#!/usr/bin/env bash

# All the prefixes to consider
prefixes=(
	"$HOME"
	"$HOME/.local.$(uname -m)"
	"$HOME/.local"
	"$HOME/.prefix.$(uname -m)"
	"$HOME/.prefix"
	"$HOME"/.gem/ruby/*
	"$HOME"/.npm-prefix
	"$HOME"/go
)

in_array() {
	local needle=$1; shift
	local haystack=("$@")
	local straw
	for straw in "${haystack[@]}"; do
		[[ "$needle" == "$straw" ]] && return 0
	done
	return 1
}

var_init() {
	eval "ary_$1=(\$$1)"
}

var_add() {
	local varname=ary_$1; shift
	local var_all="${varname}[@]"
	local dirs=("$@")

	local dir
	for dir in "${dirs[@]}"; do
		if [[ -d "$dir" ]] && ! in_array "$dir" "${!var_all}"; then
			eval "$varname=(\"\$dir\" \"\${$var_all}\")"
		fi
	done
}

var_done() {
	local var=$1
	local valref="ary_${var}[*]"
	printf '%s=%q\n' "${var}" "${!valref}"
}

main() {
	IFS=:

	# Import existing values
	var_init PATH
	var_init LD_LIBRARY_PATH
	var_init PKG_CONFIG_PATH
	var_init RUBYLIB
	var_init PERL5LIB

	# Scan through prefixes
	for prefix in "${prefixes[@]}"; do
		var_add PATH "$prefix/bin" "$prefix/sbin"
		var_add LD_LIBRARY_PATH "$prefix"/lib{,32,64}
		var_add PKG_CONFIG_PATH "$prefix"/lib{,32,64}/pkgconfig
		var_add RUBYLIB         "$prefix"/lib{,32,64}
		var_add PERL5LIB        "$prefix"/lib{,32,64}/perl5
	done

	# Finally, print the values
	for var in PATH LD_LIBRARY_PATH PKG_CONFIG_PATH RUBYLIB PERL5LIB; do
		var_done "$var"
	done
}

main "$@"