#!/bin/bash -e

# Derive a minimal rootfs for hosting systemd from a coreos release pxe image
# This is only done when we need to update ../cmd/s1rootfs.go

URL="http://stable.release.core-os.net/amd64-usr/current/coreos_production_pxe_image.cpio.gz"

function req() {
	what=$1

	which "${what}" >/dev/null || { echo "${what} required"; exit 1; }
}

req unsquashfs
req curl
req gzip
req cpio
req install
req tar
req go-bindata

# extract the squashfs from the cpio then use unsquashfs to extract the required files for systemd
WORK="mkroot"
USRFS="usr.squashfs"
ROOTDIR="${WORK}/rootfs"
BINDIR="${WORK}/bins"
USR="rootfs/usr"
FILELIST="filelist.txt"
OUTPUT=${OUTPUT:="../stage0/stage1_rootfs/bin.go"}

[ -e "${WORK}" ] && rm -Rf "${WORK}"

mkdir -p "${ROOTDIR}"

# extract $USR from $URL
pushd "${WORK}"
curl "${URL}" | gzip -cd | cpio --extract "${USRFS}"

# extra stuff for stage1 which will come/go as things mature (reaper in bash for now)
EXTRAS="bin/bash
	lib64/libreadline.so
	lib64/libreadline.so.6
	lib64/libreadline.so.6.2
	lib64/libncurses.so
	lib64/libncurses.so.5
	lib64/libncurses.so.5.9
	lib64/libdl.so
	lib64/libdl.so.2
	lib64/libdl-2.17.so
	bin/sleep"

# systemd and dependencies
cat > "${FILELIST}" <<-EOF
	${EXTRAS}
	bin/journalctl
	bin/systemctl
	bin/systemd-analyze
	bin/systemd-ask-password
	bin/systemd-cat
	bin/systemd-cgls
	bin/systemd-cgtop
	bin/systemd-coredumpctl
	bin/coredumpctl
	bin/systemd-delta
	bin/systemd-detect-virt
	bin/systemd-inhibit
	bin/systemd-machine-id-setup
	bin/systemd-notify
	bin/systemd-nspawn
	bin/systemd-path
	bin/systemd-run
	bin/systemd-stdio-bridge
	bin/systemd-sysusers
	bin/systemd-tmpfiles
	bin/systemd-tty-ask-password-agent
	lib
	lib64/libattr.so
	lib64/libitm.so
	lib64/libitm.so.1
	lib64/libitm.so.1.0.0
	lib64/libblkid.so
	lib64/libblkid.so.1
	lib64/libblkid.so.1.1.0
	lib64/libuuid.so.1
	lib64/libuuid.so.1.3.0
	lib64/libuuid.so
	lib64/libstdc++.so
	lib64/libstdc++.so.6
	lib64/libstdc++.so.6.0.17
	lib64/libgcc_s.so
	lib64/libgcc_s.so.1
	lib64/librt-2.17.so
	lib64/libz.so.1
	lib64/libc.so
	lib64/libz.so.1.2.8
	lib64/libattr.so.1.1.0
	lib64/libpthread.so.0
	lib64/libz.so
	lib64/libseccomp.so.2.1.1
	lib64/libseccomp.so
	lib64/libpthread.so
	lib64/libcap.so.2.22
	lib64/libpthread-2.17.so
	lib64/libkmod.so.2
	lib64/ld-linux-x86-64.so.2
	lib64/ld-2.17.so
	lib64/librt.so.1
	lib64/libkmod.so
	lib64/libcap.so
	lib64/libc-2.17.so
	lib64/librt.so
	lib64/libseccomp.so.2
	lib64/libattr.so.1
	lib64/libkmod.so.2.2.5
	lib64/libcap.so.2
	lib64/libc.so.6
	lib64/systemd/systemd-backlight
	lib64/systemd/systemd-update-utmp
	lib64/systemd/systemd-vconsole-setup
	lib64/systemd/systemd-journal-remote
	lib64/systemd/systemd-modules-load
	lib64/systemd/systemd-resolved
	lib64/systemd/systemd-bus-proxyd
	lib64/systemd/systemd-ac-power
	lib64/systemd/systemd-bootchart
	lib64/systemd/systemd-initctl
	lib64/systemd/systemd-shutdown
	lib64/systemd/systemd-multi-seat-x
	lib64/systemd/systemd-rfkill
	lib64/systemd/systemd-networkd
	lib64/systemd/systemd-activate
	lib64/systemd/systemd-readahead
	lib64/systemd/systemd-hostnamed
	lib64/systemd/systemd-random-seed
	lib64/systemd/systemd-cgroups-agent
	lib64/systemd/systemd-udevd
	lib64/systemd/systemd-shutdownd
	lib64/systemd/systemd-logind
	lib64/systemd/systemd
	lib64/systemd/systemd-update-done
	lib64/systemd/systemd-machined
	lib64/systemd/systemd-user-sessions
	lib64/systemd/systemd-sysctl
	lib64/systemd/systemd-journald
	lib64/systemd/systemd-timedated
	lib64/systemd/systemd-networkd-wait-online
	lib64/systemd/systemd-localed
	lib64/systemd/systemd-cryptsetup
	lib64/systemd/user-generators
	lib64/systemd/systemd-remount-fs
	lib64/systemd/systemd-coredump
	lib64/systemd/systemd-timesyncd
	lib64/systemd/systemd-socket-proxyd
	lib64/systemd/system-shutdown
	lib64/systemd/systemd-binfmt
	lib64/systemd/systemd-fsck
	lib64/systemd/system-sleep
	lib64/systemd/systemd-sleep
	lib64/systemd/systemd-reply-password
	lib64/systemd/systemd-journal-gatewayd
EOF

unsquashfs -d "${USR}" -ef "${FILELIST}" "${USRFS}" 

popd

# populate usr/lib/systemd/system with the necessary static stuff
install -d -m 0755 "${ROOTDIR}/usr/lib/systemd/system"

function putunit {
	path="${ROOTDIR}/usr/lib/systemd/system/$1"
	cat > "${path}"
}

putunit default.target <<EOF
[Unit]
Description=Rocket apps target
DefaultDependencies=false
EOF

putunit sockets.target <<EOF
[Unit]
Description=Sockets
DefaultDependencies=false
EOF

putunit local-fs.target <<EOF
[Unit]
Description=Hook into early systemd for socket-activated systemd instances
DefaultDependencies=false
Requires=sockets.target
EOF

putunit exit-watcher.service <<EOF
[Unit]
Description=Graceful exit watcher
StopWhenUnneeded=true
DefaultDependencies=false

[Service]
ExecStart=/usr/bin/sleep 9999999999d 
ExecStopPost=/usr/bin/systemctl isolate reaper.service
EOF

putunit reaper.service <<EOF
[Unit]
Description=Rocket apps reaper
AllowIsolate=true
DefaultDependencies=false

[Service]
ExecStart=/reaper.sh
EOF

install -d -m 0755 "${ROOTDIR}/usr/lib/systemd/system/default.target.wants"
install -d -m 0755 "${ROOTDIR}/usr/lib/systemd/system/sockets.target.wants"

# simple reaper script for collecting the exit statuses of the apps
cat > "${ROOTDIR}/reaper.sh" <<-'EOF'
#!/usr/bin/bash
shopt -s nullglob

SYSCTL=/usr/bin/systemctl

cd /opt/stage2
for app in *; do 
        status=$(${SYSCTL} show --property ExecMainStatus "${app}.service")
        echo "${status#*=}" > "/rkt/status/$app"
done

${SYSCTL} halt --force
EOF
chmod 755 "${ROOTDIR}/reaper.sh"

install -d "${ROOTDIR}/etc"
echo "rocket" > "${ROOTDIR}/etc/os-release"

# parent dir for the stage2 bind mounts
install -d "${ROOTDIR}/opt/stage2"

# dir for result code files
install -d "${ROOTDIR}/rkt/status"

# fin
mkdir "${BINDIR}"
tar cf "${BINDIR}/s1rootfs.tar" -C "${ROOTDIR}" .
OUTDIR=$(dirname "${OUTPUT}")
[ -d "$OUTDIR" ] || mkdir -p "${OUTDIR}"
go-bindata -o "${OUTPUT}" -prefix $(realpath "${BINDIR}") -pkg=stage1_rootfs "${BINDIR}"
rm -Rf "${WORK}"