<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\Exception\ConstraintDefinitionException;

/**
 * A constraint that is composed of other constraints.
 *
 * You should never use the nested constraint instances anywhere else, because
 * their groups are adapted when passed to the constructor of this class.
 *
 * If you want to create your own composite constraint, extend this class and
 * let {@link getCompositeOption()} return the name of the property which
 * contains the nested constraints.
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
abstract class Composite extends Constraint
{
    /**
     * {@inheritdoc}
     *
     * The groups of the composite and its nested constraints are made
     * consistent using the following strategy:
     *
     *   - If groups are passed explicitly to the composite constraint, but
     *     not to the nested constraints, the options of the composite
     *     constraint are copied to the nested constraints;
     *
     *   - If groups are passed explicitly to the nested constraints, but not
     *     to the composite constraint, the groups of all nested constraints
     *     are merged and used as groups for the composite constraint;
     *
     *   - If groups are passed explicitly to both the composite and its nested
     *     constraints, the groups of the nested constraints must be a subset
     *     of the groups of the composite constraint. If not, a
     *     {@link ConstraintDefinitionException} is thrown.
     *
     * All this is done in the constructor, because constraints can then be
     * cached. When constraints are loaded from the cache, no more group
     * checks need to be done.
     */
    public function __construct($options = null)
    {
        parent::__construct($options);

        $this->initializeNestedConstraints();

        /* @var Constraint[] $nestedConstraints */
        $compositeOption = $this->getCompositeOption();
        $nestedConstraints = $this->$compositeOption;

        if (!is_array($nestedConstraints)) {
            $nestedConstraints = array($nestedConstraints);
        }

        foreach ($nestedConstraints as $constraint) {
            if (!$constraint instanceof Constraint) {
                throw new ConstraintDefinitionException(sprintf('The value %s is not an instance of Constraint in constraint %s', $constraint, get_class($this)));
            }

            if ($constraint instanceof Valid) {
                throw new ConstraintDefinitionException(sprintf('The constraint Valid cannot be nested inside constraint %s. You can only declare the Valid constraint directly on a field or method.', get_class($this)));
            }
        }

        if (!property_exists($this, 'groups')) {
            $mergedGroups = array();

            foreach ($nestedConstraints as $constraint) {
                foreach ($constraint->groups as $group) {
                    $mergedGroups[$group] = true;
                }
            }

            $this->groups = array_keys($mergedGroups);
            $this->$compositeOption = $nestedConstraints;

            return;
        }

        foreach ($nestedConstraints as $constraint) {
            if (property_exists($constraint, 'groups')) {
                $excessGroups = array_diff($constraint->groups, $this->groups);

                if (count($excessGroups) > 0) {
                    throw new ConstraintDefinitionException(sprintf(
                        'The group(s) "%s" passed to the constraint %s '.
                        'should also be passed to its containing constraint %s',
                        implode('", "', $excessGroups),
                        get_class($constraint),
                        get_class($this)
                    ));
                }
            } else {
                $constraint->groups = $this->groups;
            }
        }

        $this->$compositeOption = $nestedConstraints;
    }

    /**
     * {@inheritdoc}
     *
     * Implicit group names are forwarded to nested constraints.
     *
     * @param string $group
     */
    public function addImplicitGroupName($group)
    {
        parent::addImplicitGroupName($group);

        /** @var Constraint[] $nestedConstraints */
        $nestedConstraints = $this->{$this->getCompositeOption()};

        foreach ($nestedConstraints as $constraint) {
            $constraint->addImplicitGroupName($group);
        }
    }

    /**
     * Returns the name of the property that contains the nested constraints.
     *
     * @return string The property name
     */
    abstract protected function getCompositeOption();

    /**
     * Initializes the nested constraints.
     *
     * This method can be overwritten in subclasses to clean up the nested
     * constraints passed to the constructor.
     *
     * @see Collection::initializeNestedConstraints()
     */
    protected function initializeNestedConstraints()
    {
    }
}
