#!/bin/bash
#########################################################################################################
#                                   GIT PRECOMMIT HOOK                                                  #
# This script checks if the formatting of .cpp and .hpp files is correct and                            #
# proposes to fix it automatically, let the user do it or ignore the formatting (don't do it!).         #
#                                                                                                       #
# This file has been entirely copied from Switcher's sources: https://github.com/sat-mtl/tools/switcher #
#                                                                                                       #
#########################################################################################################

##################################
# Global variables
CLANG_FORMAT="clang-format"
CLANG_FORMAT_DIFF="clang-format-diff"
files_unformatted=""
cpp_files=()
###################################

##################################
# Helpers

reformat_file() {
  while true
  do
    read -p "Do you want to do the reformatting (M)anually or let it be done (A)utomatically? [m/A]" reply < /dev/tty
    case $reply in
      [Mm]) echo -e "Commit will be aborted, awaiting reformatting of \e[0;32m${file}\e[0m."; files_unformatted+="\t\e[0;32m$1\e[0m\n"; return;;
      "") ;& # Fallthrough default behaviour, the reformatting is automatic.
      [Aa]) echo -e "Automatic reformatting of \e[0;32m${file}\e[0m will be done now."; git diff --cached -U0 $1 | ${CLANG_FORMAT_DIFF} -i -p1; git add $1; return;;
      *) echo "Unrecognized option." ;;
    esac
  done
}

final_check() {
  echo -e "\n\nThe following files are not correctly formatted:"
  echo -e $files_unformatted

  while true
  do
    read -p "Do you want to (I)gnore the formatting and commit anyway (not recommended) or do the reformatting (Y)ourself ? [i/Y]" reply < /dev/tty
    case $reply in
      [Ii]) echo "Ignoring the formatting and committing files as-is."; exit 0;;
      "") ;& # Fallthrough default behaviour, the commit is aborted.
      [Yy]) echo "Commit aborted, awaiting reformatting of the previously listed files."; exit 1;;
      *) echo "Unrecognized option." ;;
    esac
  done
}

check_command() {
  if ! type $1 > /dev/null
  then
    echo "Error: $1 executable not found."
    exit 1
  fi
}
##################################

##################################
# Main

check_command $CLANG_FORMAT
check_command $CLANG_FORMAT_DIFF

cpp_files=$(git diff --cached --name-only --diff-filter=ACM | grep '\.cpp$\|\.hpp$\|\.h$')

# Nothing to test if no file was added, changed or modified.
[ -z "$cpp_files" ] && exit 0

for file in $cpp_files
do
  output=$(${CLANG_FORMAT} ${file} -style=file -output-replacements-xml | grep "<replacement " > /dev/null)
  if [ $? -ne 1 ]
  then
    echo -e "\e[0;31m${file} does not conform to coding standards, here are the changes needed:\n\n\e[0m$(git diff --cached -U0 ${file} | ${CLANG_FORMAT_DIFF} -p1)"
    reformat_file $file
  fi
done

## All .[c|h]pp files are properly formatted.
[ -z "$files_unformatted" ] && exit 0

final_check

##################################