#!/bin/sh

set -e

printf "Checking dependencies...\n"
dpkg-query -W \
    git \
    debootstrap \
    squashfs-tools \
    xorriso \
    isolinux \
    syslinux-efi \
    grub-pc-bin \
    grub-efi-amd64-bin \
    mtools \
    dosfstools

mkdir -p /srv/LIVE_BOOT

debootstrap \
    --arch=amd64 \
    --variant=minbase \
    --merged-usr \
    sid \
    /srv/LIVE_BOOT/chroot \
    http://deb.debian.org/debian/

# Copy the filesystem tree
cp -R $PWD/root/* /srv/LIVE_BOOT/chroot

# Run script in chroot
chroot /srv/LIVE_BOOT/chroot /srv/entrypoint.sh

# Clean the installation
rm -rf /srv/LIVE_BOOT/chroot/srv/*

# Change password to the users
printf "Setting passwords for users...\n"
printf "root:root\n" | chpasswd --root /srv/LIVE_BOOT/chroot
printf "live-user:root\n" | chpasswd --root /srv/LIVE_BOOT/chroot

# Create directories that will contain files for our live environment files and scratch files.
bash -c "mkdir -p /srv/LIVE_BOOT/{staging/{EFI/boot,boot/grub/x86_64-efi,isolinux,live},tmp}"

# Compress the chroot environment into a Squash filesystem.
# I'm using blocks of 1MiB with xz for x86
mksquashfs \
    /srv/LIVE_BOOT/chroot \
    /srv/LIVE_BOOT/staging/live/filesystem.squashfs \
    -e boot \
    -b 1M \
    -comp xz \
    -Xbcj x86

# Copy the kernel and initramfs from inside the chroot to the live directory.
cp /srv/LIVE_BOOT/chroot/boot/vmlinuz-* \
    /srv/LIVE_BOOT/staging/live/vmlinuz && \
cp /srv/LIVE_BOOT/chroot/boot/initrd.img-* \
    /srv/LIVE_BOOT/staging/live/initrd

# Prepare Boot Loader Menus

# Create an ISOLINUX (Syslinux) boot menu. This boot menu is used when booting in BIOS/legacy mode.
cat <<'EOF' >/srv/LIVE_BOOT/staging/isolinux/isolinux.cfg
UI vesamenu.c32

MENU TITLE Boot Menu
DEFAULT linux
TIMEOUT 600
MENU RESOLUTION 640 480
MENU COLOR border       30;44   #40ffffff #a0000000 std
MENU COLOR title        1;36;44 #9033ccff #a0000000 std
MENU COLOR sel          7;37;40 #e0ffffff #20ffffff all
MENU COLOR unsel        37;44   #50ffffff #a0000000 std
MENU COLOR help         37;40   #c0ffffff #a0000000 std
MENU COLOR timeout_msg  37;40   #80ffffff #00000000 std
MENU COLOR timeout      1;37;40 #c0ffffff #00000000 std
MENU COLOR msg07        37;40   #90ffffff #a0000000 std
MENU COLOR tabmsg       31;40   #30ffffff #00000000 std

LABEL linux
  MENU LABEL Debian Live [BIOS/ISOLINUX]
  MENU DEFAULT
  KERNEL /live/vmlinuz
  APPEND initrd=/live/initrd boot=live

LABEL linux
  MENU LABEL Debian Live [BIOS/ISOLINUX] (nomodeset)
  MENU DEFAULT
  KERNEL /live/vmlinuz
  APPEND initrd=/live/initrd boot=live nomodeset
EOF

# Create a second, similar, boot menu for GRUB. This boot menu is used when booting in EFI/UEFI mode.
cat <<'EOF' >/srv/LIVE_BOOT/staging/boot/grub/grub.cfg
search --set=root --file /DEBIAN_CUSTOM

set default="0"
set timeout=30

# If X has issues finding screens, experiment with/without nomodeset.

menuentry "Debian Live [EFI/GRUB]" {
    linux ($root)/live/vmlinuz boot=live
    initrd ($root)/live/initrd
}

menuentry "Debian Live [EFI/GRUB] (nomodeset)" {
    linux ($root)/live/vmlinuz boot=live nomodeset
    initrd ($root)/live/initrd
}
EOF

# Create a third boot config.
# This config will be an early configuration file that is embedded inside GRUB in the EFI partition.
# This finds the root and loads the GRUB config from there.
cat <<'EOF' >/srv/LIVE_BOOT/tmp/grub-standalone.cfg
search --set=root --file /DEBIAN_CUSTOM
set prefix=($root)/boot/grub/
configfile /boot/grub/grub.cfg
EOF

# Create a special file in staging named DEBIAN_CUSTOM.
# This file will be used to help GRUB figure out which device contains our live filesystem.
# This file name must be unique and must match the file name in our grub.cfg config.
touch /srv/LIVE_BOOT/staging/DEBIAN_CUSTOM

# Prepare Boot Loader Files

# Copy BIOS/legacy boot required files into our workspace.
cp /usr/lib/ISOLINUX/isolinux.bin "/srv/LIVE_BOOT/staging/isolinux/" && \
cp /usr/lib/syslinux/modules/bios/* "/srv/LIVE_BOOT/staging/isolinux/"

# Copy EFI/modern boot required files into our workspace.
cp -r /usr/lib/grub/x86_64-efi/* "/srv/LIVE_BOOT/staging/boot/grub/x86_64-efi/"

# Generate an EFI bootable GRUB image.
grub-mkstandalone \
    --format=x86_64-efi \
    --output=/srv/LIVE_BOOT/tmp/bootx64.efi \
    --locales="" \
    --fonts="" \
    "boot/grub/grub.cfg=/srv/LIVE_BOOT/tmp/grub-standalone.cfg"

# Create a FAT16 UEFI boot disk image containing the EFI bootloader.
# Note the use of the mmd and mcopy commands to copy our UEFI boot loader named bootx64.efi.
(cd /srv/LIVE_BOOT/staging/EFI/boot && \
    dd if=/dev/zero of=efiboot.img bs=1M count=20 && \
    mkfs.vfat efiboot.img && \
    mmd -i efiboot.img efi efi/boot && \
    mcopy -vi efiboot.img /srv/LIVE_BOOT/tmp/bootx64.efi ::efi/boot/
)

# Create Bootable ISO/CD
xorriso \
    -as mkisofs \
    -iso-level 3 \
    -o "/srv/LIVE_BOOT/debian-custom.iso" \
    -full-iso9660-filenames \
    -volid "DEBIAN_CUSTOM" \
    -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
    -eltorito-boot \
        isolinux/isolinux.bin \
        -no-emul-boot \
        -boot-load-size 4 \
        -boot-info-table \
        --eltorito-catalog isolinux/isolinux.cat \
    -eltorito-alt-boot \
        -e /EFI/boot/efiboot.img \
        -no-emul-boot \
        -isohybrid-gpt-basdat \
    -append_partition 2 0xef /srv/LIVE_BOOT/staging/EFI/boot/efiboot.img \
    "/srv/LIVE_BOOT/staging"