<?php namespace MapGuesser\View;

class Linker
{
    private string $view;

    public function __construct(string $view)
    {
        $this->view = $view;
    }

    public function generate(): void
    {
        $input = ROOT . '/views/' . $this->view . '.php';

        $temporaryFiles = [];
        $sections = [];
        $extra = ['', ''];

        do {
            $parser = new Parser($input);
            $fragment = $parser->parse();

            $extends = $fragment->getExtends();

            $sections = array_merge($sections, $fragment->getSections()); //TODO: detect if section defined multiple times
            $extra[0] = $fragment->getExtra()[0] . $extra[0];
            $extra[1] = $extra[1] . $fragment->getExtra()[1];

            if ($extends === null) {
                $this->writeFinal($extra, $input, ROOT . '/cache/views/' . $this->view . '.php');
                break;
            }

            $tmpFile = tempnam(sys_get_temp_dir(), 'mapg-view-');
            $temporaryFiles[] = $tmpFile;

            $this->extendTemplate($sections, ROOT . '/views/' . $extends . '.php', $tmpFile);

            $input = $tmpFile;
        } while (true);

        foreach ($temporaryFiles as $tmpFile) {
            unlink($tmpFile);
        }
    }

    private function extendTemplate(array $sections, string $file, string $output): void
    {
        $inputFileHandle = fopen($file, 'r');
        if (!$inputFileHandle) {
            throw new \Exception('Cannot open file ' . $file);
        }

        $outputFileHandle = fopen($output, 'w');
        if (!$outputFileHandle) {
            throw new \Exception('Cannot open file ' . $output . 'for writing.');
        }

        $lineNumber = 0;
        while (($line = fgets($inputFileHandle)) !== false) {
            ++$lineNumber;

            if (preg_match('/^\s*@yields\(\'([\w\/]+)\'\)\s*$/', $line, $matches)) {
                if (isset($sections[$matches[1]])) {
                    fwrite($outputFileHandle, $sections[$matches[1]]);
                }
            } else {
                fwrite($outputFileHandle, $line);
            }
        }

        fclose($inputFileHandle);
        fclose($outputFileHandle);
    }

    private function writeFinal(array $extra, string $file, string $output): void
    {
        $dirname = pathinfo($output, PATHINFO_DIRNAME);
        if (!is_dir($dirname)) {
            mkdir($dirname, 0755, true);
        }

        $inputFileHandle = fopen($file, 'r');
        if (!$inputFileHandle) {
            throw new \Exception('Cannot open file ' . $file);
        }

        $outputFileHandle = fopen($output, 'w');
        if (!$outputFileHandle) {
            throw new \Exception('Cannot open file ' . $output . 'for writing.');
        }

        fwrite($outputFileHandle, $extra[0]);
        while (($line = fgets($inputFileHandle)) !== false) {
            fwrite($outputFileHandle, $line);
        }
        fwrite($outputFileHandle, $extra[1]);

        fclose($inputFileHandle);
        fclose($outputFileHandle);
    }
}