#!/usr/bin/env bash

#TODO: move to installer

function usage {
    echo "$0 [disk] [filesystem] [bootloader.efi] [bootloader.efi path] <bootloader.bios>" >&2
    exit 1
}

if [ -z "$1" ]
then
    echo "invalid disk '$1'" >&2
    usage
fi
DISK="$1"

if [ ! -f "$2" ]
then
    echo "invalid filesystem '$2'" >&2
    usage
fi
FILESYSTEM="$2"

if [ ! -f "$3" ]
then
    echo "invalid bootloader.efi '$3'" >&2
    usage
fi
BOOTLOADER_EFI="$3"

if [ ! -n "$4" ]
then
    echo "invalid bootloader.efi path '$4'" >&2
    usage
fi
BOOTLOADER_EFI_PATH="$4"

# Optional argument
if [ -n "$5" -a ! -f "$5" ]
then
    echo "invalid bootloader.bios '$5'" >&2
fi
BOOTLOADER_BIOS="$5"

set -ex

# Calculate partition sizes
MiB=1048576

fs_disk_size="$(du -m "${FILESYSTEM}" | cut -f1)"
fs_disk_blkcount="$(expr "${fs_disk_size}" \* "$(expr "${MiB}" / 512)")"
fs_start="2048"
fs_end="$(expr "${fs_start}" + "${fs_disk_blkcount}")"
fs_last="$(expr "${fs_end}" - 1)"

efi_disk_size="$(expr "$(du -m "${BOOTLOADER_EFI}" | cut -f1)" + 1)"
efi_disk_blkcount="$(expr "$efi_disk_size" \* "$(expr "${MiB}" / 512)")"
efi_start="${fs_end}"
efi_end="$(expr "${efi_start}" + "${efi_disk_blkcount}")"
efi_last="$(expr "${efi_end}" - 1)"

# Populate an EFI system partition
dd if=/dev/zero of="${DISK}.esp" bs="${MiB}" count="${efi_disk_size}"
mkfs.vfat "${DISK}.esp"
mmd -i "${DISK}.esp" efi
mmd -i "${DISK}.esp" efi/boot
mcopy -i "${DISK}.esp" "${BOOTLOADER_EFI}" "::${BOOTLOADER_EFI_PATH}"

# Create the disk
dd if=/dev/zero of="${DISK}" bs="${MiB}" count="$(expr "$(du -m "${DISK}.esp" | cut -f1)" + 2 + "$(du -m "${FILESYSTEM}" | cut -f1)")"

# Create partition table
"${PARTED}" -s -a minimal "${DISK}" mklabel gpt
"${PARTED}" -s -a minimal "${DISK}" mkpart redox ext4 "${fs_start}s" "${fs_last}"s
"${PARTED}" -s -a minimal "${DISK}" mkpart EFI fat32 "${efi_start}"s "${efi_last}s"
"${PARTED}" -s -a minimal "${DISK}" set 2 boot on
"${PARTED}" -s -a minimal "${DISK}" set 2 esp on

# Write the partitions
dd if="${FILESYSTEM}" of="${DISK}" bs=512 seek="${fs_start}" count="${fs_disk_blkcount}" conv=notrunc
dd if="${DISK}.esp" of="${DISK}" bs=512 seek="${efi_start}" count="${efi_disk_blkcount}" conv=notrunc

# Write BIOS bootloader if applicable
if [ -n "${BOOTLOADER_BIOS}" ]
then
	dd if="${BOOTLOADER_BIOS}" of="${DISK}" bs=1 count=446 conv=notrunc
	dd if="${BOOTLOADER_BIOS}" of="${DISK}" bs=512 skip=34 seek=34 conv=notrunc
fi