'use strict';

const http = require('http');
const https = require('https');
const { settings } = require('./settings');
const { baseState, nowIso, buildUpstreamUrl } = require('./upstream');

function toInt(value) {
  if (value === null || value === undefined || value === '') return null;
  const n = Number(value);
  return Number.isFinite(n) ? n : null;
}

function interpretProbe(statusCode, body, elapsedMs) {
  const state = { ...baseState(), lastChecked: nowIso() };

  if (statusCode < 200 || statusCode >= 300) {
    state.error = `http_${statusCode}`;
    return state;
  }

  let json;
  try {
    json = JSON.parse(body);
  } catch {
    state.error = 'invalid_json';
    return state;
  }

  const info = json && (json.user_info || json.userInfo);
  if (!info || typeof info !== 'object') {
    state.error = 'no_user_info';
    return state;
  }

  state.auth = info.auth === undefined ? null : info.auth;
  state.status = info.status === undefined ? null : info.status;
  state.activeCons = toInt(info.active_cons);
  state.maxCons = toInt(info.max_connections);

  if (state.auth !== null && Number(state.auth) !== 1) {
    state.error = 'not_authorized';
    return state;
  }
  if (
    state.status !== null &&
    String(state.status).toLowerCase() !== 'active'
  ) {
    state.error = `status_${state.status}`;
    return state;
  }

  state.healthy = true;
  state.latencyMs = Math.max(0, Math.round(elapsedMs));
  state.busy =
    state.maxCons !== null &&
    state.maxCons > 0 &&
    state.activeCons !== null &&
    state.activeCons >= state.maxCons;

  return state;
}

function probeUpstream(upstream) {
  const search = `?${new URLSearchParams({
    username: upstream.username,
    password: upstream.password,
  }).toString()}`;
  const target = buildUpstreamUrl(upstream, '/player_api.php', search);
  const lib = target.protocol === 'https:' ? https : http;
  const started = Date.now();

  return new Promise((resolve) => {
    let settled = false;
    let req = null;

    const finish = (state) => {
      if (settled) return;
      settled = true;
      clearTimeout(hardTimeout);
      if (req) {
        try {
          req.destroy();
        } catch {}
      }
      resolve(state);
    };

    const hardTimeout = setTimeout(
      () => finish({ ...baseState(), lastChecked: nowIso(), error: 'timeout' }),
      settings.probeTimeoutMs + 2000
    );

    try {
      req = lib.request(
        {
          protocol: target.protocol,
          hostname: target.hostname,
          port: target.port || undefined,
          path: `${target.pathname}${target.search}`,
          method: 'GET',
          headers: {
            'User-Agent': settings.userAgent,
            Accept: 'application/json',
            'Accept-Encoding': 'identity',
            Connection: 'close',
          },
          rejectUnauthorized: settings.rejectUnauthorized,
        },
        (res) => {
          let body = '';
          res.setEncoding('utf8');
          res.on('data', (chunk) => {
            if (body.length < 2_000_000) body += chunk;
          });
          res.on('end', () =>
            finish(interpretProbe(res.statusCode, body, Date.now() - started))
          );
          res.on('error', () =>
            finish({
              ...baseState(),
              lastChecked: nowIso(),
              error: 'response_error',
            })
          );
        }
      );
    } catch (e) {
      finish({
        ...baseState(),
        lastChecked: nowIso(),
        error: e.code || 'request_error',
      });
      return;
    }

    req.setTimeout(settings.probeTimeoutMs, () => {
      try {
        req.destroy();
      } catch {}
      finish({ ...baseState(), lastChecked: nowIso(), error: 'timeout' });
    });
    req.on('error', (e) =>
      finish({
        ...baseState(),
        lastChecked: nowIso(),
        error: e.code || 'request_error',
      })
    );
    req.end();
  });
}

module.exports = { interpretProbe, probeUpstream };