import os
import logging
import firebase_admin.messaging
import requests
import datetime
import asyncio
from fastapi import FastAPI, HTTPException, status, Body
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel, Field, EmailStr
from motor.motor_asyncio import AsyncIOMotorClient
from passlib.context import CryptContext
from dotenv import load_dotenv
from typing import Optional, List
import firebase_admin
from firebase_admin import credentials

# --- Load Environment Variables ---
load_dotenv()
MONGODB_URI = os.getenv("MONGODB_URI")
if not MONGODB_URI:
    raise ValueError("MONGODB_URI environment variable not set.")

# --- Configuration ---
DATABASE_NAME = "userAuthDB"
COLLECTION_NAME = "users"
TOKEN_COLLECTION_NAME = "fcmtokens"

# --- Logging Setup ---
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# --- Password Hashing Setup ---
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# --- FastAPI App Initialization ---
app = FastAPI(
    title="Backend API",
    description="API for WhereIParked Backend OPerations.",
    version="1.5.0",
)

# --- CORS Configuration ---
origins = ["*"]

app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


# --- Database Connection ---
client: Optional[AsyncIOMotorClient] = None
db = None

cred = credentials.Certificate("whereiparked-e9eb6-firebase-adminsdk-fbsvc-1691a99d68.json")

default_app = None

@app.on_event("startup")
async def startup_client():
    """Connect to MongoDB & Firebase on application startup."""
    global client, db, default_app
    logger.info("Connecting to MongoDB...")
    try:
        client = AsyncIOMotorClient(MONGODB_URI)
        db = client[DATABASE_NAME]
        # Ping the server to check connection
        await client.admin.command('ping')
        logger.info(f"Successfully connected to MongoDB database: {DATABASE_NAME}")
        try:
            if not firebase_admin._apps:
                default_app = firebase_admin.initialize_app(cred, {
                    'projectId': 'whereiparked-e9eb6'
                })
                logger.info("Firebase Admin SDK initialized successfully.")
            else:
                default_app = firebase_admin.get_app()
                logger.info("Firebase Admin SDK already initialized.")
            print(firebase_admin._apps)
        except Exception as e:
            logger.error(f"Error initializing/getting Firebase Admin SDK: {e}")
    except Exception as e:
        logger.error(f"Failed to connect to MongoDB: {e}")
        raise RuntimeError(f"Could not connect to MongoDB: {e}")

@app.on_event("shutdown")
async def shutdown_client():
    """Disconnect from MongoDB on application shutdown."""
    global client
    if client:
        logger.info("Closing MongoDB connection...")
        client.close()
        logger.info("MongoDB connection closed.")

# --- Pydantic Models ---

class UserBase(BaseModel):
    """Base model for user data."""
    email: EmailStr = Field(..., example="user@example.com")

class UserCreate(UserBase):
    """Model for user creation (signup)."""
    username: str = Field(..., min_length=3, max_length=50, example="john_doe")
    password: str = Field(..., min_length=8, example="strongpassword123")
class UserLogin(BaseModel):
    """Model for user login."""
    email: EmailStr = Field(..., example="user@example.com")
    password: str = Field(..., example="strongpassword123")

class UserInDB(UserBase):
    """Model representing user data stored in the database."""
    username: str
    hashed_password: str

class Token(BaseModel):
    """Model for returning success/token (optional)."""
    message: str

class SignupResponse(BaseModel):
    """Response model for successful signup."""
    message: str = Field(..., example="Signup successful!")

class LoginSuccessResponse(BaseModel):
    """Response model for successful login."""
    message: str = Field(..., example="Login successful!")
    email: EmailStr = Field(..., example="user@example.com")

class TokenModel(BaseModel):
    email: str
    token: str

class InAppEventNotification(BaseModel):
    token: str

# --- Helper Functions ---
def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password):
    return pwd_context.hash(password)

async def get_user_by_email(email: str) -> Optional[dict]:
    """Retrieves a user from the database by email."""
    if db is None:
         # Log the error and raise an appropriate HTTP exception
         logger.error("Database connection is not available in get_user_by_email")
         raise HTTPException(status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="Database service is unavailable.")
    try:
        user = await db[COLLECTION_NAME].find_one({"email": email})
        return user # Returns dict or None
    except Exception as e:
        logger.error(f"Error fetching user by email ({email}): {e}")
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Error accessing user data.")


async def get_user_by_username(username: str) -> Optional[dict]:
    """Retrieves a user from the database by username."""
    if db is None:
         logger.error("Database connection is not available in get_user_by_username")
         raise HTTPException(status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="Database service is unavailable.")
    try:
        user = await db[COLLECTION_NAME].find_one({"username": username})
        return user # Returns dict or None
    except Exception as e:
        logger.error(f"Error fetching user by username ({username}): {e}")
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Error accessing user data.")

FCM_SERVER_KEY = os.getenv("FCM_SERVER_KEY")

async def send_push(token: str, title: str, body: str, platform: str = "web"):
    try:
        if platform=="app":
            message = firebase_admin.messaging.Message(
            notification=firebase_admin.messaging.Notification(
            title=title,
            body=body,
            image="./icon.png"
            ),
            data={
                "title": title,
                "body": body
            },
            token=token,
        )
        else:     
            message = firebase_admin.messaging.Message(
                data={
                    "title": title,
                    "body": body
                },
                token=token,
            )
    
        response = firebase_admin.messaging.send(message)
    
        print('Successfully sent message:', response)
    
        return response
    except UnregisteredError:
        logger.warning(f"Token unregistered, removing from DB: {token}")
        asyncio.create_task(db[TOKEN_COLLECTION_NAME].delete_one({"token": token}))
        return {"error": "Token unregistered, deleted from DB."}
    except Exception as e:
        logger.error(f"Error sending message: {e}")
        raise

from firebase_admin.messaging import UnregisteredError

# --- API Endpoints ---

@app.post("/signup", response_model=SignupResponse, status_code=status.HTTP_201_CREATED)
async def signup(user_data: UserCreate = Body(...)):
    """Handles user registration."""
    if db is None: # Check added for safety, though startup should handle it
        raise HTTPException(status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="Database service is unavailable.")

    existing_user_email = await get_user_by_email(user_data.email)
    if existing_user_email:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered.",
        )
    existing_user_username = await get_user_by_username(user_data.username)
    if existing_user_username:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already taken.",
        )

    hashed_password = get_password_hash(user_data.password)
    user_in_db = UserInDB(
        username=user_data.username,
        email=user_data.email,
        hashed_password=hashed_password
    )

    try:
        new_user = await db[COLLECTION_NAME].insert_one(user_in_db.dict(by_alias=True)) # Use dict() for Pydantic v1/v2 compatibility
        logger.info(f"User created successfully with ID: {new_user.inserted_id}")
    except Exception as e:
        logger.error(f"Error inserting user into database: {e}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="An error occurred while creating the account.",
        )

    return SignupResponse(message="Signup successful!")

# Updated: Changed response_model to LoginSuccessResponse
@app.post("/login", response_model=LoginSuccessResponse)
async def login(login_data: UserLogin = Body(...)):
    """Handles user login. Returns user email on success."""
    if db is None:
        raise HTTPException(status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="Database service is unavailable.")

    user = await get_user_by_email(login_data.email)

    if not user or not verify_password(login_data.password, user["hashed_password"]):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect email or password.",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Return success message and user email
    logger.info(f"User {user['email']} logged in successfully.")
    return LoginSuccessResponse(
        message="Login successful!",
        email=user["email"]
        # username=user["username"] # Optionally include username
    )

@app.post("/api/save-token")
async def save_token(token_model: TokenModel):
    existing = await db.fcmtokens.find_one({"token": token_model.token})
    if not existing:
        await db.fcmtokens.insert_one({
            "email": token_model.email,
            "token": token_model.token,
            "createdAt": datetime.datetime.utcnow()
        })
    return {"message": "Token saved"}

@app.post("/api/parked")
async def user_parked(requestBody: InAppEventNotification = Body(...)):
    await send_push(requestBody.token, "WhereIParked", "You parked your car. Timer started!")
    return {"message": "Notification sent"}


@app.post("/api/clear-location")
async def user_cleared(requestBody: InAppEventNotification = Body(...)):
    await send_push(requestBody.token, "WhereIParked", "Parking location cleared. Safe drive!")
    return {"message": "Notification sent"}

@app.post("/api/park-duration")
async def park_duration(requestBody: InAppEventNotification = Body(...), duration = str):
    await send_push(requestBody.token, "Reminder", "You’ve been parked for over " + duration + " minutes!")
    return {"message": "Notification sent"}

@app.post("/admin/push")
async def admin_push(title: str = Body(...), body: str = Body(...)):
    tokens = await db.fcmtokens.find().to_list(length=None)
    for token_entry in tokens:
        await send_push(token_entry["token"], title, body)
    return {"message": "Notifications sent"}

@app.post("/api/app/parked")
async def app_user_parked(requestBody: InAppEventNotification = Body(...)):
    await send_push(requestBody.token, "WhereIParked", "You parked your car. Timer started!", "app")
    return {"message": "Notification sent"}


@app.post("/api/app/clear-location")
async def app_user_cleared(requestBody: InAppEventNotification = Body(...)):
    await send_push(requestBody.token, "WhereIParked", "Parking location cleared. Safe drive!", "app")
    return {"message": "Notification sent"}

@app.post("/api/app/park-duration")
async def app_park_duration(requestBody: InAppEventNotification = Body(...), duration = str):
    await send_push(requestBody.token, "Reminder", "You’ve been parked for over " + duration + " minutes!", "app")
    return {"message": "Notification sent"}

@app.post("/admin/app/push")
async def app_admin_push(title: str = Body(...), body: str = Body(...)):
    tokens = await db.fcmtokens.find().to_list(length=None)
    for token_entry in tokens:
        await send_push(token_entry["token"], title, body, "app")
    return {"message": "Notifications sent"}



@app.get("/", status_code=status.HTTP_200_OK)
async def read_root():
    """Root endpoint to check if the API is running."""
    return {"message": "Authentication API is running!"}