#!/bin/bash

<< MIT-LICENSE
Copyright (c) 2023 Jianjun Liu<jianjunliu@126.com> https://www.pkglinux.top

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.
MIT-LICENSE

PKG_CHROOT_COMMAND="/bin/bash --login"
PKG_CHROOT_DESTDIR="/mnt"
PKG_CHROOT_VERBOSE=""

pkg-chroot-usage()
{
	# Display Help
	echo "Wrapper of the chroot command and its important functionality."
	echo
	echo "Syntax: $0 [ -h|v|V|l|d ] [ --help|verbose|version|login|destdir ] [ command ]"
	echo "options:"
	echo "h     Print this help."
	echo "v     Verbose mode."
	echo "V     Print software version and exit."
	echo "l     Set default command other than just login."
	echo "d     Set directory path for destined root."
	echo
}

echo Starting $0 $@

for arg in "$@"; do
	shift
	case "$arg" in
		"--help")	set -- "$@" "-h" ;;
		"--verbose")	set -- "$@" "-v" ;;
		"--version")	set -- "$@" "-V" ;;
		"--login")	set -- "$@" "-l" ;;
		"--destdir")	set -- "$@" "-d" ;;
		*)		set -- "$@" "$arg"
	esac
done

while getopts ":hvVl:d:" option; do
	case $option in
		h)	# display usage
			pkg-chroot-usage
			exit;;
		v)	# verbose option
			PKG_CHROOT_VERBOSE="-v"
			;;
		V)	# version
			echo "1.0"	
			exit;;
		l)	# replace default command
			PKG_CHROOT_COMMAND="$OPTARG";;
		d)	# set destdir
			PKG_CHROOT_DESTDIR="$OPTARG";;
		\?)	# Invalid option
	                echo "Error: Invalid option"
			exit;;
	esac
done

shift "$(($OPTIND -1))"

[ ${UID} -ne 0 ] && echo "$0 will not be performed when not running as root" && exit 1;

[ "$#" -gt 0 ] && PKG_CHROOT_COMMAND="$@"


pkg-chroot-clean()
{
  if (( ${#PKG_CHROOT_MOUNTS[@]} )); then
    umount $PKG_CHROOT_VERBOSE "${PKG_CHROOT_MOUNTS[@]}"
  fi
  unset PKG_CHROOT_MOUNTS
}

pkg-chroot-mount()
{
  mount "$@" && PKG_CHROOT_MOUNTS=("${@: -1}" "${PKG_CHROOT_MOUNTS[@]}")
}

pkg-chroot-prepare()
{
	[[ $(trap -p EXIT) ]] && echo 'Attempting to overwrite existing EXIT trap' && exit 1;
	trap 'pkg-chroot-clean' EXIT

	pkg-chroot-mount $PKG_CHROOT_VERBOSE --bind /dev "$PKG_CHROOT_DESTDIR"/dev &&
	pkg-chroot-mount $PKG_CHROOT_VERBOSE -t devpts devpts -o gid=5,mode=620 "$PKG_CHROOT_DESTDIR"/dev/pts &&
	pkg-chroot-mount $PKG_CHROOT_VERBOSE -t proc proc "$PKG_CHROOT_DESTDIR"/proc &&
	pkg-chroot-mount $PKG_CHROOT_VERBOSE -t sysfs sysfs "$PKG_CHROOT_DESTDIR"/sys &&
	pkg-chroot-mount $PKG_CHROOT_VERBOSE -t tmpfs tmpfs "$PKG_CHROOT_DESTDIR"/run

}

pkg-chroot()
{
	pkg-chroot-prepare

	chroot "$PKG_CHROOT_DESTDIR" /usr/bin/env -i \
		HOME=/root TERM="$TERM" PS1='\u:\w\$ ' \
		PATH=/pkg/bin:/pkg/sbin:/bin:/usr/bin:/sbin:/usr/sbin \
		$PKG_CHROOT_COMMAND

	pkg-chroot-clean
}

pkg-chroot