A pre-commit-hook example with Code Sniffer + Code Fixer + PHPStan

code_check_git_hook.php

#!/usr/bin/php
<?php

/**
 * //
 * // add something like this in your "composer post-update-cmd && post-install-cmd" 
 * //
 * echo "\n\n";
 * echo "Run force \"code_check_git_hook.php\" as pre-commit-hook ...";
 * $force_pre_commit_hook_cmd = 'ln -sf YOUR_PATH_TO_CODE_CHECK_SCRIPTS/code_check_git_hook.php YOUR_PATH_TO_PROJECT_ROOT/.git/hooks/pre-commit';
 * passthru($force_pre_commit_hook_cmd, $return_var);
 * if ($return_var !== 0) {
 *    echo "\n" . 'error: ' . $force_pre_commit_hook_cmd;
 *    exit(1);
 * }
*/

use Composer\XdebugHandler\XdebugHandler;

require_once __DIR__ . '/YOUR_PATH_THE_AUTOLOADER.php';

$xdebug = new XdebugHandler('your-code-check');
$xdebug->check();
unset($xdebug);

set_time_limit(0);

if ($argc == 1) {
	echo "No commit hash passed, checking git repository staged area (pre-comit)" . \PHP_EOL;
}
if ($argc == 2) {
	// get commit hash from command line argument
	$commit_hash = $argv[1];
	$commit_as_range = $commit_hash . '^..' . $commit_hash;
	echo "Commit hash passed, checking files from commit: " . $commit_hash . \PHP_EOL;
}
if ($argc == 3) {
	// get commit hash from command line argument
	$commit_hash = $argv[1];
	// also get previous (last pushed) commit hash from command line argument
	$prev_commit_hash = $argv[2];
	$commit_as_range = $prev_commit_hash . '..' . $commit_hash;
	echo "Commit hashes passed, checking files from commit range: " . $commit_as_range . \PHP_EOL;
}

if (!empty($commit_as_range)) {

	// commit hash passed, check files from this commit
	$new_files_cmd = 'git diff --name-only --diff-filter=ACmrtd ' . $commit_as_range . ' | grep -e "\.php$"';
	exec($new_files_cmd, $new_files, $return);

	$changed_files_cmd = 'git diff --name-only --diff-filter=ACMRtd ' . $commit_as_range . ' | grep -e "\.php$"';
	exec($changed_files_cmd, $changed_files, $return);

} else {

	// no commit hash passed, check git staged area
	$merge_commit_cmd = 'git rev-parse -q --verify MERGE_HEAD';
	exec($merge_commit_cmd, $merge_commit_hash, $return);
	if ($merge_commit_hash) {
		// this is a merge commit, so skip the "pre-commit-check"
		exit(0);
	}

	$new_files_cmd = 'git diff --cached --name-only --diff-filter=ACmrtd HEAD | grep -e "\.php$"';
	exec($new_files_cmd, $new_files, $return);

	$changed_files_cmd = 'git diff --cached --name-only --diff-filter=ACMRtd HEAD | grep -e "\.php$"';
	exec($changed_files_cmd, $changed_files, $return);

}

if (!is_array($changed_files) || count($changed_files) === 0) {
	// no changes files
	echo "No changed PHP files." . \PHP_EOL;
	exit(0);
}

/*
if (is_gitlab_ci() === true) {
	echo "Changed PHP files: " . \PHP_EOL;
	echo json_encode($changed_files, \JSON_PRETTY_PRINT | \JSON_UNESCAPED_SLASHES) . \PHP_EOL;

	echo "New PHP files: " . \PHP_EOL;
	echo json_encode($new_files, \JSON_PRETTY_PRINT | \JSON_UNESCAPED_SLASHES) . \PHP_EOL;
}
*/

if (!empty($commit_as_range)) {

	// commit hash passed, check files from this commit
	echo 'Checking PHP Syntax ...' . "\n";
	$php_lint_cmd = 'git diff --name-only --diff-filter=ACMRtd ' . $commit_as_range . ' | grep -e "\.php$" | xargs -d \'\n\' -n1 -P' . get_processor_cores_number() . ' php -l | grep -v \'No syntax errors\'; test $? -eq 1';
	exec($php_lint_cmd, $php_errormsg_output, $return);
	if ($return != 0) {
		echo 'PHP-Syntax [' . $return . ']: (╯°□°）╯︵ ┻━┻  Please fix the php error before commit.' . "\n" . print_r($php_errormsg_output, true);
		exit(1);
	}

} else {

	// no commit hash passed, check git staged area
	echo 'Checking PHP Syntax ...' . "\n";
	$php_lint_cmd = 'git diff --cached --name-only --diff-filter=ACMRtd HEAD | grep -e "\.php$" | xargs -d \'\n\' -n1 -P' . get_processor_cores_number() . ' php -l | grep -v \'No syntax errors\'; test $? -eq 1';
	exec($php_lint_cmd, $php_errormsg_output, $return);
	if ($return != 0) {
		echo 'PHP-Syntax [' . $return . ']: (╯°□°）╯︵ ┻━┻  Please fix the php error before commit.' . "\n" . print_r($php_errormsg_output, true);
		exit(1);
	}

}

checkCommitChangedFiles($changed_files);

checkCommitNewFiles($new_files);

exit(0);

/**
 * @return int
 */
function get_processor_cores_number(): int {
	$command = "grep -c processor /proc/cpuinfo";

	return (int)shell_exec($command);
}

/**
 * @param string $new_file_and_path
 *
 * @return bool
 */
function isValidFileForPhpStanChecks($new_file_and_path) {

	if (\strpos($new_file_and_path, '/tests/') !== false) {
		return false;
	}

	if (\strpos($new_file_and_path, '/scripts/') !== false) {
		return false;
	}

	if (\strpos($new_file_and_path, 'Cest.php') !== false) {
		return false;
	}

	$data = file_get_contents($new_file_and_path);
	if (strpos($data, '@skipPhpStanCheck') !== false) {
		return false;
	}

	return true;
}

/**
 * @param string $new_file_and_path
 *
 * @return bool
 */
function isValidFileForCodeChecks($new_file_and_path) {

	return strpos($new_file_and_path, '/composer/') === false
	       &&
	       strpos($new_file_and_path, '/archiv/') === false
	       &&
	       strpos($new_file_and_path, '/vendor/') === false
	       &&
	       strpos($new_file_and_path, '/thirdparty/') === false
	       &&
	       strpos($new_file_and_path, '/generated/') === false
	       &&
	       strpos($new_file_and_path, '/_generated/') === false
	       &&
	       strpos($new_file_and_path, '/tmp/') === false
	       &&
	       file_exists($new_file_and_path);
}

/**
 * @param string[] $changed_files
 */
function checkCommitChangedFiles($changed_files) {
	$changed_files_string = '';
	$changed_files_string_phpstan = '';
	$fileCounterTmp = 0;
	$allCounterTmp = count($changed_files);
	foreach ($changed_files as $changed_file) {

		if ($fileCounterTmp === 0) {
			$changed_files_string = '';
			$changed_files_string_phpstan = '';
		}

		$allCounterTmp--;
		$changed_file_and_path = 'YOUR_PATH_TO_PROJECT_ROOT/' . $changed_file;

		if (isValidFileForCodeChecks($changed_file_and_path)) {
			$fileCounterTmp++;
			$changed_files_string .= ' ' . $changed_file_and_path;

			if (isValidFileForPhpStanChecks($changed_file_and_path)) {
				$changed_files_string_phpstan .= ' ' . $changed_file_and_path;
			}
		}

		if ($allCounterTmp > 0 && $fileCounterTmp < 500) {
			continue;
		}

		// reset
		$fileCounterTmp = 0;

		if (!$changed_files_string) {
			// no real changed files
			continue;
		}

		/********************************************************************
		 * 1.0 Code Sniffer
		 ********************************************************************/

		$code_sniffer_cmd = 'bash -c "php \
                YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_codesniffer.php \
                \'' . $changed_files_string . '\' \
                \'for changed files\' \
            "';
		passthru($code_sniffer_cmd, $return);
		if ($return != 0) {
			exit($return);
		}

		/********************************************************************
		 * 1.1 Code Fixer
		 ********************************************************************/

		/*
		$code_fixer_cmd = 'bash -c "php \
				YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_codefixer.php \
				\'' . $changed_files_string . '\' \
				\'for changed files\' \
			"';
		passthru($code_fixer_cmd, $return);
		if ($return != 0) {
			exit($return);
		}
		 */

		/********************************************************************
		 * 1.2 PhpStan
		 ********************************************************************/

		if ($changed_files_string_phpstan) {
			$phpstan_cmd = 'bash -c "php \
                YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_phpstan.php \
                \'' . $changed_files_string_phpstan . '\' \
                \'2\' \
                \'YOUR_PATH_TO_CODE_CHECK_SCRIPTS/phpstan_legacy.neon\' \
                \'for changed files\' \
            "';
			passthru($phpstan_cmd, $return);
			if ($return != 0) {
				exit($return);
			}
		}

	}
}

/**
 * @param string[] $new_files
 */
function checkCommitNewFiles($new_files) {
	$new_files_string = '';
	$new_files_string_phpstan = '';
	$fileCounterTmp = 0;
	$allCounterTmp = count($new_files);
	foreach ($new_files as $new_file) {

		if ($fileCounterTmp === 0) {
			$new_files_string = '';
			$new_files_string_phpstan = '';
		}

		$allCounterTmp--;
		$new_file_and_path = 'YOUR_PATH_TO_PROJECT_ROOT/' . $new_file;

		if (isValidFileForCodeChecks($new_file_and_path)) {
			$fileCounterTmp++;
			$new_files_string .= ' ' . $new_file_and_path;

			if (isValidFileForPhpStanChecks($new_file_and_path)) {
				$new_files_string_phpstan .= ' ' . $new_file_and_path;
			}
		}

		if ($allCounterTmp > 0 && $fileCounterTmp < 500) {
			continue;
		}

		// reset
		$fileCounterTmp = 0;

		if (!$new_files_string) {
			// no real changed files
			continue;
		}

		/********************************************************************
		 * 2.0 Code Sniffer
		 ********************************************************************/

		$code_sniffer_cmd = 'bash -c "php \
                YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_codesniffer.php \
                \'' . $new_files_string . '\' \
                \'for new files\' \
            "';
		passthru($code_sniffer_cmd, $return);
		if ($return != 0) {
			exit($return);
		}

		/********************************************************************
		 * 2.1 Code Fixer
		 ********************************************************************/

		$code_fixer_cmd = 'bash -c "php \
                YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_codefixer.php \
                \'' . $new_files_string . '\' \
                \'for new files\' \
            "';
		passthru($code_fixer_cmd, $return);
		if ($return != 0) {
			exit($return);
		}

		/********************************************************************
		 * 2.2 PhpStan
		 ********************************************************************/

		if ($new_files_string_phpstan) {
			$phpstan_cmd = 'bash -c "php \
                YOUR_PATH_TO_CODE_CHECK_SCRIPTS/check_code_phpstan.php \
                \'' . $new_files_string_phpstan . '\' \
                \'3\' \
                \'YOUR_PATH_TO_CODE_CHECK_SCRIPTS/phpstan.neon\' \
                \'for new files\' \
            "';
			passthru($phpstan_cmd, $return);
			if ($return != 0) {
				exit($return);
			}
		}

	}
}

@integer we run the check every night for all files on the CI server and I did not see any / many errors that where reported by the CI server, because the pre-commit hook prevent the developers to commit non valid code. :)