from __future__ import annotations

from dataclasses import dataclass

from .frames import build_frame, frame_checksum_ok
from .modules import ModuleDecision, ModuleTx


SELECTOR_IRIS_MBLACK_LINK = 0x0013
IRIS_MBLACK_LINK_CLEAR = 0x0000
IRIS_MBLACK_LINK_ACTIVE = 0x4000


def selector_from_frame(frame: bytes) -> int | None:
    if len(frame) != 6:
        return None
    if frame[1] == 0x00:
        return frame[2]
    if frame[1] == 0x01:
        return 0x0080 + frame[2]
    if frame[1] == 0x02:
        return 0x0180 + frame[2]
    return None


def value_from_frame(frame: bytes) -> int | None:
    if len(frame) != 6:
        return None
    return ((frame[3] << 8) | frame[4]) & 0xFFFF


@dataclass
class IrisMblackLinkModule:
    """Closed-loop CCU side for the IRIS/M.BLACK LINK button/report path."""

    mirror_delay: float = 0.050
    report_commands: frozenset[int] = frozenset({0x00, 0x01, 0x02})
    handled_values: frozenset[int] = frozenset({IRIS_MBLACK_LINK_CLEAR, IRIS_MBLACK_LINK_ACTIVE})
    name: str = "iris_mblack_link"

    def on_rx(self, frame: bytes, label: str = "") -> ModuleDecision | None:
        if not frame_checksum_ok(frame) or frame[0] not in self.report_commands:
            return None
        selector = selector_from_frame(frame)
        if selector != SELECTOR_IRIS_MBLACK_LINK:
            return None
        value = value_from_frame(frame)
        if value not in self.handled_values:
            return None

        state = "active" if value == IRIS_MBLACK_LINK_ACTIVE else "clear"
        ack = build_frame(0x05, SELECTOR_IRIS_MBLACK_LINK, 0x0000)
        mirror = build_frame(0x00, SELECTOR_IRIS_MBLACK_LINK, value)
        return ModuleDecision(
            tx=(
                ModuleTx(ack, f"{self.name} ack selector=0x0013 value=0x{value:04X}"),
                ModuleTx(
                    mirror,
                    f"{self.name} mirror {state} selector=0x0013 value=0x{value:04X}",
                    delay=self.mirror_delay,
                ),
            ),
            suppress_default_ack=True,
            reason=f"{self.name}_{state}_report",
        )