.travis-build.php

<?php

$readMeFilepath = __DIR__ . '/README.md';
$readMeFile = new SplFileObject($readMeFilepath);
$readMeFile->setFlags(SplFileObject::DROP_NEW_LINE);

$cliRedBackground = "\033[37;41m";
$cliReset = "\033[0m";
$exitStatus = 0;

$indentationSteps = 3;
$manIndex = 0;
$linesWithSpaces = [];
$tableOfContentsStarted = null;
$currentTableOfContentsChapters = [];
$chaptersFound = [];
foreach ($readMeFile as $lineNumber => $line) {
    if (preg_match('/\s$/', $line)) {
        $linesWithSpaces[] = sprintf('%5s: %s', 1 + $lineNumber, $line);
    }
    if (preg_match('/^(?<depth>##+)\s(?<title>.+)/', $line, $matches)) {
        if (null === $tableOfContentsStarted) {
            $tableOfContentsStarted = true;
            continue;
        }
        $tableOfContentsStarted = false;

        if (strlen($matches['depth']) === 2) {
            $depth = sprintf('  %s.', ++$manIndex);
        } else {
            $depth = sprintf(' %s*', str_repeat('  ', strlen($matches['depth']) - 1));
        }

        // ignore links in title
        $matches['title'] = preg_replace('/\[([^\]]+)\]\((?:[^\)]+)\)/u', '$1', $matches['title']);

        $link = $matches['title'];
        $link = strtolower($link);
        $link = str_replace(' ', '-', $link);
        $link = preg_replace('/[^-\w]+/u', '', $link);

        $chaptersFound[] = sprintf('%s [%s](#%s)', $depth, $matches['title'], $link);
    }
    if ($tableOfContentsStarted === true && isset($line[0])) {
        $currentTableOfContentsChapters[] = $line;
    }
}

if (count($linesWithSpaces)) {
    fwrite(STDERR, sprintf("${cliRedBackground}The following lines end with a space character:${cliReset}\n%s\n\n",
        implode(PHP_EOL, $linesWithSpaces)
    ));
    $exitStatus = 1;
}

$currentTableOfContentsChaptersFilename = __DIR__ . '/current-chapters';
$chaptersFoundFilename = __DIR__ . '/chapters-found';

file_put_contents($currentTableOfContentsChaptersFilename, implode(PHP_EOL, $currentTableOfContentsChapters));
file_put_contents($chaptersFoundFilename, implode(PHP_EOL, $chaptersFound));

$tableOfContentsDiff = shell_exec(sprintf('diff --unified %s %s',
    escapeshellarg($currentTableOfContentsChaptersFilename),
    escapeshellarg($chaptersFoundFilename)
));

@ unlink($currentTableOfContentsChaptersFilename);
@ unlink($chaptersFoundFilename);

if (!empty($tableOfContentsDiff)) {
    fwrite(STDERR, sprintf("${cliRedBackground}The table of contents is not aligned:${cliReset}\n%s\n\n",
        $tableOfContentsDiff
    ));
    $exitStatus = 1;
}

exit($exitStatus);