prepare-commit-msg

#!/usr/bin/env python

#
# Python script that implements a Git Hook of type Prepare Commit Message
# Author: Alexandre Pardo
# Date: 06/26/2019
#

from subprocess import check_output, Popen
import os, re, subprocess, sys

# First, we check if this is a NPM project

package_json_file_name = 'package.json'
is_npm_project = os.path.isfile(package_json_file_name)

if not is_npm_project: # Nothing to do
    sys.exit(0)

# If this is a NPM project, we can move on

branch = 'master' # default
try:
                          # git symbolic-ref --short HEAD
    branch = check_output(['git', 'symbolic-ref', '--short', 'HEAD']).strip()
except:
    # if HEAD is not a symbolic ref, then we might be in a dettached state (not sure).
    # As an error is thrown if we run this this during the rebase process, so we simply skip it.
    # Also, if we couldn't safely read the branch name, this hook can't continue
    print 'If you are running rebase or merge, you may ignore the message: fatal: ref HEAD is not a symbolic ref'
    print 'Otherwise, you better check what is going on'

    sys.exit(0)

# matches for branch names like:
# feature/issue-123
# feature/issue123
# hotfix/issue-123
# hotfix/issue123
regex = '(feature|hotfix)\/(\w+-\d+|\w+\d+)'
branch_match = re.match(regex, branch)

not_allowed_branches = ['master', 'dev', 'develop', 'staging', 'release']

merge_head_file_path = '.git/MERGE_HEAD'
is_merging = os.path.isfile(merge_head_file_path)

# First we check if we're not taking shortcuts ;)
if branch in not_allowed_branches and not is_merging:
    print '======================WARNING====================='
    print '  Direct commit to', branch, 'branch is not allowed'
    print '=================================================='
    sys.exit(1)

# If we're using the right branch name pattern,
# append the issue # in the beginning of the commit message
if branch_match <> None:
    issue = branch_match.group(2)

    commit_msg_filepath = sys.argv[1]
    with open(commit_msg_filepath, 'r+') as fh:
        commit_msg = fh.read()

        formatted_issue = '[' + issue + ']'
        
        starts_with_ticket = commit_msg.strip().startswith(formatted_issue)

        if not starts_with_ticket:
            fh.seek(0, 0)
            fh.write('[%s] %s' % (issue, commit_msg))
else:
    print '================================FRIENDLY REMINDER================================'
    print '=Observe the branch pattern. Its prefix should be either "feature/" or "hotfix/"='
    print '================================================================================='
    print ':-)'