"""In-process deterministic packet harness for bridge_master tests.

This module is test-only. It avoids UDP sockets and replaces production
network sends with capture functions while leaving production modules unchanged.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from types import SimpleNamespace
import copy
import importlib
import unittest


DMRD = b"DMRD"
HBPF_VOICE = 0x0
HBPF_VOICE_SYNC = 0x1
HBPF_DATA_SYNC = 0x2
HBPF_SLT_VHEAD = 0x1
HBPF_SLT_VTERM = 0x2
ID_MAX = 16776415
PEER_MAX = 4294967295


def require_bridge_master():
    """Import bridge_master or skip tests when runtime deps are unavailable."""

    try:
        return importlib.import_module("bridge_master")
    except ModuleNotFoundError as exc:
        raise unittest.SkipTest(
            f"bridge_master runtime dependency is not installed: {exc.name}"
        ) from exc


def bytes_3(value: int | bytes) -> bytes:
    if isinstance(value, bytes):
        if len(value) != 3:
            raise ValueError("expected exactly 3 bytes")
        return value
    return int(value).to_bytes(3, "big")


def bytes_4(value: int | bytes) -> bytes:
    if isinstance(value, bytes):
        if len(value) != 4:
            raise ValueError("expected exactly 4 bytes")
        return value
    return int(value).to_bytes(4, "big")


def int_id(value: int | bytes) -> int:
    if isinstance(value, int):
        return value
    return int.from_bytes(value, "big")


def acl_permit_all(max_id: int = ID_MAX) -> tuple[bool, list[tuple[int, int]]]:
    return True, [(1, max_id)]


def hbp_bits(slot: int, call_type: str, frame_type: int, dtype_vseq: int) -> int:
    bits = ((frame_type & 0x3) << 4) | (dtype_vseq & 0xF)
    if slot == 2:
        bits |= 0x80
    if call_type == "unit":
        bits |= 0x40
    return bits


def parse_dmr_fields(packet: bytes) -> dict[str, object]:
    if len(packet) < 20 or packet[:4] != DMRD:
        return {"raw": packet}

    bits = packet[15]
    if bits & 0x40:
        call_type = "unit"
    elif (bits & 0x23) == 0x23:
        call_type = "vcsbk"
    else:
        call_type = "group"

    return {
        "opcode": packet[:4],
        "seq": packet[4],
        "rf_src": packet[5:8],
        "dst_id": packet[8:11],
        "peer_id": packet[11:15],
        "bits": bits,
        "slot": 2 if bits & 0x80 else 1,
        "call_type": call_type,
        "frame_type": (bits & 0x30) >> 4,
        "dtype_vseq": bits & 0xF,
        "stream_id": packet[16:20],
        "dmr_payload": packet[20:53],
        "ber": packet[53:54],
        "rssi": packet[54:55],
    }


@dataclass(frozen=True)
class PacketSpec:
    peer_id: int | bytes = 1001
    rf_src: int | bytes = 3120001
    dst_id: int | bytes = 91
    slot: int = 2
    stream_id: int | bytes = 0x01020304
    seq: int = 0
    call_type: str = "group"
    frame_type: int = HBPF_VOICE
    dtype_vseq: int = 0
    payload: bytes = b"\x00" * 33
    ber: bytes = b"\x00"
    rssi: bytes = b"\x00"
    delay: float = 0.0

    def data(self) -> bytes:
        if len(self.payload) != 33:
            raise ValueError("DMR payload must be exactly 33 bytes")
        return b"".join(
            [
                DMRD,
                bytes([self.seq & 0xFF]),
                bytes_3(self.rf_src),
                bytes_3(self.dst_id),
                bytes_4(self.peer_id),
                bytes([hbp_bits(self.slot, self.call_type, self.frame_type, self.dtype_vseq)]),
                bytes_4(self.stream_id),
                self.payload,
                self.ber,
                self.rssi,
            ]
        )

    def decoded_args(self) -> tuple[bytes, bytes, bytes, int, int, str, int, int, bytes, bytes]:
        return (
            bytes_4(self.peer_id),
            bytes_3(self.rf_src),
            bytes_3(self.dst_id),
            self.seq & 0xFF,
            self.slot,
            self.call_type,
            self.frame_type,
            self.dtype_vseq,
            bytes_4(self.stream_id),
            self.data(),
        )

    def decoded_obp_args(
        self,
        packet_hash: bytes = b"",
        hops: bytes = b"",
        source_server: int | bytes = 9990,
        source_rptr: int | bytes = 0,
    ) -> tuple[bytes, bytes, bytes, int, int, str, int, int, bytes, bytes, bytes, bytes, bytes, bytes, bytes, bytes]:
        return (
            bytes_4(self.peer_id),
            bytes_3(self.rf_src),
            bytes_3(self.dst_id),
            self.seq & 0xFF,
            self.slot,
            self.call_type,
            self.frame_type,
            self.dtype_vseq,
            bytes_4(self.stream_id),
            self.data(),
            packet_hash,
            hops,
            bytes_4(source_server),
            self.ber,
            self.rssi,
            bytes_4(source_rptr),
        )


@dataclass
class CapturedPacket:
    target_system: str
    packet: bytes
    hops: bytes | None = None
    ber: bytes = b"\x00"
    rssi: bytes = b"\x00"
    source_server: bytes = b"\x00\x00\x00\x00"
    source_rptr: bytes = b"\x00\x00\x00\x00"
    fields: dict[str, object] = field(init=False)

    def __post_init__(self) -> None:
        self.fields = parse_dmr_fields(self.packet)


class PacketCapture:
    def __init__(self) -> None:
        self.packets: list[CapturedPacket] = []

    def recorder(self, target_system: str):
        def record(
            packet: bytes,
            hops: bytes | None = b"",
            ber: bytes = b"\x00",
            rssi: bytes = b"\x00",
            source_server: bytes = b"\x00\x00\x00\x00",
            source_rptr: bytes = b"\x00\x00\x00\x00",
        ) -> None:
            self.packets.append(
                CapturedPacket(
                    target_system=target_system,
                    packet=packet,
                    hops=hops,
                    ber=ber,
                    rssi=rssi,
                    source_server=source_server,
                    source_rptr=source_rptr,
                )
            )

        return record

    def for_system(self, system: str) -> list[CapturedPacket]:
        return [packet for packet in self.packets if packet.target_system == system]


class ReportCapture:
    def __init__(self) -> None:
        self.events: list[bytes] = []

    def send_bridgeEvent(self, data: bytes) -> None:
        self.events.append(data)


class FakeClock:
    def __init__(self, start: float = 1_700_000_000.0) -> None:
        self.now = float(start)

    def time(self) -> float:
        return self.now

    def advance(self, seconds: float) -> float:
        self.now += seconds
        return self.now


class FakeReactor:
    def __init__(self) -> None:
        self.later: list[tuple[float, object, tuple, dict]] = []
        self.thread_calls: list[tuple[object, tuple, dict]] = []

    def callLater(self, delay, func, *args, **kwargs):
        self.later.append((delay, func, args, kwargs))
        return SimpleNamespace(cancel=lambda: None, active=lambda: True)

    def callInThread(self, func, *args, **kwargs):
        self.thread_calls.append((func, args, kwargs))

    def callFromThread(self, func, *args, **kwargs):
        return func(*args, **kwargs)


class FakeTransport:
    def __init__(self) -> None:
        self.writes: list[tuple[bytes, tuple[str, int] | None]] = []

    def write(self, packet: bytes, sockaddr=None) -> None:
        self.writes.append((packet, sockaddr))


def minimal_config(system_names: tuple[str, ...] = ("MASTER-A", "MASTER-B")) -> dict:
    config = {
        "GLOBAL": {
            "SERVER_ID": bytes_4(9990),
            "USE_ACL": False,
            "TG1_ACL": acl_permit_all(),
            "TG2_ACL": acl_permit_all(),
            "SUB_ACL": acl_permit_all(),
            "GEN_STAT_BRIDGES": False,
            "DATA_GATEWAY": False,
            "VALIDATE_SERVER_IDS": False,
        },
        "REPORTS": {"REPORT": False},
        "ALIASES": {"PATH": "./", "SUB_MAP_FILE": ""},
        "ALLSTAR": {"ENABLED": False},
        "SYSTEMS": {},
        "_SUB_IDS": {},
        "_PEER_IDS": {},
        "_LOCAL_SUBSCRIBER_IDS": {},
        "_SERVER_IDS": {},
        "CHECKSUMS": {},
    }
    for name in system_names:
        config["SYSTEMS"][name] = {
            "MODE": "MASTER",
            "ENABLED": True,
            "REPEAT": True,
            "MAX_PEERS": 1,
            "IP": "127.0.0.1",
            "PORT": 0,
            "PASSPHRASE": b"",
            "GROUP_HANGTIME": 0,
            "USE_ACL": False,
            "REG_ACL": acl_permit_all(PEER_MAX),
            "SUB_ACL": acl_permit_all(),
            "TG1_ACL": acl_permit_all(),
            "TG2_ACL": acl_permit_all(),
            "DEFAULT_UA_TIMER": 1,
            "SINGLE_MODE": True,
            "VOICE_IDENT": False,
            "DIAL_A_TG": True,
            "DYNAMIC_TG_ROUTING": True,
            "TS1_STATIC": "",
            "TS2_STATIC": "",
            "DEFAULT_DIAL_TS1": 0,
            "DEFAULT_DIAL_TS2": 0,
            "DEFAULT_REFLECTOR": 0,
            "GENERATOR": 0,
            "ANNOUNCEMENT_LANGUAGE": "en_GB",
            "ALLOW_UNREG_ID": True,
            "PROXY_CONTROL": False,
            "OVERRIDE_IDENT_TG": False,
            "PEERS": {},
        }
    return config


def add_openbridge_system(config: dict, name: str = "OBP-1", network_id: int = 1) -> dict:
    config["SYSTEMS"][name] = {
        "MODE": "OPENBRIDGE",
        "ENABLED": True,
        "NETWORK_ID": bytes_4(network_id),
        "IP": "127.0.0.1",
        "PORT": 0,
        "PASSPHRASE": b"test-passphrase\x00\x00\x00\x00\x00\x00",
        "TARGET_IP": "127.0.0.1",
        "TARGET_PORT": 0,
        "TARGET_SOCK": ("127.0.0.1", 0),
        "USE_ACL": False,
        "SUB_ACL": acl_permit_all(),
        "TG1_ACL": acl_permit_all(),
        "TG2_ACL": acl_permit_all(),
        "RELAX_CHECKS": True,
        "ENHANCED_OBP": False,
        "VER": 5,
    }
    return config


def active_bridge(
    name: str,
    tg_id: int,
    entries: tuple[tuple[str, int], ...],
    timeout_minutes: int = 1,
) -> dict[str, list[dict]]:
    tg_bytes = bytes_3(tg_id)
    return {
        name: [
            {
                "SYSTEM": system,
                "TS": slot,
                "TGID": tg_bytes,
                "ACTIVE": True,
                "TIMEOUT": timeout_minutes * 60,
                "TO_TYPE": "ON",
                "OFF": [],
                "ON": [tg_bytes],
                "RESET": [],
                "TIMER": 0,
            }
            for system, slot in entries
        ]
    }


class DeterministicScenario:
    def __init__(self, config: dict | None = None, bridges: dict | None = None) -> None:
        self.config = config or minimal_config()
        self.bridges = bridges or {}
        self.clock = FakeClock()
        self.capture = PacketCapture()
        self.reports: dict[str, ReportCapture] = {}
        self.transports: dict[str, FakeTransport] = {}
        self.reactor = FakeReactor()
        self.bm = None
        self._saved_attrs: dict[str, object] = {}
        self._saved_systems: dict | None = None

    def __enter__(self):
        self.bm = require_bridge_master()
        self._saved_systems = dict(self.bm.systems)

        for attr in (
            "CONFIG",
            "BRIDGES",
            "SUB_MAP",
            "peer_ids",
            "subscriber_ids",
            "talkgroup_ids",
            "local_subscriber_ids",
            "server_ids",
            "checksums",
            "reactor",
            "time",
            "words",
        ):
            if hasattr(self.bm, attr):
                self._saved_attrs[attr] = getattr(self.bm, attr)

        self.bm.CONFIG = self.config
        self.bm.BRIDGES = copy.deepcopy(self.bridges)
        self.bm.SUB_MAP = {}
        self.bm.peer_ids = {}
        self.bm.subscriber_ids = {}
        self.bm.talkgroup_ids = {}
        self.bm.local_subscriber_ids = {}
        self.bm.server_ids = {}
        self.bm.checksums = {}
        self.bm.words = {"en_GB": {"silence": b"", "busy": b"", "notlinked": b"", "linkedto": b"", "to": b""}}
        self.bm.reactor = self.reactor
        self.bm.time = self.clock.time

        self.bm.systems.clear()
        for system_name, system_config in self.config["SYSTEMS"].items():
            report = ReportCapture()
            self.reports[system_name] = report
            if system_config["MODE"] == "MASTER":
                system = self.bm.routerHBP(system_name, self.config, report)
            elif system_config["MODE"] == "OPENBRIDGE":
                system = self.bm.routerOBP(system_name, self.config, report)
            else:
                continue
            system.send_system = self.capture.recorder(system_name)
            transport = FakeTransport()
            system.transport = transport
            self.transports[system_name] = transport
            self.bm.systems[system_name] = system

        return self

    def __exit__(self, exc_type, exc, tb) -> None:
        if self.bm is None:
            return
        self.bm.systems.clear()
        if self._saved_systems is not None:
            self.bm.systems.update(self._saved_systems)

        for attr in (
            "CONFIG",
            "BRIDGES",
            "SUB_MAP",
            "peer_ids",
            "subscriber_ids",
            "talkgroup_ids",
            "local_subscriber_ids",
            "server_ids",
            "checksums",
            "reactor",
            "time",
            "words",
        ):
            if attr in self._saved_attrs:
                setattr(self.bm, attr, self._saved_attrs[attr])
            elif hasattr(self.bm, attr):
                delattr(self.bm, attr)

    @property
    def systems(self):
        return self.bm.systems

    @property
    def bridge_state(self):
        return self.bm.BRIDGES

    def inject_hbp(self, system_name: str, packet: PacketSpec) -> None:
        self.systems[system_name].dmrd_received(*packet.decoded_args())

    def inject_obp(self, system_name: str, packet: PacketSpec) -> None:
        self.systems[system_name].dmrd_received(*packet.decoded_obp_args())

    def inject_datagram(self, system_name: str, packet: bytes, sockaddr=("127.0.0.1", 50000)) -> None:
        self.systems[system_name].datagramReceived(packet, sockaddr)

    def register_peer(
        self,
        system_name: str,
        peer_id: int | bytes = 1001,
        sockaddr=("127.0.0.1", 50000),
        callsign: bytes = b"TEST    ",
    ) -> bytes:
        peer = bytes_4(peer_id)
        self.config["SYSTEMS"][system_name]["PEERS"][peer] = {
            "CONNECTION": "YES",
            "SOCKADDR": sockaddr,
            "CALLSIGN": callsign,
            "RADIO_ID": peer,
            "LAST_PING": self.clock.time(),
        }
        return peer