#!/usr/bin/env bash
# Identify host OS and execute package manager install command on input args
#

installpkg() {

	getOS() {

		# Widely supported method to retrieve host $ID
		if [[ -e /etc/os-release ]]; then
		    source /etc/os-release
		else
		    echo "No /etc/os-release found!"
		    echo "Your OS is unsupported!"
		    return 1
		fi
	}


	setCmdArr () {

		declare -ga CMD_ARR

		# Create OS-specific package install command arrays
		if [[ "$ID" == "fedora" ]]; then
			CMD_ARR=( "dnf" "install" "-y" )
		elif [[ "$ID" == "centos" && "$VERSION_ID" -ge 8 ]]; then
			CMD_ARR=( "dnf" "install" "-y" )
		elif [[ "$ID" == "centos" && "$VERSION_ID" -le 7 ]]; then
			CMD_ARR=( "yum" "install" "-y" )
		elif [[ "$ID" == "ubuntu" || "$ID" == "debian" ]]; then
			CMD_ARR=( "apt-get" "install" "-y" )
		elif [[ "$ID" == "arch" ]]; then
			CMD_ARR=( "pacman" "-Syu" )
		else
			echo "Your OS is currently unsupported! You are welcome to add your own and submit a PR."
			return 1
		fi

		# Append sudo if not running as root
		[[ "$(whoami)" != "root" ]] && CMD_ARR=( "sudo" "${CMD_ARR[@]}" )
	}


	installPackage() {

		# Check for input arguments
		if [[ "$#" -ge 1 ]]; then
			if ! "${CMD_ARR[@]}" "$@"; then
				echo "Installation failed!"
				return 1
			fi
		else
			echo "You must supply one or more packages to install!"
			return 1
		fi
	}


	main() {

		getOS && \
		setCmdArr && \
		installPackage "$@" && \
        unset CMD_ARR
	}

	main "$@"
}

if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
	installpkg "$@"
	exit $?
fi