const test = require('node:test');
const assert = require('node:assert/strict');
const fs = require('node:fs');
const path = require('node:path');
const read = f => fs.readFileSync(path.join(__dirname, '..', f), 'utf8');

// Generated assets are served `private, no-store`, which is correct for a
// clinical app on a shared workstation. The cost was that every gallery render
// re-downloaded every image — 26 images at ~279kB to draw 56px tiles.
test('assets are still never written to disk', () => {
  const route = read('src/routes/generatedImages.js');
  assert.match(route, /Cache-Control', 'private, no-store'/,
    'the no-store posture is unchanged; caching is in memory for the session only');
});

test('the cache is scoped to the account that fetched it', () => {
  const js = read('public/js/generatedImages.js');
  // A cache keyed only by URL would let the next account read the previous
  // one's bytes out of memory.
  assert.match(js, /function cacheKey\(src, ticket\) \{ return String\(ticket && ticket\.ticket\)/,
    'entries are keyed by owner ticket as well as asset');
  assert.match(js, /clearImageCache\(\); \/\/ cached bytes must not outlive the account/,
    'and dropped when the account boundary moves');
  assert.match(js, /assertImageOwner\(ticket\)/, 'ownership is asserted on the way in');
});

test('concurrent tiles share one request instead of racing', () => {
  const js = read('public/js/generatedImages.js');
  assert.match(js, /if \(inflight\.has\(key\)\) return inflight\.get\(key\);/);
  assert.match(js, /\.finally\(\(\) => inflight\.delete\(key\)\)/, 'and the slot is released either way');
});

test('a tile fetches a server preview, not the original', () => {
  const js = read('public/js/generatedImages.js');
  assert.match(js, /const edge = Number\(img\.getAttribute\('data-image-thumb'\)\) \|\| 0;/);
  // The server stores real previews now, so a tile downloads a few kB instead of
  // pulling ~280kB and shrinking it in the browser.
  assert.match(js, /'w=' \+ edge/, 'the tile asks the server for the preview');
  assert.match(js, /\.catch\(\(\) => cachedThumbnail\(src, edge, ticket\)\)/,
    'client downscaling remains the fallback');
  // A browser without OffscreenCanvas still shows the image rather than nothing.
  assert.match(js, /if \(typeof createImageBitmap !== 'function' \|\| typeof OffscreenCanvas !== 'function'\) return blob;/);

  const assistant = read('public/js/clinicalAssistant.js');
  assert.match(assistant, /data-image-thumb="256"/, 'the 56px gallery asks for a small copy');
});

test('a preview cannot widen access or be asked for arbitrary sizes', () => {
  const utils = read('src/utils/generatedImages.js');
  const route = read('src/routes/generatedImages.js');
  // An open width parameter would let a caller drive arbitrary resizes.
  assert.match(utils, /const THUMB_WIDTHS = Object\.freeze\(\[256, 640\]\);/);
  assert.match(utils, /return THUMB_WIDTHS\.includes\(width\) \? width : null;/);
  // Permission is checked against the ORIGINAL before any preview is served.
  assert.match(route, /await images\.service\(\)\.asset\(req\.params\.id, req\.user\); \/\/ authorise/);
  // Previews carry their own checksum; the original's would be rejected.
  assert.match(route, /createHash\('sha256'\)\.update\(thumb\.bytes\)/);
  assert.match(route, /Cache-Control', 'private, no-store'/, 'and they are no-store like the original');

  const client = read('public/js/generatedImages.js');
  assert.match(client, /\\?w=\(\?:256\|640\)/, 'the client accepts only those two widths as asset URLs');
});

test('previews are rendered once and stored beside the original', () => {
  const utils = read('src/utils/generatedImages.js');
  assert.match(utils, /const cached = await getStorage\(\)\.getThumb\(id, width\);\s*\n\s*if \(cached\) return cached;/,
    'a stored preview is reused rather than re-rendered');
  assert.match(utils, /await warmThumbs\(job\.id\);/, 'and rendered when the job completes');
  // Neither caching nor warming may break the thing they are optimising.
  assert.match(utils, /catch \(_\) \{ \/\* served anyway; the next request retries the write \*\/ \}/);
  assert.match(utils, /catch \(_\) \{ \/\* previews are an optimisation; never fail the job for one \*\/ \}/);

  const storage = read('src/utils/generatedImageStorage.js');
  assert.match(storage, /return 'thumbs\/' \+ id \+ '\/' \+ width;/, 'same bucket, own prefix');
});