"""
User Management Module
======================
Handles user database storage in Hugging Face repository instead of local JSON.
Stores users_db.json in: Hamza4100/multi-pdf-storage/users_db.json
"""

import os
import json
import hashlib
import tempfile
from typing import Optional, Dict, Any
from datetime import datetime
from huggingface_hub import HfApi, hf_hub_download, login


class HFUserManager:
    """Manages user database stored in Hugging Face repository."""
    
    def __init__(self, hf_token: Optional[str], hf_repo: str):
        """
        Initialize HF User Manager.
        
        Args:
            hf_token: Hugging Face API token with write access
            hf_repo: HF repository ID (e.g., "Hamza4100/multi-pdf-storage")
        """
        self.hf_token = hf_token
        self.hf_repo = hf_repo
        self.enabled = bool(hf_token and hf_repo)
        self.api = None
        self.users_db_file = "users_db.json"  # File stored at repo root
        self.users_data: Dict[str, Any] = {}
        
        if self.enabled:
            try:
                login(token=hf_token, add_to_git_credential=True)
                self.api = HfApi()
                print(f"✅ HF User Manager initialized: {hf_repo}")
                # Load users database on init
                self._load_users_from_hf()
            except Exception as e:
                print(f"⚠️ HF User Manager initialization failed: {e}")
                self.enabled = False
        else:
            print("⚠️ HF User Manager disabled (HF_TOKEN or HF_REPO not set)")
    
    def _load_users_from_hf(self) -> bool:
        """
        Load users_db.json from HF repository.
        
        Returns:
            bool: True if loaded successfully, False otherwise
        """
        if not self.enabled:
            return False
        
        try:
            print(f"📥 Loading users database from {self.hf_repo}/{self.users_db_file}")
            
            # Download users_db.json from HF repo
            downloaded_path = hf_hub_download(
                repo_id=self.hf_repo,
                filename=self.users_db_file,
                token=self.hf_token,
                repo_type="model",
                local_dir_use_symlinks=False
            )
            
            # Read the file
            with open(downloaded_path, 'r') as f:
                self.users_data = json.load(f)
            
            print(f"✅ Loaded {len(self.users_data)} user(s) from HF repo")
            # Backfill missing user_id fields (derive from api_key) and save
            modified = False
            for username, udata in list(self.users_data.items()):
                if 'user_id' not in udata and udata.get('api_key'):
                    try:
                        udata['user_id'] = hashlib.sha256(udata['api_key'].encode()).hexdigest()[:12]
                        self.users_data[username] = udata
                        modified = True
                    except Exception:
                        continue

            if modified:
                # Save back to HF to persist user_id fields
                self._save_users_to_hf(commit_message="Backfill user_id for existing users")

            return True
        
        except Exception as e:
            # File might not exist yet (first run is okay)
            print(f"⚠️ Could not load users database from HF: {str(e)[:100]}")
            print("   Starting with empty database (will be created on first signup)")
            self.users_data = {}
            return False
    
    def _save_users_to_hf(self, commit_message: str = "Update users database") -> bool:
        """
        Save users_db.json to HF repository.
        
        Args:
            commit_message: Commit message for the upload
        
        Returns:
            bool: True if saved successfully, False otherwise
        """
        if not self.enabled:
            print("⚠️ HF User Manager disabled, cannot save to HF")
            return False
        
        try:
            print(f"📤 Saving users database to {self.hf_repo}/{self.users_db_file}")
            
            # Create a temporary file with the users data
            with tempfile.NamedTemporaryFile(mode='w', suffix='.json', delete=False) as tmp:
                json.dump(self.users_data, tmp, indent=2)
                tmp_path = tmp.name
            
            try:
                # Upload to HF repo
                self.api.upload_file(
                    path_or_fileobj=tmp_path,
                    path_in_repo=self.users_db_file,
                    repo_id=self.hf_repo,
                    token=self.hf_token,
                    repo_type="model",
                    commit_message=commit_message
                )
                
                print(f"✅ Users database saved to HF repo")
                return True
            
            finally:
                # Clean up temporary file
                if os.path.exists(tmp_path):
                    os.remove(tmp_path)
        
        except Exception as e:
            print(f"❌ Failed to save users database to HF: {e}")
            return False
    
    def get_user(self, username: str) -> Optional[Dict[str, Any]]:
        """
        Get user by username.
        
        Args:
            username: Username to retrieve
        
        Returns:
            User data dict or None if not found
        """
        return self.users_data.get(username)
    
    def user_exists(self, username: str) -> bool:
        """
        Check if user exists.
        
        Args:
            username: Username to check
        
        Returns:
            True if user exists, False otherwise
        """
        return username in self.users_data
    
    def create_user(
        self,
        username: str,
        password_hash: str,
        email: str,
        api_key: str
    ) -> bool:
        """
        Create a new user account.
        
        Args:
            username: Username
            password_hash: Hashed password
            email: User email
            api_key: API key for this user
        
        Returns:
            bool: True if user created, False if user already exists
        """
        if self.user_exists(username):
            return False
        
        # Derive stable user_id from API key for storage isolation
        try:
            user_id = hashlib.sha256(api_key.encode()).hexdigest()[:12]
        except Exception:
            user_id = None

        self.users_data[username] = {
            "password_hash": password_hash,
            "email": email,
            "api_key": api_key,
            "user_id": user_id,
            "created_at": datetime.now().isoformat()
        }
        
        # Save to HF
        success = self._save_users_to_hf(
            commit_message=f"Add new user: {username}"
        )
        
        if success:
            print(f"✅ User '{username}' created and saved to HF")
        
        return success
    
    def update_user(self, username: str, updates: Dict[str, Any]) -> bool:
        """
        Update user data.
        
        Args:
            username: Username to update
            updates: Dictionary with updates
        
        Returns:
            bool: True if updated successfully, False if user not found
        """
        if not self.user_exists(username):
            return False
        
        self.users_data[username].update(updates)
        
        # Save to HF
        success = self._save_users_to_hf(
            commit_message=f"Update user: {username}"
        )
        
        if success:
            print(f"✅ User '{username}' updated in HF")
        
        return success
    
    def delete_user(self, username: str) -> bool:
        """
        Delete a user account.
        
        Args:
            username: Username to delete
        
        Returns:
            bool: True if deleted successfully, False if user not found
        """
        if not self.user_exists(username):
            return False
        
        del self.users_data[username]
        
        # Save to HF
        success = self._save_users_to_hf(
            commit_message=f"Delete user: {username}"
        )
        
        if success:
            print(f"✅ User '{username}' deleted from HF")
        
        return success
    
    def get_all_users(self) -> Dict[str, Any]:
        """
        Get all users data.
        
        Returns:
            Dictionary of all users
        """
        return self.users_data.copy()
    
    def get_user_by_api_key(self, api_key: str) -> Optional[tuple]:
        """
        Find user by API key.
        
        Args:
            api_key: API key to search for
        
        Returns:
            Tuple of (username, user_data) or None if not found
        """
        for username, user_data in self.users_data.items():
            if user_data.get("api_key") == api_key:
                return (username, user_data)
        
        return None
    
    def get_user_by_email(self, email: str) -> Optional[tuple]:
        """
        Find user by email.
        
        Args:
            email: Email to search for
        
        Returns:
            Tuple of (username, user_data) or None if not found
        """
        for username, user_data in self.users_data.items():
            if user_data.get("email") == email:
                return (username, user_data)
        
        return None
    
    def verify_password(self, username: str, password_hash: str) -> bool:
        """
        Verify user password hash.
        
        Args:
            username: Username
            password_hash: Password hash to verify
        
        Returns:
            bool: True if password matches, False otherwise
        """
        user = self.get_user(username)
        if not user:
            return False
        
        return user.get("password_hash") == password_hash

    # ============================================
    # USER STORAGE FILE HELPERS
    # ============================================
    def _path_in_repo_for_user(self, user_id: str, filename: str) -> str:
        return f"users/{user_id}/{filename}"

    def save_user_json(self, user_id: str, filename: str, data: dict, commit_message: str = None) -> bool:
        """
        Save a JSON file into the user's storage folder in the HF repo.
        """
        if not self.enabled:
            print("⚠️ HF User Manager disabled, cannot save user file")
            return False

        if commit_message is None:
            commit_message = f"Update {user_id}/{filename}"

        try:
            # Create temp file
            import tempfile
            with tempfile.NamedTemporaryFile(mode='w', suffix='.json', delete=False) as tmp:
                json.dump(data, tmp, indent=2, ensure_ascii=False)
                tmp_path = tmp.name

            path_in_repo = self._path_in_repo_for_user(user_id, filename)

            try:
                self.api.upload_file(
                    path_or_fileobj=tmp_path,
                    path_in_repo=path_in_repo,
                    repo_id=self.hf_repo,
                    token=self.hf_token,
                    repo_type='model',
                    commit_message=commit_message
                )
                print(f"✅ Saved {path_in_repo} to HF repo")
                return True
            finally:
                if os.path.exists(tmp_path):
                    os.remove(tmp_path)

        except Exception as e:
            print(f"❌ Failed to save user file to HF: {e}")
            return False

    def load_user_json(self, user_id: str, filename: str) -> Optional[dict]:
        """
        Load a JSON file from the user's storage folder in the HF repo.
        Returns the parsed JSON dict or None if not found / error.
        """
        if not self.enabled:
            return None

        path_in_repo = self._path_in_repo_for_user(user_id, filename)
        try:
            downloaded_path = hf_hub_download(
                repo_id=self.hf_repo,
                filename=path_in_repo,
                token=self.hf_token,
                repo_type='model',
                local_dir_use_symlinks=False
            )

            with open(downloaded_path, 'r', encoding='utf-8') as f:
                return json.load(f)

        except Exception as e:
            # Not found or error
            return None


# ============================================
# CONVENIENCE FUNCTIONS
# ============================================

def create_hf_user_manager(
    hf_token: Optional[str] = None,
    hf_repo: Optional[str] = None
) -> HFUserManager:
    """
    Create and return an HF User Manager instance.
    
    Args:
        hf_token: HF token (reads from env if not provided)
        hf_repo: HF repo ID (reads from env if not provided)
    
    Returns:
        HFUserManager instance
    """
    if hf_token is None:
        hf_token = os.environ.get("HF_TOKEN")
    
    if hf_repo is None:
        hf_repo = os.environ.get("HF_REPO", "Hamza4100/multi-pdf-storage")
    
    return HFUserManager(hf_token=hf_token, hf_repo=hf_repo)