#!/usr/bin/env bash

#############
# Variables #
#############
# Define formatting variables
fb="$(tput bold)" ; readonly fb
fr="$(tput sgr0)" ; readonly fr

# Set sync primary location
syn_prime="" ; readonly syn_prime
# Set sync secondary location
syn_sec="" ; readonly syn_sec

# Create required variables array
required_vars=(
    'syn_prime'
    'syn_sec'
) ; readonly required_vars


#############
# Functions #
#############
display_usage() {
    local help_msg  # Define local variable
    help_msg="Usage: '${0}'

Purpose: Sync removable media drive.

Variables to set:
    syn_prime
        Primary sync directory.
    syn_sec
        Secondary sync directory."

    echo "${help_msg}"
}


# Verify object exists and is a directory
val_extant_dir() {
    local to_test
    to_test="${1}"
    [[ -d "${to_test}" ]] ; echo "${?}"
}


# Parse arguments
parse_args() {
    local parsed_args inv_ents

    parsed_args="$(getopt \
        -n "${0##*/}" \
        -o h \
        --long help \
        -- "${@}")"

    # Check for invalid entries
    inv_ents="${?}" ; readonly inv_ents
    if [[ "${inv_ents}" -ne 0 ]]; then
        echo ''
        display_usage
        exit 1
    fi

    # Set positional parameters using parsed argument string
    eval set -- "${parsed_args}"

    # Evaluate options
    while true; do
        case "${1}" in
            '-h' | '--help')
                display_usage
                exit 0
                ;;
            '--')
                ## End of options
                shift
                break
                ;;
        esac
    done
}


# Run initialization checks
run_init_cks() {
    local err_msg unset_vars required_var

    # Create unset variables array
    declare -a unset_vars
    # Verify that required variables are set
    for required_var in "${required_vars[@]}"; do
        if ! [[ "${!required_var}" ]]; then
            unset_vars+=("${required_var}")
        fi
    done
    # Exit script if variables are not set
    if [[ "${unset_vars[*]}" ]]; then
        err_msg='\nSet the following variable(s) before '
        err_msg+='running the script again:'
        echo -e "${err_msg}\n${fb}${unset_vars[*]}${fr}" 1>&2
        exit 1
    fi
}


# Define starting point for execution of the program
main() {
    parse_args "${@}"

    run_init_cks

    # Verify primary and secondary drive directories are present
    pass_or_fail_src="$(val_extant_dir "${syn_prime}")"
    pass_or_fail_des="$(val_extant_dir "${syn_sec}")"
    if [[ "${pass_or_fail_src}" -eq 0 && "${pass_or_fail_des}" -eq 0 ]]; then
        while true; do
            # Prompt for input, save to variable
            read -p 'Sync to (t) or from (f) secondary drive? ' -r syn_choice

            # Check for valid selection
            if [[ "${syn_choice}" == 't' || "${syn_choice}" == 'f' ]]; then
                break
            elif [[ "${syn_choice}" == 'q' ]]; then
                exit 0
            else
                err_msg='\nInvalid input. Try again or enter q to quit.'
                echo -e "${err_msg}" 1>&2
            fi
        done

        if [[ "${syn_choice}" == 't' ]]; then
            rsync \
                -aHAXx \
                --delete \
                --filter='-x security.selinux' \
                --info=progress2 \
                --inplace \
                --numeric-ids \
                "${syn_prime}/" "${syn_sec}/"
        elif [[ "${syn_choice}" == 'f' ]]; then
            rsync \
                -aHAXx \
                --delete \
                --filter='-x security.selinux' \
                --info=progress2 \
                --inplace \
                --numeric-ids \
                "${syn_sec}/" "${syn_prime}/"
        fi
    else
        err_msg='\nCheck that primary/secondary drive directories '
        err_msg+='are available.'
        echo -e "${err_msg}" 1>&2
        exit 1
    fi
}


###########
# Program #
###########
main "${@}"  # Start program

exit 0  # Exit script with successful exit status