import dataclasses
import datetime
import logging
from collections.abc import Iterator, Mapping

import requests

# Import the base Scraper class; adjust the import if your code structure differs.
from personal_data.data import Scraper

logger = logging.getLogger(__name__)


@dataclasses.dataclass(frozen=True)
class WaniKaniLessonsFetcher(Scraper):
    api_token: str

    @staticmethod
    def dataset_name() -> str:
        return 'wanikani_lessons'

    def scrape(self) -> Iterator[Mapping[str, object]]:
        """
        Fetch assignments from the WaniKani API and yield a dict for each assignment
        with a non-null unlocked_at timestamp.
        """
        url = 'https://api.wanikani.com/v2/assignments'
        headers = {
            'Authorization': f'Bearer {self.api_token}',
            'Wanikani-Revision': '20170710',
        }
        response = requests.get(url, headers=headers)
        if response.status_code != 200:
            logger.error('Error retrieving assignments: %s', response.text)
            return
        data = response.json()
        # Check that 'data' key exists in the JSON response.
        assignments = data.get('data', [])
        for assignment in assignments:
            assignment_data = assignment.get('data', {})
            # Only yield if unlocked_at is available.
            unlocked_at = assignment_data.get('unlocked_at')
            if unlocked_at:
                # Convert unlocked_at ISO8601 string (assume 'Z' for UTC) to a datetime object.
                try:
                    dt = datetime.datetime.fromisoformat(
                        unlocked_at.replace('Z', '+00:00'),
                    )
                except Exception as e:
                    logger.error("Error parsing unlocked_at '%s': %s", unlocked_at, e)
                    continue
                yield {
                    'subject_id': assignment_data.get('subject_id'),
                    'unlocked_at': dt,
                }