Git hook to add JIRA issue key from branch-name (if it exists) and add it before the commit message

prepare-commit-msg

#!/usr/bin/env php
<?php

/**
 * Add this file as "prepare-commit-msg" under /my-project/.git/hooks directory
 * and make it executable. (chmod +x)
 *
 * Example:
 * If Branchname was: "release/MYPRO-1-awesome-feature" 
 * and the commit message you typed in are: "Take this"
 * this hooks make the message: "MYPRO-1: Take this"
 */

$messageFile = $argv[1];
$message = file_get_contents($messageFile);

if (false === function_exists('exec')) {
    exit(0);
}

$branchName = exec('git symbolic-ref --short HEAD');
preg_match('/[A-Z]{3,}-[0-9]{1,}/', $branchName, $matches);

if (true === is_array($matches) && 1 === count($matches)) {
    $message = sprintf('%s: %s', current($matches), $message);
}

file_put_contents($messageFile, $message);
exit(0);