from datetime import datetime, timezone
from flask_login import UserMixin
from argon2 import PasswordHasher
from argon2.exceptions import VerifyMismatchError, VerificationError, InvalidHashError
from sqlalchemy.dialects.mysql import INTEGER

from app import db


class User(db.Model, UserMixin):
    __tablename__ = 'users'

    id = db.Column(INTEGER(unsigned=True), autoincrement=True, primary_key=True)
    email = db.Column(db.String(255), unique=True, nullable=False, index=True)
    # master_hash: Argon2id hash of the client-derived PBKDF2 auth_hash
    # The raw master password is NEVER sent to or stored on the server.
    master_hash = db.Column(db.String(255), nullable=False)
    # enc_key_salt: random 16-byte salt (base64) generated at registration.
    # Returned to the client on login so it can re-derive the AES-256-GCM vault key.
    # The server never uses this for decryption — it is opaque to us.
    enc_key_salt = db.Column(db.String(64), nullable=False)
    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc).replace(tzinfo=None), nullable=False)
    last_login = db.Column(db.DateTime, nullable=True)
    # TOTP / MFA
    # totp_secret: AES-256-GCM ciphertext of the base32 TOTP secret, base64-encoded.
    # Encrypted server-side with the TOTP_ENCRYPTION_KEY from config.
    # totp_iv: base64-encoded 12-byte GCM nonce for the above.
    totp_secret = db.Column(db.String(255), nullable=True)
    totp_iv = db.Column(db.String(64), nullable=True)
    totp_enabled = db.Column(db.Boolean, default=False, nullable=False)
    # ECDH P-256 sharing keypair
    # Public key: raw uncompressed point (65 bytes), base64-encoded (~88 chars), stored plaintext
    sharing_public_key = db.Column(db.String(128), nullable=True)
    # Private key: JWK, AES-256-GCM encrypted with the user's vault key
    sharing_private_key_enc = db.Column(db.Text, nullable=True)
    sharing_private_key_iv = db.Column(db.String(64), nullable=True)
    # Account recovery — enc_key_salt re-encrypted with a client-derived recovery key.
    # NULL means the user has not set up a recovery code yet.
    # The server never sees the recovery code — only the ciphertext of enc_key_salt.
    recovery_enc_salt = db.Column(db.String(128), nullable=True)
    recovery_iv = db.Column(db.String(64), nullable=True)
    # Brute-force lockout — incremented on every failed login attempt,
    # reset to 0 on success.  locked_until is set to now()+15min after
    # MAX_FAILED_LOGINS consecutive failures.
    failed_login_count = db.Column(db.Integer, default=0, nullable=False, server_default='0')
    locked_until = db.Column(db.DateTime, nullable=True)
    # MFA backup codes — JSON array of Argon2id-hashed one-time codes.
    # Each code is consumed (removed from the array) on use.
    # NULL means no backup codes have been generated yet.
    mfa_backup_codes = db.Column(db.Text, nullable=True)

    folders = db.relationship('Folder', backref='owner', lazy='dynamic', cascade='all, delete-orphan')
    vault_items = db.relationship('VaultItem', backref='owner', lazy='dynamic', cascade='all, delete-orphan')

    def check_password(self, auth_hash: str) -> bool:
        ph = PasswordHasher()
        try:
            return ph.verify(self.master_hash, auth_hash)
        except (VerifyMismatchError, VerificationError, InvalidHashError):
            return False

    def __repr__(self):
        return f'<User {self.email}>'