class PathDownloader

class PathDownloader extends FileDownloader implements VcsCapableDownloaderInterface {
    private const STRATEGY_SYMLINK = 10;
    private const STRATEGY_MIRROR = 20;
    
    /**
     * @inheritDoc
     */
    public function download(PackageInterface $package, string $path, ?PackageInterface $prevPackage = null, bool $output = true) : PromiseInterface {
        $path = Filesystem::trimTrailingSlash($path);
        $url = $package->getDistUrl();
        if (null === $url) {
            throw new \RuntimeException('The package ' . $package->getPrettyName() . ' has no dist url configured, cannot download.');
        }
        $realUrl = realpath($url);
        if (false === $realUrl || !file_exists($realUrl) || !is_dir($realUrl)) {
            throw new \RuntimeException(sprintf('Source path "%s" is not found for package %s', $url, $package->getName()));
        }
        if (realpath($path) === $realUrl) {
            return \React\Promise\resolve(null);
        }
        if (strpos(realpath($path) . DIRECTORY_SEPARATOR, $realUrl . DIRECTORY_SEPARATOR) === 0) {
            // IMPORTANT NOTICE: If you wish to change this, don't. You are wasting your time and ours.
            //
            // Please see https://github.com/composer/composer/pull/5974 and https://github.com/composer/composer/pull/6174
            // for previous attempts that were shut down because they did not work well enough or introduced too many risks.
            throw new \RuntimeException(sprintf('Package %s cannot install to "%s" inside its source at "%s"', $package->getName(), realpath($path), $realUrl));
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function install(PackageInterface $package, string $path, bool $output = true) : PromiseInterface {
        $path = Filesystem::trimTrailingSlash($path);
        $url = $package->getDistUrl();
        if (null === $url) {
            throw new \RuntimeException('The package ' . $package->getPrettyName() . ' has no dist url configured, cannot install.');
        }
        $realUrl = realpath($url);
        if (false === $realUrl) {
            throw new \RuntimeException('Failed to realpath ' . $url);
        }
        if (realpath($path) === $realUrl) {
            if ($output) {
                $this->io
                    ->writeError("  - " . InstallOperation::format($package) . $this->getInstallOperationAppendix($package, $path));
            }
            return \React\Promise\resolve(null);
        }
        // Get the transport options with default values
        $transportOptions = $package->getTransportOptions() + [
            'relative' => true,
        ];
        [
            $currentStrategy,
            $allowedStrategies,
        ] = $this->computeAllowedStrategies($transportOptions);
        $symfonyFilesystem = new SymfonyFilesystem();
        $this->filesystem
            ->removeDirectory($path);
        if ($output) {
            $this->io
                ->writeError("  - " . InstallOperation::format($package) . ': ', false);
        }
        $isFallback = false;
        if (self::STRATEGY_SYMLINK === $currentStrategy) {
            try {
                if (Platform::isWindows()) {
                    // Implement symlinks as NTFS junctions on Windows
                    if ($output) {
                        $this->io
                            ->writeError(sprintf('Junctioning from %s', $url), false);
                    }
                    $this->filesystem
                        ->junction($realUrl, $path);
                }
                else {
                    $path = rtrim($path, "/");
                    if ($output) {
                        $this->io
                            ->writeError(sprintf('Symlinking from %s', $url), false);
                    }
                    if ($transportOptions['relative'] === true) {
                        $absolutePath = $path;
                        if (!$this->filesystem
                            ->isAbsolutePath($absolutePath)) {
                            $absolutePath = Platform::getCwd() . DIRECTORY_SEPARATOR . $path;
                        }
                        $shortestPath = $this->filesystem
                            ->findShortestPath($absolutePath, $realUrl, false, true);
                        $symfonyFilesystem->symlink($shortestPath . '/', $path);
                    }
                    else {
                        $symfonyFilesystem->symlink($realUrl . '/', $path);
                    }
                }
            } catch (IOException $e) {
                if (in_array(self::STRATEGY_MIRROR, $allowedStrategies, true)) {
                    if ($output) {
                        $this->io
                            ->writeError('');
                        $this->io
                            ->writeError('    <error>Symlink failed, fallback to use mirroring!</error>');
                    }
                    $currentStrategy = self::STRATEGY_MIRROR;
                    $isFallback = true;
                }
                else {
                    throw new \RuntimeException(sprintf('Symlink from "%s" to "%s" failed!', $realUrl, $path));
                }
            }
        }
        // Fallback if symlink failed or if symlink is not allowed for the package
        if (self::STRATEGY_MIRROR === $currentStrategy) {
            $realUrl = $this->filesystem
                ->normalizePath($realUrl);
            if ($output) {
                $this->io
                    ->writeError(sprintf('%sMirroring from %s', $isFallback ? '    ' : '', $url), false);
            }
            $iterator = new ArchivableFilesFinder($realUrl, []);
            $symfonyFilesystem->mirror($realUrl, $path, $iterator);
        }
        if ($output) {
            $this->io
                ->writeError('');
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function remove(PackageInterface $package, string $path, bool $output = true) : PromiseInterface {
        $path = Filesystem::trimTrailingSlash($path);
        
        /**
         * realpath() may resolve Windows junctions to the source path, so we'll check for a junction first
         * to prevent a false positive when checking if the dist and install paths are the same.
         * See https://bugs.php.net/bug.php?id=77639
         *
         * For junctions don't blindly rely on Filesystem::removeDirectory as it may be overzealous. If a process
         * inadvertently locks the file the removal will fail, but it would fall back to recursive delete which
         * is disastrous within a junction. So in that case we have no other real choice but to fail hard.
         */
        if (Platform::isWindows() && $this->filesystem
            ->isJunction($path)) {
            if ($output) {
                $this->io
                    ->writeError("  - " . UninstallOperation::format($package) . ", source is still present in {$path}");
            }
            if (!$this->filesystem
                ->removeJunction($path)) {
                $this->io
                    ->writeError("    <warning>Could not remove junction at " . $path . " - is another process locking it?</warning>");
                throw new \RuntimeException('Could not reliably remove junction for package ' . $package->getName());
            }
            return \React\Promise\resolve(null);
        }
        $url = $package->getDistUrl();
        if (null === $url) {
            throw new \RuntimeException('The package ' . $package->getPrettyName() . ' has no dist url configured, cannot remove.');
        }
        // ensure that the source path (dist url) is not the same as the install path, which
        // can happen when using custom installers, see https://github.com/composer/composer/pull/9116
        // not using realpath here as we do not want to resolve the symlink to the original dist url
        // it points to
        $fs = new Filesystem();
        $absPath = $fs->isAbsolutePath($path) ? $path : Platform::getCwd() . '/' . $path;
        $absDistUrl = $fs->isAbsolutePath($url) ? $url : Platform::getCwd() . '/' . $url;
        if ($fs->normalizePath($absPath) === $fs->normalizePath($absDistUrl)) {
            if ($output) {
                $this->io
                    ->writeError("  - " . UninstallOperation::format($package) . ", source is still present in {$path}");
            }
            return \React\Promise\resolve(null);
        }
        return parent::remove($package, $path, $output);
    }
    
    /**
     * @inheritDoc
     */
    public function getVcsReference(PackageInterface $package, string $path) : ?string {
        $path = Filesystem::trimTrailingSlash($path);
        $parser = new VersionParser();
        $guesser = new VersionGuesser($this->config, $this->process, $parser, $this->io);
        $dumper = new ArrayDumper();
        $packageConfig = $dumper->dump($package);
        $packageVersion = $guesser->guessVersion($packageConfig, $path);
        if ($packageVersion !== null) {
            return $packageVersion['commit'];
        }
        return null;
    }
    
    /**
     * @inheritDoc
     */
    protected function getInstallOperationAppendix(PackageInterface $package, string $path) : string {
        $url = $package->getDistUrl();
        if (null === $url) {
            throw new \RuntimeException('The package ' . $package->getPrettyName() . ' has no dist url configured, cannot install.');
        }
        $realUrl = realpath($url);
        if (false === $realUrl) {
            throw new \RuntimeException('Failed to realpath ' . $url);
        }
        if (realpath($path) === $realUrl) {
            return ': Source already present';
        }
        [
            $currentStrategy,
        ] = $this->computeAllowedStrategies($package->getTransportOptions());
        if ($currentStrategy === self::STRATEGY_SYMLINK) {
            if (Platform::isWindows()) {
                return ': Junctioning from ' . $package->getDistUrl();
            }
            return ': Symlinking from ' . $package->getDistUrl();
        }
        return ': Mirroring from ' . $package->getDistUrl();
    }
    
    /**
     * @param mixed[] $transportOptions
     *
     * @phpstan-return array{self::STRATEGY_*, non-empty-list<self::STRATEGY_*>}
     */
    private function computeAllowedStrategies(array $transportOptions) : array {
        // When symlink transport option is null, both symlink and mirror are allowed
        $currentStrategy = self::STRATEGY_SYMLINK;
        $allowedStrategies = [
            self::STRATEGY_SYMLINK,
            self::STRATEGY_MIRROR,
        ];
        $mirrorPathRepos = Platform::getEnv('COMPOSER_MIRROR_PATH_REPOS');
        if ((bool) $mirrorPathRepos) {
            $currentStrategy = self::STRATEGY_MIRROR;
        }
        $symlinkOption = $transportOptions['symlink'] ?? null;
        if (true === $symlinkOption) {
            $currentStrategy = self::STRATEGY_SYMLINK;
            $allowedStrategies = [
                self::STRATEGY_SYMLINK,
            ];
        }
        elseif (false === $symlinkOption) {
            $currentStrategy = self::STRATEGY_MIRROR;
            $allowedStrategies = [
                self::STRATEGY_MIRROR,
            ];
        }
        // Check we can use junctions safely if we are on Windows
        if (Platform::isWindows() && self::STRATEGY_SYMLINK === $currentStrategy && !$this->safeJunctions()) {
            if (!in_array(self::STRATEGY_MIRROR, $allowedStrategies, true)) {
                throw new \RuntimeException('You are on an old Windows / old PHP combo which does not allow Composer to use junctions/symlinks and this path repository has symlink:true in its options so copying is not allowed');
            }
            $currentStrategy = self::STRATEGY_MIRROR;
            $allowedStrategies = [
                self::STRATEGY_MIRROR,
            ];
        }
        // Check we can use symlink() otherwise
        if (!Platform::isWindows() && self::STRATEGY_SYMLINK === $currentStrategy && !function_exists('symlink')) {
            if (!in_array(self::STRATEGY_MIRROR, $allowedStrategies, true)) {
                throw new \RuntimeException('Your PHP has the symlink() function disabled which does not allow Composer to use symlinks and this path repository has symlink:true in its options so copying is not allowed');
            }
            $currentStrategy = self::STRATEGY_MIRROR;
            $allowedStrategies = [
                self::STRATEGY_MIRROR,
            ];
        }
        return [
            $currentStrategy,
            $allowedStrategies,
        ];
    }
    
    /**
     * Returns true if junctions can be created and safely used on Windows
     *
     * A PHP bug makes junction detection fragile, leading to possible data loss
     * when removing a package. See https://bugs.php.net/bug.php?id=77552
     *
     * For safety we require a minimum version of Windows 7, so we can call the
     * system rmdir which will preserve target content if given a junction.
     *
     * The PHP bug was fixed in 7.2.16 and 7.3.3 (requires at least Windows 7).
     */
    private function safeJunctions() : bool {
        // We need to call mklink, and rmdir on Windows 7 (version 6.1)
        return function_exists('proc_open') && (PHP_WINDOWS_VERSION_MAJOR > 6 || PHP_WINDOWS_VERSION_MAJOR === 6 && PHP_WINDOWS_VERSION_MINOR >= 1);
    }

}