"""The séance channel: one WebSocket per contact session.

Protocol (client → server):
  {"type": "ping"}                          → {"type": "pong"}
  {"type": "set_mode", "mode": MODE}        → {"type": "mode", ...}
  {"type": "language", "language": "en"|"es"}
  {"type": "summon"}                        → {"type": "entity", ...}
  {"type": "anomaly", "source": SRC, ...}   → {"type": "utterance", ...}
  {"type": "question", "text": "..."}       → reply_start / reply_token* / reply_end
  {"type": "passive", "enabled": bool}      → ambient wire loop on/off

All server → client frames flow through a single sender task so concurrent
producers (ambient loop, reply streaming, TTS callbacks) never interleave on
the wire.
"""

import asyncio
import contextlib
import random
import time
import uuid
from dataclasses import dataclass, field
from datetime import datetime, timezone
from pathlib import Path

from fastapi import APIRouter, WebSocket, WebSocketDisconnect
from sqlalchemy import select

from app.config import settings
from app.db import async_session_maker as _default_session_maker
from app.deps import SESSION_COOKIE_NAME
from app.entities import fallback_signature, signature_from_anomalies
from app.llm.service import SpiritBusyError, spirit_service
from app.models.auth_session import AuthSession, hash_token
from app.models.contact_session import ContactSession
from app.models.entity import Entity
from app.models.entity_sighting import EntitySighting
from app.models.event import Event
from app.rate_limit import RateLimiter
from app.telemetry import detect_wire_spike, sample_network
from app.tts.piper import synthesize_spirit_voice
from app.tts.voices import pick_voice

router = APIRouter()

# Alias so tests can swap in the NullPool test session maker.
session_maker = _default_session_maker

MODES = {"wire", "evp", "radio", "ouija"}

# Per-user limiters for every LLM-triggering message type (spec §5).
fragment_limiter = RateLimiter(max_requests=30, window_seconds=60)
question_limiter = RateLimiter(max_requests=6, window_seconds=60)
summon_limiter = RateLimiter(max_requests=4, window_seconds=60)

AUDIO_DIR = Path(settings.data_dir) / "audio"


def _audio_dir() -> Path:
    AUDIO_DIR.mkdir(parents=True, exist_ok=True)
    return AUDIO_DIR


@dataclass
class SeanceState:
    user_id: uuid.UUID
    session_id: uuid.UUID
    send_queue: asyncio.Queue = field(default_factory=asyncio.Queue)
    mode: str = "unknown"
    language: str = "en"
    entity: dict | None = None
    anomalies: list[dict] = field(default_factory=list)
    history: list[dict] = field(default_factory=list)
    ambient_task: asyncio.Task | None = None
    wire_jitter_history: list[float] = field(default_factory=list)
    last_wire_anomaly_at: float = 0.0


def serialize_entity(entity: Entity) -> dict:
    return {
        "id": str(entity.id),
        "name": entity.name,
        "epithet": entity.epithet,
        "persona": entity.persona,
        "rarity": entity.rarity_tier,
        "voice": entity.voice_profile,
        "visual": entity.visual_profile,
        "quotes": entity.sample_quotes,
        "contact_count": entity.contact_count,
        "discovered_at": entity.discovered_at.isoformat(),
    }


async def _authenticate(websocket: WebSocket) -> uuid.UUID | None:
    raw_token = websocket.cookies.get(SESSION_COOKIE_NAME)
    if raw_token is None:
        return None

    token_hash = hash_token(raw_token)
    async with session_maker() as db:
        result = await db.execute(
            select(AuthSession).where(AuthSession.token_hash == token_hash)
        )
        session = result.scalar_one_or_none()
        if session is None or session.expires_at < datetime.now(timezone.utc):
            return None
        return session.user_id


async def _sender(state: SeanceState, websocket: WebSocket) -> None:
    """The only task allowed to write to the socket."""
    try:
        while True:
            message = await state.send_queue.get()
            await websocket.send_json(message)
    except asyncio.CancelledError:
        pass


async def _record_event(
    session_id: uuid.UUID,
    kind: str,
    text: str | None = None,
    payload: dict | None = None,
) -> uuid.UUID:
    async with session_maker() as db:
        event = Event(session_id=session_id, kind=kind, text=text, payload=payload)
        db.add(event)
        await db.commit()
        await db.refresh(event)
        return event.id


async def _speak(state: SeanceState, kind: str, text: str) -> None:
    """Persist an utterance, push its text immediately, synthesize audio in
    the background, and push the audio URL when the effects chain finishes."""
    event_id = await _record_event(
        state.session_id, "utterance", text=text, payload={"kind": kind}
    )
    await state.send_queue.put(
        {
            "type": "utterance",
            "id": str(event_id),
            "kind": kind,
            "text": text,
            "entity": state.entity["name"] if state.entity else None,
        }
    )

    async def _synth() -> None:
        try:
            voice_profile = state.entity.get("voice", {}) if state.entity else {}
            voice = pick_voice(voice_profile.get("voice_id"), state.language)
            wav = await synthesize_spirit_voice(text, voice, voice_profile)
            filename = f"{event_id}.wav"
            _audio_dir().joinpath(filename).write_bytes(wav)
            async with session_maker() as db:
                event = await db.get(Event, event_id)
                if event is not None:
                    event.audio_path = filename
                    await db.commit()
            await state.send_queue.put(
                {"type": "audio", "id": str(event_id), "url": f"/audio/{filename}"}
            )
        except Exception:
            # TTS is texture, not content — the words already reached the
            # seeker. Never let a synth failure kill the séance.
            pass

    asyncio.create_task(_synth())


_ROMAN = ["II", "III", "IV", "V", "VI", "VII", "VIII", "IX"]


async def _unique_entity_name(db, base_name: str) -> str:
    name = base_name
    i = 0
    while await db.scalar(select(Entity).where(Entity.name == name)) is not None:
        name = f"{base_name} {_ROMAN[i]}" if i < len(_ROMAN) else f"{base_name} {i + 2}"
        i += 1
    return name


async def _summon(state: SeanceState, channel: str) -> tuple[Entity, bool]:
    """Match this session's signature against the Codex, or mint a new entity."""
    signature = signature_from_anomalies(state.anomalies) or fallback_signature(
        str(state.session_id)
    )

    async with session_maker() as db:
        entity = await db.scalar(select(Entity).where(Entity.signature == signature))
        is_new = entity is None

        if is_new:
            profile = await spirit_service.mint_profile(
                signature, channel, state.anomalies, state.language
            )
            entity = Entity(
                name=await _unique_entity_name(db, profile["name"]),
                epithet=profile["epithet"],
                persona=profile["persona"],
                rarity_tier=profile["rarity"],
                signature=signature,
                voice_profile=profile["voice"],
                visual_profile=profile["visual"],
                sample_quotes=profile["quotes"],
                discovered_by=state.user_id,
                contact_count=1,
            )
            db.add(entity)
        else:
            entity.contact_count += 1

        await db.flush()
        session = await db.get(ContactSession, state.session_id)
        if session is not None:
            session.entity_id = entity.id
        db.add(
            EntitySighting(
                entity_id=entity.id, session_id=state.session_id, user_id=state.user_id
            )
        )
        await db.commit()
        await db.refresh(entity)
        return entity, is_new


async def _handle_summon(state: SeanceState) -> None:
    if not summon_limiter.allow(str(state.user_id)):
        await state.send_queue.put(
            {
                "type": "error",
                "code": "rate_limited",
                "message": "The veil is crowded. The spirits need a moment before another summoning.",
            }
        )
        return

    await state.send_queue.put({"type": "status", "state": "summoning"})
    entity, is_new = await _summon(state, state.mode if state.mode != "unknown" else "ouija")
    state.entity = serialize_entity(entity)
    await state.send_queue.put(
        {"type": "entity", "entity": state.entity, "is_new": is_new}
    )
    greeting = random.choice(state.entity["quotes"]) if state.entity["quotes"] else "I am here."
    await _speak(state, "greeting", greeting)


async def _handle_anomaly(state: SeanceState, message: dict) -> None:
    anomaly = {
        "source": str(message.get("source", "unknown"))[:16],
        "frequency": message.get("frequency"),
        "magnitude": message.get("magnitude"),
    }
    state.anomalies.append(anomaly)
    state.anomalies = state.anomalies[-64:]
    await _record_event(state.session_id, "anomaly", payload=anomaly)
    await state.send_queue.put({"type": "anomaly_ack", "count": len(state.anomalies)})

    if state.entity is None:
        if signature_from_anomalies(state.anomalies) is not None:
            # The signal has enough structure — something announces itself.
            await _handle_summon(state)
        else:
            await state.send_queue.put({"type": "status", "state": "attuning"})
        return

    if not fragment_limiter.allow(str(state.user_id)):
        return  # anomalies during a crowded veil just pass unheard

    try:
        fragment = await spirit_service.fragment(
            anomaly["source"], anomaly, state.language
        )
    except SpiritBusyError:
        return
    await _speak(state, "fragment", fragment)


async def _handle_question(state: SeanceState, text: str) -> None:
    if not question_limiter.allow(str(state.user_id)):
        await state.send_queue.put(
            {
                "type": "error",
                "code": "rate_limited",
                "message": "The spirit is spent. Give it a moment to gather itself.",
            }
        )
        return

    if state.entity is None:
        await _handle_summon(state)
    assert state.entity is not None

    text = text.strip()[:500]
    await _record_event(state.session_id, "question", text=text)
    await state.send_queue.put({"type": "status", "state": "gathering"})
    await state.send_queue.put({"type": "reply_start"})

    reply_parts: list[str] = []
    try:
        async for token in spirit_service.chat_stream(
            state.entity, text, state.history, state.language
        ):
            reply_parts.append(token)
            await state.send_queue.put({"type": "reply_token", "token": token})
    except SpiritBusyError:
        await state.send_queue.put(
            {
                "type": "error",
                "code": "veil_crowded",
                "message": "Too many seekers press against the veil. The spirit withdraws.",
            }
        )
        await state.send_queue.put({"type": "reply_end", "text": ""})
        return

    reply = "".join(reply_parts).strip()
    reply_id = await _record_event(state.session_id, "reply", text=reply)
    state.history.append({"role": "user", "text": text})
    state.history.append({"role": "spirit", "text": reply})
    state.history = state.history[-8:]
    await state.send_queue.put({"type": "reply_end", "id": str(reply_id), "text": reply})
    if reply:
        await _speak(state, "reply", reply)


async def _ambient_loop(state: SeanceState) -> None:
    """The Wire Ghost's pulse: telemetry every few seconds. Spikes in the
    jitter baseline become first-class anomaly events (driving fragments and
    the client's data views); quieter ticks may earn an ambient whisper."""
    try:
        while True:
            await asyncio.sleep(random.uniform(3, 5))
            try:
                sample = await sample_network(period_s=1.0)
            except Exception:
                continue
            await state.send_queue.put({"type": "telemetry", **sample.as_dict()})

            jitter = sample.jitter_bytes_per_s
            ratio = detect_wire_spike(state.wire_jitter_history, jitter)
            state.wire_jitter_history = (state.wire_jitter_history + [jitter])[-60:]

            now = time.monotonic()
            if ratio is not None and now - state.last_wire_anomaly_at > 20:
                state.last_wire_anomaly_at = now
                anomaly = {
                    "source": "wire",
                    "frequency": round(jitter, 1),
                    "magnitude": round(ratio * 10, 1),
                }
                # Tell the client first so its matrix/graph views light up,
                # then run the anomaly through the usual séance pipeline.
                await state.send_queue.put({"type": "anomaly", **anomaly})
                await _handle_anomaly(state, anomaly)
                continue

            if not spirit_service.ambient_ready():
                continue
            whisper = await spirit_service.wire_whisper(sample.as_dict(), state.language)
            await _speak(state, "ambient", whisper)
    except asyncio.CancelledError:
        pass


async def _handle_passive(state: SeanceState, enabled: bool) -> None:
    if enabled and (state.ambient_task is None or state.ambient_task.done()):
        state.ambient_task = asyncio.create_task(_ambient_loop(state))
        await state.send_queue.put({"type": "passive", "enabled": True})
    elif not enabled and state.ambient_task is not None:
        state.ambient_task.cancel()
        state.ambient_task = None
        await state.send_queue.put({"type": "passive", "enabled": False})


@router.websocket("/ws/session")
async def session_socket(websocket: WebSocket) -> None:
    user_id = await _authenticate(websocket)
    if user_id is None:
        await websocket.close(code=4401)
        return

    await websocket.accept()

    async with session_maker() as db:
        contact_session = ContactSession(user_id=user_id)
        db.add(contact_session)
        await db.commit()
        await db.refresh(contact_session)

    state = SeanceState(user_id=user_id, session_id=contact_session.id)
    sender = asyncio.create_task(_sender(state, websocket))
    await state.send_queue.put({"type": "session", "id": str(contact_session.id)})

    try:
        while True:
            message = await websocket.receive_json()
            msg_type = message.get("type")

            if msg_type == "ping":
                await state.send_queue.put({"type": "pong"})
            elif msg_type == "set_mode" and message.get("mode") in MODES:
                state.mode = message["mode"]
                async with session_maker() as db:
                    session = await db.get(ContactSession, state.session_id)
                    if session is not None:
                        session.mode = state.mode
                        await db.commit()
                await state.send_queue.put({"type": "mode", "mode": state.mode})
            elif msg_type == "language" and message.get("language") in ("en", "es"):
                state.language = message["language"]
                async with session_maker() as db:
                    session = await db.get(ContactSession, state.session_id)
                    if session is not None:
                        session.language = state.language
                        await db.commit()
            elif msg_type == "summon":
                await _handle_summon(state)
            elif msg_type == "anomaly":
                await _handle_anomaly(state, message)
            elif msg_type == "question" and isinstance(message.get("text"), str):
                await _handle_question(state, message["text"])
            elif msg_type == "passive":
                await _handle_passive(state, bool(message.get("enabled")))
    except WebSocketDisconnect:
        pass
    finally:
        if state.ambient_task is not None:
            state.ambient_task.cancel()
        sender.cancel()
        with contextlib.suppress(asyncio.CancelledError):
            await sender
        # ASGI servers may cancel the handler task as soon as the socket
        # closes, killing any await here mid-flight — so the session-close
        # write runs detached, surviving the handler's own teardown.
        asyncio.create_task(_close_session(contact_session.id))


async def _close_session(session_id: uuid.UUID) -> None:
    try:
        async with session_maker() as db:
            session_to_close = await db.get(ContactSession, session_id)
            if session_to_close is not None:
                session_to_close.ended_at = datetime.now(timezone.utc)
                await db.commit()
    except Exception:
        pass