class VcsDownloader

abstract class VcsDownloader implements DownloaderInterface, ChangeReportInterface, VcsCapableDownloaderInterface {
    
    /** @var IOInterface */
    protected $io;
    
    /** @var Config */
    protected $config;
    
    /** @var ProcessExecutor */
    protected $process;
    
    /** @var Filesystem */
    protected $filesystem;
    
    /** @var array<string, true> */
    protected $hasCleanedChanges = [];
    public function __construct(IOInterface $io, Config $config, ?ProcessExecutor $process = null, ?Filesystem $fs = null) {
        $this->io = $io;
        $this->config = $config;
        $this->process = $process ?? new ProcessExecutor($io);
        $this->filesystem = $fs ?? new Filesystem($this->process);
    }
    
    /**
     * @inheritDoc
     */
    public function getInstallationSource() : string {
        return 'source';
    }
    
    /**
     * @inheritDoc
     */
    public function download(PackageInterface $package, string $path, ?PackageInterface $prevPackage = null) : PromiseInterface {
        if (!$package->getSourceReference()) {
            throw new \InvalidArgumentException('Package ' . $package->getPrettyName() . ' is missing reference information');
        }
        $urls = $this->prepareUrls($package->getSourceUrls());
        while ($url = array_shift($urls)) {
            try {
                return $this->doDownload($package, $path, $url, $prevPackage);
            } catch (\Exception $e) {
                // rethrow phpunit exceptions to avoid hard to debug bug failures
                if ($e instanceof \PHPUnit\Framework\Exception) {
                    throw $e;
                }
                if ($this->io
                    ->isDebug()) {
                    $this->io
                        ->writeError('Failed: [' . get_class($e) . '] ' . $e->getMessage());
                }
                elseif (count($urls)) {
                    $this->io
                        ->writeError('    Failed, trying the next URL');
                }
                if (!count($urls)) {
                    throw $e;
                }
            }
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function prepare(string $type, PackageInterface $package, string $path, ?PackageInterface $prevPackage = null) : PromiseInterface {
        if ($type === 'update') {
            $this->cleanChanges($prevPackage, $path, true);
            $this->hasCleanedChanges[$prevPackage->getUniqueName()] = true;
        }
        elseif ($type === 'install') {
            $this->filesystem
                ->emptyDirectory($path);
        }
        elseif ($type === 'uninstall') {
            $this->cleanChanges($package, $path, false);
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function cleanup(string $type, PackageInterface $package, string $path, ?PackageInterface $prevPackage = null) : PromiseInterface {
        if ($type === 'update' && isset($this->hasCleanedChanges[$prevPackage->getUniqueName()])) {
            $this->reapplyChanges($path);
            unset($this->hasCleanedChanges[$prevPackage->getUniqueName()]);
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function install(PackageInterface $package, string $path) : PromiseInterface {
        if (!$package->getSourceReference()) {
            throw new \InvalidArgumentException('Package ' . $package->getPrettyName() . ' is missing reference information');
        }
        $this->io
            ->writeError("  - " . InstallOperation::format($package) . ': ', false);
        $urls = $this->prepareUrls($package->getSourceUrls());
        while ($url = array_shift($urls)) {
            try {
                $this->doInstall($package, $path, $url);
                break;
            } catch (\Exception $e) {
                // rethrow phpunit exceptions to avoid hard to debug bug failures
                if ($e instanceof \PHPUnit\Framework\Exception) {
                    throw $e;
                }
                if ($this->io
                    ->isDebug()) {
                    $this->io
                        ->writeError('Failed: [' . get_class($e) . '] ' . $e->getMessage());
                }
                elseif (count($urls)) {
                    $this->io
                        ->writeError('    Failed, trying the next URL');
                }
                if (!count($urls)) {
                    throw $e;
                }
            }
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function update(PackageInterface $initial, PackageInterface $target, string $path) : PromiseInterface {
        if (!$target->getSourceReference()) {
            throw new \InvalidArgumentException('Package ' . $target->getPrettyName() . ' is missing reference information');
        }
        $this->io
            ->writeError("  - " . UpdateOperation::format($initial, $target) . ': ', false);
        $urls = $this->prepareUrls($target->getSourceUrls());
        $exception = null;
        while ($url = array_shift($urls)) {
            try {
                $this->doUpdate($initial, $target, $path, $url);
                $exception = null;
                break;
            } catch (\Exception $exception) {
                // rethrow phpunit exceptions to avoid hard to debug bug failures
                if ($exception instanceof \PHPUnit\Framework\Exception) {
                    throw $exception;
                }
                if ($this->io
                    ->isDebug()) {
                    $this->io
                        ->writeError('Failed: [' . get_class($exception) . '] ' . $exception->getMessage());
                }
                elseif (count($urls)) {
                    $this->io
                        ->writeError('    Failed, trying the next URL');
                }
            }
        }
        // print the commit logs if in verbose mode and VCS metadata is present
        // because in case of missing metadata code would trigger another exception
        if (!$exception && $this->io
            ->isVerbose() && $this->hasMetadataRepository($path)) {
            $message = 'Pulling in changes:';
            $logs = $this->getCommitLogs($initial->getSourceReference(), $target->getSourceReference(), $path);
            if ('' === trim($logs)) {
                $message = 'Rolling back changes:';
                $logs = $this->getCommitLogs($target->getSourceReference(), $initial->getSourceReference(), $path);
            }
            if ('' !== trim($logs)) {
                $logs = implode("\n", array_map(static function ($line) : string {
                    return '      ' . $line;
                }, explode("\n", $logs)));
                // escape angle brackets for proper output in the console
                $logs = str_replace('<', '\\<', $logs);
                $this->io
                    ->writeError('    ' . $message);
                $this->io
                    ->writeError($logs);
            }
        }
        if (!$urls && $exception) {
            throw $exception;
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * @inheritDoc
     */
    public function remove(PackageInterface $package, string $path) : PromiseInterface {
        $this->io
            ->writeError("  - " . UninstallOperation::format($package));
        $promise = $this->filesystem
            ->removeDirectoryAsync($path);
        return $promise->then(static function (bool $result) use ($path) {
            if (!$result) {
                throw new \RuntimeException('Could not completely delete ' . $path . ', aborting.');
            }
        });
    }
    
    /**
     * @inheritDoc
     */
    public function getVcsReference(PackageInterface $package, string $path) : ?string {
        $parser = new VersionParser();
        $guesser = new VersionGuesser($this->config, $this->process, $parser, $this->io);
        $dumper = new ArrayDumper();
        $packageConfig = $dumper->dump($package);
        if ($packageVersion = $guesser->guessVersion($packageConfig, $path)) {
            return $packageVersion['commit'];
        }
        return null;
    }
    
    /**
     * Prompt the user to check if changes should be stashed/removed or the operation aborted
     *
     * @param  bool              $update  if true (update) the changes can be stashed and reapplied after an update,
     *                                    if false (remove) the changes should be assumed to be lost if the operation is not aborted
     *
     * @throws \RuntimeException in case the operation must be aborted
     * @phpstan-return PromiseInterface<void|null>
     */
    protected function cleanChanges(PackageInterface $package, string $path, bool $update) : PromiseInterface {
        // the default implementation just fails if there are any changes, override in child classes to provide stash-ability
        if (null !== $this->getLocalChanges($package, $path)) {
            throw new \RuntimeException('Source directory ' . $path . ' has uncommitted changes.');
        }
        return \React\Promise\resolve(null);
    }
    
    /**
     * Reapply previously stashes changes if applicable, only called after an update (regardless if successful or not)
     *
     * @throws \RuntimeException in case the operation must be aborted or the patch does not apply cleanly
     */
    protected function reapplyChanges(string $path) : void {
    }
    
    /**
     * Downloads data needed to run an install/update later
     *
     * @param PackageInterface      $package     package instance
     * @param string                $path        download path
     * @param string                $url         package url
     * @param PackageInterface|null $prevPackage previous package (in case of an update)
     * @phpstan-return PromiseInterface<void|null>
     */
    protected abstract function doDownload(PackageInterface $package, string $path, string $url, ?PackageInterface $prevPackage = null) : PromiseInterface;
    
    /**
     * Downloads specific package into specific folder.
     *
     * @param PackageInterface $package package instance
     * @param string           $path    download path
     * @param string           $url     package url
     * @phpstan-return PromiseInterface<void|null>
     */
    protected abstract function doInstall(PackageInterface $package, string $path, string $url) : PromiseInterface;
    
    /**
     * Updates specific package in specific folder from initial to target version.
     *
     * @param PackageInterface $initial initial package
     * @param PackageInterface $target  updated package
     * @param string           $path    download path
     * @param string           $url     package url
     * @phpstan-return PromiseInterface<void|null>
     */
    protected abstract function doUpdate(PackageInterface $initial, PackageInterface $target, string $path, string $url) : PromiseInterface;
    
    /**
     * Fetches the commit logs between two commits
     *
     * @param  string $fromReference the source reference
     * @param  string $toReference   the target reference
     * @param  string $path          the package path
     */
    protected abstract function getCommitLogs(string $fromReference, string $toReference, string $path) : string;
    
    /**
     * Checks if VCS metadata repository has been initialized
     * repository example: .git|.svn|.hg
     */
    protected abstract function hasMetadataRepository(string $path) : bool;
    
    /**
     * @param string[] $urls
     *
     * @return string[]
     */
    private function prepareUrls(array $urls) : array {
        foreach ($urls as $index => $url) {
            if (Filesystem::isLocalPath($url)) {
                // realpath() below will not understand
                // url that starts with "file://"
                $fileProtocol = 'file://';
                $isFileProtocol = false;
                if (0 === strpos($url, $fileProtocol)) {
                    $url = substr($url, strlen($fileProtocol));
                    $isFileProtocol = true;
                }
                // realpath() below will not understand %20 spaces etc.
                if (false !== strpos($url, '%')) {
                    $url = rawurldecode($url);
                }
                $urls[$index] = realpath($url);
                if ($isFileProtocol) {
                    $urls[$index] = $fileProtocol . $urls[$index];
                }
            }
        }
        return $urls;
    }

}