from __future__ import annotations

import os
from collections.abc import Mapping
from dataclasses import dataclass

DEFAULT_HISTORY_SIZE = 10

ENABLED_ENV = "WORLD_RUNTIME_ENABLED"
HISTORY_SIZE_ENV = "WORLD_HISTORY_SIZE"


@dataclass(frozen=True)
class WorldConfig:
    enabled: bool = True
    history_size: int = DEFAULT_HISTORY_SIZE


def load_config(env: Mapping[str, str] | None = None) -> WorldConfig:
    values = env or os.environ
    return WorldConfig(
        enabled=_parse_bool(values.get(ENABLED_ENV), default=True),
        history_size=_parse_history_size(values.get(HISTORY_SIZE_ENV)),
    )


def _parse_bool(value: str | None, *, default: bool) -> bool:
    if value is None:
        return default
    return value.strip().lower() in {"1", "true", "yes", "on", "enabled"}


def _parse_history_size(value: str | None) -> int:
    if value is None:
        return DEFAULT_HISTORY_SIZE
    try:
        size = int(value)
    except ValueError:
        return DEFAULT_HISTORY_SIZE
    return size if size > 0 else DEFAULT_HISTORY_SIZE