<?php
/**
 * Copyright 2018 Kacper Donat
 *
 * @author Kacper "Kadet" Donat <kacper@kadet.net>
 *
 * Full license available in separate LICENSE file
 */

namespace Kadet\Functional;

use Kadet\Functional\Utils\CurriedFunction;
use Kadet\Functional\Utils\FixedFunction;
use Kadet\Functional\Utils\FunctionPipeline;
use Kadet\Functional\Utils\PartiallyAppliedFunction;

function partial(callable $callable, ...$args): PartiallyAppliedFunction
{
    return new PartiallyAppliedFunction($callable, ...$args);
}

function apply(callable $callable, ...$args)
{
    $threshold = reflect($callable)->getNumberOfRequiredParameters();

    return count($args) >= $threshold
        ? $callable(...$args)
        : partial($callable, ...$args);
}

function curry(callable $callable, int $threshold = null, ...$args): CurriedFunction
{
    return new CurriedFunction($callable, $threshold, ...$args);
}

function uncurry(CurriedFunction $curried): PartiallyAppliedFunction
{
    return $curried->uncurry();
}

function pipe(...$functions)
{
    return new FunctionPipeline(...$functions);
}

function fix(callable $callable, ...$args)
{
    $f = new FixedFunction($callable);
    return $args ? apply($f, ...$args) : $f;
}