// A draft outlives its composer, and a reload: written to storage once typing
// pauses, read back by the next page, dropped when emptied. Browser-only state.
import assert from 'node:assert/strict';
import { readFile } from 'node:fs/promises';
import { stripTypeScriptTypes } from 'node:module';
import test from 'node:test';

async function load(path, prelude = '') {
  const source = stripTypeScriptTypes((await readFile(new URL(path, import.meta.url), 'utf8')).replace(/^import [\s\S]*?;$/gm, ''));
  return import(`data:text/javascript;base64,${Buffer.from(prelude + source).toString('base64')}`);
}

const store = new Map();
globalThis.localStorage = {
  getItem: (key) => store.get(key) ?? null,
  setItem: (key, value) => store.set(key, String(value)),
  removeItem: (key) => store.delete(key),
};
const { withoutMarkers } = await load('../src/lib/chat/attachments.ts');
globalThis.__drafts = { withoutMarkers };

// Each call is a page load: a module of its own, with the same storage.
let pages = 0;
const page = () => load('../src/lib/chat/drafts.ts', `const SvelteMap = Map; const { withoutMarkers } = globalThis.__drafts; /* page ${++pages} */\n`);
const paused = () => new Promise((resolve) => setTimeout(resolve, 400));

test('a draft is saved once typing pauses and the next page starts with it', async () => {
  const { draftOf } = await page();
  const draft = draftOf('s1');
  assert.equal(draft.text, '');
  draft.text = 'half a thought';
  assert.equal(store.size, 0, 'nothing is written on every keystroke');
  await paused();
  const next = (await page()).draftOf('s1');
  assert.equal(next.text, 'half a thought');
  assert.equal((await page()).draftOf('s2').text, '', 'another session has its own');
});

test('a draft keeps its words and loses the markers of images that do not survive a reload', async () => {
  const { draftOf } = await page();
  draftOf('s3').text = 'look at [Image #1] and also [Image #2], then fix it';
  await paused();
  assert.equal((await page()).draftOf('s3').text, 'look at and also, then fix it');
});

test('an emptied or sent draft leaves nothing behind', async () => {
  const { draftOf } = await page();
  const draft = draftOf('s4');
  draft.text = 'to be sent';
  await paused();
  assert.ok(store.has('albedo.draft.v1:s4'));
  draft.text = '';
  await paused();
  assert.equal(store.has('albedo.draft.v1:s4'), false);
  assert.equal((await page()).draftOf('s4').text, '');
});