<?php

/*
 * This file is part of Pimple.
 *
 * Copyright (c) 2009 Fabien Potencier
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is furnished
 * to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * Pimple main class.
 *
 * @package pimple
 * @author  Fabien Potencier
 */
class Pimple implements ArrayAccess
{
    protected $values = array();

    /**
     * Instantiate the container.
     *
     * Objects and parameters can be passed as argument to the constructor.
     *
     * @param array $values The parameters or objects.
     */
    public function __construct (array $values = array())
    {
        $this->values = $values;
    }

    /**
     * Sets a parameter or an object.
     *
     * Objects must be defined as Closures.
     *
     * Allowing any PHP callable leads to difficult to debug problems
     * as function names (strings) are callable (creating a function with
     * the same a name as an existing parameter would break your container).
     *
     * @param string $id    The unique identifier for the parameter or object
     * @param mixed  $value The value of the parameter or a closure to defined an object
     */
    public function offsetSet($id, $value)
    {
        $this->values[$id] = $value;
    }

    /**
     * Gets a parameter or an object.
     *
     * @param string $id The unique identifier for the parameter or object
     *
     * @return mixed The value of the parameter or an object
     *
     * @throws InvalidArgumentException if the identifier is not defined
     */
    public function offsetGet($id)
    {
        if (!array_key_exists($id, $this->values)) {
            throw new InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));
        }

        $isFactory = is_object($this->values[$id]) && method_exists($this->values[$id], '__invoke');

        return $isFactory ? $this->values[$id]($this) : $this->values[$id];
    }

    /**
     * Checks if a parameter or an object is set.
     *
     * @param string $id The unique identifier for the parameter or object
     *
     * @return Boolean
     */
    public function offsetExists($id)
    {
        return array_key_exists($id, $this->values);
    }

    /**
     * Unsets a parameter or an object.
     *
     * @param string $id The unique identifier for the parameter or object
     */
    public function offsetUnset($id)
    {
        unset($this->values[$id]);
    }

    /**
     * Returns a closure that stores the result of the given closure for
     * uniqueness in the scope of this instance of Pimple.
     *
     * @param Closure $callable A closure to wrap for uniqueness
     *
     * @return Closure The wrapped closure
     */
    public static function share(Closure $callable)
    {
        return function ($c) use ($callable) {
            static $object;

            if (null === $object) {
                $object = $callable($c);
            }

            return $object;
        };
    }

    /**
     * Protects a callable from being interpreted as a service.
     *
     * This is useful when you want to store a callable as a parameter.
     *
     * @param Closure $callable A closure to protect from being evaluated
     *
     * @return Closure The protected closure
     */
    public static function protect(Closure $callable)
    {
        return function ($c) use ($callable) {
            return $callable;
        };
    }

    /**
     * Gets a parameter or the closure defining an object.
     *
     * @param string $id The unique identifier for the parameter or object
     *
     * @return mixed The value of the parameter or the closure defining an object
     *
     * @throws InvalidArgumentException if the identifier is not defined
     */
    public function raw($id)
    {
        if (!array_key_exists($id, $this->values)) {
            throw new InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));
        }

        return $this->values[$id];
    }

    /**
     * Extends an object definition.
     *
     * Useful when you want to extend an existing object definition,
     * without necessarily loading that object.
     *
     * @param string  $id       The unique identifier for the object
     * @param Closure $callable A closure to extend the original
     *
     * @return Closure The wrapped closure
     *
     * @throws InvalidArgumentException if the identifier is not defined
     */
    public function extend($id, Closure $callable)
    {
        if (!array_key_exists($id, $this->values)) {
            throw new InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));
        }

        $factory = $this->values[$id];

        if (!($factory instanceof Closure)) {
            throw new InvalidArgumentException(sprintf('Identifier "%s" does not contain an object definition.', $id));
        }

        return $this->values[$id] = function ($c) use ($callable, $factory) {
            return $callable($factory($c), $c);
        };
    }

    /**
     * Returns all defined value names.
     *
     * @return array An array of value names
     */
    public function keys()
    {
        return array_keys($this->values);
    }
}