#!/bin/bash

function mount_rootfs() {
    mkdir -p chroot/dev chroot/dev/pts chroot/proc chroot/sys chroot/run
    sudo mount --bind /dev chroot/dev
    sudo mount --bind /dev/pts chroot/dev/pts
    sudo mount --bind /proc chroot/proc
    sudo mount --bind /sys chroot/sys
    sudo mount --bind /run chroot/run
}

function unmount_rootfs() {
    sudo umount chroot/dev/pts
    sudo umount chroot/dev
    sudo umount chroot/proc
    sudo umount chroot/sys
    sudo umount chroot/run
}

function chroot_cmd() {
    sudo env DEBIAN_FRONTEND=noninteractive chroot chroot "$@"
}

function chroot_apt() {
    chroot_cmd apt "$@"
}

function install_iso_build_deps() {
    sudo apt install -y debootstrap squashfs-tools syslinux xorriso p7zip-full
}

function debootstrap_base() {
    sudo debootstrap --arch=amd64 testing chroot https://mirrors.tuna.tsinghua.edu.cn/debian/
}

function update_sourcelists() {
    echo "deb https://mirrors.tuna.tsinghua.edu.cn/debian/ testing main contrib non-free non-free-firmware" | sudo tee chroot/etc/apt/sources.list
    echo "deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ testing main contrib non-free non-free-firmware" | sudo tee -a chroot/etc/apt/sources.list
}

function chroot_install_base_packages() {
    chroot_apt update
    chroot_apt upgrade -y
    chroot_apt install -y zsh
    chroot_apt install -y live-boot live-config-systemd --no-install-recommends
    # chroot_apt install -y lxqt-core sddm-theme-debian-elarun
    chroot_apt install -y linux-image-amd64
}

function chroot_create_live_user() {
    chroot_cmd useradd -m -s /bin/bash live
    echo "live:live" | chroot_cmd chpasswd
}

function make_bootable() {
    cp "$(ls -1t chroot/boot/vmlinuz-* | head -n 1)" isoroot/vmlinuz
    cp "$(ls -1t chroot/boot/initrd.img-* | head -n 1)" isoroot/initrd
    mkdir isoroot/isolinux
    cp /usr/lib/ISOLINUX/isolinux.bin isoroot/isolinux
    cp /usr/lib/syslinux/modules/bios/ldlinux.c32 isoroot/isolinux
    cp ../isolinux.cfg isoroot/isolinux/isolinux.cfg
    cat > isoroot/isolinux/isolinux.cfg <<EOL
DEFAULT live
LABEL live
    MENU LABEL ^Boot Live System
    KERNEL /vmlinuz
    APPEND initrd=/initrd boot=live components
EOL

}

function create_iso() {
    xorriso -as mkisofs -o ../debian-live.iso -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
        -c isolinux/boot.cat -b isolinux/isolinux.bin -no-emul-boot \
        -exclude chroot \
        -boot-load-size 4 -boot-info-table \
        ./isoroot/
    7z l ../debian-live.iso
}

function main() {
    set -e
    install_iso_build_deps

    mkdir chroot
    debootstrap_base
    update_sourcelists
    mount_rootfs
    chroot_install_base_packages
    chroot_create_live_user
    unmount_rootfs

    mkdir -p isoroot/live
    sudo mksquashfs chroot/ isoroot/live/filesystem.squashfs -comp xz -e boot
    make_bootable
    create_iso
}