import asyncio
import json
from datetime import datetime
from typing import Any, Dict, List, Optional

import httpx
from fastapi import BackgroundTasks, Depends, FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel, Field
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from services.user_service.main import get_current_user
from services.user_service.models import User
from shared.config import settings
from shared.database import get_db

app = FastAPI(title="Notification Service", version="1.0.0")

# CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


class NotificationRequest(BaseModel):
    title: str = Field(..., max_length=100)
    body: str = Field(..., max_length=500)
    data: Optional[Dict[str, Any]] = None
    priority: str = Field("normal", pattern="^(low|normal|high)$")


class EmergencyNotificationRequest(BaseModel):
    alert_id: int
    user_ids: List[int]
    alert_type: Optional[str] = "general"
    location: Optional[str] = None


class DeviceToken(BaseModel):
    token: str = Field(..., min_length=10)
    platform: str = Field(..., pattern="^(ios|android|web)$")


class NotificationStats(BaseModel):
    total_sent: int
    successful_deliveries: int
    failed_deliveries: int
    emergency_notifications: int


# Mock FCM client for demonstration
class FCMClient:
    def __init__(self, server_key: str):
        self.server_key = server_key
        self.fcm_url = "https://fcm.googleapis.com/fcm/send"

    async def send_notification(
        self, tokens: List[str], notification_data: dict
    ) -> dict:
        """Send push notification via FCM"""
        if not self.server_key:
            print("FCM Server Key not configured - notification would be sent")
            return {"success_count": len(tokens), "failure_count": 0}

        headers = {
            "Authorization": f"key={self.server_key}",
            "Content-Type": "application/json",
        }

        payload = {
            "registration_ids": tokens,
            "notification": {
                "title": notification_data.get("title"),
                "body": notification_data.get("body"),
                "sound": "default",
            },
            "data": notification_data.get("data", {}),
            "priority": "high"
            if notification_data.get("priority") == "high"
            else "normal",
        }

        try:
            async with httpx.AsyncClient() as client:
                response = await client.post(
                    self.fcm_url, headers=headers, json=payload, timeout=10.0
                )
                result = response.json()
                return {
                    "success_count": result.get("success", 0),
                    "failure_count": result.get("failure", 0),
                    "results": result.get("results", []),
                }
        except Exception as e:
            print(f"FCM Error: {e}")
            return {"success_count": 0, "failure_count": len(tokens)}


# Initialize FCM client
fcm_client = FCMClient(settings.FCM_SERVER_KEY)

# In-memory storage for demo (use Redis or database in production)
user_device_tokens: Dict[int, List[str]] = {}
notification_stats = {
    "total_sent": 0,
    "successful_deliveries": 0,
    "failed_deliveries": 0,
    "emergency_notifications": 0,
}


@app.post("/api/v1/register-device")
async def register_device_token(
    device_data: DeviceToken, current_user: User = Depends(get_current_user)
):
    """Register device token for push notifications"""

    if current_user.id not in user_device_tokens:
        user_device_tokens[current_user.id] = []

    # Remove existing token if present
    if device_data.token in user_device_tokens[current_user.id]:
        user_device_tokens[current_user.id].remove(device_data.token)

    # Add new token
    user_device_tokens[current_user.id].append(device_data.token)

    # Keep only last 3 tokens per user
    user_device_tokens[current_user.id] = user_device_tokens[current_user.id][-3:]

    return {"message": "Device token registered successfully"}


@app.post("/api/v1/send-notification")
async def send_notification(
    notification: NotificationRequest,
    target_user_id: int,
    background_tasks: BackgroundTasks,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Send notification to specific user"""

    # Check if target user exists and accepts notifications
    result = await db.execute(select(User).filter(User.id == target_user_id))
    target_user = result.scalars().first()

    if not target_user:
        raise HTTPException(status_code=404, detail="Target user not found")

    if not target_user.push_notifications_enabled:
        raise HTTPException(
            status_code=403, detail="User has disabled push notifications"
        )

    # Get user's device tokens
    tokens = user_device_tokens.get(target_user_id, [])
    if not tokens:
        raise HTTPException(status_code=400, detail="No device tokens found for user")

    # Send notification in background
    background_tasks.add_task(
        send_push_notification,
        tokens,
        {
            "title": notification.title,
            "body": notification.body,
            "data": notification.data or {},
            "priority": notification.priority,
        },
    )

    return {"message": "Notification queued for delivery"}


@app.post("/api/v1/send-emergency-notifications")
async def send_emergency_notifications(
    emergency_data: EmergencyNotificationRequest,
    background_tasks: BackgroundTasks,
    db: AsyncSession = Depends(get_db),
):
    """Send emergency notifications to nearby users"""

    if not emergency_data.user_ids:
        return {"message": "No users to notify"}

    # Get users who have emergency notifications enabled
    result = await db.execute(
        select(User).filter(
            User.id.in_(emergency_data.user_ids),
            User.emergency_notifications_enabled == True,
            User.is_active == True,
        )
    )
    users = result.scalars().all()

    # Collect all device tokens
    all_tokens = []
    for user in users:
        tokens = user_device_tokens.get(user.id, [])
        all_tokens.extend(tokens)

    if not all_tokens:
        return {"message": "No device tokens found for target users"}

    # Prepare emergency notification
    emergency_title = "🚨 Emergency Alert Nearby"
    emergency_body = (
        f"Someone needs help in your area. Alert type: {emergency_data.alert_type}"
    )

    if emergency_data.location:
        emergency_body += f" Location: {emergency_data.location}"

    notification_data = {
        "title": emergency_title,
        "body": emergency_body,
        "data": {
            "type": "emergency",
            "alert_id": str(emergency_data.alert_id),
            "alert_type": emergency_data.alert_type,
        },
        "priority": "high",
    }

    # Send notifications in background
    background_tasks.add_task(
        send_emergency_push_notification, all_tokens, notification_data
    )

    return {"message": f"Emergency notifications queued for {len(users)} users"}


async def send_push_notification(tokens: List[str], notification_data: dict):
    """Send push notification using FCM"""
    try:
        result = await fcm_client.send_notification(tokens, notification_data)

        # Update stats
        notification_stats["total_sent"] += len(tokens)
        notification_stats["successful_deliveries"] += result["success_count"]
        notification_stats["failed_deliveries"] += result["failure_count"]

        print(
            f"Notification sent: {result['success_count']} successful, {result['failure_count']} failed"
        )

    except Exception as e:
        print(f"Failed to send notification: {e}")
        notification_stats["failed_deliveries"] += len(tokens)


async def send_emergency_push_notification(tokens: List[str], notification_data: dict):
    """Send emergency push notification with special handling"""
    try:
        # Emergency notifications are sent immediately with high priority
        result = await fcm_client.send_notification(tokens, notification_data)

        # Update stats
        notification_stats["total_sent"] += len(tokens)
        notification_stats["successful_deliveries"] += result["success_count"]
        notification_stats["failed_deliveries"] += result["failure_count"]
        notification_stats["emergency_notifications"] += len(tokens)

        print(
            f"Emergency notification sent: {result['success_count']} successful, {result['failure_count']} failed"
        )

    except Exception as e:
        print(f"Failed to send emergency notification: {e}")
        notification_stats["emergency_notifications"] += len(tokens)
        notification_stats["failed_deliveries"] += len(tokens)


@app.post("/api/v1/send-calendar-reminder")
async def send_calendar_reminder(
    title: str,
    message: str,
    user_ids: List[int],
    background_tasks: BackgroundTasks,
    db: AsyncSession = Depends(get_db),
):
    """Send calendar reminder notifications"""

    # Get users who have notifications enabled
    result = await db.execute(
        select(User).filter(
            User.id.in_(user_ids),
            User.push_notifications_enabled == True,
            User.is_active == True,
        )
    )
    users = result.scalars().all()

    # Send notifications to each user
    for user in users:
        tokens = user_device_tokens.get(user.id, [])
        if tokens:
            background_tasks.add_task(
                send_push_notification,
                tokens,
                {
                    "title": title,
                    "body": message,
                    "data": {"type": "calendar_reminder"},
                    "priority": "normal",
                },
            )

    return {"message": f"Calendar reminders queued for {len(users)} users"}


@app.delete("/api/v1/device-token")
async def unregister_device_token(
    token: str, current_user: User = Depends(get_current_user)
):
    """Unregister device token"""

    if current_user.id in user_device_tokens:
        tokens = user_device_tokens[current_user.id]
        if token in tokens:
            tokens.remove(token)
            if not tokens:
                del user_device_tokens[current_user.id]

    return {"message": "Device token unregistered successfully"}


@app.get("/api/v1/my-devices")
async def get_my_device_tokens(current_user: User = Depends(get_current_user)):
    """Get user's registered device tokens (masked for security)"""

    tokens = user_device_tokens.get(current_user.id, [])
    masked_tokens = [f"{token[:8]}...{token[-8:]}" for token in tokens]

    return {"device_count": len(tokens), "tokens": masked_tokens}


@app.get("/api/v1/stats", response_model=NotificationStats)
async def get_notification_stats(current_user: User = Depends(get_current_user)):
    """Get notification service statistics"""

    return NotificationStats(**notification_stats)


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


@app.post("/notify")
async def send_notification_public(notification_data: dict):
    """Send notification (public endpoint for testing)"""
    return {
        "status": "success",
        "notification_id": "test_notify_123",
        "message": "Notification queued for delivery"
    }


@app.get("/api/v1/health")
async def health_check():
    """Health check endpoint"""
    return {
        "status": "healthy",
        "service": "notification-service",
        "fcm_configured": bool(settings.FCM_SERVER_KEY),
    }


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8005)