import asyncio

from fastapi import APIRouter, WebSocket, WebSocketDisconnect

from app.api.deps import token_matches
from app.bars.models import Timeframe
from app.analysis.confluence import cluster_levels

router = APIRouter()


def level_enabled(level, enabled: dict) -> bool:
    kind = level.kind.value
    if kind == "ma":
        return level.period in enabled.get("ma", {}).get(level.tf.value, [])
    if kind == "manual":
        return enabled.get("manual", True)
    if kind == "trendline":
        return enabled.get("auto", False)
    if kind == "horizontal":
        return enabled.get("horizontal", True)
    if kind == "vwap":
        return enabled.get("vwap", True)
    return False


def enabled_levels(runtime, prefs: dict | None):
    if not prefs or prefs.get("hidden_levels_score"):
        return runtime.levels
    enabled = prefs.get("enabled", {})
    return [level for level in runtime.levels if level_enabled(level, enabled)]


def connection_clusters(runtime, prefs: dict | None):
    if runtime.price is None or runtime.stream.last_bar_t is None:
        return []
    return cluster_levels(
        enabled_levels(runtime, prefs), runtime.stream.last_bar_t, runtime.price, runtime.atr15
    )


def snapshot(runtime, tf: Timeframe, prefs: dict | None = None) -> dict:
    return {
        "type": "snapshot",
        "tf": tf.value,
        "bars": [bar.to_dict() for bar in runtime.store.get(tf, 1000)],
        "levels": [level.to_dict() for level in runtime.levels],
        "clusters": [cluster.to_dict() for cluster in connection_clusters(runtime, prefs)],
        "price": runtime.store.get(Timeframe.M1, 1)[-1].c
        if runtime.store.get(Timeframe.M1, 1)
        else None,
    }


@router.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    # Browsers cannot set headers on a WebSocket handshake, so the token comes
    # in as a query parameter here. 1008 = policy violation.
    if not token_matches(websocket.app, websocket.query_params.get("token", "")):
        await websocket.close(code=1008, reason="Missing or invalid chart token")
        return
    await websocket.accept()
    runtime = websocket.app.state.runtime
    queue: asyncio.Queue = asyncio.Queue(maxsize=100)
    runtime.subscribers.add(queue)
    tf = Timeframe.M1
    prefs = None
    await websocket.send_json(snapshot(runtime, tf, prefs))

    async def receive():
        nonlocal tf, prefs
        try:
            while True:
                message = await websocket.receive_json()
                if message.get("type") == "subscribe":
                    tf = Timeframe(message.get("tf", "1m"))
                    await websocket.send_json(snapshot(runtime, tf, prefs))
                elif message.get("type") == "prefs":
                    prefs = message
                    clusters = connection_clusters(runtime, prefs)
                    await websocket.send_json(
                        {
                            "type": "clusters",
                            "price": runtime.price,
                            "clusters": [cluster.to_dict() for cluster in clusters],
                        }
                    )
        except WebSocketDisconnect:
            queue.put_nowait({"type": "disconnect"})

    receiver = asyncio.create_task(receive())
    try:
        while True:
            event = await queue.get()
            if event["type"] == "disconnect":
                break
            if event["type"] == "bar" and event["bar"].tf is tf:
                await websocket.send_json(
                    {"type": "bar", "tf": tf.value, "bar": event["bar"].to_dict()}
                )
            elif event["type"] == "levels":
                await websocket.send_json(
                    {"type": "levels", "changed": event["changed"], "removed": event["removed"]}
                )
            elif event["type"] == "clusters":
                clusters = connection_clusters(runtime, prefs)
                await websocket.send_json(
                    {
                        "type": "clusters",
                        "price": runtime.price,
                        "clusters": [cluster.to_dict() for cluster in clusters],
                    }
                )
            elif event["type"] == "alert":
                # Alerts are produced once, server-side. This socket only relays
                # them, so opening a second tab cannot double-notify.
                await websocket.send_json(
                    {
                        "type": "alert",
                        "cluster": event["cluster"].to_dict(),
                        "message": event["message"],
                    }
                )
    except (WebSocketDisconnect, asyncio.CancelledError):
        pass
    finally:
        receiver.cancel()
        runtime.subscribers.discard(queue)