#!/bin/bash
set -euo pipefail

if [ "$#" -lt 1 ]; then
  echo "Usage: git cb <target-branch>"
  exit 1
fi

TARGET_BRANCH="$1"

if [ "$TARGET_BRANCH" != "-" ]; then
  if ! git rev-parse --verify --quiet "$TARGET_BRANCH" >/dev/null; then
    echo "Error: branch '$TARGET_BRANCH' does not exist." >&2
    exit 1
  fi
fi

git add -A
if ! git diff --cached --quiet || [ -n "$(git ls-files --others --exclude-standard)" ]; then
  git commit -m "tmp"
fi

git checkout "$TARGET_BRANCH"

LATEST_AUTHOR=$(git log -1 --pretty=format:'%an')
LATEST_MESSAGE=$(git log -1 --pretty=format:'%s')
CURRENT_USER=$(git config user.name)
if [ "$LATEST_AUTHOR" = "$CURRENT_USER" ] && [ "$LATEST_MESSAGE" = "tmp" ]; then
  echo "Resetting last 'tmp' commit by $CURRENT_USER..."
  git reset --mixed HEAD~1
fi