"""Resolver di ambiente (testnet/mainnet) per MCP exchange.

Precedenza: env var > campo secret > default True (testnet).
"""
from __future__ import annotations

import os
from dataclasses import dataclass
from typing import Literal

Environment = Literal["testnet", "mainnet"]
Source = Literal["env", "credentials", "default"]

TRUTHY = {"1", "true", "yes", "on"}


@dataclass(frozen=True)
class EnvironmentInfo:
    exchange: str
    environment: Environment
    source: Source
    env_value: str | None
    base_url: str


def resolve_environment(
    creds: dict,
    *,
    env_var: str,
    flag_key: str,
    exchange: str,
    default_base_url_live: str | None = None,
    default_base_url_testnet: str | None = None,
) -> EnvironmentInfo:
    """Risolvi l'ambiente per un MCP exchange.

    creds: dict letto dal secret JSON. Può contenere base_url_live/base_url_testnet
        per override; in assenza vengono usati i default kwargs.
    env_var: nome della env var di override (es. DERIBIT_TESTNET).
    flag_key: chiave booleana nel secret JSON (es. "testnet" o "paper" per alpaca).
    exchange: nome exchange per logging/info.
    default_base_url_live / default_base_url_testnet: URL canonici dell'exchange,
        applicati se non presenti in creds.
    """
    env_value = os.environ.get(env_var)
    if env_value is not None:
        is_test = env_value.strip().lower() in TRUTHY
        environment: Environment = "testnet" if is_test else "mainnet"
        source: Source = "env"
    elif flag_key in creds:
        environment = "testnet" if bool(creds[flag_key]) else "mainnet"
        source = "credentials"
    else:
        environment = "testnet"
        source = "default"

    if default_base_url_live is not None:
        creds.setdefault("base_url_live", default_base_url_live)
    if default_base_url_testnet is not None:
        creds.setdefault("base_url_testnet", default_base_url_testnet)

    base_url = creds["base_url_testnet"] if environment == "testnet" else creds["base_url_live"]
    return EnvironmentInfo(
        exchange=exchange,
        environment=environment,
        source=source,
        env_value=env_value,
        base_url=base_url,
    )