#!/bin/sh

# Copyright (C) 2024-2025 T2 SDE Project
# SPDX-License-Identifier: GPL-2.0
# Takeover based on Copyright 2017 Hector Martin "marcan" <marcan@marcan.st>

# TODO: check cpio, tar, zstd
# TODO: include ca-certificates in the installer stage2
# TODO: check essential tools
# TODO: more error handling
# TODO: check for X, Wayland and drmcon and do special things
# TODO: testing, testing, and the most more testing
# TODO: support taking over macOS! !!! x86 and Apple Silicon!!
# TODO: support ssh remote login
# TODO: option to preserve mounts (and improve t2/installer, too)
# TODO: add size check also to t2/installer
# TODO: can we support taking over Windows (Subsystem for Linux), too? EFI part?

set -e

# Resistance is Futile
# ourhardworkbythesewordsguardedpleasedontsteal(c)T2ComputerInc
# Here is to the troublemakers, the crazy on


# *, base/*,  base/* but not */x11, base/{firmware,kernel,boot}
extract() {
	echo "$pkg ($ver)"
	$curl $curlopt $URL/$ID/pkgs/$pkg-$ver.tar.zst |
		zstd -d | tar x -C "$TO"
}

bootstrap() {
    pkgsel=$1
    section=0
    ID=$(curl $curlopt $URL/ | grep linux | cut -d '"' -f 2)
    [ ! "$ID" ] && echo "Could not extract ID" && exit

    $curl $curlopt $URL/$ID/pkgs/packages.db | gunzip |
    while read line; do
	if [ "${line}" = $'\004' ]; then
		section=0
		[ $selected = 1 ] && extract
	elif [ "${line}" = $'\027' ]; then
		((++section))
	else
		# each 1st new section line pkg name
		if [ $section = 0 ]; then
			pkg=$line
			selected=0
		else
			if [[ $section = 1 && "$line" = "[V]"* ]]; then
				ver=${line#\[V\] }
			elif [[ $section = 1 && "$line" = "[C]"* ]]; then
				cat=${line#\[C\] }
				# TODO: iterate multiple Categories!
				#echo "$pkg> $cat"

				selected=1
				case "$cat" in
				*/kernel*|*/firmware*|*/boot*)
					[ $pkgsel = minimal-container ] && selected=0 ;;
				*base/x11*)
					[ $pkgsel = minimal -o $pkgsel = minimal-container ] && selected=0 ;;
				*base/*)
					: ;;
				*)
				       	[ $pkgsel = all ] || selected=0
				esac
			fi
		fi
	fi
    done
}


isLE() {
	elf_magic="$(head -c 6 /proc/self/exe | tail -c 1)"
	[ "$elf_magic" = "$(printf '\001')" ]
}

arch=$(uname -s -m)
arch2=${arch#* }
BASE=https://dl.t2sde.org/binary
URL2=.$arch2
INITRD=boot/initrd-6.14.1-t2
VER=25.4
case ${arch} in
Linux*aarch64)
	URL=2025/t2-$VER-arm64-base-wayland-glibc-gcc.d ;;
Linux*armv7)
	URL=2025/t2-$VER-armv7-base-wayland-glibc-gcc-armv7-a.d ;;
Linux*alpha)
	INITRD=boot/initrd-6.14.2-t2
	URL=2025/t2-$VER-alpha-base-wayland-glibc-gcc-ev56.d ;;
Linux*hppa)
	URL=2025/t2-$VER-hppa-base-desktop-glibc-gcc.d ;;
Linux*hppa64)
	URL=2025/t2-$VER-hppa6432-base-desktop-glibc-gcc.d ;;
Linux*ia64)
	URL=2025/t2-$VER-ia64-base-desktop-glibc-gcc-itanium2.d ;;
Linux*mips)
	isLE && URL2=.mipsel &&
	URL=2025/t2-$VER-mipsel-base-wayland-glibc-gcc-mips32r2.d ;;
Linux*ppc)
	URL=2025/t2-$VER-ppc-base-wayland-glibc-gcc-603.d ;;
Linux*ppc64)
	URL2=.ppc6432
	URL=2025/t2-$VER-ppc6432-base-wayland-glibc-gcc-970.d
	isLE && URL2=.ppc64le &&
		URL=2025/t2-$VER-ppc64le-base-wayland-glibc-gcc-power8.d
	;;
Linux*riscv32)
	URL=2025/t2-$VER-riscv-base-desktop-glibc-gcc.d ;;
Linux*riscv64)
	URL=2025/t2-$VER-riscv64-base-wayland-glibc-gcc.d ;;
Linus*sparc64*)
	URL2=.sparc6432
	INITRD=boot/initrd-6.14.2-t21
	URL=2025/t2-$VER-sparc6432-base-wayland-glibc-gcc.d ;;
Linux*x86_64)
	URL=2025/t2-$VER-x86-64-base-wayland-glibc-gcc-nocona.d ;;
Linux*i?86)
	URL2=.i486
	URL=2025/t2-$VER-i586-base-wayland-glibc-gcc-i586.d ;;
esac

if [ -z "$URL" ]; then
	echo "T2/install does not yet support '$arch'."
	curl -Ls -A "curl ($arch)" https://t2linux.com/no-install >/dev/null
	echo "Please let us know at: https://t2linux.com/support"
	exit 1
fi

xtractonly=

# get actual shell tty, as we run from a curl pipe, ...
[ -e /proc/$PPID/fd ] && TTY=$(readlink -f /proc/$PPID/fd/0) || TTY=/dev/tty
if [ "${TTY##/dev/pts}" != "${TTY}" ]; then
    # check parent, e.g.sudo
    TTY2=$(sed -n 's/PPid:\t*//p' /proc/$$/status)
    TTY2=$(sed -n 's/PPid:\t*//p' /proc/$TTY2/status)
    TTY2=$(readlink /proc/$TTY2/fd/0)
    case "$TTY2" in
    /dev/pts*|/dev/null)
	echo "T2/install does not yet support takeover on $TTY,$TTY2."
	xtractonly=1
	;;
    *)
	TTY=$TTY2 ;;
    esac
fi


if [ $(id -u) != 0 ]; then
	echo "T2/install takeover requires root permissions, e.g. via su or sudo."
	xtractonly=1
fi

TO=/T2
curl=curl
curlopt="-L --progress-bar"
if ! type $curl >/dev/null; then
	curl=wget
	curlopt="--progress=bar -O -"
fi

URL=$BASE/$URL URL2=$BASE/$URL2

echo
echo "!!!          EXPERIMENTAL new code v0.2.1           !!!"
echo "!!! It may or may NOT WORK AND DELETE ALL YOUR DATA !!!"
echo "       ${URL##*/}"

[ "$xtractonly" ] &&
echo -n "Package selection to bootstrap (minimal{,-xorg,-container},all)? " ||
echo -n "Package selection to bootstrap, or system takeover (minimal{,-xorg,-container},all,takeover)? "


read pkgset < /dev/tty
case "$pkgset" in
  xorg|container)
	pkgset=minimal-$pkgset ;;
  minimal|minimal-xorg|minimal-container|all)
	: ;;
  "")
	exit ;;
  *)
	if [ "$pkgset" = takeover -a ! "$xtractonly" ]; then
		:
	else
		echo "Unmatched '$pkgset'"
		exit 1
	fi
	;;
esac


if [ "$pkgset" != takeover ]; then
	echo -n "Directory name to bootstrap into: "
	read TO < /dev/tty
	[ "$TO" ] || exit
	mkdir -p "$TO" || exit
	bootstrap $pkgset
	echo "Done. You can now chroot into '$TO' and have fun!"
	exit
fi


OLD_INIT=$(readlink -f /proc/1/exe)
OLD_TELINIT=
if type telinit >/dev/null; then OLD_TELINIT=$(which telinit); fi

mkdir -p $TO
mount -t tmpfs tmpfs $TO
cd $TO

echo ""
echo "Loading required files..."
$curl $curlopt $URL/${INITRD:-initrd} | zstd -d | cpio -i
$curl $curlopt $URL/stage2.tar.zst | zstd -d | tar x
$curl $curlopt $URL/stage2ext.tar.zst | zstd -d | tar x
$curl $curlopt ${URL2:-$URL}/fakeinit > fakeinit && chmod +x fakeinit
$curl $curlopt ${URL2:-$URL}/busybox > busybox && chmod +x busybox

echo
echo "Setting up new filesystem..."
mkdir -p etc dev proc sys run tmp mnt
if ! mount -t devtmpfs dev dev; then
    echo "Failed to mount dev"
    exit 1
fi
mount -t tmpfs tmp tmp
mount -t proc proc proc
mount -t sysfs sys sys
mount --bind /dev/pts dev/pts
ln -s /proc/mounts etc/mtab

swapon --show --noheadings | while read s _; do
    case $s in
	/dev/zram*|/dev/ps3vram*) : ;;
	*) swapoff $s ;;
    esac
done

#echo "Switching <-> $TTY..."
#exec <$TO$TTY >$TO$TTY 2>$TO$TTY

# sanity check supported term
case $TERM in
	linux|screen|tmux|xterm) : ;;
	*) TERM=vt102 ;;
esac

cat /etc/resolv.conf > etc/resolv.conf.t
sed -n 's/^# name/name/p' etc/resolv.conf >> etc/resolv.conf.t
mv -f etc/resolv.conf{.t,}

cat > tmp/${OLD_INIT##*/} <<EOF
#!$TO/busybox sh

export PATH="/sbin:/bin:/usr/sbin:/usr/bin"

#set -x
exec <$TO$TTY >$TO$TTY 2>$TO$TTY

#echo "\$\$ \$*"

export TERM=$TERM

echo "Init takeover successful"
echo "Pivoting root..."
cd $TO
./busybox mount --make-rprivate /
./busybox pivot_root . mnt

echo "Chrooting and running fakeinit..."
export TTY=$TTY
exec chroot . /fakeinit /init2
EOF
chmod +x tmp/${OLD_INIT##*/}

cat > init2 <<EOF
#!/bin/sh

#LIBPROC_HIDE_KERNEL=1 ps faxu

echo -n "Terminating Other OS:"
for p in /proc/[0-9]*/exe; do
    exe=\$(readlink -f \$p)
    if [ \$? = 0 ]; then
	p=\${p#/proc/}; p=\${p%/exe}
	[ \$p = 1 ] && continue
	echo -n " \$exe(\$p)"
	kill -9 \$p
exec <$TTY >$TTY 2>$TTY
    fi
done
exec <$TTY >$TTY 2>$TTY
echo

sleep 1
#LIBPROC_HIDE_KERNEL=1 ps faxu

echo -n "Umounting:"
for m in \$(grep /mnt/ /proc/mounts | cut -d " " -f 2 | tac) # /mnt
do
	echo -n " \$m"
	umount \$m
done
echo

#/sbin/agetty -i -J -n -N -l /sbin/login-shell ${TTY##*/} &

udevd &
udevadm trigger --action=add

export ROCK_INSTALL_SOURCE_URL=http:${URL#https:} # TODO!

echo "Done. Have fun! You might want to run: 'exec /sbin/init' to install T2."
exec /bin/sh #/fakeinit
EOF
chmod +x init2

[ "$OLD_TELINIT" ] && cp -Lf ${OLD_TELINIT} tmp/${OLD_TELINIT##*/}
mount --bind tmp/${OLD_INIT##*/} ${OLD_INIT}

echo
echo "About to take over init. If successful, you will see output from the new init:"

[ $OLD_TELINIT ] && tmp/telinit u || systemctl daemon-reexec

sleep 23
echo "Takeover probably failed."