## library of useful functions, usually prefixed with '_'

## ===============
## ARRAY Functions
## ===============

function _array_contains {
	local -n array=$1
	local element=$2
	[[ " ${array[@]} " =~ " ${element} " ]] && return 0 || return 1
}

function _array_intersect {
	local -n arr1=$1
	local -n arr2=$2
	local -n result=$3

	declare -A include
	for item in "${arr2[@]}"; do include["$item"]=1; done

	result=()
	for item in "${arr1[@]}"; do [[ -n ${include["$item"]} ]] && result+=("$item"); done
}

function _array_subtract {
	local -n arr1=$1   # First array
	local -n arr2=$2   # Array to subtract
	local -n result=$3 # Output array

	[[ ${#arr2[@]} == 0 ]] && result=("${arr1[@]}") && return

	declare -A exclude
	for item in "${arr2[@]}"; do exclude["$item"]=1; done

	result=()
	for item in "${arr1[@]}"; do [[ -z ${exclude["$item"]} ]] && result+=("$item"); done
}

## ==============
## TEXT Functions
## ==============

function _pluralize_simple {
	echo -n "$1 "
	[[ $1 -eq 1 || $1 -eq -1 ]] && echo ${2} || echo ${2}s
}

## ==============
## READ Functions
## ==============

function _confirm_destructive {
	local message="${1:-This cannot be undone!}"
	echo "⚠️  WARNING: $message"
	read -p "Type YES to confirm: " response
	case "$response" in
	[yY][eE][sS] | [yY]) return 0 ;;
	*) echo "canceled!" && return 1 ;;
	esac
}

## ==============
## Deprecated: FIXME: to remove
## ==============

##
# return 0 (true) if array (passed by name) contains element
# usage:
#   ARRAY=( a b c )
#   containsElement ARRAY 'a' => 0
function containsElement {
	isArray "$1" || (echo >&2 "ERROR: <$1> not an array!" && return 2)
	array_inter="$1[@]"
	array=("${!array_inter}")
	for i in "${array[@]}"; do [[ "$i" == "$2" ]] && return 0; done
	return 1
}

## return 0 (true) if arg1 (passed by name) is an array
function isArray {
	[[ "$(declare -p "$1" 2>/dev/null)" =~ "declare -a" ]] || return 1
}

function isDebian {
	grep ^ID=debian /etc/os-release
}

function isArch {
	grep ^ID=arch /etc/os-release
}

function os-release {
	grep ^ID= /etc/os-release | cut -d '=' -f2
}

function askConfirmation {
	case "$1" in
	y | Y | yes | YES)
		QUESTION="(Y/n)?"
		DEFAULT=0
		;;
	*)
		QUESTION="(y/N)?"
		DEFAULT=1
		;;
	esac
	read -rp "$QUESTION : " choice
	case "$choice" in
	y | Y | yes | YES) return 0 ;; #true
	n | no | N | NO) return 1 ;;   #false
	*) return $DEFAULT ;;
	esac
}