import os
import uuid
import logging
from datetime import datetime, timedelta
from urllib.parse import quote_plus
from typing import List, Optional, Any

from dotenv import load_dotenv
from fastapi import APIRouter, HTTPException, Depends, Request, UploadFile, File, Form
from fastapi.responses import JSONResponse, StreamingResponse
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel, EmailStr, Field, validator
from pymongo import MongoClient
import os.path
import gridfs  # For storing binary files in MongoDB

load_dotenv()

# Setup logging
logger = logging.getLogger("uvicorn")
logger.setLevel(logging.INFO)

# MongoDB setup for user management
password = quote_plus(os.getenv("MONGO_PASSWORD"))
MONGO_URL = os.getenv("CONNECTION_STRING").replace("${PASSWORD}", password)
client = MongoClient(MONGO_URL)
db = client.users_database
users_collection = db.users
# Create a GridFS instance for storing avatars in the "avatars" collection
fs = gridfs.GridFS(db, collection="avatars")

# OAuth2 setup
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

# Create an APIRouter instance
router = APIRouter()

# Pydantic models
class User(BaseModel):
    name: str = Field(..., min_length=3, max_length=50)
    email: EmailStr
    password: str

    @validator("password")
    def validate_password(cls, value):
        if len(value) < 8:
            raise ValueError("Password must be at least 8 characters long.")
        if not any(char.isdigit() for char in value):
            raise ValueError("Password must include at least one number.")
        if not any(char.isupper() for char in value):
            raise ValueError("Password must include at least one uppercase letter.")
        if not any(char.islower() for char in value):
            raise ValueError("Password must include at least one lowercase letter.")
        if not any(char in "!@#$%^&*()-_+=<>?/" for char in value):
            raise ValueError("Password must include at least one special character.")
        return value

class UserUpdate(BaseModel):
    name: Optional[str] = Field(None, min_length=3, max_length=50)
    email: Optional[EmailStr]
    password: Optional[str]

    @validator("password")
    def validate_password(cls, value):
        if value is not None:
            if len(value) < 8:
                raise ValueError("Password must be at least 8 characters long.")
            if not any(char.isdigit() for char in value):
                raise ValueError("Password must include at least one number.")
            if not any(char.isupper() for char in value):
                raise ValueError("Password must include at least one uppercase letter.")
            if not any(char.islower() for char in value):
                raise ValueError("Password must include at least one lowercase letter.")
            if not any(char in "!@#$%^&*()-_+=<>?/" for char in value):
                raise ValueError("Password must include at least one special character.")
        return value

class Token(BaseModel):
    access_token: str
    refresh_token: str
    token_type: str

class LoginResponse(Token):
    name: str
    avatar: Optional[str] = None

class TokenData(BaseModel):
    email: Optional[str] = None

# Password hashing
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)

def get_user(email: str) -> Optional[dict]:
    return users_collection.find_one({"email": email})

def authenticate_user(email: str, password: str) -> Optional[dict]:
    user = get_user(email)
    if not user or not verify_password(password, user["hashed_password"]):
        return None
    return user

def create_token(data: dict, expires_delta: timedelta = None) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + (expires_delta or timedelta(minutes=15))
    to_encode.update({"exp": expire})
    secret_key = os.getenv("SECRET_KEY")
    algorithm = "HS256"
    return jwt.encode(to_encode, secret_key, algorithm=algorithm)

def create_access_token(email: str) -> str:
    return create_token({"sub": email}, timedelta(minutes=int(os.getenv("ACCESS_TOKEN_EXPIRE_MINUTES", "90"))))

def create_refresh_token(email: str) -> str:
    return create_token({"sub": email}, timedelta(days=int(os.getenv("REFRESH_TOKEN_EXPIRE_DAYS", "7"))))

def get_current_user(token: str = Depends(oauth2_scheme)) -> dict:
    secret_key = os.getenv("SECRET_KEY")
    try:
        payload = jwt.decode(token, secret_key, algorithms=["HS256"])
        email: str = payload.get("sub")
        if not email:
            raise HTTPException(status_code=401, detail="Invalid credentials")
        user = get_user(email)
        if not user:
            raise HTTPException(status_code=401, detail="User not found")
        return user
    except JWTError:
        raise HTTPException(status_code=401, detail="Invalid token")

# Instead of saving avatar to disk, store it in GridFS.
async def save_avatar_file_to_gridfs(file: UploadFile) -> str:
    allowed_types = ["image/jpeg", "image/png", "image/gif"]
    if file.content_type not in allowed_types:
        logger.error(f"Unsupported file type: {file.content_type}")
        raise HTTPException(
            status_code=400,
            detail="Invalid image format. Only JPEG, PNG, and GIF are accepted."
        )
    try:
        contents = await file.read()
        file_id = fs.put(contents, filename=file.filename, contentType=file.content_type)
        logger.info(f"Avatar stored in GridFS with file_id: {file_id}")
        return str(file_id)
    except Exception as e:
        logger.exception("Failed to store avatar in GridFS")
        raise HTTPException(status_code=500, detail="Could not store avatar file in MongoDB.")

# ----- Auth Endpoints -----

@router.post("/signup", response_model=Token)
async def signup(
    request: Request,
    name: str = Form(...),
    email: EmailStr = Form(...),
    password: str = Form(...),
    avatar: Optional[UploadFile] = File(None)
):
    try:
        _ = User(name=name, email=email, password=password)
    except Exception as e:
        logger.error(f"Validation error during signup: {e}")
        raise HTTPException(status_code=400, detail=str(e))
    if get_user(email):
        logger.warning(f"Attempt to register already existing email: {email}")
        raise HTTPException(status_code=400, detail="Email already registered")
    hashed_password = get_password_hash(password)
    user_data = {
        "name": name,
        "email": email,
        "hashed_password": hashed_password,
        "chat_histories": []
    }
    if avatar:
        file_id = await save_avatar_file_to_gridfs(avatar)
        user_data["avatar"] = file_id  # store the GridFS file id
    users_collection.insert_one(user_data)
    logger.info(f"New user registered: {email}")
    return {
        "access_token": create_access_token(email),
        "refresh_token": create_refresh_token(email),
        "token_type": "bearer"
    }

@router.post("/login", response_model=LoginResponse)
async def login(request: Request, form_data: OAuth2PasswordRequestForm = Depends()):
    user = authenticate_user(form_data.username, form_data.password)
    if not user:
        logger.warning(f"Failed login attempt for: {form_data.username}")
        raise HTTPException(status_code=401, detail="Incorrect username or password")
    logger.info(f"User logged in: {user['email']}")
    avatar_url = None
    if "avatar" in user and user["avatar"]:
        avatar_url = f"/auth/avatar/{user['avatar']}"
    return {
        "access_token": create_access_token(user["email"]),
        "refresh_token": create_refresh_token(user["email"]),
        "token_type": "bearer",
        "name": user["name"],
        "avatar": avatar_url
    }

@router.get("/user/data")
async def get_user_data(request: Request, current_user: dict = Depends(get_current_user)):
    avatar_url = None
    if "avatar" in current_user and current_user["avatar"]:
        avatar_url = f"/auth/avatar/{current_user['avatar']}"
    return {
        "name": current_user["name"],
        "email": current_user["email"],
        "avatar": avatar_url,
        "chat_histories": current_user.get("chat_histories", [])
    }

@router.put("/user/update")
async def update_user(
    request: Request,
    name: Optional[str] = Form(None),
    email: Optional[EmailStr] = Form(None),
    password: Optional[str] = Form(None),
    avatar: Optional[UploadFile] = File(None),
    current_user: dict = Depends(get_current_user)
):
    update_data = {}
    if name is not None:
        update_data["name"] = name
    if email is not None:
        update_data["email"] = email
    if password is not None:
        try:
            _ = User(name=current_user["name"], email=current_user["email"], password=password)
        except Exception as e:
            logger.error(f"Password validation error during update: {e}")
            raise HTTPException(status_code=400, detail=str(e))
        update_data["hashed_password"] = get_password_hash(password)
    if avatar:
        file_id = await save_avatar_file_to_gridfs(avatar)
        update_data["avatar"] = file_id
    if not update_data:
        logger.info("No update parameters provided")
        raise HTTPException(status_code=400, detail="No update parameters provided")
    users_collection.update_one({"email": current_user["email"]}, {"$set": update_data})
    logger.info(f"User updated: {current_user['email']}")
    return {"message": "User updated successfully"}

@router.post("/logout")
async def logout(request: Request, current_user: dict = Depends(get_current_user)):
    logger.info(f"User logged out: {current_user['email']}")
    return {"message": "User logged out successfully"}

@router.get("/avatar/{file_id}")
async def get_avatar(file_id: str):
    try:
        file = fs.get(file_id)
        return StreamingResponse(file, media_type=file.content_type)
    except Exception as e:
        logger.error(f"Avatar not found for file_id {file_id}: {e}")
        raise HTTPException(status_code=404, detail="Avatar not found")