<?php
/**
 * Copyright 2026 Kacper Donat
 *
 * @author Kacper "Kadet" Donat <kacper@kadet.net>
 *
 * Full license available in separate LICENSE file
 */

use Kadet\Functional as f;
use function Kadet\Functional\Internal\callback;
use const Kadet\Functional\_;

class CallbackTest extends \PHPUnit\Framework\TestCase
{
    public function testInternalFunctionGetsValueOnly()
    {
        $this->assertSame('a', callback(trim(...))(' a ', 'xyz'));
    }

    public function testInternalStringCallableGetsValueOnly()
    {
        $this->assertSame('A', callback('strtoupper')('a', 'key'));
    }

    public function testSingleParamClosureIsNotWrapped()
    {
        // PHP drops the key on its own: a userland closure ignores arguments past its parameters.
        $closure = fn ($v) => $v;

        $this->assertSame($closure, callback($closure));
    }

    public function testDecoratedSingleParamClosureGetsValueOnly()
    {
        $this->assertSame([1], callback(f\memoize(function ($v) { return func_get_args(); }))(1, 'k'));
    }

    public function testPipelineStartingWithInternalFunctionGetsValueOnly()
    {
        $this->assertSame('a', callback(f\pipe(trim(...)))(' a ', 'xyz'));
    }

    public function testPipelineStartingWithTwoParamClosureGetsKey()
    {
        $this->assertSame('k=v', callback(f\pipe(fn ($v, $k) => "$k=$v"))('v', 'k'));
    }

    public function testCarryAndValueOnlyForTwoParamTarget()
    {
        $this->assertSame([1, 2], callback(f\memoize(function ($c, $v) { return func_get_args(); }), 2)(1, 2, 'k'));
    }

    public function testCarryValueAndKeyForThreeParamTarget()
    {
        $this->assertSame('1+2@k', callback(fn ($c, $v, $k) => "$c+$v@$k", 2)(1, 2, 'k'));
    }

    public function testTwoParamClosureGetsKey()
    {
        $this->assertSame('k=v', callback(fn ($v, $k) => "$k=$v")('v', 'k'));
    }

    public function testVariadicClosureGetsKey()
    {
        $this->assertSame(['v', 'k'], callback(fn (...$args) => $args)('v', 'k'));
    }

    public function testPartialOfInternalFunctionDoesNotGetKey()
    {
        $this->assertSame('a', callback(f\partial(trim(...), _, 'x'))('xax', 'key'));
    }

    public function testPartialOfInternalFunctionDoesNotFillOptionalParameterWithKey()
    {
        $this->assertSame(['a', 'b'], callback(f\partial(explode(...), ','))('a,b', 0));
    }

    public function testPartialOfInternalFunctionWithoutArgumentsGetsValueOnly()
    {
        $this->assertSame('a', callback(f\partial(trim(...)))(' a ', 'k'));
    }

    public function testCompiledMemoizedInternalFunctionGetsValueOnly()
    {
        $this->assertSame('a', callback(f\compile(f\memoize(trim(...))))(' a ', 'k'));
    }

    public function testDecoratorIsCompiled()
    {
        $callback = callback(f\partial(fn ($prefix, $v, $k) => "$prefix$k=$v", '>'));

        $this->assertSame('>k=v', $callback('v', 'k'));
    }
}