#!/bin/bash
# Made by Matthias Quintern
# 02/2022
# This software comes with no warranty.

# ABOUT
# Synchronizes files from a sender to a receiver using rsync
# The files can be encrypted before or decrypted after the transfer using the mkrypt script

#
# SETTINGS
#
# The directory that is searched for config files
CONFIG_DIR=~/.config/msynk/
# When using encrypt/decrypt, the source is en/decrypted to TMP_DIR and then rsynced to receiver from there
# Path must contain 'msynk'
TMP_DIR=/tmp/msynk/
# When using --delete, this file is used to determine the files that will be deleted
TMP_FILE=/tmp/msynk_file
# Path to the mkrypt script
mkrypt=/usr/bin/mkrypt
# Additional flags for mkrypt
mkrypt_flags=

rsync_flags=(-ruvh)
# rsync_flags+=(--rsh="ssh -p 69")
# r - relative
# v - verbose
# Ut - preserve modification&access times
# u - update, skip files that are newer on the receiver
# P - show progress and keep partially transferred files
# h - human readable
# see "man rsync" for more


#
# UTILITY
#
FMT_MESSAGE="\e[1;34m%s\e[0m\n"
FMT_ERROR="\e[1;31mERROR: \e[0m%s\n"
FMT_SYNC="\e[1;32m:Syncing\e[0m %s\n"
# FMT_UPDATE="\e[1;33mUpdating:\e[0m %s\n"
FMT_CONFIG="\e[34m%s\e:\t\e[1;33m%s\e[0m\n"

quiet() { "$@" > /dev/null 2>&1; }

# check if a passed parameter is contained in file
check_path_in_args()
{
    if [ $all = 1 ]; then
        return 0
    fi
    for string in ${FILES[@]}; do
        if [[ $path == *$string* ]]; then
            return 0
        fi
    done
    return 1
}


#
# sync sender to receiver
#
sync_sender_to_receiver()
{
    # perform a dry run to see which files would be deleted
    if [[ -n $delete && -z $skip_dryrun ]]; then
        [[ $v -ge 1 ]] && printf "$FMT_MESSAGE" "Performing dryrun to generate list of files that will be deleted from $receiver..."
        echo "" > $TMP_FILE
        for path in "${filtered_paths[@]}"; do
            dest_subdir=$receiver$(basename $path)
            rsync $rsync_flags -v --dry-run --delete $path $dest_subdir | grep deleting | sed "s(deleting (${BACKUP_SUBDIR}/(" >> $TMP_FILE
        done
        # print files that will be deleted and ask if continue
        # grep deleting $TMP_FILE | sed "s(deleting (${receiver}/(" | less
        less $TMP_FILE 

        printf "$FMT_MESSAGE" "The listed files will be deleted from $receiver."
        # FMT_UPDATE="\e[1;33mUpdating:\e[0m %s\n"
        printf "Proceed?\e[34m (y/n)\e[0m: "
        read answer
        case $answer in
            y|Y)
                # printf "$FMT_MESSAGE" "Backing up to $receiver..."
                ;;
            *)
                printf "$FMT_MESSAGE" "Cancelled."
                exit 0 ;;
        esac
    fi

    # actual syncing
    for path in "${filtered_paths[@]}"; do
        [[ $v -ge 1 ]] && printf "$FMT_SYNC" "$path"
        if [[ -d $path ]]; then
            dest=$receiver$(basename $path)
        elif [[ -f $path ]]; then
            dest=$receiver
        elif [[ $sender == *@*:* ]]; then  # if sender is remote, assume the path is a dir if it has a slash and a file otherwise
            [[ $path == *"/" ]] && dest=$receiver$(basename $path) || dest=$receiver
        else
            printf "$FMT_ERROR" "Invalid path: $path"; exit 1
        fi
        if [[ -n $encrypt || -n $decrypt ]]; then
            [[ -d $path ]] && tmp_source=$TMP_DIR

            if [[ -n $encrypt ]]; then
                [[ -f $path ]] && tmp_source=$TMP_DIR$(basename $path).gpg
                [[ $v -ge 3 ]] && printf "$FMT_CMD" "bash $mkrypt --encrypt $path --output $TMP_DIR $mkrypt_flags"
                bash $mkrypt --encrypt $path --output $TMP_DIR $mkrypt_flags || exit 1
                [[ $v -ge 3 ]] && printf "$FMT_CMD" "rsync ${rsync_flags[@]} $tmp_source $dest"
                rsync "${rsync_flags[@]}" $tmp_source $dest
            else
                [[ -f $path ]] && tmp_source=$TMP_DIR$(basename $path)
                [[ $v -ge 3 ]] && printf "$FMT_CMD" "rsync ${rsync_flags[@]} $path $TMP_DIR"
                rsync "${rsync_flags[@]}" $path $TMP_DIR
                [[ $v -ge 3 ]] && printf "$FMT_CMD" "bash $mkrypt --decrypt $tmp_source --output $(readlink -f $dest) $mkrypt_flags"
                bash $mkrypt --decrypt $tmp_source --output $(readlink -f $dest) $mkrypt_flags || exit 1
            fi
        else
            printf "$FMT_CMD" "rsync ${rsync_flags[@]} $delete $path $dest"
            rsync "${rsync_flags[@]}" $delete $path $dest
        fi
        [[ $TMP_DIR == *msynk* ]] && { 
            rm -rf $TMP_DIR/* || { printf "$FMT_ERROR" "Can not delete \$TMP_DIR: $TMP_DIR"; exit 1; }
        } || { printf "$FMT_ERROR" "Will not delete \$TMP_DIR because it might be dangerous (path does not contain 'msynk'): $TMP_DIR"; exit 1; }
    done

    [[ $v -ge 2 ]] && printf "$FMT_MESSAGE" "Running 'sync' to write cached writes to persistent storage"
    sync
    [[ $v -ge 1 ]] && printf "$FMT_MESSAGE" "Done!"
}
    

#
# HELP
#
show_help()
{
    printf "\e[33mArgument        Short   Action:\e[0m
--help              -h      show this
--settings          -s      show current settings

--config [name]     -c      use sender, receiver, paths from config file with [name]

--sender [path]     -s      sender directory, with trailing slash! Defaults to the current working directory
--receiver [path]   -r      receiver directory, with trailing slash!
--reverse                   swap receiver and sender

--encrypt                   encrypt files before syncing
--decrypt                   decrypt files before syncing
--mkrypt-flags [flags]      additional flags for mkrypt

--delete            -d      delete files that exist on receiver, but not on sender
--skip-dryrun               delete without asking first
--rsync-flags [flags]       additional flags for rsync

--verbose           -v      increase verbosity
--silent                    decrease verbosity
--debug                     maximum verbosity

Positional arguments are: 
- if using a config: a string that must be in the configs paths: eg. 'foo' will include ~/foo but nor ~/bar
- if not using a config: paths to sync (must be relative to --sender)

See the manpage for more information.
"
}


show_settings()
{
    printf "\e[1mThe current settings are:\e[0m\n"
    printf "$FMT_CONFIG" "\$TMP_FILE        " "$TMP_FILE"
    printf "$FMT_CONFIG" "\$rsync_flags     " "${rsync_flags[*]}"
}


#
# PARSE ARGS
#
if [ -z $1 ]; then
    show_help
    exit 0
fi



all=0
BACKUP=1  # use if the script gets more functions later
# all command line args with no "-" are interpreted as part of filepaths. 
paths_2=()
while (( "$#" )); do
    case "$1" in
        -h|--help)
            show_help
            exit 0 ;;
        --settings)
            show_settings
            exit 0 ;;
        -c|--config)
            if [[ -n $2 && ${2:0:1} != "-" ]]; then
                config=$2
                shift 2
            else printf "$FMT_ERROR" "Missing argument for $1"; exit 1; fi ;;
        -s|--sender)
            if [[ -n $2 && ${2:0:1} != "-" ]]; then
                sender_2=$2
                shift 2
            else printf "$FMT_ERROR" "Missing argument for $1"; exit 1; fi ;;
        -r|--receiver)
            if [[ -n $2 && ${2:0:1} != "-" ]]; then
                receiver_2=$2
                shift 2
            else printf "$FMT_ERROR" "Missing argument for $1"; exit 1; fi ;;
        --reverse)
            reverse=1
            shift ;;
        --encrypt)
            encrypt=1
            shift ;;
        --decrypt)
            decrypt=1
            shift;;
        -d|--delete)
            delete=--delete
            shift ;;
        --skip-dryrun)
            skip_dryrun=1
            shift ;;
        --rsync-flags)
            if [[ -n ${2} ]]; then  # && "${2:0:1}" != "-" ]]; then  # possibly problematic if $2 is an msynk flag
                rsync_flags+=("${2}")
                shift 2
            else printf "$FMT_ERROR" "Missing argument for $1"; exit 1; fi ;;
        --msynk-flags)
            if [[ -n ${2} ]]; then  # && "${2:0:1}" != "-" ]]; then  # possibly problematic if $2 is an msynk flag
                mkrypt_flags+=("${2}")
                shift 2
            else printf "$FMT_ERROR" "Missing argument for $1"; exit 1; fi ;;
        -v|--verbose)
            v=2
            rsync_flags+=(-v)
            mkrypt_flags+=(-v)
            shift ;;
        --silent)
            v=0
            mkrypt_flags+=(--silent)
            shift ;;
        --debug)
            v=3
            rsync_flags+=(-v)
            mkrypt_flags+=(-v)
            shift;;
        -*|--*=) # unsupported flags
            printf "$FMT_ERROR" "Unsupported flag $1" >&2
            exit 1 ;;
        *) # everything that does not have a - is interpreted as filepath
            all=
            paths_2+=($1)
            shift ;;
    esac
done

# check if rsync is installed
if ! command -v rsync &> /dev/null; then
    printf "$FMT_ERROR" "rsync is not installed."
fi

# if using a config
if [[ -n $config ]]; then
    bash $CONFIG_DIR/$config || { printf "$FMT_ERROR" "Error running the config file: $CONFIG_DIR/$config"; exit 1; }
fi

# overwrite stuff from the config if anything else was given / set variables of no config was given
[[ -n $sender_2 ]] && sender=$sender_2
[[ -n $receiver_2 ]] && receiver=$receiver_2
[[ -z $sender ]] && {
    [[ $v -ge 1 ]] && printf "$FMT_MESSAGE" "Missing sender. Using working directory: $(pwd)"; 
    sender="$(pwd)/"
}

# reverse: swap sender and reveiver
if [[ -n $reverse ]]; then
    tmp_sender=$sender
    sender=$receiver 
    receiver=$tmp_sender
fi

# make sure sender is absolute with slash
wd=$PWD
# quiet cd $sender && sender="$PWD/" || { printf "$FMT_ERROR" "Sender directory does not exist: $sender"; exit 1; }
# make sure reveiver is absolute
# cd $wd
# mkdir -p $receiver || { printf "$FMT_ERROR" "Can not create config dir: $receiver"; exit 1; }
# quiet cd $receiver && receiver="$PWD/" || { printf "$FMT_ERROR" "Receiver directory does not exist: $receiver"; exit 1; }
# make sure receiver has trailing slash
[[ $receiver != *"/" ]] && receiver=$receiver"/"

echo "sender:$sender rec:$receiver paths=$paths paths2=$paths_2"

# filter paths: 
# - if using config: all paths from config that have a pos.arg in them
# - else: pos.args, must be relative to specified --sender
filtered_paths=()
if [[ -n $config ]]; then
    for path in ${paths[@]}; do
        if check_path_in_args; then
            filtered_paths+=($sender$path)
        fi
    done
else
    for path in ${paths_2[@]}; do  # add slash if directory
    #     quiet cd $sender
        [[ -d $path ]] && [[ $path != *"/" ]] && path=$path"/"
    #     quiet cd $sender && quiet cd $path && filtered_paths+=($PWD/) || {
    #         quiet cd $sender && ls -d $path && filtered_paths+=($PWD/$path)
    #     }
        filtered_paths+=($sender$path)
    done
fi
cd $wd
echo "FPaths: ${filtered_paths[@]}"

# sanity checks
[[ -z $filtered_paths ]] && { printf "$FMT_ERROR" "Missing valid paths."; exit 1; }
[[ -z $receiver ]] && { printf "$FMT_ERROR" "Missing receiver. Specifiy with --receiver"; exit 1; }

sync_sender_to_receiver
exit 0