<?php

declare(strict_types=1);

/*
 * This file is part of PHP CS Fixer.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

namespace PhpCsFixer;

use Composer\Semver\Semver;
use Symfony\Component\Filesystem\Exception\IOException;

/**
 * @author Dariusz Rumiński <dariusz.ruminski@gmail.com>
 *
 * @internal
 *
 * @no-named-arguments Parameter names are not covered by the backward compatibility promise.
 */
final class ComposerJsonReader
{
    private const COMPOSER_FILENAME = 'composer.json';

    private bool $isProcessed = false;

    private ?string $php = null;

    private ?string $phpUnit = null;

    public static function createSingleton(): self
    {
        static $instance = null;

        if (!$instance) {
            $instance = new self();
        }

        return $instance;
    }

    public function getPhp(): ?string
    {
        $this->processFile();

        return $this->php;
    }

    public function getPhpUnit(): ?string
    {
        $this->processFile();

        return $this->phpUnit;
    }

    private function processFile(): void
    {
        if (true === $this->isProcessed) {
            return;
        }

        if (!file_exists(self::COMPOSER_FILENAME)) {
            throw new IOException(\sprintf('Failed to read file "%s".', self::COMPOSER_FILENAME));
        }

        $readResult = file_get_contents(self::COMPOSER_FILENAME);
        if (false === $readResult) {
            throw new IOException(\sprintf('Failed to read file "%s".', self::COMPOSER_FILENAME));
        }

        $this->processJson($readResult);
    }

    private function processJson(string $json): void
    {
        if (true === $this->isProcessed) {
            return;
        }

        $composerJson = json_decode($json, true, 512, \JSON_THROW_ON_ERROR);

        $this->php = self::getMinSemVer(self::detectPhp($composerJson));
        $this->phpUnit = self::getMinSemVer(self::detectPackage($composerJson, 'phpunit/phpunit'));

        $this->isProcessed = true;
    }

    private static function getMinSemVer(?string $version): ?string
    {
        if ('' === $version || null === $version) {
            return null;
        }

        /** @var non-empty-list<string> $arr */
        $arr = Preg::split('/\s*\|\|?\s*/', $version);

        $arr = array_map(static function ($v) {
            $v = ltrim($v, '^~>=');

            $space = strpos($v, ' ');
            if (false !== $space) {
                $v = substr($v, 0, $space);
            }

            return $v;
        }, $arr);

        $textVersion = array_find($arr, static fn ($v) => true === Preg::match('/^\D/', $v));

        if (null !== $textVersion) {
            return null;
        }

        /** @var non-empty-list<string> $sortedArr */
        $sortedArr = Semver::sort($arr);

        $min = $sortedArr[0];
        $parts = explode('.', $min);

        return \sprintf('%s.%s', (int) $parts[0], (int) ($parts[1] ?? 0));
    }

    /**
     * @param array<string, mixed> $composerJson
     */
    private static function detectPhp(array $composerJson): ?string
    {
        $version = [];

        if (isset($composerJson['config']['platform']['php'])) {
            $version[] = $composerJson['config']['platform']['php'];
        }

        if (isset($composerJson['require-dev']['php'])) {
            $version[] = $composerJson['require-dev']['php'];
        }

        if (isset($composerJson['require']['php'])) {
            $version[] = $composerJson['require']['php'];
        }

        if (\count($version) > 0) {
            return implode(' || ', $version);
        }

        return null;
    }

    /**
     * @param array<string, mixed> $composerJson
     * @param non-empty-string     $package
     */
    private static function detectPackage(array $composerJson, string $package): ?string
    {
        $version = [];

        if (isset($composerJson['require-dev'][$package])) {
            $version[] = $composerJson['require-dev'][$package];
        }

        if (isset($composerJson['require'][$package])) {
            $version[] = $composerJson['require'][$package];
        }

        if (\count($version) > 0) {
            return implode(' || ', $version);
        }

        return null;
    }
}
