from flask import current_app
from flask_login import UserMixin
from itsdangerous import TimedJSONWebSignatureSerializer as Serializer
from itsdangerous import BadSignature, SignatureExpired
from werkzeug.security import check_password_hash, generate_password_hash

from .. import db, login_manager


class Role(db.Model):
    __tablename__ = 'roles'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String, unique=True)
    users = db.relationship('User', backref='role', lazy='dynamic')

class User(UserMixin, db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    confirmed = db.Column(db.Boolean, default=False)
    name = db.Column(db.String(64), unique=True, index=True)
    email = db.Column(db.String(64), unique=True, index=True)
    password_hash = db.Column(db.String(128))
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))

    @property
    def password(self):
        raise AttributeError('`password` is not a readable attribute')

    @password.setter
    def password(self, password):
        self.password_hash = generate_password_hash(password)

    def verify_password(self, password):
        return check_password_hash(self.password_hash, password)

    def generate_confirmation_token(self, expiration=604800):
        """Generate a confirmation token to email a new user."""

        s = Serializer(current_app.config['SECRET_KEY'], expiration)
        return s.dumps({'confirm': self.id})

    def generate_email_change_token(self, new_email, expiration=3600):
        """Generate an email change token to email an existing user."""
        s = Serializer(current_app.config['SECRET_KEY'], expiration)
        return s.dumps({'change_email': self.id, 'new_email': new_email})

    def generate_password_reset_token(self, expiration=3600):
        """
        Generate a password reset change token to email to an existing user.
        """
        s = Serializer(current_app.config['SECRET_KEY'], expiration)
        return s.dumps({'reset': self.id})

    def confirm_account(self, token):
        """Verify that the provided token is for this user's id."""
        s = Serializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token)
        except (BadSignature, SignatureExpired):
            return False
        if data.get('confirm') != self.id:
            return False
        self.confirmed = True
        db.session.add(self)
        db.session.commit()
        return True

    def change_email(self, token):
        """Verify the new email for this user."""
        s = Serializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token)
        except (BadSignature, SignatureExpired):
            return False
        if data.get('change_email') != self.id:
            return False
        new_email = data.get('new_email')
        if new_email is None:
            return False
        if self.query.filter_by(email=new_email).first() is not None:
            return False
        self.email = new_email
        db.session.add(self)
        db.session.commit()
        return True

    def reset_password(self, token, new_password):
        """Verify the new password for this user."""
        s = Serializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token)
        except (BadSignature, SignatureExpired):
            return False
        if data.get('reset') != self.id:
            return False
        self.password = new_password
        db.session.add(self)
        db.session.commit()
        return True

    def __repr__(self):
        return '<User \'%s\'>' % self.name

@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))
