'use strict';

function readNumber(value, fallback, min, max) {
  const n = Number(value);
  if (value === undefined || value === null || value === '' || !Number.isFinite(n)) {
    return fallback;
  }
  return Math.min(Math.max(n, min), max);
}

const settings = {
  xtreamUrl: (process.env.XTREAM_URL || '').trim().replace(/\/+$/, ''),
  xtreamUsername: process.env.XTREAM_USERNAME || '',
  xtreamPassword: process.env.XTREAM_PASSWORD || '',
  searchTerm: (process.env.SEARCH_TERM || '').trim(),
  maxChannels: Math.round(readNumber(process.env.MAX_CHANNELS, 3, 1, 10)),
  language: (process.env.LANGUAGE || 'nl').trim().toLowerCase(),
  eventDurationMin: readNumber(process.env.EVENT_DURATION_MIN, 150, 1, 1440),
  startGraceMin: readNumber(process.env.START_GRACE_MIN, 10, 0, 1440),
  refreshIntervalSec: readNumber(process.env.REFRESH_INTERVAL_SEC, 60, 10, 3600),
  sourceTimezone: (process.env.SOURCE_TIMEZONE || 'UTC').trim() || 'UTC',
  timezone: (process.env.TIMEZONE || 'Europe/Brussels').trim() || 'Europe/Brussels',
  listenPort: Math.round(readNumber(process.env.LISTEN_PORT, 8080, 1, 65535)),
  upstreamTimeoutMs: readNumber(process.env.UPSTREAM_TIMEOUT_MS, 15000, 1000, 120000),
  rejectUnauthorized: process.env.PROXY_INSECURE_TLS !== '1',
  logLevel: (process.env.LOG_LEVEL || 'info').trim().toLowerCase(),
  userAgent: process.env.USER_AGENT || 'xtream-ppv-bundler/1.0',
  healthFailThreshold: 3,
  eventDurationMs: 0,
  startGraceMs: 0,
};

settings.eventDurationMs = settings.eventDurationMin * 60 * 1000;
settings.startGraceMs = settings.startGraceMin * 60 * 1000;

function validateTimezone(timezone, envName) {
  try {
    new Intl.DateTimeFormat('en-US', { timeZone: timezone });
  } catch {
    throw new Error(`Invalid ${envName}: ${timezone}`);
  }
}

function validate() {
  const missing = [];
  if (!settings.xtreamUrl) missing.push('XTREAM_URL');
  if (!settings.xtreamUsername) missing.push('XTREAM_USERNAME');
  if (!settings.xtreamPassword) missing.push('XTREAM_PASSWORD');
  if (!settings.searchTerm) missing.push('SEARCH_TERM');
  if (missing.length) {
    throw new Error(`Missing required environment variables: ${missing.join(', ')}`);
  }

  let parsed;
  try {
    parsed = new URL(settings.xtreamUrl);
  } catch {
    throw new Error(`XTREAM_URL is not a valid URL: ${settings.xtreamUrl}`);
  }
  if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
    throw new Error('XTREAM_URL must use http or https');
  }

  validateTimezone(settings.sourceTimezone, 'SOURCE_TIMEZONE');
  validateTimezone(settings.timezone, 'TIMEZONE');

  if (!settings.language) {
    throw new Error('LANGUAGE must not be empty');
  }
}

module.exports = { settings, validate };