import datetime
import logging
import requests
import dataclasses
from typing import Iterator, Mapping
# 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
                }