno);
    }

    public function decideBlockEnd(Token $token): bool
    {
        return $token->test('endmacro');
    }

    public function getTag(): string
    {
        return 'macro';
    }

    private function parseDefinition(): ArrayExpression
    {
        $arguments = new ArrayExpression([], $this->parser->getCurrentToken()->getLine());
        $stream = $this->parser->getStream();
        $stream->expect(Token::OPERATOR_TYPE, '(', 'A list of arguments must begin with an opening parenthesis');
        while (!$stream->test(Token::PUNCTUATION_TYPE, ')')) {
            if (\count($arguments)) {
                $stream->expect(Token::PUNCTUATION_TYPE, ',', 'Arguments must be separated by a comma');

                // if the comma above was a trailing comma, early exit the argument parse loop
                if ($stream->test(Token::PUNCTUATION_TYPE, ')')) {
                    break;
                }
            }

            $token = $stream->expect(Token::NAME_TYPE, null, 'An argument must be a name');
            $name = new LocalVariable($token->getValue(), $this->parser->getCurrentToken()->getLine());
            if ($token = $stream->nextIf(Token::OPERATOR_TYPE, '=')) {
                $default = $this->parser->parseExpression();
            } else {
                $default = new ConstantExpression(null, $this->parser->getCurrentToken()->getLine());
                $default->setAttribute('is_implicit', true);
            }

            if (!$this->checkConstantExpression($default)) {
                throw new SyntaxError('A default value for an argument must be a constant (a boolean, a string, a number, a sequence, or a mapping).', $token->getLine(), $stream->getSourceContext());
            }
            $arguments->addElement($default, $name);
        }
        $stream->expect(Token::PUNCTUATION_TYPE, ')', 'A list of arguments must be closed by a parenthesis');

        return $arguments;
    }

    // checks that the node only contains "constant" elements
    private function checkConstantExpression(Node $node): bool
    {
        if (!($node instanceof ConstantExpression || $node instanceof ArrayExpression
            || $node instanceof NegUnary || $node instanceof PosUnary
        )) {
            return false;
        }

        foreach ($node as $n) {
            if (!$this->checkConstantExpression($n)) {
                return false;
            }
        }

        return true;
    }
}
