import streamlit as st
import hashlib
import re
from models import User, SessionLocal

def validate_password(password: str) -> tuple[bool, str]:
    """Validate password requirements."""
    if len(password) < 8:
        return False, "Password must be at least 8 characters long"
    if not any(c.isupper() for c in password):
        return False, "Password must contain at least one uppercase letter"
    return True, ""

def hash_password(password: str) -> str:
    """Hash a password for storing."""
    return hashlib.sha256(password.encode()).hexdigest()

def verify_password(stored_password: str, provided_password: str) -> bool:
    """Verify a stored password against one provided by user"""
    return stored_password == hash_password(provided_password)

def login_user(username: str, password: str) -> bool:
    """Verify user credentials and log them in."""
    db = SessionLocal()
    try:
        user = db.query(User).filter(User.username == username).first()
        if user and verify_password(user.password, password):
            st.session_state.user_id = user.id
            st.session_state.username = user.username
            return True
        return False
    finally:
        db.close()

def signup_user(username: str, password: str) -> tuple[bool, str]:
    """Create a new user account."""
    # Validate password
    is_valid, message = validate_password(password)
    if not is_valid:
        return False, message

    db = SessionLocal()
    try:
        # Check if username already exists
        if db.query(User).filter(User.username == username).first():
            return False, "Username already exists"

        # Create new user
        user = User(
            username=username,
            password=hash_password(password)
        )
        db.add(user)
        db.commit()

        # Log in the new user
        st.session_state.user_id = user.id
        st.session_state.username = user.username
        return True, "Account created successfully"
    except Exception as e:
        db.rollback()
        return False, str(e)
    finally:
        db.close()

def update_profile(user_id: int, **profile_data) -> tuple[bool, str]:
    """Update user profile information."""
    db = SessionLocal()
    try:
        user = db.query(User).filter(User.id == user_id).first()
        if not user:
            return False, "User not found"

        # Update user fields
        for field, value in profile_data.items():
            if hasattr(user, field):
                setattr(user, field, value)

        db.commit()
        return True, "Profile updated successfully"
    except Exception as e:
        db.rollback()
        return False, str(e)
    finally:
        db.close()

def get_user_profile(user_id: int) -> User:
    """Get user profile information."""
    db = SessionLocal()
    try:
        return db.query(User).filter(User.id == user_id).first()
    finally:
        db.close()

def change_password(user_id: int, current_password: str, new_password: str) -> tuple[bool, str]:
    """Change user password."""
    # Validate new password
    is_valid, message = validate_password(new_password)
    if not is_valid:
        return False, message

    db = SessionLocal()
    try:
        user = db.query(User).filter(User.id == user_id).first()
        if not user:
            return False, "User not found"

        # Verify current password
        if not verify_password(user.password, current_password):
            return False, "Current password is incorrect"

        # Update password
        user.password = hash_password(new_password)
        db.commit()
        return True, "Password updated successfully"
    except Exception as e:
        db.rollback()
        return False, str(e)
    finally:
        db.close()

def is_logged_in() -> bool:
    """Check if user is logged in."""
    return 'user_id' in st.session_state

def logout_user():
    """Log out the current user."""
    if 'user_id' in st.session_state:
        del st.session_state.user_id
    if 'username' in st.session_state:
        del st.session_state.username