#!/bin/bash
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

ignore_error() {
	"$@" 2>/dev/null
	return 0
}

parse_fstab(){
	echo $(perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^UUID=#;' $1/etc/fstab)
# 	perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^/dev#;' $1/etc/fstab
# 	perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^LABEL=#;' $1/etc/fstab
}

detect(){
	local detected=( "$(os-prober | tr ' ' '_' | paste -s -d ' ')" )
	echo ${detected[@]}
}

set_os(){
	local count=${#os_list[@]}
	if [[ ${count} -gt 1 ]];then
		msg "List of found systems"
		for((i=0; i < ${count}; i++)); do
			msg3 "$i) $(get_os_name ${os_list[$i]})"
		done
		msg "Please enter your choice [0-$((count-1))] : "
		while read selection; do
			if [[ -n ${os_list[$selection]} ]];then
				echo ${selection}
				break
			else
				msg "Please enter your choice [0-$((count-1))] : "
			fi
		done
	else
		echo 0
	fi
}

# $1: os-prober array
get_os_name(){
        local str=$1
        str="${str#*:}"
        str="${str#*:}"
        str="${str//:/}"
        echo "$str"
}

get_chroot_arch(){
	local elf=$(file $1/usr/bin/file)
	elf=${elf//*executable,}
	echo ${elf%%,*}
}

chroot_part_mount() {
	mount "$@" && CHROOT_ACTIVE_PART_MOUNTS=("$2" "${CHROOT_ACTIVE_PART_MOUNTS[@]}")
	msg2 "active_mounts: ${CHROOT_ACTIVE_PART_MOUNTS[@]}"
}

# $1: os-prober string
# $2: index
get_root(){
    local os_string=$1
    echo ${os_string[$2]%%:*}
}

select_os(){
	for system in ${os_list[@]};do
		case "${system##*:}" in
			'linux') chroot_mount_partitions "${chrootdir}" "${system}" ;;
			*) die "Detected: ${system##*:} is not a Linux" ;;
		esac
	done
}

chroot_mount_partitions(){
	CHROOT_ACTIVE_PART_MOUNTS=()
	CHROOT_ACTIVE_MOUNTS=()

	[[ $(trap -p EXIT) ]] && die 'Error! Attempting to overwrite existing EXIT trap'
	trap 'trap_handler' EXIT

	local osind=$(set_os)
	msg "Selected OS: $(get_os_name ${os_list[$osind]})"
	local root=$(get_root "${os_list}" "$osind")

	chroot_part_mount ${root} $1

	local mounts=$(parse_fstab "$1")

	for entry in ${mounts[@]}; do
		entry=${entry//UUID=}
		local dev=${entry%:*}
		local mp=${entry#*:}
		case "${entry#*:}" in
			'/'|'/home'|'swap'|'none') continue ;;
			*) chroot_part_mount "/dev/disk/by-uuid/${dev}" "$1${mp}" ;;
		esac
	done
	
        local chroot_arch=$(get_chroot_arch $1)
	[[ ${chroot_arch} == x86-64 ]] && chroot_arch=${chroot_arch/-/_}
	case ${arch} in
		i686)
			if [[ ${chroot_arch} == x86_64 ]];then
				die "You can't chroot from ${arch} host into ${chroot_arch}!"
			fi
		;;
	esac

	chroot_mount_conditional "! mountpoint -q '$1'" "$1" "$1" --bind &&
	chroot_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
	chroot_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
# 	ignore_error chroot_mount_conditional "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
# 	efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
	chroot_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
	chroot_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
	chroot_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
	chroot_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
	chroot_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
	chroot_mount /etc/resolv.conf "$1/etc/resolv.conf" --bind
}

chroot_mount() {
	mount "$@" && CHROOT_ACTIVE_MOUNTS=("$2" "${CHROOT_ACTIVE_MOUNTS[@]}")
	msg2 "active_mounts: ${CHROOT_ACTIVE_MOUNTS[@]}"
}

chroot_mount_conditional() {
	local cond=$1; shift
	if eval "$cond"; then
		chroot_mount "$@"
	fi
}

chroot_api_mount() {
	CHROOT_ACTIVE_MOUNTS=()
	[[ $(trap -p EXIT) ]] && die 'Error! Attempting to overwrite existing EXIT trap'
	trap 'chroot_api_umount' EXIT

	chroot_mount_conditional "! mountpoint -q '$1'" "$1" "$1" --bind &&
	chroot_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
	chroot_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
# 	ignore_error chroot_mount_conditional "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
# 	   efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
	chroot_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
	chroot_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
	chroot_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
	chroot_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
	chroot_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
}

chroot_part_umount() {
	umount "${CHROOT_ACTIVE_PART_MOUNTS[@]}"
	unset CHROOT_ACTIVE_PART_MOUNTS
}

chroot_api_umount() {
	umount "${CHROOT_ACTIVE_MOUNTS[@]}"
	unset CHROOT_ACTIVE_MOUNTS
}

trap_handler(){
    chroot_api_umount
    chroot_part_umount
}