#!/bin/bash
# Copyright (c) 2017 Google Inc.

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# This script determines if the source code in a Pull Request is properly formatted.
# Exits with non 0 exit code if formatting is needed.
# Assumptions:
#    - git and python3 are on the path
#    - Runs from the project root diretory.
#    - 'clang-format' is on the path, or env var CLANG_FORMAT points to it.
#    - 'clang-format-diff.py' is in the utils directory, or env var
#       points to it.CLANG_FORMAT_DIFF

BASE_BRANCH=$(git merge-base main HEAD)

CLANG_FORMAT=${CLANG_FORMAT:-clang-format}
if [ ! -f "$CLANG_FORMAT" ]; then
  echo missing clang-format: set CLANG_FORMAT or put clang-format in the PATH
  exit 1
fi

# Find clang-format-diff.py from an environment variable, or use a default
CLANG_FORMAT_DIFF=${CLANG_FORMAT_DIFF:-./utils/clang-format-diff.py}
if [ ! -f "$CLANG_FORMAT_DIFF" ]; then
  echo missing clang-format-diffy.py: set CLANG_FORMAT_DIFF or put it in ./utils/clang-format-diff.py
  exit 1
fi

echo "Comparing "$(git rev-parse HEAD)" against $BASE_BRANCH"
echo Using $("$CLANG_FORMAT" --version)

FILES_TO_CHECK=$(git diff --name-only ${BASE_BRANCH} | grep -E ".*\.(cpp|cc|c\+\+|cxx|c|h|hpp)$")

if [ -z "${FILES_TO_CHECK}" ]; then
  echo "No source code to check for formatting."
  exit 0
fi
echo "Checking Formatting for the following files"
echo "${FILES_TO_CHECK}"
echo

FORMAT_DIFF=$(git diff -U0 ${BASE_BRANCH} -- ${FILES_TO_CHECK} | python3 "${CLANG_FORMAT_DIFF}" -p1 -style=file -binary "$CLANG_FORMAT")

if [ -z "${FORMAT_DIFF}" ]; then
  echo "All source code in PR properly formatted."
  exit 0
else
  echo "Found formatting errors!"
  echo "${FORMAT_DIFF}"
  exit 1
fi