from sqlalchemy import Table, Column, Integer, String, MetaData, ForeignKey, create_engine, DateTime, Boolean, or_
from sqlalchemy.orm import sessionmaker, relationship, backref
from sqlalchemy.ext.declarative import declarative_base
from math import ceil
import datetime
import conf

engine = create_engine(conf.db_url)
Base = declarative_base()
Session = sessionmaker(bind=engine)

class User(Base):
    __tablename__ = 'users'
    name = Column(String(10), primary_key=True)
    card = Column(String(10))
    rfid = Column(String(10))
    credit = Column(Integer)

    name_re = r"[a-z]+"
    card_re = r"(([Nn][Tt][Nn][Uu])?[0-9]+)?"
    rfid_re = r"[0-9]*"

    def __init__(self, name, card, rfid, credit=0):
        self.name = name
        if card == '':
            card = None
        self.card = card
        if rfid == '':
            rfid = None
        self.rfid = rfid
        self.credit = credit

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

    def __str__(self):
        return self.name

    def is_anonymous(self):
        return self.card == '11122233'

class Product(Base):
    __tablename__ = 'products'

    bar_code = Column(String(13), primary_key=True)
    name = Column(String(45))
    price = Column(Integer)
    stock = Column(Integer)

    bar_code_re = r"[0-9]+"
    name_re = r".+"
    name_length = 45

    def __init__(self, bar_code, name, price, stock=0):
        self.name = name
        self.bar_code = bar_code
        self.price = price
        self.stock = stock

    def __repr__(self):
        return "<Product('%s', '%s', '%s', '%s')>" % (self.name, self.bar_code, self.price, self.stock)

    def __str__(self):
        return self.name

class PurchaseEntry(Base):
    __tablename__ = 'purchase_entries'
    id = Column(Integer, primary_key=True)
    purchase_id = Column(Integer,ForeignKey("purchases.id"))
    product_bar_code = Column(String(13),ForeignKey("products.bar_code"))
    amount = Column(Integer)

    product = relationship(Product,backref="purchases")

    def __init__(self, purchase, product, amount):
        self.product = product
        self.product_bar_code = product.bar_code
        self.purchase = purchase
        self.amount = amount
    def __repr__(self):
        return "<PurchaseEntry('%s', '%s')>" % (self.product.name, self.amount )


class Transaction(Base):
    __tablename__ = 'transactions'

    id = Column(Integer, primary_key=True)
    time = Column(DateTime)
    user_name = Column(String(10), ForeignKey('users.name'))
    amount = Column(Integer)
    description = Column(String(50))
    purchase_id = Column(Integer, ForeignKey('purchases.id'))
    #penalty = Column(Integer)

    user = relationship(User, backref=backref('transactions', order_by=time))

    def __init__(self, user, amount=0, description=None, purchase=None, penalty_ratio=1):
        self.user = user
        self.amount = amount
        self.description = description
        self.purchase = purchase
        self.penalty = penalty_ratio

    def perform_transaction(self):
        self.time = datetime.datetime.now()
        self.amount *= self.penalty
        self.user.credit -= self.amount
        if self.purchase:
            for entry in self.purchase.entries:
                entry.product.stock -= entry.amount


class Purchase(Base):
    __tablename__ = 'purchases'

    id = Column(Integer, primary_key=True)
    time = Column(DateTime)
    #	user_name = Column(Integer, ForeignKey('users.name'))
    price = Column(Integer)
    #	performed = Column(Boolean)

    #	user = relationship(User, backref=backref('purchases', order_by=id))
    #	users = relationship(User, secondary=purchase_user, backref='purhcases'
    transactions = relationship(Transaction, order_by=Transaction.user_name, backref='purchase')
    entries = relationship(PurchaseEntry, backref=backref("purchase"))

    def __init__(self):
        pass

    def __repr__(self):
        return "<Purchase(%d, %d, '%s')>" % (self.id, self.price, self.time.strftime('%c'))

    def is_complete(self):
        return len(self.transactions) > 0 and len(self.entries) > 0

    def price_per_transaction(self):
        return int(ceil(float(self.price)/len(self.transactions)))

    def set_price(self):
        self.price = 0
        for entry in self.entries:
            self.price += entry.amount*entry.product.price
        if len(self.transactions) > 0:
            for t in self.transactions:
                t.amount = self.price_per_transaction()

    def perform_purchase(self):
        self.time = datetime.datetime.now()
        self.set_price()
        for t in self.transactions:
            t.perform_transaction()
#		self.user.credit -= self.price
#		self.performed = True