<?php

/** @see FLY_Func_Interface */
require_once 'FLY/Func/Interface.php';


/**
 * This class can be used to register and call global functions.
 *
 * @package FLY
 * @subpackage Func
 * @author Yves Feupi Lepatio
 */
class FLY_Func_Function implements FLY_Func_Interface
{
    /**
     * The reflection function.
     * @var ReflectionFunction
     */
    protected $_reflectionFunction = null;

    /**
     * getReflectionFunction()
     *
     * @return ReflectionFunction
     */
    public function getReflectionFunction()
    {
        return $this->_reflectionFunction;
    }

    /**
     * Constructor
     *
     * @param string $functionName
     * @return void
     * @throws FLY_Func_FunctionNotFoundException
     */
    public function __construct($functionName)
    {
        if ( ! function_exists($functionName))
        {
            /** @see FLY_Func_FunctionNotFoundException */
            require_once 'FLY/Func/FunctionNotFoundException.php';
            throw new FLY_Func_FunctionNotFoundException(
                'The function `' . $functionName . '()` is not found');
        }

        $this->_reflectionFunction = new ReflectionFunction($functionName);
    }

    /**
     * @see FLY_Func_Interface::invoke()
     */
    public function invoke()
    {
        $params     = func_get_args();
        $evalParams = '';

        for ($i = 0, $length = func_num_args(); $i < $length; $i++)
        {
            $evalParams .= '$params[' . $i . '], ';
        }
        $evalParams = substr($evalParams, 0, -2);

        return (($evalParams == '')
                ? $this->_reflectionFunction->invoke()
                : $this->_reflectionFunction->invoke(eval('return ' . $evalParams . ';')));
    }
}