Pre populate the jira prefix on commit messages

prepare-commit-msg

# abort if .git-hooks is not present
# add .git-hooks to .git-ignore so people can opt-in
if [ ! -f .git-hooks ]; then
    exit 0
fi

# some commit operations we dont want to prefix the message
if [[ "$2" == "merge" || "$2" == "commit" || "$2" == "template" || "$2" == "squash" ]]; then
    echo "Not a regular commit so ignoring.."
    exit 0
fi

# get initials from the dev's GIT config
# got to be a tidier regex for this
initials=$(git var GIT_AUTHOR_IDENT | sed 's/^\([A-Za-z]\{1\}\).* \([A-Za-z]\{1\}\).*$/\1\2/')

##
# override the prefix
##

# 1. default is just the dev's initials
prefix="[$initials][]"

# 2. dev is continuing a line of commits on the same ticket (i.e not after a merge or after someone elses line of commits)
# [RS DW][MR-312] updated... -> extract [RS DW][MR-312]
# [DW JR][MR-310] send.... -> ignore
# Merged branch... -> ignore

regex="^\[${initials}"
match=$(git log -1 --pretty=%B | grep -e "$regex")

if [ -n "$match" ]; then
    prefix=$(git log -1 --pretty=%B | sed  's/^\(\[.*\]\).*$/\1/')
fi


# add prefix
echo "$prefix\n$(cat $1)" >  "$1"