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, Body
from fastapi.responses import JSONResponse
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

# ----- OTP and Email Imports -----
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
try:
    import markdown
except ImportError:
    markdown = None
import secrets
# ----------------------------------

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
# New collection to store OTP records
otp_collection = db.otp_verifications

# 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")

# Setup for avatar file saving
AVATAR_DIR = "avatars"
if not os.path.exists(AVATAR_DIR):
    os.makedirs(AVATAR_DIR)

def save_avatar_file(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."
        )
    file_extension = os.path.splitext(file.filename)[1]
    unique_filename = f"{uuid.uuid4()}{file_extension}"
    file_path = os.path.join(AVATAR_DIR, unique_filename)
    try:
        contents = file.file.read()
        with open(file_path, "wb") as f:
            f.write(contents)
        logger.info(f"Avatar saved as {file_path}")
    except Exception as e:
        logger.exception("Failed to save avatar file")
        raise HTTPException(status_code=500, detail="Could not save avatar file.")
    finally:
        file.file.close()
    return file_path

# ----- OTP and Email Functions -----
def generate_otp(length=6):
    """Generate a numeric OTP of specified length."""
    digits = "0123456789"
    otp = ''.join(secrets.choice(digits) for _ in range(length))
    return otp

def send_email_func(sender_email, sender_password, receiver_email, subject, body):
    smtp_server = "smtp.gmail.com"
    port = 587
    message = MIMEMultipart("alternative")
    message["Subject"] = subject
    message["From"] = sender_email
    message["To"] = receiver_email

    part1 = MIMEText(body, "plain")
    if markdown:
        html_content = markdown.markdown(body)
    else:
        html_content = f"<pre>{body}</pre>"

    html_template = f"""\
<html>
  <head>
    <style>
      body {{
        font-family: Arial, sans-serif;
        line-height: 1.6;
        margin: 20px;
      }}
      h1, h2, h3 {{
        color: #333;
      }}
      pre {{
        background: #f4f4f4;
        padding: 10px;
        border: 1px solid #ddd;
      }}
    </style>
  </head>
  <body>
    {html_content}
  </body>
</html>
"""
    part2 = MIMEText(html_template, "html")
    message.attach(part1)
    message.attach(part2)

    try:
        with smtplib.SMTP(smtp_server, port, timeout=10) as server:
            server.starttls()
            server.login(sender_email, sender_password)
            server.sendmail(sender_email, receiver_email, message.as_string())
        logger.info("Successfully sent email")
    except Exception as e:
        logger.error(f"Error sending email: {e}")
        raise e
# ------------------------------------

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

@router.post("/send_otp")
async def send_otp(receiver_email: EmailStr = Body(..., embed=True)):
    """
    Generates an OTP and sends it via email to the provided receiver_email.
    (For demonstration purposes, the OTP is returned. Remove it in production.)
    """
    sender_email = os.getenv("SENDER_EMAIL")
    sender_password = os.getenv("SENDER_PASSWORD")
    if not sender_email or not sender_password:
        raise HTTPException(status_code=500, detail="Email sender credentials are not configured.")
    
    otp = generate_otp(6)
    subject = "Your One-Time Password (OTP)"
    body = f"""\
# Your OTP

Here is your one-time password (OTP):

`{otp}`

Please use the code above to verify your email and proceed with account creation.
"""
    try:
        send_email_func(sender_email, sender_password, receiver_email, subject, body)
        # Store OTP record with a 10-minute expiration
        otp_record = {
            "email": receiver_email,
            "otp": otp,
            "expires_at": datetime.utcnow() + timedelta(minutes=1)
        }
        otp_collection.update_one({"email": receiver_email}, {"$set": otp_record}, upsert=True)
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Error sending OTP email: {str(e)}")
    return {"message": "OTP sent successfully", "otp": otp}  # Remove OTP from response in production

@router.post("/signup", response_model=Token)
async def signup(
    request: Request,
    name: str = Form(...),
    email: EmailStr = Form(...),
    password: str = Form(...),
    otp: str = Form(...),
    avatar: Optional[UploadFile] = File(None)
):
    # Verify OTP for this email
    otp_record = otp_collection.find_one({"email": email})
    if not otp_record:
        raise HTTPException(status_code=400, detail="No OTP sent to this email. Please request an OTP first.")
    if otp_record["otp"] != otp:
        raise HTTPException(status_code=400, detail="Invalid OTP provided.")
    if datetime.utcnow() > otp_record["expires_at"]:
        raise HTTPException(status_code=400, detail="OTP has expired. Please request a new one.")
    # Remove the OTP record after successful verification
    otp_collection.delete_one({"email": email})
    
    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:
        avatar_path = save_avatar_file(avatar)
        user_data["avatar"] = f"/avatars/{os.path.basename(avatar_path)}"
    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']}")
    return {
        "access_token": create_access_token(user["email"]),
        "refresh_token": create_refresh_token(user["email"]),
        "token_type": "bearer",
        "name": user["name"],
        "avatar": user.get("avatar")
    }

@router.get("/user/data")
async def get_user_data(request: Request, current_user: dict = Depends(get_current_user)):
    return {
        "name": current_user["name"],
        "email": current_user["email"],
        "avatar": current_user.get("avatar"),
        "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:
        avatar_path = save_avatar_file(avatar)
        update_data["avatar"] = f"/avatars/{os.path.basename(avatar_path)}"
    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"}