#!/bin/bash

# Desc: Checks that a valid tar archive exists, creates one otherwise

# Yell, Die, Try Three-Fingered Claw technique
# Ref/Attrib: https://stackoverflow.com/a/25515370
yell() { echo "$0: $*" >&2; }
die() { yell "$*"; exit 111; }
try() { "$@" || die "cannot $*"; }

checkTar() {
    # Desc: Checks that a valid tar archive exists, creates one otherwise
    # Usage: checkTar [ path ]
    # Input: arg1: path of tar archive
    # Output: exit code 0: tar exists and is valid
    # Depends: try, tar, date
    local PATH_TAR="$1"

    # Check if file is a valid tar archive
    if tar --list --file="$PATH_TAR" 1>/dev/null 2>&1; then
	## T1: return success
	return 0;
    else
	## F1: Check if file exists
	if [[ -f "$PATH_TAR" ]]; then
	    ### T: Rename file
	    try mv "$PATH_TAR" "$PATH_TAR""--broken--""$(date +%Y%m%dT%H%M%S)";
	else
	    ### F: -
	    :
	fi
	## F2: Create tar archive
	try tar --create --file="$PATH_TAR" --files-from=/dev/null;
    fi
} # checks if arg1 is tar; creates one otherwise