"""Build a CoCo 3 Program Pak cartridge ROM (.ccc): GIME viewer + 15360-byte image.

The CoCo 3 autostarts the cartridge at $C000.  Layout: viewer code, then the
linear GIME image, padded to a 16KB ROM."""
from __future__ import annotations

from . import viewer

CART_BASE = 0xC000
CART_SIZE = 0x4000             # 16 KB


def build_rom(data: bytes, cres: int, inks, border: int) -> bytes:
    if len(data) != viewer.IMG_LEN:
        raise ValueError(f"unexpected image length {len(data)}")
    kw = dict(cres=cres, inks=inks, border=border)
    code = viewer.build(0, **kw)                  # pass 1: measure code length
    data_src = CART_BASE + len(code)
    code = viewer.build(data_src, **kw)           # pass 2: real data address
    rom = code + bytes(data)
    if len(rom) > 0x3F00:                         # keep clear of the $FF00 I/O page
        raise ValueError("viewer + image exceed the cartridge ROM window")
    return rom + bytes(CART_SIZE - len(rom))


def write_ccc(rom: bytes, path: str) -> str:
    with open(path, "wb") as f:
        f.write(rom)
    return path