#!/bin/bash

# matter-chroot | Matterlinux Chroot Script 
# Copyright (C) 2023 Matterlinux 

# 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, either version 3 of the License, or
# (at your option) any later version.

# 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.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

############################
## logging functions/vars ##
############################
RED="\e[31m"
BOLD="\e[1m"
RESET="\e[0m"

error() {
  echo -e "$BOLD$RED>>>$RESET$BOLD $1$RESET"
  exit 1
}

####################
## util functions ##
####################
chrt() {
  mount -t proc proc "$TARGET/proc"
  mount -t sysfs sysfs "$TARGET/sys"
  if [[ -d "$TARGET/sys/firmware/efi/efivars" ]]; then
    mount -t efivarfs efivarfs "$TARGET/sys/firmware/efi/efivars"
  fi

  mount -o bind /dev "$TARGET/dev"
  mount -t devpts none "$TARGET/dev/pts"
  mount -t tmpfs tmpfs "$TARGET/run"

  if [ -h $TARGET/dev/shm ]; then
    mkdir -p $TARGET/$(readlink $TARGET/dev/shm)
  else
    mount -t tmpfs -o nosuid,nodev tmpfs "$TARGET/dev/shm"
  fi
  
  local prompt='\['$BOLD'\['$RED'(chroot)\['$RESET'\['$BOLD' \u@\h:\w#\['$RESET' '
  chroot "$TARGET" /usr/bin/env -i      \
    HOME=/root                          \
    TERM="$TERM"                        \
    PS1="$prompt"                       \
    PATH=/usr/bin:/usr/sbin             \
    "$@"

  # kill procs that may prevent umount
  killall -9 dirmngr  2> /dev/null
  killall -9 gpg-agent 2> /dev/null

  umount "$TARGET/proc"
  mountpoint -q "$TARGET/sys/firmware/efi/efivars" && umount "$TARGET/sys/firmware/efi/efivars"
  umount "$TARGET/sys"

  umount "$TARGET/dev/pts"
  mountpoint -q "$TARGET/dev/shm" && umount "$TARGET/dev/shm"
  umount "$TARGET/dev"
  umount "$TARGET/run"
}

#################
## main script ##
#################
if [ "$EUID" -ne 0 ]; then
  error "Cannot chroot without root"
fi

if [ $# -eq 0 ]; then
  error "Please specify a directory"
fi

TARGET=$(realpath $1) 
if [ -f $TARGET ]; then
  error "$TARGET is a file"
fi

if [ ! -d $TARGET ]; then
  error "$TARGET does not exist"
fi 

if [ $# -gt 1 ]; then
  chrt ${@:2}
  exit 0
fi

chrt bash --login