#!/usr/bin/env python3
from __future__ import annotations

import datetime
import io
import sys
from pathlib import Path

import click


BOARDLOADER_START = 0x08000000
BOARDLOADER_END = 0x0800C000
BOOTLOADER_START = 0x08020000
FIRMWARE_START = 0x08040000


@click.command()
@click.argument(
    "boardloader",
    type=click.Path(exists=True, dir_okay=False, readable=True, path_type=Path),
)
@click.argument(
    "bootloader",
    type=click.Path(exists=True, dir_okay=False, readable=True, path_type=Path),
)
@click.argument(
    "firmware",
    type=click.Path(exists=True, dir_okay=False, readable=True, path_type=Path),
)
@click.argument(
    "outfile",
    type=click.Path(dir_okay=False, writable=True, path_type=Path),
    required=False,
)
def main(
    boardloader: Path, bootloader: Path, firmware: Path, outfile: Path | None
) -> None:
    if outfile is None:
        today = datetime.date.today().strftime(r"%Y-%m-%d")
        outfile = Path(f"combined-{today}.bin")

    offset = BOARDLOADER_START
    out_bytes = io.BytesIO()

    # write boardloader
    offset += out_bytes.write(boardloader.read_bytes())
    if offset > BOARDLOADER_END:
        raise Exception("Boardloader too big")

    # zero-pad until next section:
    offset += out_bytes.write(b"\x00" * (BOOTLOADER_START - offset))
    assert offset == BOOTLOADER_START

    # write bootlaoder
    offset += out_bytes.write(bootloader.read_bytes())
    if offset > FIRMWARE_START:
        raise Exception("Bootloader too big")

    # zero-pad until next section:
    offset += out_bytes.write(b"\x00" * (FIRMWARE_START - offset))
    assert offset == FIRMWARE_START

    # write firmware
    offset += out_bytes.write(firmware.read_bytes())

    # write out contents
    click.echo(f"Writing {outfile} ({offset - BOARDLOADER_START} bytes)")
    outfile.write_bytes(out_bytes.getvalue())


if __name__ == "__main__":
    main()