import bcrypt
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, DateTime, Boolean, Numeric
from sqlalchemy.orm import relationship, backref
from sqlalchemy.schema import CreateColumn
from sqlalchemy.sql import expression
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.types import DateTime as DateTimeType

BCRYPT_LOG_ROUNDS = 11


# can be moved to models util?
class utcnow(expression.FunctionElement):
    type = DateTimeType()


# Can be moved to the models util?
@compiles(utcnow, 'postgresql')
def pg_utcnow(element, compiler, **kw):
    return "TIMEZONE('utc', CURRENT_TIMESTAMP)"


@compiles(CreateColumn, 'postgresql')
def use_identity(element, compiler, **kw):
    text = compiler.visit_create_column(element, **kw)
    text = text.replace("SERIAL", "INT GENERATED BY DEFAULT AS IDENTITY")
    return text


Base = declarative_base()


class DBMixin:
    id = Column(Integer, primary_key=True, autoincrement=True)
    created_date = Column(DateTime(timezone=True), server_default=utcnow())
    modified_date = Column(DateTime(timezone=True), server_default=utcnow(), onupdate=utcnow())

    def to_dict(self):
        d = self.__dict__.copy()
        if '_sa_instance_state' in d:
            d.pop('_sa_instance_state')
        return d


def ReferenceCol(tablename, nullable=False, **kw):
    return Column(ForeignKey('{}.id'.format(tablename)), nullable=nullable, **kw)


class Cookie(Base, DBMixin):
    __tablename__ = 'cookies'

    name = Column(String(50), index=True)
    recipe_url = Column(String(255))
    sku = Column(String(55))
    qoh = Column(Integer)
    unit_cost = Column(Numeric(12, 2))


class User(DBMixin, Base):
    __tablename__ = 'users'

    email = Column(String(255), nullable=False, unique=True)
    password = Column(String(255))
    admin = Column(Boolean, nullable=False, default=False)
    confirmed = Column(Boolean, nullable=False, default=False)
    active = Column(Boolean, nullable=False, default=True)

    def __init__(self, email, password, admin=False):
        self.email = email
        self.password = bcrypt.hashpw(password.encode('utf-8'), bcrypt.gensalt(BCRYPT_LOG_ROUNDS)).decode()
        self.admin = admin

    def check_password(self, password):
        return bcrypt.checkpw(password.encode('utf-8'), self.password.encode('utf-8'))

    def to_dict(self):
        d = self.__dict__.copy()
        if '_sa_instance_state' in d:
            d.pop('_sa_instance_state')
            d.pop('password')
        return d


class Order(DBMixin, Base):
    __tablename__ = 'orders'

    user_id = ReferenceCol('users')
    shipped = Column(Boolean, default=False)

    user = relationship('User', backref=backref('orders'))


class LineItem(DBMixin, Base):
    __tablename__ = 'line_items'

    order_id = ReferenceCol('orders')
    cookie_id = ReferenceCol('cookies')
    quantity = Column(Integer)
    extended_cost = Column(Numeric(12, 2))

    order = relationship('Order', backref=backref('line_items'))
    cookie = relationship('Cookie', uselist=False)