#!/data/data/com.termux/files/usr/bin/sh

#
# some configuration. adapt this to your needs
#
DO_FIRST_STAGE=:  #false   # required (unpack phase/ executes outside guest invironment)
DO_SECOND_STAGE=: #false   # required (complete the install/ executes inside guest invironment)
DO_THIRD_STAGE=:  #false   # optional (enable local policies/ executes inside guest invironment)
VERSION=stable             # debian versions: stable, testing, unstable
ROOTFS_TOP=deboot_debian   # name of the top install directory

#
# some automatic configuration.
#
set -e
trap '[ $? -eq 0 ] && exit 0 || (echo; echo "termux-info:"; termux-info)' EXIT
ZONEINFO=$(getprop persist.sys.timezone)     # set your desired time zone
ARCHITECTURE=$(uname -m)
case $ARCHITECTURE in    # supported architectures include: armel, armhf, arm64, i386, amd64
    aarch64) ARCHITECTURE=arm64 ;;
    x86_64) ARCHITECTURE=amd64 ;;
    i686) ARCHITECTURE=i386 ;;
    armv7l) ARCHITECTURE=armhf ;;
    armv8l) apt-get -qq install getconf; if [ $(getconf LONG_BIT) -eq 64 ]; then ARCHITECTURE=arm64; else ARCHITECTURE=armhf; fi ;;
    armel|armhf|arm64|amd64|mips|mips64el|mipsel|ppc64el|s390x) ;;
    # Officially supported Debian Stretch architectures
    *) echo "Unsupported architecture $ARCHITECTURE"; exit ;;
esac

patchme() {
#
# minimum patch needed for debootstrap to work in this environment
#
patch -l << 'EOF' 
--- functions.a 2020-02-27 13:16:24.000000000 +0100
+++ functions   2020-03-03 11:24:15.810995745 +0100
@@ -1154,6 +1154,10 @@
 }
 
 setup_proc () {
+
+echo skipping setup_proc
+return 0
+
        case "$HOST_OS" in
            *freebsd*)
                umount_on_exit /dev
@@ -1265,6 +1269,10 @@
 
 
 setup_devices_simple () {
+
+echo skipping setup_devices_simple
+return 0
+
        # The list of devices that can be created in a container comes from
        # src/core/cgroup.c in the systemd source tree.
        mknod_if_needed "$TARGET/dev/null"        c 1 3
@@ -1589,6 +1597,11 @@
 # this directory. (Both may be forbidden by mount options, e.g. nodev and
 # noexec respectively.)
 check_sane_mount () {
+
+# these checks make no sense in our environment and fail anyway -> skip
+echo skipping check_sane_mount
+return 0
+
        mkdir -p "$1"
 
        case "$HOST_OS" in
EOF
    return $?
}

USER_ID=$(id -u)
USER_NAME=$(id -un)
unset LD_PRELOAD # just in case termux-exec is installed
#
# workaround https://github.com/termux/termux-app/issues/306
# workaround https://github.com/termux/termux-packages/issues/1644
# or expect 'patch' to fail when doin the install via ssh and sh (not bash) is used
#
export TMPDIR=$PREFIX/tmp
cd

#
# ===============================================================
# first stage - do the initial unpack phase of bootstrapping only
#
$DO_FIRST_STAGE && {
echo ======== DO_FIRST_STAGE ========

[ -e "$HOME/$ROOTFS_TOP" ] && {
    echo the target install directory already exists, to continue please remove it by
    echo rm -rf "$HOME/$ROOTFS_TOP"
    exit
}
apt-get -qq update

unset RESOLV
[ -e "$PREFIX/etc/resolv.conf" ] || {
    RESOLV=resolv-conf
}

DEBIAN_FRONTEND=noninteractive apt-get -yqq install coreutils perl proot sed wget gnupg $RESOLV
hash -r

# first try to patch the most recent original of debian debootstrap script
rm -rf debootstrap
V=$(wget http://http.debian.net/debian/pool/main/d/debootstrap/ -qO - \
    | sed 's/<[^>]*>//g' \
    | grep -E '\.[0-9]+\.tar\.gz' \
    | tail -n 1 \
    | sed 's/^ +//g;s/.tar.gz.*//g')
wget "http://http.debian.net/debian/pool/main/d/debootstrap/$V.tar.gz" -qO - | tar xfz -
V=$(echo "$V" | sed 's/_/-/g')
ln -nfs "$V" debootstrap
cd debootstrap

patchme || {
# if the above fails patch the last known good backup of an 
# older version of debian debootstrap script
cd
echo "patching $V failed using fallback"
rm -rf debootstrap
V=debootstrap_1.0.119
wget "https://github.com/sp4rkie/debian-on-termux/blob/master/$V.tgz?raw=true" -qO - \
        | tar xfz -
V=$(echo "$V" | sed 's/_/-/g')
ln -nfs "$V" debootstrap
cd debootstrap
patchme
}

#
# fix https://github.com/sp4rkie/debian-on-termux/issues/21
# fix https://github.com/sp4rkie/debian-on-termux/issues/63
#
# add the key for stable (Debian Stable Release Key)
# Fix "gpg: keyserver receive failed: No name and apt-key(8) Deprecated"
gpg --keyserver keyserver.ubuntu.com --recv-keys DCC9EFBF77E11517

# add the keys for testing, unstable (Debian Archive Automatic Signing Key)
gpg --keyserver keyserver.ubuntu.com --recv-keys 648ACFD622F3D138


#
# you can watch the debootstrap progress via
# tail -F $HOME/$ROOTFS_TOP/debootstrap/debootstrap.log
#
DEBOOTSTRAP_DIR="$(pwd)"
export DEBOOTSTRAP_DIR
O="$("$PREFIX/bin/proot" \
    -b /system \
    -b /vendor \
    -b /data \
    -b "$PREFIX/bin:/bin" \
    -b "$PREFIX/etc:/etc" \
    -b "$PREFIX/lib:/lib" \
    -b "$PREFIX/share:/share" \
    -b "$PREFIX/tmp:/tmp" \
    -b "$PREFIX/var:/var" \
    -b /dev \
    -b /proc \
    -r "$PREFIX/.." \
    -0 \
    --link2symlink \
    ./debootstrap --keyring="$PREFIX/etc/apt/trusted.gpg" \
        --foreign --arch="$ARCHITECTURE" "$VERSION" "$HOME/$ROOTFS_TOP" 2>&1 || true)"
echo "$O" > ~/debian-on-termux_debootstrap.log
# proot returns invalid exit status
if echo "$O" | grep " error: " > /dev/null ; then
    echo "$O"
    exit 1
fi
} # end DO_FIRST_STAGE

#
# =================================================
# second stage - complete the bootstrapping process
#
$DO_SECOND_STAGE && {
echo ======== DO_SECOND_STAGE ========

# since there are issues with proot and /proc mounts (https://github.com/termux/termux-packages/issues/1679)
# we currently cease from mounting /proc.
# the guest system now is setup to complete the installation - just dive in
# UPDATE as of 2017_11_27:
# issue https://github.com/termux/termux-packages/issues/1679#ref-commit-bcc972c now got fixed.
# /proc now included in mount list
O="$("$PREFIX/bin/proot" \
    -b /dev \
    -b /proc \
    -r "$HOME/$ROOTFS_TOP" \
    -w /root \
    -0 \
    --link2symlink /usr/bin/env \
    -i HOME=/root TERM=xterm /debootstrap/debootstrap --second-stage 2>&1 || true)"
echo "$O" > ~/debian-on-termux_debootstrap_stage2.log
# proot returns invalid exit status
if echo "$O" | grep " error: " > /dev/null ; then
    echo "$O"
    exit 1
fi
#
# Add termux user in the passwd, group and shadow.
#
echo "$USER_NAME:x:$USER_ID:$USER_ID::/home/$USER_NAME:/bin/bash" >> \
    "$HOME/$ROOTFS_TOP/etc/passwd"
echo "$USER_NAME:x:$USER_ID:" >> \
    "$HOME/$ROOTFS_TOP/etc/group"
echo "$USER_NAME:*:15277:0:99999:7:::" >> \
    "$HOME/$ROOTFS_TOP/etc/shadow"

#
# add the termux user homedir to the new debian guest system
#
mkdir -p "$HOME/$ROOTFS_TOP/home/$USER_NAME"
chmod 755 "$HOME/$ROOTFS_TOP/home/$USER_NAME"
} # end DO_SECOND_STAGE

#
# ======================================================================================
# optional third stage - if enabled edit some system defaults - adapt this to your needs
#
$DO_THIRD_STAGE && {
echo ======== DO_THIRD_STAGE ========

#
# take over an existing 'resolv.conf' from the host system (if there is one)
#
[ -e "$HOME/$ROOTFS_TOP/etc/resolv.conf" ] || {
    cp "$PREFIX/etc/resolv.conf" "$HOME/$ROOTFS_TOP/etc/resolv.conf"
    chmod 644 "$HOME/$ROOTFS_TOP/etc/resolv.conf"
}

#
# to enter the debian guest system execute '$HOME/bin/enter_deb' on the termux host system
#
mkdir -p "$HOME/bin"
cat << EOF > "$HOME/bin/enter_deb"
#!/data/data/com.termux/files/usr/bin/sh

unset LD_PRELOAD
SHELL_=/bin/bash
ROOTFS_TOP_=$ROOTFS_TOP
ROOT_=1
USER_=$USER_NAME
EOF
cat << 'EOF' >> "$HOME/bin/enter_deb"

SCRIPTNAME=enter_deb
show_usage () {
    echo "Usage: $SCRIPTNAME [options] [command]"
    echo "$SCRIPTNAME: enter the installed debian guest system"
    echo ""
    echo "  -0 - mimic root (default)"
    echo "  -n - prefer regular termux uid ($USER_)"
    exit 0
}

while getopts :h0n option
do
    case "$option" in
        h) show_usage;;
        0) ;;
        n) ROOT_=0;;
        ?) echo "$SCRIPTNAME: illegal option -$OPTARG"; exit 1;
    esac
done
shift $(($OPTIND-1))

HOMEDIR_=/home/$USER_
[ $ROOT_ = 1 ] && {
    CAPS_=$CAPS_"-0 "
    HOMEDIR_=/root
}
CMD_="$SHELL_ -l"
[ -z "$*" ] || {
    CMD_='sh -c "$*"'
}
eval $PREFIX/bin/proot \
    -b /dev \
    -b /proc \
    -r $HOME/$ROOTFS_TOP_ \
    -w $HOMEDIR_ \
    $CAPS_ \
    --link2symlink \
    /usr/bin/env -i HOME=$HOMEDIR_ TERM=$TERM LANG=$LANG $CMD_
EOF
chmod 755 "$HOME/bin/enter_deb"

cat << 'EOF' > "$HOME/$ROOTFS_TOP/root/.profile"
# ~/.profile: executed by Bourne-compatible login shells.

if [ "$BASH" ]; then
  if [ -f ~/.bashrc ]; then
    . ~/.bashrc
  fi
fi
EOF

cat << EOF > "$HOME/$ROOTFS_TOP/tmp/dot_tmp.sh"
#!/bin/sh

filter() {
    egrep -v '^$|^WARNING: apt does'
}

#
# select 'vi' as default editor for debconf/frontend
#
update-alternatives --config editor << !
2
!
#
# prefer a text editor for debconf (a GUI makes no sense here)
#
cat << ! | debconf-set-selections -v
debconf debconf/frontend                       select Editor
debconf debconf/priority                       select low
locales locales/locales_to_be_generated        select en_US.UTF-8 UTF-8
locales locales/default_environment_locale     select en_US.UTF-8
!
ln -nfs /usr/share/zoneinfo/$ZONEINFO /etc/localtime
dpkg-reconfigure -fnoninteractive tzdata
dpkg-reconfigure -fnoninteractive debconf

DEBIAN_FRONTEND=noninteractive apt -y update 2>&1 | filter                    
DEBIAN_FRONTEND=noninteractive apt -y upgrade 2>&1 | filter
DEBIAN_FRONTEND=noninteractive apt -y install locales 2>&1 | filter
update-locale LANG=en_US.UTF-8 LC_COLLATE=C
#
# place any additional packages here as you like
#
#DEBIAN_FRONTEND=noninteractive apt -y install rsync less gawk ssh 2>&1 | filter  
apt clean 2>&1 | filter
EOF
chmod 755 "$HOME/$ROOTFS_TOP/tmp/dot_tmp.sh"

"$PREFIX/bin/proot" \
    -b /dev \
    -b /proc \
    -r "$HOME/$ROOTFS_TOP" \
    -w /root \
    -0 \
    --link2symlink \
    /usr/bin/env -i HOME=/root TERM=xterm PATH=/usr/sbin:/usr/bin:/sbin:/bin /tmp/dot_tmp.sh \
        || : # proot returns invalid exit status
echo 
echo installation successfully completed
echo to enter the guest system type:
echo "\$HOME/bin/enter_deb"
echo

} # end DO_THIRD_STAGE