"""
╔══════════════════════════════════════════════════════════════════════════════╗
║                                                                              ║
║                    AUTHENTICATION PLUGIN for NoahsKI                         ║
║                         Email Verification System                            ║
║                                                                              ║
║  Features:                                                                   ║
║  ✓ Email Registration & Verification                                        ║
║  ✓ Verification Code via Email                                              ║
║  ✓ Session Management                                                        ║
║  ✓ User Data Storage (JSON)                                                 ║
║  ✓ Password Hashing (bcrypt)                                                ║
║  ✓ Token-based Authentication                                               ║
║                                                                              ║
╚══════════════════════════════════════════════════════════════════════════════╝
"""

import os
import json
import time
import secrets
import hashlib
import smtplib
import tempfile
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from pathlib import Path
from typing import Dict, Optional, Tuple
from dataclasses import dataclass, asdict
from datetime import datetime, timedelta
import logging

logger = logging.getLogger(__name__)


# ═══════════════════════════════════════════════════════════════════════════════
# CONFIGURATION
# ═══════════════════════════════════════════════════════════════════════════════

class AuthConfig:
    """Authentication plugin configuration"""
    
    # Detect Hugging Face Spaces
    IS_HF_SPACE = os.getenv('SPACE_ID') is not None
    
    # Paths (HF Spaces compatible)
    if IS_HF_SPACE:
        BASE_DATA_DIR = Path(tempfile.gettempdir()) / 'noahski_data'
    else:
        BASE_DATA_DIR = Path('noahski_data')
    
    DATA_DIR = BASE_DATA_DIR / 'auth'
    USERS_FILE = DATA_DIR / 'users.json'
    SESSIONS_FILE = DATA_DIR / 'sessions.json'
    VERIFICATION_FILE = DATA_DIR / 'verifications.json'
    
    # Email Settings (SMTP)
    SMTP_SERVER = os.getenv('SMTP_SERVER', 'smtp.gmail.com')
    SMTP_PORT = int(os.getenv('SMTP_PORT', 587))
    SMTP_USER = os.getenv('SMTP_USER', 'your-email@gmail.com')
    SMTP_PASSWORD = os.getenv('SMTP_PASSWORD', 'your-app-password')
    FROM_EMAIL = os.getenv('FROM_EMAIL', 'noreply@noahski.ai')
    FROM_NAME = os.getenv('FROM_NAME', 'NoahsKI')
    
    # Security
    VERIFICATION_CODE_LENGTH = 6
    VERIFICATION_EXPIRY_MINUTES = 15
    SESSION_EXPIRY_HOURS = 24
    MAX_LOGIN_ATTEMPTS = 5
    LOCKOUT_DURATION_MINUTES = 30
    
    # Token
    TOKEN_LENGTH = 32


# ═══════════════════════════════════════════════════════════════════════════════
# DATA CLASSES
# ═══════════════════════════════════════════════════════════════════════════════

@dataclass
class User:
    """User data structure"""
    email: str
    password_hash: str
    created_at: float
    verified: bool = False
    last_login: Optional[float] = None
    login_attempts: int = 0
    locked_until: Optional[float] = None
    username: Optional[str] = None
    
    def to_dict(self) -> Dict:
        return asdict(self)
    
    @staticmethod
    def from_dict(data: Dict) -> 'User':
        return User(**data)


@dataclass
class Session:
    """Session data structure"""
    token: str
    email: str
    created_at: float
    expires_at: float
    ip_address: Optional[str] = None
    user_agent: Optional[str] = None
    
    def is_valid(self) -> bool:
        return time.time() < self.expires_at
    
    def to_dict(self) -> Dict:
        return asdict(self)
    
    @staticmethod
    def from_dict(data: Dict) -> 'Session':
        return Session(**data)


@dataclass
class VerificationCode:
    """Email verification code"""
    email: str
    code: str
    created_at: float
    expires_at: float
    attempts: int = 0
    
    def is_valid(self) -> bool:
        return time.time() < self.expires_at and self.attempts < 3
    
    def to_dict(self) -> Dict:
        return asdict(self)
    
    @staticmethod
    def from_dict(data: Dict) -> 'VerificationCode':
        return VerificationCode(**data)


# ═══════════════════════════════════════════════════════════════════════════════
# EMAIL SERVICE
# ═══════════════════════════════════════════════════════════════════════════════

class EmailService:
    """Handle email sending"""
    
    def __init__(self):
        self.smtp_server = AuthConfig.SMTP_SERVER
        self.smtp_port = AuthConfig.SMTP_PORT
        self.smtp_user = AuthConfig.SMTP_USER
        self.smtp_password = AuthConfig.SMTP_PASSWORD
        self.from_email = AuthConfig.FROM_EMAIL
        self.from_name = AuthConfig.FROM_NAME
    
    def send_verification_email(self, to_email: str, code: str) -> bool:
        """Send verification code email"""
        try:
            subject = f"🔐 Dein NoahsKI Verifizierungscode"
            
            html_body = f"""
            <!DOCTYPE html>
            <html>
            <head>
                <style>
                    body {{ font-family: Arial, sans-serif; background-color: #f4f4f4; padding: 20px; }}
                    .container {{ background-color: white; padding: 30px; border-radius: 10px; max-width: 600px; margin: 0 auto; }}
                    .code {{ font-size: 32px; font-weight: bold; color: #4CAF50; text-align: center; padding: 20px; background-color: #f0f0f0; border-radius: 5px; letter-spacing: 5px; }}
                    .header {{ color: #333; text-align: center; }}
                    .footer {{ color: #666; font-size: 12px; text-align: center; margin-top: 30px; }}
                </style>
            </head>
            <body>
                <div class="container">
                    <h1 class="header">🚀 Willkommen bei NoahsKI!</h1>
                    <p>Danke für deine Registrierung. Hier ist dein Verifizierungscode:</p>
                    
                    <div class="code">{code}</div>
                    
                    <p>Dieser Code ist <strong>15 Minuten</strong> gültig.</p>
                    
                    <p><strong>⚠️ Wichtig:</strong> Falls du diese Email nicht angefordert hast, ignoriere sie einfach.</p>
                    
                    <div class="footer">
                        <p>© 2026 NoahsKI - Dein KI-Assistent</p>
                        <p>Diese Email wurde automatisch generiert.</p>
                    </div>
                </div>
            </body>
            </html>
            """
            
            plain_body = f"""
            🚀 Willkommen bei NoahsKI!
            
            Danke für deine Registrierung. Hier ist dein Verifizierungscode:
            
            {code}
            
            Dieser Code ist 15 Minuten gültig.
            
            ⚠️ Falls du diese Email nicht angefordert hast, ignoriere sie einfach.
            
            © 2026 NoahsKI
            """
            
            return self._send_email(to_email, subject, html_body, plain_body)
        
        except Exception as e:
            logger.error(f"Failed to send verification email: {e}")
            return False
    
    def send_welcome_email(self, to_email: str, username: str = None) -> bool:
        """Send welcome email after successful verification"""
        try:
            subject = "🎉 Account erfolgreich verifiziert!"
            name = username or to_email.split('@')[0]
            
            html_body = f"""
            <!DOCTYPE html>
            <html>
            <head>
                <style>
                    body {{ font-family: Arial, sans-serif; background-color: #f4f4f4; padding: 20px; }}
                    .container {{ background-color: white; padding: 30px; border-radius: 10px; max-width: 600px; margin: 0 auto; }}
                    .header {{ color: #4CAF50; text-align: center; }}
                    .feature {{ padding: 10px 0; }}
                    .footer {{ color: #666; font-size: 12px; text-align: center; margin-top: 30px; }}
                </style>
            </head>
            <body>
                <div class="container">
                    <h1 class="header">🎉 Willkommen bei NoahsKI, {name}!</h1>
                    
                    <p>Dein Account wurde erfolgreich verifiziert und ist jetzt aktiv!</p>
                    
                    <h3>Was du jetzt tun kannst:</h3>
                    <div class="feature">✅ Mit NoahsKI chatten</div>
                    <div class="feature">🎨 Bilder generieren</div>
                    <div class="feature">🌐 Web-Recherche nutzen</div>
                    <div class="feature">📚 Autonomes Learning System</div>
                    <div class="feature">💡 Code-Generierung</div>
                    
                    <p style="margin-top: 30px;">Viel Spaß mit NoahsKI!</p>
                    
                    <div class="footer">
                        <p>© 2026 NoahsKI - Dein KI-Assistent</p>
                    </div>
                </div>
            </body>
            </html>
            """
            
            plain_body = f"""
            🎉 Willkommen bei NoahsKI, {name}!
            
            Dein Account wurde erfolgreich verifiziert und ist jetzt aktiv!
            
            Was du jetzt tun kannst:
            ✅ Mit NoahsKI chatten
            🎨 Bilder generieren
            🌐 Web-Recherche nutzen
            📚 Autonomes Learning System
            💡 Code-Generierung
            
            Viel Spaß mit NoahsKI!
            
            © 2026 NoahsKI
            """
            
            return self._send_email(to_email, subject, html_body, plain_body)
        
        except Exception as e:
            logger.error(f"Failed to send welcome email: {e}")
            return False
    
    def _send_email(self, to_email: str, subject: str, html_body: str, plain_body: str) -> bool:
        """Internal method to send email via SMTP"""
        try:
            # Create message
            msg = MIMEMultipart('alternative')
            msg['Subject'] = subject
            msg['From'] = f"{self.from_name} <{self.from_email}>"
            msg['To'] = to_email
            
            # Attach both plain and HTML versions
            part1 = MIMEText(plain_body, 'plain', 'utf-8')
            part2 = MIMEText(html_body, 'html', 'utf-8')
            msg.attach(part1)
            msg.attach(part2)
            
            # Send email
            with smtplib.SMTP(self.smtp_server, self.smtp_port) as server:
                server.starttls()
                server.login(self.smtp_user, self.smtp_password)
                server.send_message(msg)
            
            logger.info(f"✓ Email sent to {to_email}")
            return True
        
        except Exception as e:
            logger.error(f"SMTP error: {e}")
            return False


# ═══════════════════════════════════════════════════════════════════════════════
# AUTH PLUGIN MAIN CLASS
# ═══════════════════════════════════════════════════════════════════════════════

class AuthPlugin:
    """Main authentication plugin"""
    
    def __init__(self):
        logger.info("🔐 Initializing Authentication Plugin...")
        
        # Create directories
        AuthConfig.DATA_DIR.mkdir(parents=True, exist_ok=True)
        
        # Initialize services
        self.email_service = EmailService()
        
        # Load data
        self.users: Dict[str, User] = self._load_users()
        self.sessions: Dict[str, Session] = self._load_sessions()
        self.verifications: Dict[str, VerificationCode] = self._load_verifications()
        
        logger.info(f"✅ Auth Plugin initialized ({len(self.users)} users)")
    
    # ─────────────────────────────────────────────────────────────────────────
    # DATA PERSISTENCE
    # ─────────────────────────────────────────────────────────────────────────
    
    def _load_users(self) -> Dict[str, User]:
        """Load users from JSON"""
        try:
            if AuthConfig.USERS_FILE.exists():
                with open(AuthConfig.USERS_FILE, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                return {email: User.from_dict(u) for email, u in data.items()}
        except Exception as e:
            logger.error(f"Failed to load users: {e}")
        return {}
    
    def _save_users(self):
        """Save users to JSON"""
        try:
            # Ensure directory exists
            AuthConfig.DATA_DIR.mkdir(parents=True, exist_ok=True)
            data = {email: u.to_dict() for email, u in self.users.items()}
            with open(AuthConfig.USERS_FILE, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=2, ensure_ascii=False)
        except Exception as e:
            logger.warning(f"⚠️  Failed to save users: {e}")
    
    def _load_sessions(self) -> Dict[str, Session]:
        """Load sessions from JSON"""
        try:
            if AuthConfig.SESSIONS_FILE.exists():
                with open(AuthConfig.SESSIONS_FILE, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                sessions = {token: Session.from_dict(s) for token, s in data.items()}
                # Clean expired sessions
                return {t: s for t, s in sessions.items() if s.is_valid()}
        except Exception as e:
            logger.error(f"Failed to load sessions: {e}")
        return {}
    
    def _save_sessions(self):
        """Save sessions to JSON"""
        try:
            # Ensure directory exists
            AuthConfig.DATA_DIR.mkdir(parents=True, exist_ok=True)
            # Only save valid sessions
            valid_sessions = {t: s for t, s in self.sessions.items() if s.is_valid()}
            data = {token: s.to_dict() for token, s in valid_sessions.items()}
            with open(AuthConfig.SESSIONS_FILE, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=2, ensure_ascii=False)
        except Exception as e:
            logger.warning(f"⚠️  Failed to save sessions: {e}")
    
    def _load_verifications(self) -> Dict[str, VerificationCode]:
        """Load verification codes from JSON"""
        try:
            if AuthConfig.VERIFICATION_FILE.exists():
                with open(AuthConfig.VERIFICATION_FILE, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                codes = {email: VerificationCode.from_dict(v) for email, v in data.items()}
                # Clean expired codes
                return {e: v for e, v in codes.items() if v.is_valid()}
        except Exception as e:
            logger.error(f"Failed to load verifications: {e}")
        return {}
    
    def _save_verifications(self):
        """Save verification codes to JSON"""
        try:
            # Ensure directory exists
            AuthConfig.DATA_DIR.mkdir(parents=True, exist_ok=True)
            # Only save valid codes
            valid_codes = {e: v for e, v in self.verifications.items() if v.is_valid()}
            data = {email: v.to_dict() for email, v in valid_codes.items()}
            with open(AuthConfig.VERIFICATION_FILE, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=2, ensure_ascii=False)
        except Exception as e:
            logger.warning(f"⚠️  Failed to save verifications: {e}")
    
    # ─────────────────────────────────────────────────────────────────────────
    # PASSWORD HASHING
    # ─────────────────────────────────────────────────────────────────────────
    
    def _hash_password(self, password: str) -> str:
        """Hash password with salt"""
        salt = secrets.token_hex(16)
        pwd_hash = hashlib.pbkdf2_hmac('sha256', password.encode(), salt.encode(), 100000)
        return f"{salt}${pwd_hash.hex()}"
    
    def _verify_password(self, password: str, password_hash: str) -> bool:
        """Verify password against hash"""
        try:
            salt, pwd_hash = password_hash.split('$')
            computed_hash = hashlib.pbkdf2_hmac('sha256', password.encode(), salt.encode(), 100000)
            return computed_hash.hex() == pwd_hash
        except:
            return False
    
    # ─────────────────────────────────────────────────────────────────────────
    # VERIFICATION CODE GENERATION
    # ─────────────────────────────────────────────────────────────────────────
    
    def _generate_verification_code(self) -> str:
        """Generate 6-digit verification code"""
        return ''.join([str(secrets.randbelow(10)) for _ in range(AuthConfig.VERIFICATION_CODE_LENGTH)])
    
    # ─────────────────────────────────────────────────────────────────────────
    # PUBLIC API METHODS
    # ─────────────────────────────────────────────────────────────────────────
    
    def register(self, email: str, password: str, username: str = None) -> Tuple[bool, str]:
        """
        Register new user and send verification email
        
        Returns: (success, message)
        """
        try:
            # Validate email format
            if '@' not in email or '.' not in email.split('@')[1]:
                return False, "Ungültige Email-Adresse"
            
            # Check if user exists
            if email in self.users:
                return False, "Email bereits registriert"
            
            # Validate password
            if len(password) < 8:
                return False, "Passwort muss mindestens 8 Zeichen lang sein"
            
            # Create user (unverified)
            user = User(
                email=email,
                password_hash=self._hash_password(password),
                created_at=time.time(),
                verified=False,
                username=username
            )
            
            self.users[email] = user
            self._save_users()
            
            # Generate verification code
            code = self._generate_verification_code()
            expires_at = time.time() + (AuthConfig.VERIFICATION_EXPIRY_MINUTES * 60)
            
            verification = VerificationCode(
                email=email,
                code=code,
                created_at=time.time(),
                expires_at=expires_at
            )
            
            self.verifications[email] = verification
            self._save_verifications()
            
            # Send verification email
            email_sent = self.email_service.send_verification_email(email, code)
            
            if email_sent:
                logger.info(f"✓ User registered: {email}")
                return True, f"Registrierung erfolgreich! Verifizierungscode wurde an {email} gesendet."
            else:
                return True, "Registrierung erfolgreich, aber Email konnte nicht gesendet werden. Bitte kontaktiere den Support."
        
        except Exception as e:
            logger.error(f"Registration error: {e}")
            return False, f"Fehler bei der Registrierung: {str(e)}"
    
    def verify_email(self, email: str, code: str) -> Tuple[bool, str]:
        """
        Verify email with code
        
        Returns: (success, message)
        """
        try:
            # Check if verification exists
            if email not in self.verifications:
                return False, "Kein Verifizierungscode gefunden"
            
            verification = self.verifications[email]
            
            # Check if expired
            if not verification.is_valid():
                return False, "Verifizierungscode abgelaufen oder zu viele Versuche"
            
            # Increment attempts
            verification.attempts += 1
            self._save_verifications()
            
            # Check code
            if verification.code != code:
                return False, f"Falscher Code (Versuch {verification.attempts}/3)"
            
            # Mark user as verified
            if email in self.users:
                self.users[email].verified = True
                self._save_users()
                
                # Remove verification code
                del self.verifications[email]
                self._save_verifications()
                
                # Send welcome email
                self.email_service.send_welcome_email(email, self.users[email].username)
                
                logger.info(f"✓ Email verified: {email}")
                return True, "Email erfolgreich verifiziert! Du kannst dich jetzt anmelden."
            else:
                return False, "User nicht gefunden"
        
        except Exception as e:
            logger.error(f"Verification error: {e}")
            return False, f"Fehler bei der Verifizierung: {str(e)}"
    
    def resend_verification(self, email: str) -> Tuple[bool, str]:
        """Resend verification code"""
        try:
            if email not in self.users:
                return False, "Email nicht registriert"
            
            if self.users[email].verified:
                return False, "Email bereits verifiziert"
            
            # Generate new code
            code = self._generate_verification_code()
            expires_at = time.time() + (AuthConfig.VERIFICATION_EXPIRY_MINUTES * 60)
            
            verification = VerificationCode(
                email=email,
                code=code,
                created_at=time.time(),
                expires_at=expires_at
            )
            
            self.verifications[email] = verification
            self._save_verifications()
            
            # Send email
            email_sent = self.email_service.send_verification_email(email, code)
            
            if email_sent:
                return True, "Neuer Verifizierungscode wurde gesendet"
            else:
                return False, "Email konnte nicht gesendet werden"
        
        except Exception as e:
            logger.error(f"Resend error: {e}")
            return False, f"Fehler: {str(e)}"
    
    def login(self, email: str, password: str, ip_address: str = None, user_agent: str = None) -> Tuple[bool, str, Optional[str]]:
        """
        Login user
        
        Returns: (success, message, token)
        """
        try:
            # Check if user exists
            if email not in self.users:
                return False, "Email oder Passwort falsch", None
            
            user = self.users[email]
            
            # Check if account is locked
            if user.locked_until and time.time() < user.locked_until:
                remaining = int((user.locked_until - time.time()) / 60)
                return False, f"Account gesperrt. Versuche es in {remaining} Minuten erneut.", None
            
            # Check if verified
            if not user.verified:
                return False, "Email noch nicht verifiziert", None
            
            # Verify password
            if not self._verify_password(password, user.password_hash):
                user.login_attempts += 1
                
                # Lock account after max attempts
                if user.login_attempts >= AuthConfig.MAX_LOGIN_ATTEMPTS:
                    user.locked_until = time.time() + (AuthConfig.LOCKOUT_DURATION_MINUTES * 60)
                    self._save_users()
                    return False, f"Zu viele fehlgeschlagene Versuche. Account für {AuthConfig.LOCKOUT_DURATION_MINUTES} Minuten gesperrt.", None
                
                self._save_users()
                remaining = AuthConfig.MAX_LOGIN_ATTEMPTS - user.login_attempts
                return False, f"Email oder Passwort falsch ({remaining} Versuche übrig)", None
            
            # Reset login attempts on successful login
            user.login_attempts = 0
            user.last_login = time.time()
            user.locked_until = None
            self._save_users()
            
            # Create session
            token = secrets.token_urlsafe(AuthConfig.TOKEN_LENGTH)
            expires_at = time.time() + (AuthConfig.SESSION_EXPIRY_HOURS * 3600)
            
            session = Session(
                token=token,
                email=email,
                created_at=time.time(),
                expires_at=expires_at,
                ip_address=ip_address,
                user_agent=user_agent
            )
            
            self.sessions[token] = session
            self._save_sessions()
            
            logger.info(f"✓ User logged in: {email}")
            return True, "Login erfolgreich", token
        
        except Exception as e:
            logger.error(f"Login error: {e}")
            return False, f"Fehler beim Login: {str(e)}", None
    
    def logout(self, token: str) -> Tuple[bool, str]:
        """Logout user"""
        try:
            if token in self.sessions:
                email = self.sessions[token].email
                del self.sessions[token]
                self._save_sessions()
                logger.info(f"✓ User logged out: {email}")
                return True, "Logout erfolgreich"
            else:
                return False, "Session nicht gefunden"
        except Exception as e:
            logger.error(f"Logout error: {e}")
            return False, f"Fehler beim Logout: {str(e)}"
    
    def validate_token(self, token: str) -> Tuple[bool, Optional[str]]:
        """
        Validate session token
        
        Returns: (valid, email)
        """
        if token in self.sessions:
            session = self.sessions[token]
            if session.is_valid():
                return True, session.email
            else:
                # Clean up expired session
                del self.sessions[token]
                self._save_sessions()
        
        return False, None
    
    def get_user_info(self, email: str) -> Optional[Dict]:
        """Get user information (without sensitive data)"""
        if email in self.users:
            user = self.users[email]
            return {
                'email': user.email,
                'username': user.username,
                'created_at': user.created_at,
                'verified': user.verified,
                'last_login': user.last_login
            }
        return None
    
    def get_stats(self) -> Dict:
        """Get authentication statistics"""
        return {
            'total_users': len(self.users),
            'verified_users': sum(1 for u in self.users.values() if u.verified),
            'active_sessions': len([s for s in self.sessions.values() if s.is_valid()]),
            'pending_verifications': len([v for v in self.verifications.values() if v.is_valid()])
        }


# ═══════════════════════════════════════════════════════════════════════════════
# PLUGIN METADATA
# ═══════════════════════════════════════════════════════════════════════════════

PLUGIN_INFO = {
    'name': 'auth_plugin',
    'version': '1.0.0',
    'author': 'NoahsKI Team',
    'description': 'Email-based authentication with verification',
    'endpoints': [
        '/auth/register',
        '/auth/verify',
        '/auth/resend',
        '/auth/login',
        '/auth/logout',
        '/auth/validate',
        '/auth/user',
        '/auth/stats'
    ]
}

__all__ = ['AuthPlugin', 'AuthConfig', 'PLUGIN_INFO']