class HtmlOutputLogger

final class HtmlOutputLogger {
    
    /**
     * The singleton instance.
     */
    private static ?self $instance = NULL;
    
    /**
     * A file with list of links to HTML pages generated.
     */
    private ?string $browserOutputFile = NULL;
    
    /**
     * @throws \PHPUnit\Event\EventFacadeIsSealedException
     * @throws \PHPUnit\Util\Exception
     * @throws \PHPUnit\Event\UnknownSubscriberTypeException
     * @throws \RuntimeException
     */
    private function __construct(string $outputDirectory, bool $outputVerbose, Facade $facade) {
        $this->facade
            ->registerSubscriber(new TestRunnerStartedSubscriber($this));
        $this->facade
            ->registerSubscriber(new TestRunnerFinishedSubscriber($this));
    }
    
    /**
     * Initializes the extension.
     *
     * @param string $outputDirectory
     *   The directory where the HTML pages should be generated.
     * @param bool $outputVerbose
     *   If TRUE, a list of links generated will be output at the end of the test
     *   run; if FALSE, only a summary with the count of pages generated.
     *
     * @throws \PHPUnit\Event\EventFacadeIsSealedException
     * @throws \PHPUnit\Util\Exception
     * @throws \PHPUnit\Event\UnknownSubscriberTypeException
     * @throws \RuntimeException
     */
    public static function init(string $outputDirectory, bool $outputVerbose) : void {
        if (self::$instance === NULL) {
            $realDirectory = realpath($outputDirectory);
            if ($realDirectory === FALSE || !is_dir($realDirectory) || !is_writable($realDirectory)) {
                print "HTML output directory {$outputDirectory} is not a writable directory.\n\n";
                return;
            }
            self::$instance = new self($realDirectory, $outputVerbose, Facade::instance());
        }
    }
    
    /**
     * Determines if the extension is enabled.
     *
     * @return bool
     *   TRUE if enabled, FALSE if disabled.
     */
    public static function isEnabled() : bool {
        return self::$instance !== NULL;
    }
    
    /**
     * Logs a link to a generated HTML page.
     *
     * @param string $logEntry
     *   A link to a generated HTML page, should not contain a trailing newline.
     *
     * @throws \RuntimeException
     */
    public static function log(string $logEntry) : void {
        if (!self::isEnabled()) {
            throw new \RuntimeException("HTML output is not enabled");
        }
        $browserOutputFile = getenv('BROWSERTEST_OUTPUT_FILE');
        file_put_contents($browserOutputFile, $logEntry . "\n", FILE_APPEND);
    }
    
    /**
     * Empties the list of the HTML output created during the test run.
     */
    public function testRunnerStarted(TestRunnerStarted $event) : void {
        if (!self::isEnabled()) {
            throw new \RuntimeException("HTML output is not enabled");
        }
        // Convert to a canonicalized absolute pathname just in case the current
        // working directory is changed.
        $this->browserOutputFile = tempnam($this->outputDirectory, 'browser_output_');
        if ($this->browserOutputFile) {
            touch($this->browserOutputFile);
            putenv('BROWSERTEST_OUTPUT_FILE=' . $this->browserOutputFile);
        }
        else {
            // Remove any environment variable.
            putenv('BROWSERTEST_OUTPUT_FILE');
            throw new \RuntimeException("Unable to create a temporary file in {$this->outputDirectory}.");
        }
    }
    
    /**
     * Prints the list of HTML output generated during the test.
     */
    public function testRunnerFinished(TestRunnerFinished $event) : void {
        if (!self::isEnabled()) {
            throw new \RuntimeException("HTML output is not enabled");
        }
        $contents = file_get_contents($this->browserOutputFile);
        if ($contents) {
            print "\n\n";
            if ($this->outputVerbose) {
                print "HTML output was generated.\n";
                print $contents;
            }
            else {
                print "HTML output was generated, " . count(explode("\n", $contents)) . " page(s).\n";
            }
        }
        // No need to keep the file around any more.
        unlink($this->browserOutputFile);
        putenv('BROWSERTEST_OUTPUT_FILE');
        $this->browserOutputFile = NULL;
    }

}