/**
 * Configuration management for unified email worker
 *
 * All settings are read from environment variables with sensible defaults.
 * Domain helpers (bucket name, queue name, internal check) are co-located here
 * so every module can import { config, domainToBucket, ... } from './config'.
 */

import { readFileSync, existsSync } from 'node:fs';

// ---------------------------------------------------------------------------
// Config object
// ---------------------------------------------------------------------------
export const config = {
  // AWS
  awsRegion: process.env.AWS_REGION ?? 'us-east-2',

  // Domains
  domainsList: process.env.DOMAINS ?? '',
  domainsFile: process.env.DOMAINS_FILE ?? '/etc/email-worker/domains.txt',

  // Worker
  workerThreads: parseInt(process.env.WORKER_THREADS ?? '10', 10),
  pollInterval: parseInt(process.env.POLL_INTERVAL ?? '20', 10),
  maxMessages: parseInt(process.env.MAX_MESSAGES ?? '10', 10),
  visibilityTimeout: parseInt(process.env.VISIBILITY_TIMEOUT ?? '300', 10),

  // SMTP delivery (local DMS)
  smtpHost: process.env.SMTP_HOST ?? 'localhost',
  smtpPort: parseInt(process.env.SMTP_PORT ?? '25', 10),
  smtpUseTls: (process.env.SMTP_USE_TLS ?? 'false').toLowerCase() === 'true',
  smtpUser: process.env.SMTP_USER ?? '',
  smtpPass: process.env.SMTP_PASS ?? '',
  smtpPoolSize: parseInt(process.env.SMTP_POOL_SIZE ?? '5', 10),

  // Internal SMTP port (for OOO / forwards to managed domains)
  internalSmtpPort: parseInt(process.env.INTERNAL_SMTP_PORT ?? '25', 10),

  // DynamoDB tables
  rulesTable: process.env.DYNAMODB_RULES_TABLE ?? 'email-rules',
  messagesTable: process.env.DYNAMODB_MESSAGES_TABLE ?? 'ses-outbound-messages',
  blockedTable: process.env.DYNAMODB_BLOCKED_TABLE ?? 'email-blocked-senders',

  // Bounce handling
  bounceLookupRetries: parseInt(process.env.BOUNCE_LOOKUP_RETRIES ?? '3', 10),
  bounceLookupDelay: parseFloat(process.env.BOUNCE_LOOKUP_DELAY ?? '1.0'),

  // Monitoring
  metricsPort: parseInt(process.env.METRICS_PORT ?? '8000', 10),
  healthPort: parseInt(process.env.HEALTH_PORT ?? '8080', 10),
} as const;

export type Config = typeof config;

// ---------------------------------------------------------------------------
// Managed domains (populated by loadDomains())
// ---------------------------------------------------------------------------
const managedDomains = new Set<string>();

/**
 * Load domains from env var and/or file, populate the internal set.
 */
export function loadDomains(): string[] {
  const domains: string[] = [];

  // From env
  if (config.domainsList) {
    for (const d of config.domainsList.split(',')) {
      const trimmed = d.trim();
      if (trimmed) domains.push(trimmed);
    }
  }

  // From file
  if (existsSync(config.domainsFile)) {
    const content = readFileSync(config.domainsFile, 'utf-8');
    for (const line of content.split('\n')) {
      const trimmed = line.trim();
      if (trimmed && !trimmed.startsWith('#')) {
        domains.push(trimmed);
      }
    }
  }

  // Deduplicate
  const unique = [...new Set(domains)];

  managedDomains.clear();
  for (const d of unique) {
    managedDomains.add(d.toLowerCase());
  }

  return unique;
}

// ---------------------------------------------------------------------------
// Domain helpers
// ---------------------------------------------------------------------------

/** Check whether an email address belongs to one of our managed domains */
export function isInternalAddress(email: string): boolean {
  const atIdx = email.indexOf('@');
  if (atIdx < 0) return false;
  return managedDomains.has(email.slice(atIdx + 1).toLowerCase());
}

/** Convert domain to SQS queue name: bizmatch.net → bizmatch-net-queue */
export function domainToQueueName(domain: string): string {
  return domain.replace(/\./g, '-') + '-queue';
}

/** Convert domain to S3 bucket name: bizmatch.net → bizmatch-net-emails */
export function domainToBucketName(domain: string): string {
  return domain.replace(/\./g, '-') + '-emails';
}