Git Commit Hooks

prepare-commit-msg

#!/bin/bash
#
# An example hook script to prepare the commit log message.
# Called by "git commit" with the name of the file that has the
# commit message, followed by the description of the commit
# message's source.  The hook's purpose is to edit the commit
# message file.  If the hook fails with a non-zero status,
# the commit is aborted.
#
# To enable this hook, rename this file to "prepare-commit-msg".

COMMIT_MSG_FILE=$1
COMMIT_SOURCE=$2
SHA1=$3

# Only add custom message when there is no commit source
# ($COMMIT_SOURCE is empty). Otherwise, keep the default message
# proposed by Git. Possible commit source: message, template,
# merge, squash or commit. See https://git-scm.com/docs/githooks
if [[ -z "$COMMIT_SOURCE" ]]; then
    # https://regex101.com/r/jQgLYo/1
    branch_name="$(git rev-parse --abbrev-ref HEAD)"
    commit_prefix="$([[ $branch_name =~ ^(.*\/)?([a-zA-Z0-9]+-[0-9]+)(.+)?$ ]] && echo "${BASH_REMATCH[2]}")"

    if [[ ! -z "$commit_prefix" ]]; then
        hint=$(cat "$COMMIT_MSG_FILE")
        ticket="[$commit_prefix] "

        echo "$ticket" > "$COMMIT_MSG_FILE"
        echo "$hint" >> "$COMMIT_MSG_FILE"
    fi
fi