How to auto prepend Jira ticket id to git commit msg?

prepare-commit-msg.sh

#!/usr/bin/env bash

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

BRANCH_NAME=$(git rev-parse --abbrev-ref HEAD)

if [ -n "$BRANCH_NAME" ] && [ "$BRANCH_NAME" != "HEAD" ]; then
    PREFIX_PATTERN="[A-Z]{2,5}-[0-9]+"

    [[ $BRANCH_NAME =~ $PREFIX_PATTERN ]]

    PREFIX=${BASH_REMATCH[0]}
    PREFIX_IN_COMMIT=$(grep -c "\[$PREFIX\]" "$COMMIT_MSG_FILE")

    if [[ -n "$PREFIX" ]] && ! [[ $PREFIX_IN_COMMIT -ge 1 ]]; then
        sed -i.bak -e "1s~^~[$PREFIX] ~" "$COMMIT_MSG_FILE"
    fi
fi