#!/bin/bash

# snap-pac
# https://github.com/wesbarnett/snap-pac
# Copyright (C) 2016, 2017, 2018 James W. Barnett
#
# 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 2 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

set -o errtrace

readonly argv0="snap-pac"
readonly SNAPPAC_CONFIG_FILE=/etc/snap-pac.conf
readonly SNAPPER_CONFIG_FILE=/etc/conf.d/snapper
readonly pacman_cmd="$(ps -q $(ps -p "$$" -o ppid=) -o args=)"
readonly pre_or_post=$1

out() { printf "$1 $2\n" "${@:3}"; }

error() { out "==> \033[00;31merror:\033[00m" "$@"; } >&2

die() { 
    [[ $ABORT_ON_FAIL == "no" ]] && exit 0
    exit 1
}

read_config() {
    CONFIG_FILE="$1"
    if [[ -f "$CONFIG_FILE" ]] && [[ -r "$CONFIG_FILE" ]]; then
        while IFS='= ' read lhs rhs; do
            if [[ ! $lhs =~ ^\ *# && -n $lhs ]]; then
                rhs="${rhs%%\#*}"
                rhs="${rhs%%*( )}"
                rhs="${rhs%\"*}"
                rhs="${rhs#\"*}"
                declare -g $lhs="$rhs"
            fi
        done < "$CONFIG_FILE"
    fi
}


trapkill() { 
    error "Exited due to user intervention."
    die
}

traperror() {
    error "Exited due to error on line $1"
    out "exit status:" "$2"
    out "command:" "$3"
    out "bash line:" "$4"
    out "function argv0:" "$5"
    die
}

truncate_description() {
    desc="$@"
    if [[ "${#desc}" -gt $DESC_LIMIT ]]; then 
        echo "$(echo $desc | cut -c 1-$DESC_LIMIT)..."
    else
        echo $desc
    fi
}

trap 'traperror ${LINENO} $? "$BASH_COMMAND" $BASH_LINENO "${FUNCNAME[@]}"' ERR
trap trapkill SIGTERM SIGINT

readonly -f read_config out error die trapkill traperror truncate_description

SNAPPER_CONFIGS=$(awk -F'=' '/SNAPPER_CONFIGS/ {gsub(/"/, "", $2); print $2}' "$SNAPPER_CONFIG_FILE")

read_config "$SNAPPAC_CONFIG_FILE"

readonly DESC_LIMIT=${DESC_LIMIT:-48}
readonly ABORT_ON_FAIL=${ABORT_ON_FAIL:-"no"}

for CONFIG in $SNAPPER_CONFIGS; do

    unset SNAPSHOT
    unset PRE_DESCRIPTION
    unset POST_DESCRIPTION
    unset CLEANUP_ALGORITHM

    read_config "/etc/snap-pac/$CONFIG.conf"

    if [[ $CONFIG == "root" ]]; then 
        SNAPSHOT=${SNAPSHOT:-"yes"}
    else
        SNAPSHOT=${SNAPSHOT:-"no"}
    fi
    PRE_DESCRIPTION=${PRE_DESCRIPTION:-"$pacman_cmd"}
    POST_DESCRIPTION=${POST_DESCRIPTION:-"$pacman_cmd"}
    CLEANUP_ALGORITHM=${CLEANUP_ALGORITHM:-"number"}

    [[ $SNAPSHOT == "no" ]] && continue

    prefile="/tmp/$argv0-pre_$CONFIG"
    snapper_cmd="snapper --config $CONFIG create --type $pre_or_post --cleanup-algorithm $CLEANUP_ALGORITHM --print-number --description"

    if [[ "$pre_or_post" == "pre" ]]; then
        x=$($snapper_cmd "$(truncate_description $PRE_DESCRIPTION)")
        printf "==> %s: $(echo $x | tee "$prefile")\n" "$CONFIG"
    elif [[ -f $prefile && "$pre_or_post" == "post" ]]; then
        x=$($snapper_cmd "$(truncate_description $POST_DESCRIPTION)" --pre-number "$(< "$prefile")")
        printf "==> %s: %s\n" "$CONFIG" "$x"
        rm -f "$prefile"
    fi

done

exit 0