from __future__ import annotations

import json
from dataclasses import asdict, dataclass, field
from pathlib import Path


@dataclass(slots=True)
class OpenLaneCheckpoint:
    max_pages: int
    completed_pages: list[int] = field(default_factory=list)
    failed_pages: list[int] = field(default_factory=list)
    total_records: int = 0
    last_saved_at: str | None = None

    @property
    def completed_set(self) -> set[int]:
        return set(self.completed_pages)


class OpenLaneCheckpointStore:
    def __init__(self, path: str | Path) -> None:
        self.path = Path(path)

    def load(self, max_pages: int) -> OpenLaneCheckpoint:
        if not self.path.exists():
            return OpenLaneCheckpoint(max_pages=max_pages)
        data = json.loads(self.path.read_text(encoding="utf-8"))
        return OpenLaneCheckpoint(
            max_pages=int(data.get("max_pages") or max_pages),
            completed_pages=sorted({int(page) for page in data.get("completed_pages", [])}),
            failed_pages=sorted({int(page) for page in data.get("failed_pages", [])}),
            total_records=int(data.get("total_records") or 0),
            last_saved_at=data.get("last_saved_at"),
        )

    def save(self, checkpoint: OpenLaneCheckpoint) -> None:
        self.path.parent.mkdir(parents=True, exist_ok=True)
        payload = asdict(checkpoint)
        self.path.write_text(
            json.dumps(payload, ensure_ascii=False, indent=2, sort_keys=True),
            encoding="utf-8",
        )