"""Org/workspace credits for metered sandbox consumption."""

from __future__ import annotations

import json
import os
from pathlib import Path


def _default_credits_path() -> Path:
    base = Path(os.environ.get("XDG_DATA_HOME", Path.home() / ".local" / "share"))
    return base / "sandboxer" / "credits.json"


class CreditsStore:
    def __init__(self, path: Path | None = None) -> None:
        self.path = path or _default_credits_path()
        self.path.parent.mkdir(parents=True, exist_ok=True)

    def _read(self) -> dict:
        if not self.path.exists():
            default = float(os.environ.get("SANDBOXER_DEFAULT_CREDITS", "10.0"))
            return {"balance_usd": default, "currency": "USD"}
        return json.loads(self.path.read_text())

    def _write(self, data: dict) -> None:
        self.path.write_text(json.dumps(data, indent=2))

    def balance(self) -> float:
        return float(self._read().get("balance_usd", 0.0))

    def can_afford(self, amount_usd: float) -> bool:
        return self.balance() >= amount_usd

    def add(self, amount_usd: float) -> float:
        data = self._read()
        data["balance_usd"] = round(float(data.get("balance_usd", 0.0)) + amount_usd, 4)
        self._write(data)
        return data["balance_usd"]

    def debit(self, amount_usd: float) -> float:
        data = self._read()
        new_balance = round(float(data.get("balance_usd", 0.0)) - amount_usd, 4)
        if new_balance < 0:
            raise ValueError(f"Insufficient credits: need {amount_usd:.4f} USD")
        data["balance_usd"] = new_balance
        self._write(data)
        return new_balance