#!/bin/sh
# readlink -f replacement for macOS
# taken from https://github.com/mkropat/sh-realpath (MIT licenced)

# The MIT License (MIT)

# Copyright (c) 2014 Michael Kropat

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

realpath() {
	canonicalize_path "$(resolve_symlinks "$1")"
}

resolve_symlinks() {
	_resolve_symlinks "$1"
}

_resolve_symlinks() {
	_assert_no_path_cycles "$@" || return

	local dir_context
	local path
	path=$(readlink -- "$1")
	if [ $? -eq 0 ]; then
		dir_context=$(dirname -- "$1")
		_resolve_symlinks "$(_prepend_dir_context_if_necessary "$dir_context" "$path")" "$@"
	else
		printf '%s\n' "$1"
	fi
}

_prepend_dir_context_if_necessary() {
	if [ "$1" = . ]; then
		printf '%s\n' "$2"
	else
		_prepend_path_if_relative "$1" "$2"
	fi
}

_prepend_path_if_relative() {
	case "$2" in
	/*) printf '%s\n' "$2" ;;
	*) printf '%s\n' "$1/$2" ;;
	esac
}

_assert_no_path_cycles() {
	local target
	local path

	target=$1
	shift

	for path in "$@"; do
		if [ "$path" = "$target" ]; then
			return 1
		fi
	done
}

canonicalize_path() {
	if [ -d "$1" ]; then
		_canonicalize_dir_path "$1"
	else
		_canonicalize_file_path "$1"
	fi
}

_canonicalize_dir_path() {
	(cd "$1" 2> /dev/null && pwd -P)
}

_canonicalize_file_path() {
	local dir
	local file
	dir=$(dirname -- "$1")
	file=$(basename -- "$1")
	(cd "$dir" 2> /dev/null && printf '%s/%s\n' "$(pwd -P)" "$file")
}
