#!/usr/bin/env bash
#
# Runs clang-format on changed regions before commit.
#
# To install this, copy it to .git/hooks/pre-commit in your repo.
# Remaining installation checks/instructions will be printed when you commit.
#

read -d '' help <<- EOF
This repository requires you to install the clang-format command. This hook has
been tested with clang-format-10, so remove all previous versions and reinstall:
$ sudo apt-get remove clang-format-*
$ sudo apt-get install clang-format-10
You should now have clang-format-10 installed. Then, update the configuration
as follows:
$ git config --global clangFormat.binary clang-format-10
$ git config --global clangFormat.style file
$ git config --global alias.clang-format clang-format-10
EOF

check_clang_format() {
  if hash git clang-format 2>/dev/null; then
    return
  else
    echo "SETUP ERROR: no git clang-format executable found, or it is not executable"
    echo "$help"
    exit 1
  fi
}

check_git_config() {
  if [[ "$(git config --get clangFormat.binary)" != "clang-format-10" ]]; then
    echo "SETUP ERROR: git config clangFormat.binary should be \"clang-format-10\"."
    echo "$help"
    exit 1
  fi
  if [[ "$(git config --get clangFormat.style)" != "file" ]]; then
    echo "SETUP ERROR: git config clangFormat.style should be \"file\"."
    echo "$help"
    exit 1
  fi
}

check_clang_format
check_git_config

readonly out=$(git clang-format -v --diff)

if [[ "$out" == *"no modified files to format"* ]]; then exit 0; fi
if [[ "$out" == *"clang-format did not modify any files"* ]]; then exit 0; fi

echo "ERROR: the code to be committed is not formatted properly"
echo "you need to run \"git clang-format\" on your commit"
exit 1