#!/bin/bash
#
# Format C/C++ code using clang-format.
#
# To ensure reproducible formatting the script checks that clang-format
# is from the most recent version of LLVM supported by Scala Native.
#
# Usage: $0 [--test]
#
# Set CLANG_FORMAT_PATH to configure path to clang-format.

set -euo pipefail
IFS=$'\n\t'

# The required version of clang-format.
CLANG_FORMAT_VERSION=5.0
CLANG_FORMAT_VERSION_STRING="clang-format version $CLANG_FORMAT_VERSION"

die() {
  while [ "$#" -gt 0 ]; do
    echo >&2 "$1"; shift
  done
  exit 1
}

check_clang_format_version() {
  cmd="$1"
  [ -e "$(type -P "$cmd")" ] && \
    "$cmd" --version 2> /dev/null | grep -q "$CLANG_FORMAT_VERSION_STRING"
}

clang_format=

if [ -n "${CLANG_FORMAT_PATH:-}" ]; then
  check_clang_format_version "$CLANG_FORMAT_PATH" || \
    die "CLANG_FORMAT_PATH does not have required version $CLANG_FORMAT_VERSION" \
        "CLANG_FORMAT_PATH points to $CLANG_FORMAT_PATH"
  clang_format="$CLANG_FORMAT_PATH"
else
  for cmd in "clang-format-$CLANG_FORMAT_VERSION" clang-format; do
    if check_clang_format_version "$cmd"; then
      clang_format="$cmd"
      break
    fi
  done
fi

if [ -z "$clang_format" ]; then
  die "clang-format version $CLANG_FORMAT_VERSION not found" \
      "Install LLVM version $CLANG_FORMAT_VERSION and rerun."
fi

test_mode=

while [ "$#" -gt 0 ]; do
  arg="$1"
  case "$arg" in
    --test) test_mode=true; shift ;;
    --*)    die "Unknown argument: $arg" "Usage: $0 [--test]" ;;
    *)      break ;;
  esac
done

if [ "$#" -gt 0 ]; then
  "$clang_format" --style=file -i "$@"
else
  find . -name "*.[ch]" -or -name "*.cpp" | xargs "$clang_format" --style=file -i
fi

if [ "$test_mode" = true ]; then
  git diff --quiet --exit-code || \
    die "C/C++ code formatting changes detected" \
        "Run \`$0\` to reformat."
fi