/**
 * CM-1: Mailchimp Marketing API integration (one-way push, CRM → Mailchimp).
 *
 * SCOPE NOTE: per the locked CM-1 decision, the exact group → tag/segment
 * mapping is finalised only once we have the client's actual Mailchimp account.
 * So this module ships the config plumbing + an inert sync that no-ops until
 * (a) an admin stores an API key + audience ID and (b) the mapping is wired.
 * The members viewer + copy-emails features do NOT depend on Mailchimp.
 *
 * Settings keys (per-port, in system_settings):
 *   - `mailchimp_api_key`     (AES-encrypted at rest, like SMTP/IMAP creds)
 *   - `mailchimp_audience_id` (the single audience all groups map into)
 */

import { logger } from '@/lib/logger';
import { getSetting } from '@/lib/services/settings.service';
import { decrypt } from '@/lib/utils/encryption';

export interface MailchimpConfig {
  apiKey: string;
  audienceId: string;
  /** Datacenter prefix derived from the key suffix (e.g. `us21`). */
  serverPrefix: string;
}

/** Resolve + decrypt the per-port Mailchimp config, or null when unset. */
export async function getMailchimpConfig(portId: string): Promise<MailchimpConfig | null> {
  const keyRow = await getSetting('mailchimp_api_key', portId);
  const audRow = await getSetting('mailchimp_audience_id', portId);
  const encKey = typeof keyRow?.value === 'string' ? keyRow.value : null;
  const audienceId = typeof audRow?.value === 'string' ? audRow.value : null;
  if (!encKey || !audienceId) return null;
  let apiKey: string;
  try {
    apiKey = decrypt(encKey);
  } catch {
    return null;
  }
  // Mailchimp keys are `<hex>-<dc>`; the datacenter is the API host prefix.
  const serverPrefix = apiKey.split('-')[1] ?? '';
  if (!serverPrefix) return null;
  return { apiKey, audienceId, serverPrefix };
}

export async function isMailchimpConfigured(portId: string): Promise<boolean> {
  return (await getMailchimpConfig(portId)) !== null;
}

export type MailchimpSyncResult = { skipped: string } | { synced: true; count: number };

/**
 * Push a group's members to Mailchimp as a tag/segment on the port's audience.
 * Inert until configured AND the mapping is confirmed (see SCOPE NOTE).
 */
export async function syncGroupToMailchimp(
  groupId: string,
  portId: string,
): Promise<MailchimpSyncResult> {
  const config = await getMailchimpConfig(portId);
  if (!config) return { skipped: 'not-configured' };
  // TODO(CM-1): mapping pending the client's Mailchimp account. Once confirmed,
  // upsert each member via
  //   PUT https://{serverPrefix}.api.mailchimp.com/3.0/lists/{audienceId}/members/{md5(lowercased-email)}
  // then apply the group's tag. Only push subscribed/opted-in contacts (GDPR).
  logger.info({ groupId, portId }, 'Mailchimp sync requested (mapping pending client account)');
  return { skipped: 'mapping-pending' };
}