Setup Development Environment.bash

#!/usr/bin/env bash
# shellcheck disable=SC2034

# Setup environment suitable for developing the project
# 林博仁 © 2017,2018

## Makes debuggers' life easier - Unofficial Bash Strict Mode
## BASHDOC: Shell Builtin Commands - Modifying Shell Behavior - The Set Builtin
set -o errexit
set -o errtrace
set -o nounset
set -o pipefail

## Runtime Dependencies Checking
declare \
    runtime_dependency_checking_result=still-pass \
    required_software

for required_command in \
    basename \
    dirname \
    realpath; do
    if ! command -v "${required_command}" &>/dev/null; then
        runtime_dependency_checking_result=fail

        case "${required_command}" in
            basename | \
                dirname | \
                ln | \
                realpath)
                required_software='GNU Coreutils'
                ;;
            git)
                required_software='Git'
                ;;
            *)
                required_software="${required_command}"
                ;;
        esac

        printf -- \
            'Error: This program requires "%s" to be installed and its executables in the executable searching paths.\n' \
            "${required_software}" \
            1>&2
        unset required_software
    fi
done
unset required_command required_software

if [ "${runtime_dependency_checking_result}" = fail ]; then
    printf -- \
        'Error: Runtime dependency checking fail, the progrom cannot continue.\n' 1>&2
    exit 1
fi
unset runtime_dependency_checking_result

## Non-overridable Primitive Variables
## BASHDOC: Shell Variables » Bash Variables
## BASHDOC: Basic Shell Features » Shell Parameters » Special Parameters
if [ -v 'BASH_SOURCE[0]' ]; then
    RUNTIME_EXECUTABLE_PATH="$(realpath --strip "${BASH_SOURCE[0]}")"
    RUNTIME_EXECUTABLE_FILENAME="$(basename "${RUNTIME_EXECUTABLE_PATH}")"
    RUNTIME_EXECUTABLE_NAME="${RUNTIME_EXECUTABLE_FILENAME%.*}"
    RUNTIME_EXECUTABLE_DIRECTORY="$(dirname "${RUNTIME_EXECUTABLE_PATH}")"
    RUNTIME_COMMANDLINE_BASECOMMAND="${0}"
    declare -r \
        RUNTIME_EXECUTABLE_FILENAME \
        RUNTIME_EXECUTABLE_DIRECTORY \
        RUNTIME_EXECUTABLE_PATHABSOLUTE \
        RUNTIME_COMMANDLINE_BASECOMMAND
fi
declare -ar RUNTIME_COMMANDLINE_ARGUMENTS=("${@}")

## init function: entrypoint of main program
## This function is called near the end of the file,
## with the script's command-line parameters as arguments
init() {
    if ! process_commandline_arguments; then
        printf -- \
            'Error: %s: Invalid command-line parameters.\n' \
            "${FUNCNAME[0]}" \
            1>&2
        print_help
        exit 1
    fi

    export \
        GIT_DIR="${RUNTIME_EXECUTABLE_DIRECTORY}/.git" \
        GIT_WORK_TREE="${RUNTIME_EXECUTABLE_DIRECTORY}"
    git config \
        --local \
        include.path \
        ../.gitconfig

    printf \
        '\n%s: All set, happy hacking! :-)\n' \
        "${RUNTIME_EXECUTABLE_NAME}"
    exit 0
}
declare -fr init

print_help() {
    printf 'Currently no help messages are available for this program\n' 1>&2
    return 0
}
declare -fr print_help

process_commandline_arguments() {
    if [ "${#RUNTIME_COMMANDLINE_ARGUMENTS[@]}" -eq 0 ]; then
        return 0
    fi

    # modifyable parameters for parsing by consuming
    local -a parameters=("${RUNTIME_COMMANDLINE_ARGUMENTS[@]}")

    # Normally we won't want debug traces to appear during parameter parsing, so we  add this flag and defer it activation till returning(Y: Do debug)
    local enable_debug=N

    while true; do
        if [ "${#parameters[@]}" -eq 0 ]; then
            break
        else
            case "${parameters[0]}" in
                --help | \
                    -h)
                    print_help
                    exit 0
                    ;;
                --debug | \
                    -d)
                    enable_debug=Y
                    ;;
                *)
                    printf 'ERROR: Unknown command-line argument "%s"\n' "${parameters[0]}" >&2
                    return 1
                    ;;
            esac
            # shift array by 1 = unset 1st then repack
            unset 'parameters[0]'
            if [ "${#parameters[@]}" -ne 0 ]; then
                parameters=("${parameters[@]}")
            fi
        fi
    done

    if [ "${enable_debug}" = Y ]; then
        trap 'trap_return "${FUNCNAME[0]}"' RETURN
        set -o xtrace
    fi
    return 0
}
declare -fr process_commandline_arguments

## Traps: Functions that are triggered when certain condition occurred
## Shell Builtin Commands » Bourne Shell Builtins » trap
trap_errexit() {
    printf 'An error occurred and the script is prematurely aborted\n' 1>&2
    return 0
}
declare -fr trap_errexit
trap trap_errexit ERR

trap_exit() {
    return 0
}
declare -fr trap_exit
trap trap_exit EXIT

trap_return() {
    local returning_function="${1}"

    printf 'DEBUG: %s: returning from %s\n' "${FUNCNAME[0]}" "${returning_function}" 1>&2
}
declare -fr trap_return

trap_interrupt() {
    printf '\n' # Separate previous output
    printf 'Recieved SIGINT, script is interrupted.' 1>&2
    return 1
}
declare -fr trap_interrupt
trap trap_interrupt INT

init "${@}"

## This script is based on the GNU Bash Shell Script Template project
## https://github.com/Lin-Buo-Ren/GNU-Bash-Shell-Script-Template
## and is based on the following version:
## GNU_BASH_SHELL_SCRIPT_TEMPLATE_VERSION="v3.0.9"
## You may rebase your script to incorporate new features and fixes from the template