#!/bin/bash

# This hook purpose is to keep coding style consistent between all developers
# It is automatically installed in .git/hooks folder by cmake on first run.

# From https://github.com/tatsuhiro-t/nghttp2/blob/master/pre-commit

function invalid-format-detected {
        cat git-clang-format.diff
        echo "*****************"
        echo "$0: Invalid coding style detected (see git-clang-format.diff for issues). Please correct it using one of the following:"
        echo "1) Apply patch located at git-clang-format.diff using:"
        echo "  cd $(git rev-parse --show-toplevel) && $1"
        echo "2) Use clang-format to correctly format source code using:"
        echo "  $2"
        echo "3) Reformat these lines manually."
        echo "*** Aborting commit.***"
        exit 1
}
function git-clang-format-diffing {
    format_diff=$(which git-clang-format)
    format_diff_options="--style=file"

    #only diffing commited files, ignored staged one
    $format_diff $format_diff_options --diff $(git --no-pager diff --cached --name-status | grep -v '^D' | cut -f2) > git-clang-format.diff

    if ! grep -q -E '(no modified files to format|clang-format did not modify any files)' git-clang-format.diff; then
        invalid-format-detected "git apply git-clang-format.diff" "clang-format $format_diff_options -i <some_file.c>"
    fi
}

function clang-format-diff-diffing {
    format_diff=$(find /usr/bin/ -name 'clang-format-diff*' -type f | tail -n1)
    format_diff_options="-style file"

    git diff-index --cached --diff-filter=ACMR -p HEAD -- | $format_diff $format_diff_options -p1 > git-clang-format.diff
    if [ -s git-clang-format.diff ]; then
        invalid-format-detected "patch -p0 < git-clang-format.diff" "${format_diff/-diff/} $format_diff_options -i <some_file.cpp>"
    fi
}

set -e
if which git-clang-format &>/dev/null; then
    git-clang-format-diffing $@
elif [ ! -z "$(find /usr/bin/ /usr/local/bin/ /opt/bin/ -name 'clang-format-diff*' -type f 2>/dev/null)" ]; then
    # Warning! We need at least version 1.6...
    clang-format-diff-diffing $@
else
    echo "$0: Please install clang-format (coding style checker) - could not find git-clang-format nor clang-format-diff in PATH. Skipping code verification..."
    exit 0
fi
