#!/bin/bash

set -eu

PARTITION_LABEL="multiboot"
MULTIBOOT_MNT="/mnt/multiboot"

function cmd_format {
    if [ ! -b "${1:-}" ]; then
        echo "Usage: $0 format /dev/sdX"
        exit 1
    fi
    set -x

    sudo -k
    DISK_DEVICE="$1"
    PARTITION_DEVICE="${DISK_DEVICE}1"
    echo -ne 'label: dos\ntype=c, bootable\n' | sudo sfdisk "$DISK_DEVICE"
    sudo mkfs.vfat -n "$PARTITION_LABEL" "$PARTITION_DEVICE"
}

function cmd_grub {
    DISK_DEVICE="$(findmnt -n -o source "$MULTIBOOT_MNT" | sed 's/[0-9]*$//')"
    if [ ! -b "$DISK_DEVICE" ]; then
        echo "ERROR! Could not find disk to install bootloader. Try using mount."
        exit 1
    fi
    set -x

    sudo -k
    install_grub_bios
    install_grub_efi
    install_grub_cfg
}

function cmd_grubcfg {
    set -x
    install_grub_cfg
}

function install_grub_bios {
    sudo grub-install \
        --target=i386-pc \
        --boot-directory="$MULTIBOOT_MNT" \
        "$DISK_DEVICE"
}

function install_grub_efi {
    for arch in i386-efi x86_64-efi; do
        sudo grub-install \
            --target="$arch" \
            --no-nvram \
            --removable \
            --efi-directory="$MULTIBOOT_MNT" \
            --boot-directory="$MULTIBOOT_MNT" \
            "$DISK_DEVICE"
    done
}

function install_grub_cfg {
    print_grub_cfg | sudo tee "${MULTIBOOT_MNT}/grub/grub.cfg" > /dev/null
}

function cmd_mount {
    set -x

    PARTITION_DEVICE="$(readlink -f "/dev/disk/by-label/${PARTITION_LABEL}")"
    sudo mkdir -p "$MULTIBOOT_MNT"
    while sudo umount "$PARTITION_DEVICE" &> /dev/null; do true; done
    sudo mount "$PARTITION_DEVICE" "$MULTIBOOT_MNT" -o "uid=$(whoami)"
}

function cmd_umount {
    set -x

    sudo umount "$MULTIBOOT_MNT"
    sudo rmdir "$MULTIBOOT_MNT"
}

function cmd_freedos {
    set -x

    local SYSLINUX_VERSION="6.03"
    local SYSLINUX_URL="https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-${SYSLINUX_VERSION}.tar.gz"
    local FREEDOS_URL="http://www.freedos.org/download/download/FD12LITE.zip"

    curl -fL "$SYSLINUX_URL" | \
        tar xz --no-same-owner --strip-components=3 -C "$MULTIBOOT_MNT" \
        "syslinux-${SYSLINUX_VERSION}/bios/memdisk/memdisk"

    curl -fL "$FREEDOS_URL" > "${MULTIBOOT_MNT}/FD12LITE.zip"
}

function print_grub_cfg {
    cat <<EOT
insmod all_video
insmod part_msdos
insmod progress
insmod regexp
search --set=root --label $PARTITION_LABEL

function setup_arch {
  menuentry "\$1" {
    loopback loop \$1
    linux (loop)/arch/boot/x86_64/vmlinuz img_label=${PARTITION_LABEL} img_loop=\$1 archisobasedir=arch earlymodules=loop
    initrd (loop)/arch/boot/x86_64/archiso.img
  }
}
for iso in /archlinux-*.iso; do
  if [ -f "\$iso" ]; then
    setup_arch \$iso
  fi
done

function setup_debian {
  menuentry "\$1" {
    linux \$1/vmlinuz
    initrd \$1/initrd.gz
  }
}
for d in /debian-*-hd-media; do
  if [ -d "\$d" ]; then
    setup_debian \$d
  fi
done

if [ -f /memdisk -a -f /FD12LITE.zip ]; then
  menuentry /FD12LITE.zip {
    if [ \${grub_platform} = pc ]; then
      linux16 /memdisk raw
      initrd16 /FD12LITE.zip
    else
      echo "FreeDOS only works with BIOS boot."
      sleep 3
    fi
  }
fi

function setup_fedora {
  menuentry "\$1" {
    loopback loop \$1
    probe -s iso_label -l (loop)
    linux (loop)/isolinux/vmlinuz root=live:CDLABEL=\$iso_label rd.live.image quiet iso-scan/filename=\$1
    initrd (loop)/isolinux/initrd.img
  }
}
for iso in /Fedora-Workstation-Live-*.iso; do
  if [ -f "\$iso" ]; then
    setup_fedora \$iso
  fi
done

function setup_ubuntu {
  menuentry "\$1" {
    loopback loop \$1
    linux (loop)/casper/vmlinuz* boot=casper quiet iso-scan/filename=\$1
    initrd (loop)/casper/initrd*
  }
}
for iso in /ubuntu-*-desktop-*.iso; do
  if [ -f "\$iso" ]; then
    setup_ubuntu \$iso
  fi
done

EOT
}

CMD="cmd_${1:-}"
shift || true

if [ "$(type -t -- "$CMD")" = "function" ]; then
    "${CMD}" "$@"
else
    echo "Usage: $0 [format|mount|grub|grubcfg|freedos|umount]"
    exit 1
fi