import random
import time as _time
from datetime import datetime
from bcrypt import hashpw, gensalt, checkpw
import logging
from ..core.db_connector import users_collection
from ..core.caching import (
    cache_result, cache_user_data, cache_login_data, 
    clear_user_cache as clear_user_cache_func, 
    USER_DATA_CACHE_DURATION, LOGIN_CACHE_DURATION
)

logger = logging.getLogger(__name__)

def generate_unique_id():
    """Generate a unique 6-digit ID for a user."""
    while True:
        _id = random.randint(100000, 999999)
        if users_collection.find_one({"_id": _id}) is None:
            return _id

def create_user(username, password, email=None):
    """Create a new user with a unique ID, including email support."""
    _id = generate_unique_id()
    hashed_password = hashpw(password.encode('utf-8'), gensalt())
    
    user_doc = {
        "_id": _id,
        "username": username,
        "password": hashed_password,
        "created_at": datetime.utcnow(),
        "updated_at": datetime.utcnow()
    }
    
    # Add email if provided
    if email:
        user_doc["email"] = email
    
    users_collection.insert_one(user_doc)
    return _id  # Return the new user's ID

def create_anilist_user(anilist_user_info, access_token):
    """Create a new user from AniList OAuth data."""
    _id = generate_unique_id()
    
    # Extract user information from AniList data
    username = anilist_user_info['name']
    anilist_id = anilist_user_info['id']
    avatar = anilist_user_info.get('avatar', {}).get('large') or anilist_user_info.get('avatar', {}).get('medium')
    
    # Prepare statistics if available
    stats = {}
    if 'statistics' in anilist_user_info and 'anime' in anilist_user_info['statistics']:
        anime_stats = anilist_user_info['statistics']['anime']
        stats = {
            'anime_count': anime_stats.get('count', 0),
            'mean_score': anime_stats.get('meanScore', 0),
            'minutes_watched': anime_stats.get('minutesWatched', 0)
        }
    
    user_doc = {
        "_id": _id,
        "username": username,
        "anilist_id": anilist_id,
        "anilist_access_token": access_token,
        "avatar": avatar,
        "anilist_stats": stats,
        "banner_image": anilist_user_info.get('bannerImage'),
        "created_at": datetime.utcnow(),
        "updated_at": datetime.utcnow(),
        "auth_method": "anilist"
    }
    
    users_collection.insert_one(user_doc)
    return _id

def update_anilist_user(user_id, anilist_user_info, access_token):
    """Update existing user with latest AniList information."""
    avatar = anilist_user_info.get('avatar', {}).get('large') or anilist_user_info.get('avatar', {}).get('medium')
    
    # Prepare statistics if available
    stats = {}
    if 'statistics' in anilist_user_info and 'anime' in anilist_user_info['statistics']:
        anime_stats = anilist_user_info['statistics']['anime']
        stats = {
            'anime_count': anime_stats.get('count', 0),
            'mean_score': anime_stats.get('meanScore', 0),
            'minutes_watched': anime_stats.get('minutesWatched', 0)
        }
    
    update_doc = {
        "$set": {
            "anilist_access_token": access_token,
            "avatar": avatar,
            "anilist_stats": stats,
            "banner_image": anilist_user_info.get('bannerImage'),
            "updated_at": datetime.utcnow()
        }
    }
    
    users_collection.update_one({"_id": user_id}, update_doc)
    clear_user_cache_func(user_id)
    return True

def get_user_by_anilist_id(anilist_id):
    """Get user by AniList ID."""
    return users_collection.find_one({"anilist_id": anilist_id})

def get_user(username, password):
    """Retrieve a user by username and password."""
    user = users_collection.find_one({"username": username})
    if user and user.get('password') and checkpw(password.encode('utf-8'), user['password']):
        return user
    return None

@cache_user_data(duration=LOGIN_CACHE_DURATION)
def get_user_by_id(_id):
    """Get user by ID (cached for 1 hour)."""
    return users_collection.find_one({"_id": _id})

def get_user_by_email(email):
    """Get user by email (case-insensitive)."""
    import re as _re
    return users_collection.find_one({"email": _re.compile(f'^{_re.escape(email)}$', _re.IGNORECASE)})

def user_exists(username):
    """Check if a user with the given username already exists."""
    return users_collection.find_one({"username": username}) is not None

def email_exists(email):
    """Check if a user with the given email already exists."""
    if not email:
        return False
    return users_collection.find_one({"email": email}) is not None

def update_user_avatar(_id, avatar_url):
    """Update user's avatar."""
    users_collection.update_one(
        {"_id": _id},
        {
            "$set": {
                "avatar": avatar_url,
                "updated_at": datetime.utcnow()
            }
        }
    )
    clear_user_cache_func(_id)

def update_user_email(_id, email):
    """Update user's email if it doesn't already exist."""
    if email_exists(email):
        return False  # Email already taken
    
    users_collection.update_one(
        {"_id": _id},
        {
            "$set": {
                "email": email,
                "updated_at": datetime.utcnow()
            }
        }
    )
    clear_user_cache_func(_id)
    return True

def change_password(_id, old_password, new_password):
    """Change user's password after verifying old password."""
    user = get_user_by_id(_id)
    if not user or not user.get('password'):
        return False
    
    # Verify old password
    if not checkpw(old_password.encode('utf-8'), user['password']):
        return False
    
    # Hash new password
    new_hashed_password = hashpw(new_password.encode('utf-8'), gensalt())
    
    current_version = user.get('password_version', 0)
    
    # Update password
    users_collection.update_one(
        {"_id": _id},
        {
            "$set": {
                "password": new_hashed_password,
                "password_version": current_version + 1,
                "updated_at": datetime.utcnow()
            }
        }
    )
    clear_user_cache_func(_id)
    return True

def delete_user(_id):
    """Delete a user by ID."""
    result = users_collection.delete_one({"_id": _id})
    return result.deleted_count > 0

def get_all_users():
    """Get all users (for admin purposes - exclude passwords)."""
    return list(users_collection.find({}, {"password": 0}))

def get_user_count():
    """Get total number of users."""
    return users_collection.count_documents({})

# Additional utility functions for user management

def search_users(query, limit=10):
    """Search users by username or email."""
    search_filter = {
        "$or": [
            {"username": {"$regex": query, "$options": "i"}},
            {"email": {"$regex": query, "$options": "i"}}
        ]
    }
    return list(users_collection.find(search_filter, {"password": 0}).limit(limit))

def get_recent_users(limit=10):
    """Get recently registered users."""
    return list(users_collection.find({}, {"password": 0})
                .sort("created_at", -1)
                .limit(limit))

def link_anilist_to_existing_user(user_id, anilist_user_info, access_token):
    """
    Link an AniList account to an existing user.

    Args:
        user_id (int): Existing user's internal ID (_id).
        anilist_user_info (dict): AniList user information (from AniList API).
        access_token (str): AniList OAuth access token.

    Returns:
        bool: True if updated successfully, False otherwise.
    """
    user = get_user_by_id(user_id)
    if not user:
        return False  # User not found

    # Prevent linking if AniList ID is already linked to another account
    existing = get_user_by_anilist_id(anilist_user_info['id'])
    if existing and existing['_id'] != user_id:
        return False  # AniList account already linked elsewhere

    avatar = anilist_user_info.get('avatar', {}).get('large') or anilist_user_info.get('avatar', {}).get('medium')

    stats = {}
    if 'statistics' in anilist_user_info and 'anime' in anilist_user_info['statistics']:
        anime_stats = anilist_user_info['statistics']['anime']
        stats = {
            'anime_count': anime_stats.get('count', 0),
            'mean_score': anime_stats.get('meanScore', 0),
            'minutes_watched': anime_stats.get('minutesWatched', 0)
        }

    update_doc = {
        "$set": {
            "anilist_id": anilist_user_info['id'],
            "anilist_access_token": access_token,
            "avatar": avatar,
            "anilist_stats": stats,
            "banner_image": anilist_user_info.get('bannerImage'),
            "updated_at": datetime.utcnow(),
            "auth_method": "anilist_linked"
        }
    }

    users_collection.update_one({"_id": user_id}, update_doc)
    return True

def unlink_anilist_from_user(user_id: str) -> bool:
    """Remove AniList credentials from a user."""
    result = users_collection.update_one(
        {"_id": user_id},
        {"$unset": {
            "anilist_access_token": "",
            "anilist_refresh_token": "",
            "anilist_expires_at": ""
        }}
    )
    return result.modified_count > 0

def delete_anilist_data(user_id: int) -> bool:
    """Completely remove all AniList-related data from a user account."""
    try:
        # First, get the current user data to log what we're removing
        user = get_user_by_id(user_id)
        if not user:
            logger.warning(f"User {user_id} not found when trying to delete AniList data")
            return False
        
        anilist_id = user.get('anilist_id')
        username = user.get('username', 'Unknown')
        
        # Remove all AniList-related fields from the user document
        result = users_collection.update_one(
            {"_id": user_id},
            {
                "$unset": {
                    "anilist_id": "",
                    "anilist_access_token": "",
                    "anilist_refresh_token": "",
                    "anilist_expires_at": "",
                    "anilist_stats": "",
                    "banner_image": "",  # Remove AniList banner
                },
                "$set": {
                    "updated_at": datetime.utcnow(),
                    "auth_method": "local"  # Reset to local authentication only
                }
            }
        )
        
        if result.modified_count > 0:
            logger.info(f"Successfully deleted AniList data for user {username} (ID: {user_id}, AniList ID: {anilist_id})")
            return True
        else:
            logger.warning(f"No AniList data found to delete for user {username} (ID: {user_id})")
            # Return True anyway since the goal (no AniList data) is achieved
            return True
            
    except Exception as e:
        logger.error(f"Error deleting AniList data for user {user_id}: {e}")
        return False

def connect_anilist_to_user(user_id: int, anilist_user_info: dict, access_token: str) -> bool:
    """Connect an AniList account to an existing user."""
    try:
        user = get_user_by_id(user_id)
        if not user:
            logger.error(f"User {user_id} not found")
            return False
        
        # Check if AniList account is already connected to another user
        existing = get_user_by_anilist_id(anilist_user_info['id'])
        if existing and existing['_id'] != user_id:
            logger.error(f"AniList account {anilist_user_info['id']} already connected to user {existing['_id']}")
            return False
        
        avatar = anilist_user_info.get('avatar', {}).get('large') or anilist_user_info.get('avatar', {}).get('medium')
        
        stats = {}
        if 'statistics' in anilist_user_info and 'anime' in anilist_user_info['statistics']:
            anime_stats = anilist_user_info['statistics']['anime']
            stats = {
                'anime_count': anime_stats.get('count', 0),
                'mean_score': anime_stats.get('meanScore', 0),
                'minutes_watched': anime_stats.get('minutesWatched', 0)
            }
        
        update_doc = {
            "$set": {
                "anilist_id": anilist_user_info['id'],
                "anilist_access_token": access_token,
                "avatar": avatar,
                "anilist_stats": stats,
                "banner_image": anilist_user_info.get('bannerImage'),
                "updated_at": datetime.utcnow(),
                "auth_method": "anilist_linked"
            }
        }
        
        result = users_collection.update_one({"_id": user_id}, update_doc)
        
        if result.modified_count > 0:
            logger.info(f"Successfully connected AniList account {anilist_user_info['id']} to user {user_id}")
            clear_user_cache_func(user_id)
            return True
        else:
            logger.error(f"Failed to update user {user_id} with AniList data")
            return False
            
    except Exception as e:
        logger.error(f"Error connecting AniList account to user {user_id}: {e}")
        return False

def get_anilist_connection_info(user_id: int) -> dict:
    """Get detailed AniList connection information for a user (cached)."""
    return _get_anilist_connection_info_uncached(user_id)

@cache_user_data(duration=LOGIN_CACHE_DURATION)
def _get_anilist_connection_info_uncached(user_id: int) -> dict:
    """Internal uncached version of get_anilist_connection_info."""
    try:
        user = users_collection.find_one({"_id": user_id})
        if not user:
            return {'connected': False, 'error': 'User not found'}
        
        is_connected = bool(user.get('anilist_id'))
        
        if not is_connected:
            return {
                'connected': False,
                'user_id': user_id,
                'username': user.get('username')
            }
        
        return {
            'connected': True,
            'user_id': user_id,
            'username': user.get('username'),
            'anilist_id': user.get('anilist_id'),
            'avatar': user.get('avatar'),
            'anilist_stats': user.get('anilist_stats', {}),
            'banner_image': user.get('banner_image'),
            'auth_method': user.get('auth_method'),
            'connected_at': user.get('updated_at'),
            'has_access_token': bool(user.get('anilist_access_token'))
        }
        
    except Exception as e:
        logger.error(f"Error getting AniList connection info for user {user_id}: {e}")
        return {'connected': False, 'error': str(e)}


# ──────────────────────────────────────────────
# Password Reset (Forgot Password) helpers
# ──────────────────────────────────────────────

def store_reset_code(email: str, hashed_code: bytes, expires_at: datetime) -> bool:
    """Store a bcrypt-hashed reset code and expiry on the user document."""
    result = users_collection.update_one(
        {"email": email},
        {"$set": {
            "reset_code": hashed_code,
            "reset_code_expires": expires_at,
            "updated_at": datetime.utcnow()
        }}
    )
    return result.modified_count > 0


def verify_reset_code(email: str, code: str) -> bool:
    """Check that *code* matches the stored hash and has not expired."""
    user = users_collection.find_one(
        {"email": email},
        {"reset_code": 1, "reset_code_expires": 1}
    )
    if not user or not user.get("reset_code") or not user.get("reset_code_expires"):
        return False

    if datetime.utcnow() > user["reset_code_expires"]:
        # Expired — clean up
        clear_reset_code(email)
        return False

    return checkpw(code.encode("utf-8"), user["reset_code"])


def clear_reset_code(email: str) -> None:
    """Remove reset-code fields from the user document."""
    users_collection.update_one(
        {"email": email},
        {"$unset": {"reset_code": "", "reset_code_expires": ""}}
    )


def reset_password(email: str, new_password: str) -> bool:
    """Set a new password for the user identified by *email* (no old password needed)."""
    hashed = hashpw(new_password.encode("utf-8"), gensalt())
    
    user = users_collection.find_one({"email": email})
    if not user:
        return False
    current_version = user.get('password_version', 0)
        
    result = users_collection.update_one(
        {"email": email},
        {"$set": {
            "password": hashed,
            "password_version": current_version + 1,
            "updated_at": datetime.utcnow()
        }}
    )
    if result.modified_count > 0:
        user = users_collection.find_one({"email": email}, {"_id": 1})
        if user:
            clear_user_cache_func(user["_id"])
        clear_reset_code(email)
        return True
    return False


# ──────────────────────────────────────────────
# MyAnimeList integration helpers
# ──────────────────────────────────────────────

def connect_mal_to_user(user_id: int, mal_user_info: dict, access_token: str,
                        refresh_token: str, expires_in: int) -> bool:
    """Store MAL credentials on an existing user document."""
    try:
        update_doc = {
            "$set": {
                "mal_id": mal_user_info.get("id"),
                "mal_username": mal_user_info.get("name"),
                "mal_access_token": access_token,
                "mal_refresh_token": refresh_token,
                "mal_token_expires_at": _time.time() + expires_in,
                "updated_at": datetime.utcnow(),
            }
        }
        result = users_collection.update_one({"_id": user_id}, update_doc)
        if result.modified_count > 0:
            logger.info(f"MAL account {mal_user_info.get('id')} connected to user {user_id}")
            clear_user_cache_func(user_id)
            return True
        return False
    except Exception as e:
        logger.error(f"Error connecting MAL to user {user_id}: {e}")
        return False


def delete_mal_data(user_id: int) -> bool:
    """Remove all MAL-related fields from a user document."""
    try:
        result = users_collection.update_one(
            {"_id": user_id},
            {
                "$unset": {
                    "mal_id": "",
                    "mal_username": "",
                    "mal_access_token": "",
                    "mal_refresh_token": "",
                    "mal_token_expires_at": "",
                },
                "$set": {"updated_at": datetime.utcnow()},
            }
        )
        if result.modified_count > 0:
            logger.info(f"MAL data deleted for user {user_id}")
            clear_user_cache_func(user_id)
        return True
    except Exception as e:
        logger.error(f"Error deleting MAL data for user {user_id}: {e}")
        return False


def get_mal_tokens(user_id: int) -> dict | None:
    """Return MAL tokens for a user, or None if not connected."""
    try:
        user = users_collection.find_one(
            {"_id": user_id},
            {"mal_access_token": 1, "mal_refresh_token": 1, "mal_token_expires_at": 1, "mal_id": 1}
        )
        if not user or not user.get("mal_access_token"):
            return None
        return {
            "access_token": user["mal_access_token"],
            "refresh_token": user.get("mal_refresh_token"),
            "expires_at": user.get("mal_token_expires_at", 0),
            "mal_id": user.get("mal_id"),
        }
    except Exception as e:
        logger.error(f"Error getting MAL tokens for user {user_id}: {e}")
        return None


def update_mal_tokens(user_id: int, access_token: str, refresh_token: str, expires_in: int) -> bool:
    """Update MAL tokens after a refresh."""
    try:
        result = users_collection.update_one(
            {"_id": user_id},
            {"$set": {
                "mal_access_token": access_token,
                "mal_refresh_token": refresh_token,
                "mal_token_expires_at": _time.time() + expires_in,
                "updated_at": datetime.utcnow(),
            }}
        )
        if result.modified_count > 0:
            clear_user_cache_func(user_id)
        return True
    except Exception as e:
        logger.error(f"Error updating MAL tokens for user {user_id}: {e}")
        return False