#!/usr/bin/env bash

# yadm - Yet Another Dotfiles Manager
# Copyright (C) 2015-2019 Tim Byrne and Martin Zuther

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.


YADM_DIRECTORY=$(dirname $YADM_HOOK_REPO)
YADM_CHECKSUMS=$YADM_DIRECTORY/files.checksums

CHECKSUM_ALGORITHM="512256"
CHECKSUM_ALGORITHM_NAME="SHA-512/256"
WARNING_MESSAGE="No checksums were created."


function print_warning_and_exit {
    MESSAGE=$1

    # set output color to yellow
    echo -e "\033[1;33m"
    echo "WARNING: $MESSAGE  $WARNING_MESSAGE"

    # reset output color
    echo -e "\033[0m"

    exit $YADM_HOOK_EXIT
}


function ensure_command {
    COMMAND_NAME=$1

    # check if command exists
    if ! command -v "$COMMAND_NAME" > /dev/null; then
        print_warning_and_exit "command \"$COMMAND_NAME\" not found."
    fi
}


function ensure_algorithm {
    # check if "shasum" supports algorithm
    echo -n | shasum --algorithm "$CHECKSUM_ALGORITHM" &> /dev/null

    if [ $? -ne 0 ]; then
        print_warning_and_exit "\"shasum\" does not support $CHECKSUM_ALGORITHM_NAME."
    fi
}


# check if "shasum" exists and supports algorithm
ensure_command shasum
ensure_algorithm

# empty checksum file
echo -n > $YADM_CHECKSUMS

# calculate checksums for encrypted files
for included in ${YADM_ENCRYPT_INCLUDE_FILES[@]}; do
    shasum --algorithm $CHECKSUM_ALGORITHM $included >> $YADM_CHECKSUMS

    # signal errors
    if [ $? -ne 0 ]; then
        exit $?
    fi
done

echo "Wrote checksums: $YADM_CHECKSUMS ($CHECKSUM_ALGORITHM_NAME)"

# return exit status of the yadm command
exit $YADM_HOOK_EXIT