#!/usr/bin/env bash

# bafscript -- backup automation micro-framework.
# Copyright (c) 2022 ge <https://nixhacks.net/>
#
# 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/>.

__version='0.0.0'
__config=
__verbose=
__log_file='./log.txt'
__log_date_fmt='%d/%b/%Y:%H:%M:%S %z'
__tar_options='-acf'
__tar_compression='gzip'
__name_date_fmt='_%Y%m%d-%H%M'

if [ -n "$BAFLIB" ]; then
    __library="$BAFLIB"
else
    __library='./lib'
fi

# Source library
for file in "$__library"/*; do
    . "$file"
done

print_help() {
    cat <<- EOF
Backup files and databases.

Usage: $0 [-cvlhV] ARGUMENTS..

Options:
    -c, --config    config file.
    -v, --verbose   verbose output.
    -l, --log-file  log file.
    -h, --help      print this help messagea and exit.
    -V, --version   print version and exit.

Environment:
    BAFLIB          path to baf library [current: $__library]
EOF
}

# ---------------------------------------------------------- #
# * CLI Arguments Parser                                     #
# ---------------------------------------------------------- #

optval() {
    # GNU-style CLI options parser.
    #
    # Parse --opt VAL and --opt=VAL options.
    # Requires 2 arguments: $1, $2.
    # Return variables:
    #   opt     option name.
    #   val     option value.
    #   sft     value for shift.

    if [[ "$1" =~ .+=.+ ]]; then
        opt="${1%%=*}"; val="${1#*=}"; sft=1
    elif [[ ! "$1" =~ .+=$ ]] && [ "$2" ] && [ "${2:0:1}" != "-" ]; then
        opt="$1"; val="$2"; sft=2
    else
        opt="$1"
        if [[ "$1" =~ .+=$ ]]; then opt="${1:0: -1}"; fi
        echo "Error: Missing argument for $opt" >&2; exit 1
    fi
}

# Print help if no arguments passed
[[ "$#" == 0 ]] && { print_help; exit 1; }

# Split combined short options, e.g. '-abc' to '-a' '-b' '-c'
for args in "$@"; do
    shift
    case "$args" in
        --*)
            set -- "$@" "$args";; # save long options
        -*)
            args="$(echo "${args:1}" | grep -o . | xargs -I {} echo -n '-{} ')"
            set -- "$@" $args;;
        *)
            set -- "$@" "$args";;  # save positional arguments
    esac
done

# Final arguments parser
while (( "$#" )); do
    case "$1" in
        -c|--config|--config=*) optval "$1" "$2"; __config="$val"; shift "$sft";;
        -v|--verbose) __verbose=1; shift;;
        -l|--log-file|--log-file=*) optval "$1" "$2"; __log_file="$val"; shift "$sft";;
        -h|--help) print_help; exit 1;;
        -V|--version) echo "$__version"; exit 0;;
        -*) echo "Error: Unknown option: $1" >&2; exit 1;;
        *)  __args+=("$1"); shift;; # Save positional args
    esac
done

# ---------------------------------------------------------- #
# * Do backups                                               #
# ---------------------------------------------------------- #

# Scripts counter.
__count=${#__args[@]}    # count
__iter=1                 # iterator

# Startup log.
date +'Start: %d %b %Y %T %z'
log "Backup STARTED"
log -p "Configuration file: $([ "$__config" ] || echo not specified && echo "$__config")"
log "Scripts to process (${__count}): ${__args[@]}"


for script in "${__args[@]}"; do
    # Source scripts
    source_script "$script"
    # Config can ovewrite script functions and variables
    [ -n "$__config" ] && . "$__config"

    echo
    echo -e "\e[1m==> Script: ${__args[__iter-1]##*/} [$__iter/$__count]\e[0m" | log -p

    # Initialise variables
    __user_script="$script"
    backups=()  # Array of created backups, contains full pathes

    # Run prepare() before all if set
    if is_function_set prepare; then
        log -p "Execute prepare() ..."
        prepare
        unset prepare
    fi

    # Run user defined backup() if set or builtin_backup()
    if is_function_set backup; then
        echo -e "Execute \e[1mbackup()\e[0m ..." | log -p
        backup
        unset backup
    else
        echo -e "Execute \e[1mbuiltin_backup()\e[0m ..." | log -p
        builtin_backup
    fi

    # Run post backup function if set
    if is_function_set finalise; then
        echo -e "Execute \e[1mfinalise()\e[0m ..." | log -p
        finalise
        unset finalise
    fi

    # Increase counter
    ((__iter++)) || true

    # Unset user defined variables
    unset tar_options
    unset tar_compression
    unset name_date_fmt
done

log "Backup FINISHED"
echo -e "\nBackup [Done]"