#!/bin/sh
#
# Usage: preseed.sh preseeded.iso source.iso [udebs]
#
# Credits: https://wiki.debian.org/DebianInstaller/Preseed/EditIso
#          https://wiki.debian.org/DebianInstaller/Modify/CD
#
# Install with 'Advanced options > Automated install'

set -ue

newiso=$(readlink -f "$1")
[ -e "$newiso" ] && rm -f "$newiso"

# Generate a (hybrid) ISO or an HDD image?  The latter should only be
# useful for older BIOSes that don't support hybrid ISOs.
case "$newiso" in
    *.iso) type=iso;;
    *.tar) type=hdd; archive=;;
    *.tar.gz|*.tgz) type=hdd; archive=z;;
    *.tar.bz|*.tar.bz2|*.tbz|*.tbz2) type=hdd; archive=j;;
    *.tar.xz|*.txz) type=hdd; archive=J;;
    *) echo "Error: $newiso: Unknown file type" >&2; exit 1;;
esac

iso="$2"
test -r "$iso" || exit 1
shift; shift
pwd=$(pwd)

for prog in fuseiso fusermount rsync md5sum xorriso find; do
    if ! which "$prog" >/dev/null; then
        echo "Error: Missing $prog" >&2
        exit 1
    fi
done

mountdir=$(mktemp -d)
fuseiso "$iso" "$mountdir"

isoeditdir=$(mktemp -d)
rsync -aH --exclude=TRANS.TBL --chmod=u+w "$mountdir"/ "$isoeditdir"/

fusermount -u "$mountdir"
rmdir "$mountdir"

cp preseed.cfg "$isoeditdir/"
md5sum ./preseed.cfg >> "$isoeditdir/md5sum.txt"

kernel="$(sed -rn '/^\s+kernel\s+/                           {s///p;  q}' $isoeditdir/isolinux/txt.cfg)"
initrd="$(sed -rn '/^\s+append\s(.*\s)?initrd=(\S+)(\s.*)?$/ {s//\2/p;q}' $isoeditdir/isolinux/txt.cfg)"
cat >$isoeditdir/isolinux/isolinux.cfg <<-EOF
	default install
	label install
	    kernel $kernel
	    append initrd=$initrd preseed/file=/cdrom/preseed.cfg auto=true --- fb=false
EOF
# ^ no need to update isolinux' checksum, as it's not in './md5sum.txt'.

if [ -f $isoeditdir/boot/grub/grub.cfg ]; then
    sed -ri 's@^\s+linux\s(.*\s)?auto=true\s(.*\s)?priority=critical\b@& preseed/file=/cdrom/preseed.cfg@' \
		"$isoeditdir/boot/grub/grub.cfg"
fi

mkdir "$isoeditdir/include"
rsync -aL ./include/ "$isoeditdir/include"/
find -L ./include \( \! -name '.*' -a -type f \) -print0 | \
    xargs -r0 md5sum >> "$isoeditdir/md5sum.txt"

# non-free firmwares:
# wget -O - http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/wheezy/current/firmware.tar.gz | tar -C ./firmware -xz
#rsync -aL ./firmware/ "$isoeditdir/firmware"/
#find ./firmware \( \! -name '.*' -a -type f \) -print0 | \
#    xargs -r0 md5sum >> "$isoeditdir/md5sum.txt"

dist=$(readlink "$isoeditdir/dists/stable")
packages="dists/$dist/main/debian-installer/binary-$DEB_ARCH/Packages"
gunzip "$isoeditdir/$packages.gz"
while [ $# -gt 0 ]; do
    cd "${1%%_*}-udeb"; shift
    name="$(sed -n 's/Package:\s\s*//p' ./debian/control)"
    udeb="$(sed -nr '/^(\S+\.udeb)(\s.*)?$/ {s//\1/p;q}' ./debian/files)"
    dir="pool/main/$(expr substr "$name" 1 1)/$name"
    mkdir -p "$isoeditdir/$dir/"
    cp ../"$udeb" "$isoeditdir/$dir/"

    cat "./debian/$name/DEBIAN/control"                    >> "$isoeditdir/$packages"
    echo "Filename: $dir/$udeb"                            >> "$isoeditdir/$packages"
    echo "MD5sum: $(md5sum    ../"$udeb" | cut -d' ' -f1)" >> "$isoeditdir/$packages"
    echo "SHA1:   $(sha1sum   ../"$udeb" | cut -d' ' -f1)" >> "$isoeditdir/$packages"
    echo "SHA256: $(sha256sum ../"$udeb" | cut -d' ' -f1)" >> "$isoeditdir/$packages"
    echo                                                   >> "$isoeditdir/$packages"

    cd "$isoeditdir"
    md5sum "./$dir/$udeb" >> "$isoeditdir/md5sum.txt"
    cd "$pwd"
done

gzip "$isoeditdir/$packages"

md5sums=$(mktemp)
cd "$isoeditdir"
while read sum file; do
    if [ "$file" = "./${packages}" -o \
         "$file" = "./${packages}.gz" -o \
         "$file" = "./boot/grub/grub.cfg" ]; then
         md5sum "$file"
     else
         echo "$sum  $file"
     fi
done < ./md5sum.txt > "$md5sums"
mv "$md5sums" "$isoeditdir/md5sum.txt"

if [ $type = hdd ]; then
    # Generate a HDD image
    mv ./isolinux                      ./syslinux
    mv ./syslinux/isolinux.cfg         ./syslinux/syslinux.cfg
    mv ./syslinux/isolinux.bin         ./syslinux/syslinux.bin
    sed -i 's/\bisolinux\b/syslinux/g' ./syslinux/*.cfg
    # Dereference links, which are not compatible with FAT devices
    tar --exclude='./debian' --hard-dereference --dereference \
        -c ${archive:+-$archive} \
        -f "$newiso" ./

    ## To burn the archive onto a USB stick:
    # device=/dev/disk/by-id/...    # FIXME
    # mountpoint=/mnt/usbkey        # FIXME
    #
    # device=$(readlink -f "$device")
    # parted $device mklabel msdos
    # parted $device mkpart primary 1 1G
    # parted $device set 1 boot on
    # mkdosfs ${device}1
    #
    # install-mbr $device
    # syslinux -i ${device}1
    #
    # mount ${device}1 $mountpoint
    # tar -x -C "$mountpoint" -f "$image" --no-same-owner
    # umount "$mountpoint"

elif [ $type = iso ]; then
    # Generate a hybrid ISO image
    if [ -f ./boot/grub/efi.img ]; then
        efi_opts="--efi-boot boot/grub/efi.img -append_partition 2 0x01 ./boot/grub/efi.img"
    else
        efi_opts=
    fi

    # /usr/lib/ISOLINUX/isohdpfx.bin is in the 'isolinux' package
    xorriso -as mkisofs -r \
        -checksum_algorithm_iso all \
        -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
        -b isolinux/isolinux.bin -c isolinux/boot.cat \
        -partition_offset 16 \
        -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot $efi_opts \
        -o "$newiso" \
        ./

    # To burn the ISO onto a USB stick, see
    # http://www.debian.org/CD/faq/#write-usb
fi

rm -rf "$isoeditdir"