class HttpDownloader

class HttpDownloader {
    private const STATUS_QUEUED = 1;
    private const STATUS_STARTED = 2;
    private const STATUS_COMPLETED = 3;
    private const STATUS_FAILED = 4;
    private const STATUS_ABORTED = 5;
    
    /** @var IOInterface */
    private $io;
    
    /** @var Config */
    private $config;
    
    /** @var array<Job> */
    private $jobs = [];
    
    /** @var mixed[] */
    private $options = [];
    
    /** @var int */
    private $runningJobs = 0;
    
    /** @var int */
    private $maxJobs = 12;
    
    /** @var ?CurlDownloader */
    private $curl;
    
    /** @var ?RemoteFilesystem */
    private $rfs;
    
    /** @var int */
    private $idGen = 0;
    
    /** @var bool */
    private $disabled;
    
    /** @var bool */
    private $allowAsync = false;
    
    /**
     * @param IOInterface $io         The IO instance
     * @param Config      $config     The config
     * @param mixed[]     $options    The options
     */
    public function __construct(IOInterface $io, Config $config, array $options = [], bool $disableTls = false) {
        $this->io = $io;
        $this->disabled = (bool) Platform::getEnv('COMPOSER_DISABLE_NETWORK');
        // Setup TLS options
        // The cafile option can be set via config.json
        if ($disableTls === false) {
            $this->options = StreamContextFactory::getTlsDefaults($options, $io);
        }
        // handle the other externally set options normally.
        $this->options = array_replace_recursive($this->options, $options);
        $this->config = $config;
        if (self::isCurlEnabled()) {
            $this->curl = new CurlDownloader($io, $config, $options, $disableTls);
        }
        $this->rfs = new RemoteFilesystem($io, $config, $options, $disableTls);
        if (is_numeric($maxJobs = Platform::getEnv('COMPOSER_MAX_PARALLEL_HTTP'))) {
            $this->maxJobs = max(1, min(50, (int) $maxJobs));
        }
    }
    
    /**
     * Download a file synchronously
     *
     * @param  string             $url     URL to download
     * @param  mixed[]            $options Stream context options e.g. https://www.php.net/manual/en/context.http.php
     *                                     although not all options are supported when using the default curl downloader
     * @throws TransportException
     * @return Response
     */
    public function get(string $url, array $options = []) {
        if ('' === $url) {
            throw new \InvalidArgumentException('$url must not be an empty string');
        }
        [
            $job,
            $promise,
        ] = $this->addJob([
            'url' => $url,
            'options' => $options,
            'copyTo' => null,
        ], true);
        $promise->then(null, function (\Throwable $e) {
            // suppress error as it is rethrown to the caller by getResponse() a few lines below
        });
        $this->wait($job['id']);
        $response = $this->getResponse($job['id']);
        return $response;
    }
    
    /**
     * Create an async download operation
     *
     * @param  string             $url     URL to download
     * @param  mixed[]            $options Stream context options e.g. https://www.php.net/manual/en/context.http.php
     *                                     although not all options are supported when using the default curl downloader
     * @throws TransportException
     * @return PromiseInterface
     * @phpstan-return PromiseInterface<Http\Response>
     */
    public function add(string $url, array $options = []) {
        if ('' === $url) {
            throw new \InvalidArgumentException('$url must not be an empty string');
        }
        [
            ,
            $promise,
        ] = $this->addJob([
            'url' => $url,
            'options' => $options,
            'copyTo' => null,
        ]);
        return $promise;
    }
    
    /**
     * Copy a file synchronously
     *
     * @param  string             $url     URL to download
     * @param  string             $to      Path to copy to
     * @param  mixed[]            $options Stream context options e.g. https://www.php.net/manual/en/context.http.php
     *                                     although not all options are supported when using the default curl downloader
     * @throws TransportException
     * @return Response
     */
    public function copy(string $url, string $to, array $options = []) {
        if ('' === $url) {
            throw new \InvalidArgumentException('$url must not be an empty string');
        }
        [
            $job,
        ] = $this->addJob([
            'url' => $url,
            'options' => $options,
            'copyTo' => $to,
        ], true);
        $this->wait($job['id']);
        return $this->getResponse($job['id']);
    }
    
    /**
     * Create an async copy operation
     *
     * @param  string             $url     URL to download
     * @param  string             $to      Path to copy to
     * @param  mixed[]            $options Stream context options e.g. https://www.php.net/manual/en/context.http.php
     *                                     although not all options are supported when using the default curl downloader
     * @throws TransportException
     * @return PromiseInterface
     * @phpstan-return PromiseInterface<Http\Response>
     */
    public function addCopy(string $url, string $to, array $options = []) {
        if ('' === $url) {
            throw new \InvalidArgumentException('$url must not be an empty string');
        }
        [
            ,
            $promise,
        ] = $this->addJob([
            'url' => $url,
            'options' => $options,
            'copyTo' => $to,
        ]);
        return $promise;
    }
    
    /**
     * Retrieve the options set in the constructor
     *
     * @return mixed[] Options
     */
    public function getOptions() {
        return $this->options;
    }
    
    /**
     * Merges new options
     *
     * @param  mixed[] $options
     * @return void
     */
    public function setOptions(array $options) {
        $this->options = array_replace_recursive($this->options, $options);
    }
    
    /**
     * @phpstan-param Request $request
     * @return array{Job, PromiseInterface}
     * @phpstan-return array{Job, PromiseInterface<Http\Response>}
     */
    private function addJob(array $request, bool $sync = false) : array {
        $request['options'] = array_replace_recursive($this->options, $request['options']);
        
        /** @var Job */
        $job = [
            'id' => $this->idGen++,
            'status' => self::STATUS_QUEUED,
            'request' => $request,
            'sync' => $sync,
            'origin' => Url::getOrigin($this->config, $request['url']),
        ];
        if (!$sync && !$this->allowAsync) {
            throw new \LogicException('You must use the HttpDownloader instance which is part of a Composer\\Loop instance to be able to run async http requests');
        }
        // capture username/password from URL if there is one
        if (Preg::isMatchStrictGroups('{^https?://([^:/]+):([^@/]+)@([^/]+)}i', $request['url'], $match)) {
            $this->io
                ->setAuthentication($job['origin'], rawurldecode($match[1]), rawurldecode($match[2]));
        }
        $rfs = $this->rfs;
        if ($this->canUseCurl($job)) {
            $resolver = static function ($resolve, $reject) use (&$job) : void {
                $job['status'] = HttpDownloader::STATUS_QUEUED;
                $job['resolve'] = $resolve;
                $job['reject'] = $reject;
            };
        }
        else {
            $resolver = static function ($resolve, $reject) use (&$job, $rfs) : void {
                // start job
                $url = $job['request']['url'];
                $options = $job['request']['options'];
                $job['status'] = HttpDownloader::STATUS_STARTED;
                if ($job['request']['copyTo']) {
                    $rfs->copy($job['origin'], $url, $job['request']['copyTo'], false, $options);
                    $headers = $rfs->getLastHeaders();
                    $response = new Http\Response($job['request'], $rfs->findStatusCode($headers), $headers, $job['request']['copyTo'] . '~');
                    $resolve($response);
                }
                else {
                    $body = $rfs->getContents($job['origin'], $url, false, $options);
                    $headers = $rfs->getLastHeaders();
                    $response = new Http\Response($job['request'], $rfs->findStatusCode($headers), $headers, $body);
                    $resolve($response);
                }
            };
        }
        $curl = $this->curl;
        $canceler = static function () use (&$job, $curl) : void {
            if ($job['status'] === HttpDownloader::STATUS_QUEUED) {
                $job['status'] = HttpDownloader::STATUS_ABORTED;
            }
            if ($job['status'] !== HttpDownloader::STATUS_STARTED) {
                return;
            }
            $job['status'] = HttpDownloader::STATUS_ABORTED;
            if (isset($job['curl_id'])) {
                $curl->abortRequest($job['curl_id']);
            }
            throw new IrrecoverableDownloadException('Download of ' . Url::sanitize($job['request']['url']) . ' canceled');
        };
        $promise = new Promise($resolver, $canceler);
        $promise = $promise->then(function ($response) use (&$job) {
            $job['status'] = HttpDownloader::STATUS_COMPLETED;
            $job['response'] = $response;
            $this->markJobDone();
            return $response;
        }, function ($e) use (&$job) : void {
            $job['status'] = HttpDownloader::STATUS_FAILED;
            $job['exception'] = $e;
            $this->markJobDone();
            throw $e;
        });
        $this->jobs[$job['id']] =& $job;
        if ($this->runningJobs < $this->maxJobs) {
            $this->startJob($job['id']);
        }
        return [
            $job,
            $promise,
        ];
    }
    private function startJob(int $id) : void {
        $job =& $this->jobs[$id];
        if ($job['status'] !== self::STATUS_QUEUED) {
            return;
        }
        // start job
        $job['status'] = self::STATUS_STARTED;
        $this->runningJobs++;
        assert(isset($job['resolve']));
        assert(isset($job['reject']));
        $resolve = $job['resolve'];
        $reject = $job['reject'];
        $url = $job['request']['url'];
        $options = $job['request']['options'];
        $origin = $job['origin'];
        if ($this->disabled) {
            if (isset($job['request']['options']['http']['header']) && false !== stripos(implode('', $job['request']['options']['http']['header']), 'if-modified-since')) {
                $resolve(new Response([
                    'url' => $url,
                ], 304, [], ''));
            }
            else {
                $e = new TransportException('Network disabled, request canceled: ' . Url::sanitize($url), 499);
                $e->setStatusCode(499);
                $reject($e);
            }
            return;
        }
        try {
            if ($job['request']['copyTo']) {
                $job['curl_id'] = $this->curl
                    ->download($resolve, $reject, $origin, $url, $options, $job['request']['copyTo']);
            }
            else {
                $job['curl_id'] = $this->curl
                    ->download($resolve, $reject, $origin, $url, $options);
            }
        } catch (\Exception $exception) {
            $reject($exception);
        }
    }
    private function markJobDone() : void {
        $this->runningJobs--;
    }
    
    /**
     * Wait for current async download jobs to complete
     *
     * @param int|null $index For internal use only, the job id
     *
     * @return void
     */
    public function wait(?int $index = null) {
        do {
            $jobCount = $this->countActiveJobs($index);
        } while ($jobCount);
    }
    
    /**
     * @internal
     */
    public function enableAsync() : void {
        $this->allowAsync = true;
    }
    
    /**
     * @internal
     *
     * @param  int|null $index For internal use only, the job id
     * @return int      number of active (queued or started) jobs
     */
    public function countActiveJobs(?int $index = null) : int {
        if ($this->runningJobs < $this->maxJobs) {
            foreach ($this->jobs as $job) {
                if ($job['status'] === self::STATUS_QUEUED && $this->runningJobs < $this->maxJobs) {
                    $this->startJob($job['id']);
                }
            }
        }
        if ($this->curl) {
            $this->curl
                ->tick();
        }
        if (null !== $index) {
            return $this->jobs[$index]['status'] < self::STATUS_COMPLETED ? 1 : 0;
        }
        $active = 0;
        foreach ($this->jobs as $job) {
            if ($job['status'] < self::STATUS_COMPLETED) {
                $active++;
            }
            elseif (!$job['sync']) {
                unset($this->jobs[$job['id']]);
            }
        }
        return $active;
    }
    
    /**
     * @param  int $index Job id
     */
    private function getResponse(int $index) : Response {
        if (!isset($this->jobs[$index])) {
            throw new \LogicException('Invalid request id');
        }
        if ($this->jobs[$index]['status'] === self::STATUS_FAILED) {
            assert(isset($this->jobs[$index]['exception']));
            throw $this->jobs[$index]['exception'];
        }
        if (!isset($this->jobs[$index]['response'])) {
            throw new \LogicException('Response not available yet, call wait() first');
        }
        $resp = $this->jobs[$index]['response'];
        unset($this->jobs[$index]);
        return $resp;
    }
    
    /**
     * @internal
     *
     * @param  array{warning?: string, info?: string, warning-versions?: string, info-versions?: string, warnings?: array<array{versions: string, message: string}>, infos?: array<array{versions: string, message: string}>} $data
     */
    public static function outputWarnings(IOInterface $io, string $url, $data) : void {
        $cleanMessage = static function ($msg) use ($io) {
            if (!$io->isDecorated()) {
                $msg = Preg::replace('{' . chr(27) . '\\[[;\\d]*m}u', '', $msg);
            }
            return $msg;
        };
        // legacy warning/info keys
        foreach ([
            'warning',
            'info',
        ] as $type) {
            if (empty($data[$type])) {
                continue;
            }
            if (!empty($data[$type . '-versions'])) {
                $versionParser = new VersionParser();
                $constraint = $versionParser->parseConstraints($data[$type . '-versions']);
                $composer = new Constraint('==', $versionParser->normalize(Composer::getVersion()));
                if (!$constraint->matches($composer)) {
                    continue;
                }
            }
            $io->writeError('<' . $type . '>' . ucfirst($type) . ' from ' . Url::sanitize($url) . ': ' . $cleanMessage($data[$type]) . '</' . $type . '>');
        }
        // modern Composer 2.2+ format with support for multiple warning/info messages
        foreach ([
            'warnings',
            'infos',
        ] as $key) {
            if (empty($data[$key])) {
                continue;
            }
            $versionParser = new VersionParser();
            foreach ($data[$key] as $spec) {
                $type = substr($key, 0, -1);
                $constraint = $versionParser->parseConstraints($spec['versions']);
                $composer = new Constraint('==', $versionParser->normalize(Composer::getVersion()));
                if (!$constraint->matches($composer)) {
                    continue;
                }
                $io->writeError('<' . $type . '>' . ucfirst($type) . ' from ' . Url::sanitize($url) . ': ' . $cleanMessage($spec['message']) . '</' . $type . '>');
            }
        }
    }
    
    /**
     * @internal
     *
     * @return ?string[]
     */
    public static function getExceptionHints(\Throwable $e) : ?array {
        if (!$e instanceof TransportException) {
            return null;
        }
        if (false !== strpos($e->getMessage(), 'Resolving timed out') || false !== strpos($e->getMessage(), 'Could not resolve host')) {
            Silencer::suppress();
            $testConnectivity = file_get_contents('https://8.8.8.8', false, stream_context_create([
                'ssl' => [
                    'verify_peer' => false,
                ],
                'http' => [
                    'follow_location' => false,
                    'ignore_errors' => true,
                ],
            ]));
            Silencer::restore();
            if (false !== $testConnectivity) {
                return [
                    '<error>The following exception probably indicates you have misconfigured DNS resolver(s)</error>',
                ];
            }
            return [
                '<error>The following exception probably indicates you are offline or have misconfigured DNS resolver(s)</error>',
            ];
        }
        return null;
    }
    
    /**
     * @param  Job  $job
     */
    private function canUseCurl(array $job) : bool {
        if (!$this->curl) {
            return false;
        }
        if (!Preg::isMatch('{^https?://}i', $job['request']['url'])) {
            return false;
        }
        if (!empty($job['request']['options']['ssl']['allow_self_signed'])) {
            return false;
        }
        return true;
    }
    
    /**
     * @internal
     */
    public static function isCurlEnabled() : bool {
        return \extension_loaded('curl') && \function_exists('curl_multi_exec') && \function_exists('curl_multi_init');
    }

}