/**
 * Reader for ~/.a2a/credentials.json — same file the Python `a2a` CLI writes.
 *
 * We deliberately *only read* this file (and overwrite it on `a2amcp login`)
 * so a single login flow is shared between the Python and Node tooling.
 */
import { promises as fs } from "node:fs";
import os from "node:os";
import path from "node:path";

export const DEFAULT_API_URL = "https://api.a2acloud.io";

export interface Credentials {
  apiUrl: string;
  token: string;
  email: string;
  userId?: number;
  bucket?: string;
}

const credsDir = () => path.join(os.homedir(), ".a2a");
const credsFile = () => path.join(credsDir(), "credentials.json");

export async function loadCredentials(): Promise<Credentials | null> {
  try {
    const raw = await fs.readFile(credsFile(), "utf8");
    const data = JSON.parse(raw);
    if (!data?.token) return null;
    return {
      apiUrl: data.api_url ?? DEFAULT_API_URL,
      token: data.token,
      email: data.email ?? "",
      userId: typeof data.user_id === "number" ? data.user_id : undefined,
      bucket: typeof data.bucket === "string" ? data.bucket : undefined,
    };
  } catch (err: any) {
    if (err?.code === "ENOENT") return null;
    throw err;
  }
}

export async function saveCredentials(c: Credentials): Promise<void> {
  await fs.mkdir(credsDir(), { recursive: true });
  const out: Record<string, unknown> = {
    api_url: c.apiUrl,
    token: c.token,
    email: c.email,
  };
  if (c.userId !== undefined) out.user_id = c.userId;
  if (c.bucket !== undefined) out.bucket = c.bucket;
  await fs.writeFile(credsFile(), JSON.stringify(out), { mode: 0o600 });
}

export async function clearCredentials(): Promise<boolean> {
  try {
    await fs.unlink(credsFile());
    return true;
  } catch (err: any) {
    if (err?.code === "ENOENT") return false;
    throw err;
  }
}

export function resolveApiUrl(override?: string): string {
  if (override) return override;
  if (process.env.A2A_API_URL) return process.env.A2A_API_URL;
  return DEFAULT_API_URL;
}