/**
 * A stand-in for the two Dropbox Sign endpoints the NDA inbox uses, with the
 * one property that broke the refresh in production: **the search index lags
 * behind the list**.
 *
 * `GET /v3/signature_request/list` answers from two different sources:
 *
 * * without `query=` — the live list, ordered by last activity (signed_at,
 *   falling back to created_at), exactly like the real endpoint;
 * * with `query=` — the *index*, which only holds the snapshot a fixture entry
 *   declares in `indexed`. A brand-new request is missing from it entirely,
 *   and a request signed a minute ago is still in it as pending. That is what
 *   an incremental refresh must not depend on.
 *
 * The range syntax is parsed for real, brackets and all, so `[a TO b]`
 * (inclusive) and `{a TO b}` (exclusive) actually behave differently — which
 * is what makes the boundary-day assertion meaningful.
 *
 * Run standalone for manual pokes:
 *   node scripts/ds-stub.mjs --port 8099 --fixture some.json
 */
import { createServer } from 'node:http';
import { readFile } from 'node:fs/promises';

const dayOf = (unixSeconds) => new Date(unixSeconds * 1000).toISOString().slice(0, 10);

/** signed_at when there is one, created_at otherwise — the list's sort key. */
const activityOf = (request) => request.signatures?.[0]?.signed_at ?? request.created_at;

/**
 * The subset of the query language the refresh sends:
 * `title:"<phrase>" AND created:[<day> TO <day|*>]`, either bracket style.
 */
export function matchesQuery(request, queryString) {
  const phrase = /title:"([^"]*)"/.exec(queryString)?.[1];
  if (phrase && !(request.title ?? '').includes(phrase)) return false;

  const range = /created:([[{])\s*(\S+)\s+TO\s+(\S+?)\s*([\]}])/.exec(queryString);
  if (range) {
    const [, open, from, to, close] = range;
    const day = dayOf(request.created_at);
    // '[' includes the boundary day, '{' excludes it — the whole point.
    if (from !== '*' && (open === '[' ? day < from : day <= from)) return false;
    if (to !== '*' && (close === ']' ? day > to : day >= to)) return false;
  }
  return true;
}

/**
 * `fixture` is a list of `{request, indexed}`: the truth the list and the
 * per-id endpoint serve, and the possibly stale (or missing) copy the search
 * index has of it.
 */
export function createStub(fixture) {
  /** Every call the app made — the test asserts on what it asked for. */
  const calls = [];

  const byActivity = (a, b) => activityOf(b) - activityOf(a);

  const server = createServer((req, res) => {
    const url = new URL(req.url, 'http://stub');
    const send = (status, body) => {
      const payload = JSON.stringify(body);
      res.writeHead(status, { 'content-type': 'application/json' });
      res.end(payload);
    };

    if (url.pathname === '/v3/signature_request/list') {
      const page = Number(url.searchParams.get('page') ?? '1');
      const pageSize = Number(url.searchParams.get('page_size') ?? '20');
      const queryString = url.searchParams.get('query');
      calls.push({ endpoint: 'list', page, query: queryString });

      const source = queryString
        ? fixture
            .map((entry) => entry.indexed)
            .filter(Boolean)
            .filter((request) => matchesQuery(request, queryString))
        : fixture.map((entry) => entry.request);
      const ordered = [...source].sort(byActivity);
      const numPages = Math.max(1, Math.ceil(ordered.length / pageSize));
      const slice = ordered.slice((page - 1) * pageSize, page * pageSize);
      return send(200, {
        signature_requests: slice,
        list_info: { page, num_pages: numPages, num_results: ordered.length },
      });
    }

    const single = /^\/v3\/signature_request\/([^/]+)$/.exec(url.pathname);
    if (single) {
      const id = decodeURIComponent(single[1]);
      calls.push({ endpoint: 'get', id });
      const entry = fixture.find((e) => e.request.signature_request_id === id);
      // Unknown ids 404 like the real API — the sync walks over real rows the
      // stub knows nothing about and must simply report them as failures.
      if (!entry) return send(404, { error: { error_msg: `no such request: ${id}` } });
      return send(200, { signature_request: entry.request });
    }

    return send(404, { error: { error_msg: `unhandled path: ${url.pathname}` } });
  });

  return {
    calls,
    /** Resolves to the base URL once it is listening. */
    listen(port = 0) {
      return new Promise((resolve) => {
        server.listen(port, '127.0.0.1', () =>
          resolve(`http://127.0.0.1:${server.address().port}`),
        );
      });
    },
    close: () => new Promise((resolve) => server.close(resolve)),
    /** What a searching walk would have found — the lag, made visible. */
    search: (queryString) =>
      fixture
        .map((entry) => entry.indexed)
        .filter(Boolean)
        .filter((request) => matchesQuery(request, queryString)),
  };
}

// -------------------------------------------------------- standalone mode
if (process.argv[1] && import.meta.url.endsWith(process.argv[1].replace(/^.*\//, ''))) {
  const args = process.argv.slice(2);
  const arg = (name, fallback) => {
    const at = args.indexOf(`--${name}`);
    return at === -1 ? fallback : args[at + 1];
  };
  const file = arg('fixture');
  if (file) {
    const fixture = JSON.parse(await readFile(file, 'utf8'));
    const stub = createStub(fixture);
    console.log(`[ds-stub] listening on ${await stub.listen(Number(arg('port', '8099')))}`);
  } else {
    console.error('usage: node scripts/ds-stub.mjs --fixture <file.json> [--port 8099]');
    process.exit(2);
  }
}