#!/bin/sh
#
# tiny initramfs generation tool

# print message
msg() {
    case "$1" in
	warn)
	    printf "warning >> %s\n" "$2"
	    ;;
	info)
	    printf "info >> %s\n" "$2"
	    ;;
	panic)
	    printf "panic >> %s\n" "$2"
	    exit 1
	    ;;
    esac
}

# remove tmpdir
remove_tmpdir() {
    rm -rf "$tmpdir"
}

# change current directory to script directory if user haven't do it
check_currentdir() {
    script_dir=$(dirname $(readlink -f -- "$0"))
    [ "$PWD" = "$script_dir" ] || {
	cd "$script_dir" || msg panic "failed to change directory"
    }
}

# check needed files
check_requirements() {
    # TODO use system busybox
    for f in ./init ./busybox; do
	[ -e "$f" ] || msg panic "$f doesn't exists"
    done

    # TODO handle busybox requirements ( busybox --list | grep ash )
}

# create FHS directory structure
create_structure() {
    for d in dev tmp var run etc usr/lib usr/bin mnt/root proc root sys; do
	mkdir -p "${tmpdir}/${d}"
    done
}

# some dynamically linked libraries and binaries compiled with hardcoded
# dependencies path. to make it worked we need create symlinks for them.
# also POSIX ln doesn't have --relative flag like in GNU ln. as workaround
# we change directory to tmpdir and make needed symlinks.
create_symlinks() {
    ( cd "$tmpdir" && {
	ln -s usr/lib lib
	ln -s usr/lib lib64
	ln -s usr/bin bin
	ln -s usr/bin sbin
	ln -s ../run var/run
	cd "${tmpdir}/usr"
	ln -s bin sbin
	ln -s lib lib64
    } )
}

#parse_fstab() {
# TODO parse fstab
#while [ "$use_fstab" -eq 1 ] && read fs dir type opts; do thing; done < /etc/fstab
#}

#parse_crypttab() {
# TODO parse crypttab
#}

# install mdev
install_mdev() {
    install -m644 mdev.conf -t "${tmpdir}/etc"
    install -Dm755 storage-device -t "${tmpdir}/lib/mdev"
}

# install mdevd
install_mdevd() {
    install_binaries mdevd mdevd-coldplug
    install -m644 mdev.conf -t "${tmpdir}/etc"
    install -Dm755 storage-device -t "${tmpdir}/lib/mdev"
}

# install udev
install_udev() {
    install_binaries udevd udevadm dmsetup
    # FIXME rewrite this piece of crap
    find /usr/lib/udev -type f | grep -v "rc_keymaps\|hwdb.d" | cpio -pd "$tmpdir" >/dev/null 2>&1
}

# handle lvm
install_lvm() {
    install_binaries lvm

    # if hostonly mode enabled install only needed drivers
    [ "$hostonly" = 1 ] && {
	for lvm_driver in dm-thin-pool dm-multipath dm-snapshot dm-cache dm-log dm-mirror; do
	    for lvm_driver_dep in $(modprobe -D "$lvm_driver" 2>/dev/null | cut -d " " -f 2); do
		install -Dm644 "$lvm_driver_dep" "${tmpdir}${lvm_driver_dep}" 2>/dev/null
	    done
	done
    }

    # FIXME this code doesn't working with udev
    #mkdir "$tmpdir/etc/lvm"
    # use_lvmetad = 0 - avoid lvmetad missing warning message
    #cat <<EOF > "$tmpdir/etc/lvm/lvmlocal.conf"
    #local {
    #	issue_discards = ${lvm_discard:-0}
    #	use_lvmetad = 0
    #}
    #EOF
    # TODO implement use_lvmconf
}

# handle luks
install_luks() {
    install_binaries cryptsetup

    # if hostonly mode enabled install only needed drivers
    [ "$hostonly" = 1 ] && {
	for luks_driver in aes dm-crypt sha256 sha512 wp512 ecb lrw xts twofish serpent; do
	    for luks_driver_dep in $(modprobe -D "$luks_driver" 2>/dev/null | cut -d " " -f 2); do
		install -Dm644 "$luks_driver_dep" "${tmpdir}${luks_driver_dep}" 2>/dev/null
	    done
	done
    }

    # avoid locking directory missing warning message
    mkdir "${tmpdir}/run/cryptsetup"

    # TODO get rid of this workaround
    # workaround for luks2
    install -s -m755 /usr/lib/libgcc_s.so.1 -t "${tmpdir}/usr/lib"

    # block discard support
    [ "$luks_discard" = 1 ] && luks_args="--allow-discards $luks_args"

    # copy luks header
    [ -f "$luks_header" ] && {
	install -m400 "$luks_header" "${tmpdir}/root/luks_header"
	luks_args="--header=/root/luks_header $luks_args"
    }

    # copy luks keyfile
    [ -f "$luks_keyfile" ] && {
	install -m400 "$luks_keyfile" "${tmpdir}/root/luks_keyfile"
	luks_args="--key-file=/root/luks_keyfile $luks_args"
    }
}

# install drivers
install_drivers() {
    [ -n "$root_type" ] || msg panic "hostonly mode required root_type option to be configured"

    # perform autodetection of drivers via /sys
    for driver in $(find /sys/devices -name modalias -exec sort -u "{}" "+"); do
        for driver_dep in $(modprobe -D "$driver" 2>/dev/null | cut -d " " -f 2); do
	    install -Dm644 "$driver_dep" "${tmpdir}${driver_dep}" 2>/dev/null
        done
    done

    # TODO autodetect root fs driver
    # TODO separate root type option
    # install root fs driver
    for root_driver in $(modprobe -D "$root_type" 2>/dev/null | cut -d " " -f 2); do
        install -Dm644 "$root_driver" "${tmpdir}${root_driver}" 2>/dev/null
    done

    # install user specified drivers
    [ -n "$drivers" ] && {
	for custom_driver in $(printf "%s\n" "$drivers" | tr " " "\n"); do
	    for custom_driver_dep in $(modprobe -D "$custom_driver" 2>/dev/null | cut -d " " -f 2); do
		install -Dm644 "$custom_driver_dep" "${tmpdir}${custom_driver_dep}" 2>/dev/null
	    done
	done
    }
}

# find and install all drivers
install_all_drivers() {
    find \
        "${modker}/kernel/arch" \
        "${modker}/kernel/crypto" \
        "${modker}/kernel/fs" \
        "${modker}/kernel/lib" \
        "${modker}/kernel/drivers/block" \
        "${modker}/kernel/drivers/ata" \
        "${modker}/kernel/drivers/md" \
        "${modker}/kernel/drivers/scsi" \
        "${modker}/kernel/drivers/usb/storage" \
        "${modker}/kernel/drivers/usb/host" \
        "${modker}/kernel/drivers/virtio" \
        -type f | cpio -pd "$tmpdir" >/dev/null 2>&1
}

# generate "modules" files
generate_depmod() {
    # install list of drivers
    cp "${modker}/modules.softdep" "${modker}/modules.builtin" "${modker}/modules.order" "${tmpdir}/${modker}"

    # generate dependencies list of drivers
    depmod -b "$tmpdir" "$kernel"
}

# TODO make strip optional
# handle binaries
install_binaries() {
    for b in $(printf "%s\n" "$@" | tr " " "\n"); do
	# check binary existence
	command -v "$b" >/dev/null 2>&1 || msg panic "$b doesn't exists"

	# install and strip binary
	install -s -m755 "$(command -v $b)" -t "${tmpdir}/usr/bin"

        # check statically linking
	ldd "$(command -v $b)" >/dev/null 2>&1 || continue

	# install libraries
	install_libraries $b
    done
}

# TODO make strip optional
# handle libraries
install_libraries() {
    for l in $(ldd "$(command -v $1)" | sed -nre 's,.* (/.*lib.*/.*.so.*) .*,\1,p' -e 's,.*(/lib.*/ld.*.so.*) .*,\1,p'); do
	# check symlink
	if [ -h "$l" ]; then
	    # check lib already existence
	    if [ ! -e "${tmpdir}/usr/lib/${l##*/}" ] && [ ! -e "${tmpdir}/$(readlink -f $l)" ]; then
		# regular
		install -s -m755 "$(readlink -f $l)" -t "${tmpdir}/usr/lib"

		# FIXME handle all symlinks
		# symlink may link to symlink
		[ -h "/usr/lib/$(readlink $l)" ] && cp -a "/usr/lib/$(readlink $l)" "${tmpdir}/usr/lib"

		# symlink
		cp -a "$l" "${tmpdir}/usr/lib"
	    fi
	else
	    if [ ! -e "${tmpdir}/usr/lib/${l##*/}" ]; then
		install -s -m755 "$l" -t "${tmpdir}/usr/lib"
	    fi
	fi
    done
}

# install important files
install_files() {
    # FIXME eof broken
    # initialize config
    cat <<EOF > "${tmpdir}/config"
debug="$debug"
root="$root"
root_type="$root_type"
root_args="$root_args"
devmgr="$devmgr"
#drivers="$drivers"
use_lvm="$use_lvm"
use_luks="$use_luks"
luks_root="$luks_root"
luks_args="$luks_args"
EOF

    # needed for devmgr
    cat <<EOF > "${tmpdir}/etc/group"
root:x:0:
tty:x:5:
dialout:x:11:
uucp:x:14:
kmem:x:3:
input:x:25:
video:x:13:
audio:x:12:
lp:x:10:
disk:x:9:
cdrom:x:16:
tape:x:6:
kvm:x:24:
floppy:x:8:
EOF

    # needed for devmgr
    cat <<EOF > "${tmpdir}/etc/passwd"
root:x:0:0::/root:/bin/sh
nobody:x:99:99::/:/bin/false
EOF

    # install init script
    install -m755 ./init -t "$tmpdir"
}

# TODO add more compession tools
# create and compress cpio archive
create_initramfs() {
    {
	( cd "$tmpdir" && {
	    find . | cpio -oH newc | gzip -9
	} ) > "${script_dir}/initramfs-${kernel}.img.gz"
    } >/dev/null 2>&1

    [ "$?" = 0 ] || msg panic "failed to generate initramfs image"
}

# check root
[ "$(id -u)" = 0 ] || msg panic "must be run as root"

# remove tmpdir on exit or unexpected error
trap remove_tmpdir EXIT INT

check_currentdir

# source config
. ./config || msg panic "./config doesn't exists"

# handle debug mode
[ "$debug" = 1 ] && {
    # debug shell commands
    set -x
    # don't remove anything
    trap : EXIT INT
}

# variables
tmpdir="$(mktemp -d /tmp/initramfs.XXXXXXXX)" || msg panic "failed to create working directory"
kernel="$(uname -r)"
moddir="/lib/modules/"
modker="${moddir}${kernel}"

check_requirements

create_structure
create_symlinks
#parse_fstab
#parse_crypttab
install_binaries $binaries

if [ "$hostonly" = 1 ]; then
    install_drivers
else
    install_all_drivers
fi

generate_depmod

# handle device manager
case "$devmgr" in
    mdev) install_mdev ;;
    mdevd) install_mdevd ;;
    udev) install_udev ;;
    *) msg panic "devmgr option broken" ;;
esac

[ "$use_luks" = 1 ] && install_luks
[ "$use_lvm" = 1 ] && install_lvm

install_files
create_initramfs

msg info "done! check out initramfs-${kernel}.img.gz"