#!/usr/bin/env bash
# pre-commit hook for degette project.
#
# Run formatters first, then checkers.
# Formatters which changed a file must set the flag 'formatter_updated'.

exit_code=0
formatter_updated=0
checker_dirty=0

printf "Stash all unstaged changes.\n"
git stash save --keep-index &> /dev/null
STAGED_PYTHON_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep ".py$")

# Formatter: black

printf "> black ... "

if type black &>/dev/null; then
    if [ -z "$STAGED_PYTHON_FILES" ]; then
        printf "OK\n"
    else
        BLACK_OUTPUT="/tmp/gc-black-output.log"
        touch $BLACK_OUTPUT

        if ! echo "$STAGED_PYTHON_FILES" | xargs -d'\n' black --check &>$BLACK_OUTPUT; then
            echo "$STAGED_PYTHON_FILES" | xargs -d'\n' black &>$BLACK_OUTPUT
            tail -1 $BLACK_OUTPUT
            formatter_updated=1
        else
            printf "OK\n"
        fi
    fi
else
    printf "SKIP: program not found\n"
    printf "HINT: Install black with 'pip3 install black' (black requires Python>=3.6)\n"
fi

# Formatter: isort

printf "> isort ... "

if type isort &>/dev/null; then
    if [ -z "$STAGED_PYTHON_FILES" ]; then
        printf "OK\n"
    else
        ISORT_OUTPUT="/tmp/gc-isort-output.log"
        touch $ISORT_OUTPUT

        if ! echo "$STAGED_PYTHON_FILES" | xargs -d'\n' isort --check-only &>$ISORT_OUTPUT; then
            echo "$STAGED_PYTHON_FILES" | xargs -d'\n' isort &>$ISORT_OUTPUT
            printf "Reformatted.\n"
            formatter_updated=1
        else
            printf "OK\n"
        fi
    fi
else
    printf "SKIP: program not found\n"
    printf "HINT: Install isort with 'pip install isort'\n"
fi

# Checker: flake8

printf "> flake8 ... "

if type flake8 &>/dev/null; then
    if [ -z "$STAGED_PYTHON_FILES" ]; then
        printf "OK\n"
    else
        FLAKE8_OUTPUT="/tmp/gc-flake8-output.log"
        touch $FLAKE8_OUTPUT

        # fix black incompatibility, sometimes flake8 is not PEP8-compliant
        if ! echo "$STAGED_PYTHON_FILES" | xargs -d'\n' flake8 --ignore=E203,W503 &>$FLAKE8_OUTPUT; then
            printf "FAIL\n"
            cat $FLAKE8_OUTPUT
            checker_dirty=1
        else
            printf "OK\n"
        fi
    fi
else
    printf "SKIP: program not found\n"
    printf "HINT: Install flake8 with 'pip install flake8'\n"
fi

# End

if [ $checker_dirty -ne 0 ]
then
    printf ">>> Checker(s) detect(s) issue(s)\n"
    printf "    You can still commit and push :)\n"
    printf "    Be warned that our CI may cause you more trouble.\n"
fi

# In some cases, black makes some changes that are reverted by isort:
# the second condition checks whether some changes have been made at the end of the day.
# Indeed, when this case applies, one cannot commit using this hook.
if [ $formatter_updated -ne 0 ]
then
    printf ">>> Working tree updated by formatter(s)\n"
    printf "    Add changes to staging area and retry.\n"
    exit_code=1
fi

printf "\n"

printf "Unstash all unstaged changes.\n"
git stash pop &> /dev/null

exit $exit_code