data_loader.py

import json
from ride import Ride
from rider import Rider
from driver import Driver
from repositories import save_ride, save_rider, save_driver
from validators import validate_ride_record, validate_rider_record, validate_driver_record
from exceptions import DataLoadError, DataFormatError

def load_json(filename):
  try:
    with open(filename, "r", encoding="utf-8") as f:
      data = json.load(f)
  except FileNotFoundError as e:
    raise DataLoadError(f"File not found: {filename}") from e
  except UnicodeDecodeError as e:
    raise DataLoadError(f"Encoding error while reading {filename}") from e
  except json.JSONDecodeError as e:
    raise DataFormatError(
      f"Malformed JSON in {filename} (line {e.lineno}, col {e.colno})"
    ) from e
  except PermissionError as e:
    raise DataLoadError(f"Permission denied reading: {filename}") from e

  if not isinstance(data, list):
    raise DataFormatError(
      f"Top-level JSON in {filename} must be a list, got {type(data).__name__}"
    )

  return data

def load_rides_from_json(path="data/rides.json", riders_by_user_id=None, drivers_by_user_id=None):
    data = load_json(path)
    ride_ids = []

    if riders_by_user_id is None:
        riders_by_user_id = {}

    if drivers_by_user_id is None:
        drivers_by_user_id = {}

    for r in data:
        validate_ride_record(r)

        rider_user_id = r["rider_id"]
        driver_user_id = r.get("driver_id")

        if rider_user_id not in riders_by_user_id:
            raise ValueError(f"Unknown rider_id in rides.json: {rider_user_id}")

        if driver_user_id is not None and driver_user_id not in drivers_by_user_id:
            raise ValueError(f"Unknown driver_id in rides.json: {driver_user_id}")

        rider = riders_by_user_id[rider_user_id]
        driver = drivers_by_user_id[driver_user_id] if driver_user_id is not None else None

        ride = Ride(
            rider=rider,
            driver=driver,
            pickup_location=r["pickup_location_id"],
            dropoff_location=r["dropoff_location_id"]
        )

        ride.status = r.get("status", "requested")
        ride.fare = r.get("fare_amount")
        ride.requested_at = r.get("requested_at")

        rider_db_id = getattr(rider, "db_id", None)
        driver_db_id = getattr(driver, "db_id", None) if driver is not None else None

        if rider_db_id is None:
            raise ValueError(f"Rider {rider.name} is missing db_id. Save riders before loading rides.")

        if driver is not None and driver_db_id is None:
            raise ValueError(f"Driver {driver.name} is missing db_id. Save drivers before loading rides.")

        ride_db_id = save_ride(ride, rider_db_id, driver_db_id)
        ride_ids.append(ride_db_id)

    print(f"Loaded {len(ride_ids)} rides into DB")
    return ride_ids

def load_riders_from_json(path="data/riders.json"):
    data = load_json(path)

    ids = []
    riders_by_user_id = {}

    for r in data:
        validate_rider_record(r)

        rider = Rider(
            name=r["name"],
            user_id=r["user_id"],
            current_location=r.get("current_location_id", 0)
        )

        rider_db_id = save_rider(rider)
        rider.db_id = rider_db_id

        ids.append(rider_db_id)
        riders_by_user_id[r["user_id"]] = rider

    print(f"Loaded {len(ids)} riders into DB")
    return ids, riders_by_user_id

def load_drivers_from_json(path="data/drivers.json"):
    data = load_json(path)

    ids = []
    drivers_by_user_id = {}

    for d in data:
        validate_driver_record(d)

        driver = Driver(
            name=d["name"],
            user_id=d["user_id"],
            current_location=d.get("current_location_id", 0),
            language=d.get("language", "English")
        )
        driver.go_online()

        driver_db_id = save_driver(driver)
        driver.db_id = driver_db_id

        ids.append(driver_db_id)
        drivers_by_user_id[d["user_id"]] = driver

    print(f"Loaded {len(ids)} drivers into DB")
    return ids, drivers_by_user_id