import type { JetstreamEvent } from '@atcute/jetstream';
import type { RecordValue, UrlEntry } from './types';
import { sanitizeLastmod } from './xml';

// uri is the record's at-uri, deletes carry no record so it's what finds their url
export type ExtractedAction =
  | { type: 'delete'; uri: string; url: string }
  | { type: 'upsert'; uri: string; url: string; entry: UrlEntry };

interface CollectionSpec {
  buildPath: (owner: string, rkey: string, record?: RecordValue) => string;
  changefreq: UrlEntry['changefreq'];
  priority: number;
}

export const COLLECTION_SPECS: Record<string, CollectionSpec> = {
  'sh.tangled.repo': {
    buildPath: (owner, rkey, record) => `${owner}/${(record?.name as string) || rkey}`,
    changefreq: 'daily',
    priority: 0.8,
  },
  'sh.tangled.actor.profile': {
    buildPath: (owner) => owner,
    changefreq: 'daily',
    priority: 0.8,
  },
  'sh.tangled.string': {
    buildPath: (owner, rkey) => `strings/${owner}/${rkey}`,
    changefreq: 'weekly',
    priority: 0.6,
  },
};

// owners are dids rather than handles, so a url never moves when someone
// changes handle, and the web redirects it to the handle anyway
export function extractUrlAction(
  event: JetstreamEvent,
  baseUrl: string,
  now = new Date(),
): ExtractedAction | null {
  if (event.kind !== 'commit') {
    return null;
  }

  const { collection, rkey, operation } = event.commit;
  const spec = COLLECTION_SPECS[collection];
  if (!spec) {
    return null;
  }

  const record = event.commit.operation === 'delete' ? undefined : (event.commit.record as RecordValue);
  const uri = `at://${event.did}/${collection}/${rkey}`;
  const normalizedBase = baseUrl.replace(/\/+$/, '');
  const path = spec.buildPath(event.did, rkey, record);
  const url = `${normalizedBase}/${path}`;

  if (operation === 'delete') {
    return { type: 'delete', uri, url };
  }

  const lastmod = sanitizeLastmod(record?.createdAt as string | undefined, now);
  return {
    type: 'upsert',
    uri,
    url,
    entry: {
      loc: url,
      lastmod,
      changefreq: spec.changefreq,
      priority: spec.priority,
    },
  };
}