#!/usr/bin/env bash
#
# Extract ISSUE_ID from branch (e.g. JS-1234, GO-4222, FOO-99999) and
# prepend it to your commit message if not already present.

REGEX_ISSUE_ID='[A-Za-z]+-[0-9]+'    # letters-dash-numbers
BRANCH_NAME=$(git rev-parse --abbrev-ref HEAD)
COMMIT_MSG_FILE=$1
COMMIT_TEXT=$(< "$COMMIT_MSG_FILE")

# Find and uppercase the first matching issue key
ISSUE_ID=$(echo "$BRANCH_NAME" \
  | grep -oE "$REGEX_ISSUE_ID" \
  | head -1 \
  | tr '[:lower:]' '[:upper:]')

# If no issue key, reject the commit
if [[ -z "$ISSUE_ID" ]]; then
  echo "ERROR: Branch name must contain an issue key (e.g. GO-1234)." >&2
  exit 1
fi

# If the commit message doesn’t already start with ISSUE_ID, prepend it
if [[ ! "$COMMIT_TEXT" =~ ^$ISSUE_ID ]]; then
  printf "%s %s\n" "$ISSUE_ID" "$COMMIT_TEXT" > "$COMMIT_MSG_FILE"
fi

exit 0