from sqlalchemy import Column, Integer, String
from sqlalchemy import create_engine, ForeignKey
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base

import json

Base = declarative_base()

class Shipment(Base):
    __tablename__ = 'shipments'

    id = Column(Integer, primary_key=True)
    tracking_number = Column(String)
    carrier = Column(String)
    description = Column(String)

    events = relationship("Event")

class Event(Base):
    __tablename__ = 'events'

    id = Column(Integer, primary_key=True)
    shipment_id = Column(Integer, ForeignKey('shipments.id'))
    event_time = Column(String)
    event_description = Column(String)
    raw_event = Column(String)

class Database:
    def __init__(self, database_uri):
        self.engine = create_engine(database_uri)
        Session = sessionmaker(bind=self.engine)
        self.session = Session()

    def create_shipment(self, tracking_number, carrier, description=""):
        new_shipment = Shipment(tracking_number=tracking_number, carrier=carrier, description=description)
        self.session.add(new_shipment)
        self.session.commit()

    def get_shipment(self, tracking_number):
        shipment = self.session.query(Shipment).filter(Shipment.tracking_number == tracking_number).first()
        return shipment

    def get_shipments(self):
        shipments = self.session.query(Shipment).all()
        return shipments

    def create_event(self, shipment_id, event_time, event_description, raw_event):
        if isinstance(raw_event, dict):
            raw_event = json.dumps(raw_event)

        new_event = Event(shipment_id=shipment_id, event_time=event_time, event_description=event_description, raw_event=raw_event)
        self.write_event(new_event)

    def write_event(self, event):
        self.session.add(event)
        self.session.commit()

    def get_shipment_events(self, shipment_id):
        shipment = self.session.query(Shipment).filter(Shipment.id == shipment_id).first()
        return shipment.events if shipment else None

    def get_latest_event(self, shipment_id):
        event = self.session.query(Event).filter(Event.shipment_id == shipment_id).order_by(Event.event_time.desc()).first()
        return event

    def initialize_db(self):
        Base.metadata.create_all(self.engine)