/**
 * Atlas (Xyte) HTTP client.
 *
 * Atlas is the SaaS that monitors AV hardware (AMPs, displays, etc.) for the
 * organization. Auth is a single long-lived API key sent verbatim in the
 * `Authorization` header — no OAuth/rotation, in contrast to the Webex
 * Service App. Configure with `ATLAS_AUTH_KEY`.
 *
 * `atlasGet` returns the response body and wraps transient failures via
 * withRetry. Missing-key conditions throw `AtlasUnavailableError` so the
 * upstream renderer can surface a clean banner instead of a stack trace.
 */

const axios = require('axios');
const { withRetry } = require('../../utils/retry');
const logger = require('../../utils/logger');

const DEFAULT_BASE_URL = 'https://hub.xyte.io/core/v1';
const REQUEST_TIMEOUT_MS = 15000;
const RETRY_OPTS = { retries: 2, initialDelayMs: 500 };

class AtlasUnavailableError extends Error {
  constructor(message) {
    super(message);
    this.name = 'AtlasUnavailableError';
  }
}

// We construct the axios instance lazily so process.env changes between test
// cases are picked up, and so importing this module never throws when the
// key is absent (the renderer prefers a banner over a startup failure).
let _client = null;

function getClient() {
  if (_client) return _client;

  const authKey = process.env.ATLAS_AUTH_KEY;
  if (!authKey) {
    throw new AtlasUnavailableError(
      'ATLAS_AUTH_KEY is not set. Add it to the environment and restart the bot.'
    );
  }

  _client = axios.create({
    baseURL: process.env.ATLAS_BASE_URL || DEFAULT_BASE_URL,
    timeout: REQUEST_TIMEOUT_MS,
    headers: {
      'Content-Type': 'application/json',
      // Atlas accepts the raw key in the Authorization header (no "Bearer ").
      Authorization: authKey,
    },
  });

  return _client;
}

/**
 * GET against the Atlas API. Returns `response.data` (or `{}`). Wraps
 * transient failures via withRetry.
 *
 * Throws AtlasUnavailableError when ATLAS_AUTH_KEY is missing, or a plain
 * Error with status context on hard transport failures.
 */
async function atlasGet(endpoint, params = {}) {
  const client = getClient();
  const path = String(endpoint).replace(/^\/+/, '');

  try {
    const res = await withRetry(
      () =>
        client.get(`/${path}`, {
          params,
          // Validate manually so 4xx don't burn retry budget.
          validateStatus: status => status >= 200 && status < 500,
        }),
      RETRY_OPTS
    );

    if (res.status >= 400) {
      const detail =
        res.data?.message || res.data?.error || `${res.status} ${res.statusText || ''}`.trim();
      throw new Error(`Atlas GET /${path} failed: ${detail}`);
    }

    return res.data ?? {};
  } catch (err) {
    if (err instanceof AtlasUnavailableError) throw err;
    logger.error('Atlas request failed', {
      endpoint: path,
      error: err.message,
      status: err.response?.status,
    });
    throw err;
  }
}

function resetClientForTests() {
  _client = null;
}

module.exports = {
  atlasGet,
  AtlasUnavailableError,
  resetClientForTests,
  // Exposed so tests can assert defaults without poking the cached client.
  DEFAULT_BASE_URL,
};