#!/usr/bin/env python3
"""GATT service 0xA000 — Sensor Report + Slot & Config."""
from __future__ import annotations

import logging
from typing import Callable, Optional

from config import CHAR_REPORT_UUID, CHAR_SLOT_UUID, POLL_PERIOD_S, SERVICE_UUID
from protocol import (
    CFG_JOIN_OPEN,
    CFG_POOL_FULL,
    SLOT_UNASSIGNED,
    pack_slot_config,
    unpack_report,
)
from registry import Registry

log = logging.getLogger("collector.gatt")

WriteHandler = Callable[[str, bytes], None]
ReadSlotHandler = Callable[[str], bytes]
ConnectHandler = Callable[[str], bool]  # return False → should disconnect
DisconnectHandler = Callable[[str], None]


class CollectorGatt:
    """GATT callbacks over bless; address resolution is injected by main."""

    def __init__(self, registry: Registry):
        self.registry = registry
        self._current_addr: Optional[str] = None
        self.on_write: Optional[WriteHandler] = None
        self.on_read_slot: Optional[ReadSlotHandler] = None
        self.on_connect: Optional[ConnectHandler] = None
        self.on_disconnect: Optional[DisconnectHandler] = None

    def set_current_addr(self, addr: Optional[str]) -> None:
        self._current_addr = addr

    def current_addr(self) -> Optional[str]:
        return self._current_addr

    def handle_write(self, characteristic, value: bytearray, **kwargs) -> None:
        try:
            data = bytes(value) if value is not None else b""
            addr = self._current_addr or kwargs.get("address") or ""
            uuid = str(getattr(characteristic, "uuid", "") or "").lower()
            if CHAR_REPORT_UUID.lower() not in uuid and "a001" not in uuid:
                log.debug("write to unexpected char %s", uuid)
                return
            if len(data) != 4:
                log.warning("bad report length=%d from %s — discarded", len(data), addr)
                return
            report = unpack_report(data)
            if report is None:
                log.warning("bad report parse from %s — discarded", addr)
                return
            if self.on_write:
                self.on_write(addr, data)
        except Exception as e:
            log.error("write handler error: %s", e)

    def handle_read(self, characteristic, **kwargs) -> bytearray:
        try:
            uuid = str(getattr(characteristic, "uuid", "") or "").lower()
            addr = self._current_addr or kwargs.get("address") or ""
            if CHAR_SLOT_UUID.lower() in uuid or "a011" in uuid:
                if self.on_read_slot:
                    return bytearray(self.on_read_slot(addr))
                return bytearray(self.default_slot_value(addr))
            return bytearray(b"\x00\x00\x00\x00")
        except Exception as e:
            log.error("read handler error: %s", e)
            return bytearray(b"\xff\x00\x00\x00")

    def default_slot_value(self, addr: str) -> bytes:
        sensor = self.registry.get(addr) if addr else None
        slot = sensor.slot if sensor else SLOT_UNASSIGNED
        flags = 0
        if not self.registry.pool_full():
            flags |= CFG_JOIN_OPEN
        else:
            flags |= CFG_POOL_FULL
        return pack_slot_config(slot, flags, POLL_PERIOD_S)


async def build_bless_server(gatt: CollectorGatt, loop, name: str):
    """Create and configure a BlessServer. Returns the server instance."""
    from bless import (  # type: ignore
        BlessServer,
        GATTAttributePermissions,
        GATTCharacteristicProperties,
    )

    server = BlessServer(name=name, loop=loop)
    server.read_request_func = gatt.handle_read
    server.write_request_func = gatt.handle_write

    await server.add_new_service(SERVICE_UUID)

    # Signature: (service, char, properties, value, permissions)
    # Sensor Report — write-without-response
    await server.add_new_characteristic(
        SERVICE_UUID,
        CHAR_REPORT_UUID,
        GATTCharacteristicProperties.write_without_response
        | GATTCharacteristicProperties.write,
        bytearray(b"\x00\x00\x00\x00"),
        GATTAttributePermissions.writeable,
    )

    # Slot & Config — read
    await server.add_new_characteristic(
        SERVICE_UUID,
        CHAR_SLOT_UUID,
        GATTCharacteristicProperties.read,
        bytearray(gatt.default_slot_value("")),
        GATTAttributePermissions.readable,
    )

    return server