from __future__ import annotations

import json
from datetime import datetime, timezone
from pathlib import Path
from typing import Any

STATE_FILENAME = ".copienator-gui.json"


class StateStore:
    def __init__(self) -> None:
        self.evaluation: Path | None = None
        self.data: dict[str, Any] = self._empty_data()

    @staticmethod
    def _empty_data() -> dict[str, Any]:
        return {"version": 1, "steps": {}, "history": []}

    def load(self, evaluation: Path) -> None:
        self.evaluation = evaluation
        path = evaluation / STATE_FILENAME
        try:
            loaded = json.loads(path.read_text(encoding="utf-8"))
            self.data = loaded if isinstance(loaded, dict) else self._empty_data()
        except (OSError, json.JSONDecodeError):
            self.data = self._empty_data()
        self.data.setdefault("version", 1)
        self.data.setdefault("steps", {})
        self.data.setdefault("history", [])

    def save(self) -> None:
        if not self.evaluation:
            return
        path = self.evaluation / STATE_FILENAME
        temporary = path.with_suffix(path.suffix + ".tmp")
        temporary.write_text(
            json.dumps(self.data, indent=2, ensure_ascii=False), encoding="utf-8"
        )
        temporary.replace(path)

    def step(self, step_id: str) -> dict[str, Any]:
        return self.data["steps"].setdefault(step_id, {})

    def update_step(self, step_id: str, **changes: Any) -> None:
        entry = self.step(step_id)
        entry.update(changes)
        entry["updated_at"] = datetime.now(timezone.utc).isoformat()
        self.save()

    def add_history(self, entry: dict[str, Any]) -> None:
        entry = dict(entry)
        entry["timestamp"] = datetime.now(timezone.utc).isoformat()
        self.data["history"].append(entry)
        self.data["history"] = self.data["history"][-200:]
        self.save()

    def invalidate_after(self, ordered_ids: list[str], current_id: str) -> None:
        try:
            index = ordered_ids.index(current_id)
        except ValueError:
            return
        for step_id in ordered_ids[index + 1 :]:
            entry = self.step(step_id)
            if entry.get("status") in {"success", "detected", "skipped"}:
                entry["status"] = "stale"
        self.save()