"""Gateway service - FastAPI with WebSocket for real-time dashboard."""

import asyncio
import json
import sys
from contextlib import asynccontextmanager
from datetime import datetime, timedelta
from pathlib import Path
from typing import Any

import grpc
from fastapi import FastAPI, HTTPException, Query, WebSocket, WebSocketDisconnect
from fastapi.requests import Request
from fastapi.responses import HTMLResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates

# Add project root to path for imports
sys.path.insert(0, str(Path(__file__).parent.parent.parent))

from services.aggregator.storage import TimescaleStorage
from shared import metrics_pb2, metrics_pb2_grpc
from shared.config import get_gateway_config
from shared.events import get_subscriber
from shared.logging import setup_logging

# Global state
config = get_gateway_config()
logger = setup_logging(
    service_name=config.service_name,
    log_level=config.log_level,
    log_format=config.log_format,
)


# WebSocket connection manager
class ConnectionManager:
    """Manages WebSocket connections for real-time updates."""

    def __init__(self):
        self.active_connections: list[WebSocket] = []

    async def connect(self, websocket: WebSocket) -> None:
        await websocket.accept()
        self.active_connections.append(websocket)
        logger.info("websocket_connected", total=len(self.active_connections))

    def disconnect(self, websocket: WebSocket) -> None:
        self.active_connections.remove(websocket)
        logger.info("websocket_disconnected", total=len(self.active_connections))

    async def broadcast(self, message: dict) -> None:
        """Broadcast message to all connected clients."""
        if not self.active_connections:
            return

        data = json.dumps(message)
        disconnected = []

        for connection in self.active_connections:
            try:
                await connection.send_text(data)
            except Exception:
                disconnected.append(connection)

        # Clean up disconnected
        for conn in disconnected:
            try:
                self.active_connections.remove(conn)
            except ValueError:
                pass


manager = ConnectionManager()
internals_manager = ConnectionManager()  # Separate manager for internals page
timescale: TimescaleStorage | None = None
grpc_channel: grpc.aio.Channel | None = None
grpc_stub: metrics_pb2_grpc.MetricsServiceStub | None = None

# Track recent events for internals view
recent_events: list[dict] = []
MAX_RECENT_EVENTS = 100
service_stats = {
    "events_received": 0,
    "websocket_broadcasts": 0,
    "started_at": None,
}

# Cache of latest full metrics per machine (merges partial batches)
machine_metrics_cache: dict[str, dict] = {}


async def event_listener():
    """Background task that listens for metric events and broadcasts to WebSocket clients."""
    logger.info("event_listener_starting")

    async with get_subscriber(topics=["metrics.raw", "alerts.*"]) as subscriber:
        async for event in subscriber.consume():
            try:
                service_stats["events_received"] += 1

                # Track for internals view
                event_record = {
                    "id": event.event_id[:8],
                    "topic": event.topic,
                    "source": event.source,
                    "timestamp": event.timestamp.isoformat(),
                    "machine_id": event.payload.get("machine_id", ""),
                    "metrics_count": len(event.payload.get("metrics", {})),
                }
                recent_events.insert(0, event_record)
                if len(recent_events) > MAX_RECENT_EVENTS:
                    recent_events.pop()

                # Merge partial batch metrics into cache
                machine_id = event.payload.get("machine_id", "")
                incoming_metrics = event.payload.get("metrics", {})

                if machine_id:
                    if machine_id not in machine_metrics_cache:
                        machine_metrics_cache[machine_id] = {}
                    # Merge new metrics into existing (accumulate across batches)
                    machine_metrics_cache[machine_id].update(incoming_metrics)

                    # Build complete payload with merged metrics
                    merged_payload = {
                        "machine_id": machine_id,
                        "hostname": event.payload.get("hostname", ""),
                        "timestamp_ms": event.payload.get("timestamp_ms", 0),
                        "metrics": machine_metrics_cache[machine_id],
                    }
                else:
                    merged_payload = event.payload

                # Broadcast merged data to dashboard
                await manager.broadcast(
                    {
                        "type": "metrics",
                        "data": merged_payload,
                        "timestamp": event.timestamp.isoformat(),
                    }
                )
                service_stats["websocket_broadcasts"] += 1

                # Broadcast to internals (show raw event, not merged)
                await internals_manager.broadcast(
                    {
                        "type": "event",
                        "data": event_record,
                    }
                )

            except Exception as e:
                logger.warning("broadcast_error", error=str(e))


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Application lifespan manager."""
    global timescale, grpc_channel, grpc_stub

    logger.info("gateway_starting", port=config.http_port)

    # Connect to TimescaleDB for historical queries
    timescale = TimescaleStorage(config.timescale_url)
    try:
        await timescale.connect()
    except Exception as e:
        logger.warning("timescale_connection_failed", error=str(e))
        timescale = None

    # Connect to aggregator via gRPC
    grpc_channel = grpc.aio.insecure_channel(config.aggregator_url)
    grpc_stub = metrics_pb2_grpc.MetricsServiceStub(grpc_channel)

    # Start event listener in background
    listener_task = asyncio.create_task(event_listener())

    service_stats["started_at"] = datetime.utcnow().isoformat()
    logger.info("gateway_started")

    yield

    # Cleanup
    listener_task.cancel()
    try:
        await listener_task
    except asyncio.CancelledError:
        pass

    if grpc_channel:
        await grpc_channel.close()

    if timescale:
        await timescale.disconnect()

    logger.info("gateway_stopped")


# Create FastAPI app
app = FastAPI(
    title="System Monitor Gateway",
    description="Real-time system monitoring dashboard",
    version="0.1.0",
    lifespan=lifespan,
)

# Mount static files
static_path = Path(__file__).parent.parent.parent / "web" / "static"
if static_path.exists():
    app.mount("/static", StaticFiles(directory=str(static_path)), name="static")

# Templates
templates_path = Path(__file__).parent.parent.parent / "web" / "templates"
templates = (
    Jinja2Templates(directory=str(templates_path)) if templates_path.exists() else None
)


# ============================================================================
# Health endpoints
# ============================================================================


@app.get("/health")
async def health_check():
    """Health check endpoint."""
    return {"status": "healthy", "service": "gateway"}


@app.get("/ready")
async def readiness_check():
    """Readiness check - verifies dependencies."""
    checks = {"gateway": "ok"}

    # Check gRPC connection
    try:
        if grpc_stub:
            await grpc_stub.GetAllStates(metrics_pb2.Empty(), timeout=2.0)
            checks["aggregator"] = "ok"
    except Exception as e:
        checks["aggregator"] = f"error: {str(e)}"

    # Check TimescaleDB
    if timescale and timescale._pool:
        checks["timescaledb"] = "ok"
    else:
        checks["timescaledb"] = "not connected"

    return {"status": "ready", "checks": checks}


# ============================================================================
# REST API endpoints
# ============================================================================


@app.get("/api/machines")
async def get_machines():
    """Get current state of all machines."""
    if not grpc_stub:
        raise HTTPException(status_code=503, detail="Aggregator not connected")

    try:
        response = await grpc_stub.GetAllStates(metrics_pb2.Empty(), timeout=5.0)

        machines = []
        for state in response.machines:
            metrics = {}
            for m in state.current_metrics:
                metric_type = metrics_pb2.MetricType.Name(m.type)
                metrics[metric_type] = m.value

            machines.append(
                {
                    "machine_id": state.machine_id,
                    "hostname": state.hostname,
                    "last_seen_ms": state.last_seen_ms,
                    "health": metrics_pb2.HealthStatus.Name(state.health),
                    "metrics": metrics,
                }
            )

        return {"machines": machines}

    except grpc.aio.AioRpcError as e:
        raise HTTPException(status_code=503, detail=f"Aggregator error: {e.details()}")


@app.get("/api/machines/{machine_id}")
async def get_machine(machine_id: str):
    """Get current state of a specific machine."""
    if not grpc_stub:
        raise HTTPException(status_code=503, detail="Aggregator not connected")

    try:
        response = await grpc_stub.GetCurrentState(
            metrics_pb2.StateRequest(machine_id=machine_id),
            timeout=5.0,
        )

        if not response.machine_id:
            raise HTTPException(status_code=404, detail="Machine not found")

        metrics = {}
        for m in response.current_metrics:
            metric_type = metrics_pb2.MetricType.Name(m.type)
            metrics[metric_type] = m.value

        return {
            "machine_id": response.machine_id,
            "hostname": response.hostname,
            "last_seen_ms": response.last_seen_ms,
            "health": metrics_pb2.HealthStatus.Name(response.health),
            "metrics": metrics,
        }

    except grpc.aio.AioRpcError as e:
        if e.code() == grpc.StatusCode.NOT_FOUND:
            raise HTTPException(status_code=404, detail="Machine not found")
        raise HTTPException(status_code=503, detail=f"Aggregator error: {e.details()}")


@app.get("/api/metrics")
async def get_metrics(
    machine_id: str | None = Query(None),
    metric_type: str | None = Query(None),
    minutes: int = Query(60, ge=1, le=1440),
    limit: int = Query(1000, ge=1, le=10000),
):
    """Get historical metrics."""
    if not timescale:
        raise HTTPException(status_code=503, detail="TimescaleDB not connected")

    end_time = datetime.utcnow()
    start_time = end_time - timedelta(minutes=minutes)

    try:
        metrics = await timescale.get_metrics(
            machine_id=machine_id,
            metric_type=metric_type,
            start_time=start_time,
            end_time=end_time,
            limit=limit,
        )

        return {"metrics": metrics, "count": len(metrics)}

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


# ============================================================================
# WebSocket endpoint
# ============================================================================


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    """WebSocket endpoint for real-time metric updates."""
    await manager.connect(websocket)

    try:
        # Send initial state
        if grpc_stub:
            try:
                response = await grpc_stub.GetAllStates(
                    metrics_pb2.Empty(), timeout=5.0
                )

                for state in response.machines:
                    metrics = {}
                    for m in state.current_metrics:
                        metric_type = metrics_pb2.MetricType.Name(m.type)
                        metrics[metric_type] = m.value

                    await websocket.send_json(
                        {
                            "type": "initial",
                            "data": {
                                "machine_id": state.machine_id,
                                "hostname": state.hostname,
                                "metrics": metrics,
                            },
                        }
                    )
            except Exception as e:
                logger.warning("initial_state_error", error=str(e))

        # Keep connection alive and handle incoming messages
        while True:
            try:
                data = await websocket.receive_text()
                # Handle ping/pong or commands from client
                if data == "ping":
                    await websocket.send_text("pong")
            except WebSocketDisconnect:
                break

    finally:
        manager.disconnect(websocket)


# ============================================================================
# Internals / Debug endpoints
# ============================================================================


@app.get("/api/internals")
async def get_internals():
    """Get internal service stats and recent events."""
    # Get service health
    services = {
        "gateway": {"status": "healthy", "started_at": service_stats["started_at"]},
        "aggregator": {"status": "unknown"},
        "redis": {"status": "unknown"},
        "timescaledb": {"status": "unknown"},
    }

    # Check aggregator
    try:
        if grpc_stub:
            await grpc_stub.GetAllStates(metrics_pb2.Empty(), timeout=2.0)
            services["aggregator"]["status"] = "healthy"
    except Exception as e:
        services["aggregator"]["status"] = f"error: {str(e)[:50]}"

    # Check TimescaleDB
    if timescale and timescale._pool:
        services["timescaledb"]["status"] = "healthy"
    else:
        services["timescaledb"]["status"] = "not connected"

    # Redis is healthy if we're receiving events
    if service_stats["events_received"] > 0:
        services["redis"]["status"] = "healthy"

    return {
        "stats": {
            "events_received": service_stats["events_received"],
            "websocket_broadcasts": service_stats["websocket_broadcasts"],
            "dashboard_connections": len(manager.active_connections),
            "internals_connections": len(internals_manager.active_connections),
            "cached_machines": len(machine_metrics_cache),
        },
        "services": services,
        "recent_events": recent_events[:20],
    }


@app.websocket("/ws/internals")
async def internals_websocket(websocket: WebSocket):
    """WebSocket for real-time internals updates."""
    await internals_manager.connect(websocket)

    try:
        # Send initial state
        await websocket.send_json(
            {
                "type": "init",
                "data": {
                    "stats": {
                        "events_received": service_stats["events_received"],
                        "websocket_broadcasts": service_stats["websocket_broadcasts"],
                        "cached_machines": len(machine_metrics_cache),
                    },
                    "recent_events": recent_events[:20],
                },
            }
        )

        while True:
            try:
                data = await websocket.receive_text()
                if data == "ping":
                    await websocket.send_text("pong")
            except WebSocketDisconnect:
                break
    finally:
        internals_manager.disconnect(websocket)


# ============================================================================
# Dashboard (HTML)
# ============================================================================


@app.get("/", response_class=HTMLResponse)
async def dashboard(request: Request):
    """Serve the dashboard HTML."""
    if templates:
        return templates.TemplateResponse("dashboard.html", {"request": request})
    return HTMLResponse(
        "<h1>Dashboard template not found</h1><p><a href='/internals'>Internals</a> | <a href='/docs'>API Docs</a></p>"
    )


@app.get("/internals", response_class=HTMLResponse)
async def internals_page(request: Request):
    """Serve the internals/debug HTML page."""
    if templates:
        return templates.TemplateResponse("internals.html", {"request": request})
    return HTMLResponse("<h1>Internals template not found</h1>")


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=config.http_port)