import type { ConnectionConfig } from "./types.js";

export interface Configuration {
  connection: ConnectionConfig;
  environmentId?: string;
  idleMs: number;
}

export function configuration(flag: (name: string) => unknown, env: NodeJS.ProcessEnv = process.env): Configuration {
  const endpoint = String(flag("substrate-endpoint") ?? env.SUBSTRATE_ENDPOINT ?? "").trim();
  if (!endpoint) throw new Error("Set --substrate-endpoint or SUBSTRATE_ENDPOINT to a private ate-env-api endpoint. No local fallback is available.");
  const atespace = String(flag("substrate-atespace") ?? env.SUBSTRATE_ATESPACE ?? "ate-env");
  const environmentId = String(flag("substrate-env") ?? env.SUBSTRATE_ENV ?? "").trim() || undefined;
  const idle = Number(flag("substrate-idle-seconds") ?? env.SUBSTRATE_IDLE_SECONDS ?? 0);
  if (!Number.isFinite(idle) || idle < 0 || idle > 86_400) throw new Error("substrate-idle-seconds must be between 0 (disabled) and 86400.");
  validName(atespace, "atespace");
  if (environmentId) validName(environmentId, "environment ID");
  return {
    connection: { endpoint, atespace, token: env.SUBSTRATE_TOKEN, timeoutMs: 120_000, maxBytes: 1_048_576 },
    environmentId,
    idleMs: idle * 1000,
  };
}

export function validName(value: string, label = "environment ID"): string {
  if (!/^[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?$/.test(value)) throw new Error(`${label} must be a DNS label: 1-63 lowercase letters, digits or internal hyphens.`);
  return value;
}