config.ts

import { logger } from './logger';

/**
 * Read a required environment variable, exiting the process if it is missing.
 */
function requireEnv(name: string): string {
  const value = process.env[name];
  if (!value || value.trim() === '') {
    logger.error(`Missing required environment variable: ${name}`);
    process.exit(1);
  }
  return value.trim();
}

/**
 * Read an integer environment variable, falling back to a default when unset or
 * not a valid number.
 */
function intFromEnv(name: string, fallback: number): number {
  const raw = process.env[name];
  if (raw === undefined) return fallback;
  const parsed = Number.parseInt(raw, 10);
  return Number.isNaN(parsed) ? fallback : parsed;
}

/**
 * Read a boolean-ish environment variable ('1', 'true', 'yes').
 */
function boolFromEnv(name: string): boolean {
  const raw = process.env[name]?.trim().toLowerCase();
  return raw === '1' || raw === 'true' || raw === 'yes';
}

/**
 * Bot configuration, read once at startup. Required Discord credentials cause an
 * early exit if missing; everything else has a sensible default so the bot keeps
 * working against the public MDN MCP server out of the box.
 */
export const config = {
  discordToken: requireEnv('DISCORD_TOKEN'),
  discordClientId: requireEnv('DISCORD_CLIENT_ID'),

  // When set, commands deploy to this single guild (instant updates) instead of
  // globally (which can take up to an hour to propagate). Ideal for development.
  guildId: process.env.DISCORD_GUILD_ID?.trim() || undefined,

  // The MDN MCP endpoint. Overridable for local development against mdn/mcp.
  mcpUrl: process.env.MDN_MCP_URL?.trim() || 'https://mcp.mdn.mozilla.net/',

  // Optional prefix applied to every generated command name, e.g. 'mdn-' turns
  // the 'search' tool into '/mdn-search'. Useful to avoid clashes with other bots.
  commandPrefix: process.env.COMMAND_PREFIX?.trim() || '',

  // Send the documented opt-out header so MDN does not log query analytics.
  optOutAnalytics: boolFromEnv('MDN_OPT_OUT'),

  // How often to re-poll the MCP tool list and re-deploy commands if it changed.
  refreshIntervalMs: intFromEnv('REFRESH_INTERVAL_MS', 15 * 60 * 1000),
} as const;