from __future__ import annotations

import json
from pathlib import Path

from .models import AgentState


class StateStore:
    def __init__(self, state_file: str) -> None:
        self.path = Path(state_file)
        self.path.parent.mkdir(parents=True, exist_ok=True)

    def load(self, vehicle_id: str, vin: str, current_release: str) -> AgentState:
        if not self.path.exists() or self._is_empty_file():
            state = AgentState(vehicle_id=vehicle_id, vin=vin, current_release=current_release)
            self.save(state)
            return state

        try:
            raw = json.loads(self.path.read_text(encoding="utf-8"))
        except json.JSONDecodeError:
            state = AgentState(vehicle_id=vehicle_id, vin=vin, current_release=current_release)
            self.save(state)
            return state

        raw["vehicle_id"] = vehicle_id
        raw["vin"] = vin
        raw["current_release"] = current_release
        return AgentState(**raw)

    def save(self, state: AgentState) -> None:
        self.path.write_text(
            state.model_dump_json(indent=2),
            encoding="utf-8",
        )

    def _is_empty_file(self) -> bool:
        return self.path.stat().st_size == 0