#!/bin/bash
set -eE

function clean() {
    echo "==== CLEAN ERR ===="
    sudo umount "$WORKDIR/squashfs" || :
    sudo umount /tmp/livecd || :
}

trap clean ERR

SPATH=$(cd $(dirname $0) && pwd)
if [ -z $1 ]; then
	echo "Usage: prepare.sh <iso_path>"
	exit 1
fi
full_iso=$1
iso_wo_ext=${full_iso##*/}
iso_wo_ext=${iso_wo_ext%.iso}

WORKDIR="$SPATH/$iso_wo_ext"

echo "==== Prepare CD ===="
mkdir /tmp/livecd || :
sudo mount -o loop "$1" /tmp/livecd

mkdir -p "$WORKDIR"
rsync --exclude=/casper/filesystem.squashfs -a /tmp/livecd/ "$WORKDIR/cd"
mkdir "$WORKDIR/squashfs" "$WORKDIR/custom"
sudo modprobe squashfs
sudo mount -t squashfs -o loop /tmp/livecd/casper/filesystem.squashfs "$WORKDIR/squashfs/"

echo "==== Copy squashfs contents to $WORKDIR/custom ===="
sudo cp -a "$WORKDIR"/squashfs/* "$WORKDIR/custom"

# network access
sudo cp /etc/resolv.conf /etc/hosts "$WORKDIR/custom/etc/"

# mount proc, sys, opens a shell (for changes), and clean everything after
echo "==== CHROOT ===="
cat "$SPATH/tasks.sh" | sudo chroot "$WORKDIR/custom" /bin/bash

echo "==== Mod ISOLINUX (BIOS) AND GRUB (EFI) ===="
# isolinux
chmod -R +w "$WORKDIR/cd/isolinux"
cp isolinux/* "$WORKDIR/cd/isolinux/"
# grub
chmod -R +w "$WORKDIR/cd/boot/grub"
cp grub/* "$WORKDIR/cd/boot/grub/"

# setup iso
echo "==== Setup ISO ===="
chmod +w "$WORKDIR/cd/casper/filesystem.manifest"
sudo chroot "$WORKDIR/custom" dpkg-query -W --showformat='${Package} ${Version}\n' > "$WORKDIR/cd/casper/filesystem.manifest"
sudo cp "$WORKDIR/cd/casper/filesystem.manifest" "$WORKDIR/cd/casper/filesystem.manifest-desktop"
sudo mksquashfs "$WORKDIR/custom" "$WORKDIR/cd/casper/filesystem.squashfs"
sudo rm "$WORKDIR/cd/MD5SUMS"
sudo chmod +w "$WORKDIR/cd"
sudo bash -c 'cd '"$WORKDIR"'/cd && find . -type f -exec md5sum {} +' > "$WORKDIR"/cd/MD5SUMS

# create iso
echo "==== Create ISO ===="
cd "$WORKDIR/cd"
# create a DVD-burnable ISO with BIOS (isolinux) and EFI (grub) support
sudo mkisofs -U -A "$iso_wo_ext-LIS67" -V "$iso_wo_ext-LIS67" -volset "$iso_wo_ext-LIS67" -J -joliet-long -r -v -T -o "$WORKDIR/$iso_wo_ext-lis67.iso" -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot .

# convert iso to a bootable USB drive iso
sudo isohybrid --uefi "$WORKDIR/$iso_wo_ext-lis67.iso"

# umount & clean
echo "==== Clean ===="
sudo umount "$WORKDIR/squashfs"
sudo umount /tmp/livecd
sudo chown -R $USER: "$WORKDIR"

echo "Final ISO: $WORKDIR/$iso_wo_ext-lis67.iso"
echo "Done"