'use strict';
const { test } = require('node:test');
const assert = require('node:assert');
const R = require('./resume-core');

test('nextRange walks the file in chunks and stops at the end', () => {
  assert.deepStrictEqual(R.nextRange(0, 20, 8), { start: 0, end: 7 });
  assert.deepStrictEqual(R.nextRange(16, 20, 8), { start: 16, end: 19 });
  assert.strictEqual(R.nextRange(20, 20, 8), null);
  assert.strictEqual(R.nextRange(0, 0, 8), null);
});

test('parseContentRange reads start, end and total', () => {
  assert.deepStrictEqual(R.parseContentRange('bytes 8-15/20'), { start: 8, end: 15, total: 20 });
  assert.deepStrictEqual(R.parseContentRange('bytes 0-1/*'), { start: 0, end: 1, total: null });
  assert.strictEqual(R.parseContentRange('bytes */20'), null);
  assert.strictEqual(R.parseContentRange(null), null);
});

test('backoff grows and caps at 30 s', () => {
  assert.deepStrictEqual([0, 1, 2, 3, 4, 9].map(R.backoffMs), [2000, 4000, 8000, 16000, 30000, 30000]);
});

test('a partial is reused only for the same server copy', () => {
  const t = { etag: '"a.1"', size: 100 };
  assert.strictEqual(R.resumeFrom({ etag: '"a.1"', size: 100 }, 40, t), 40);
  assert.strictEqual(R.resumeFrom({ etag: '"a.0"', size: 100 }, 40, t), 0, 'older generation');
  assert.strictEqual(R.resumeFrom({ etag: '"a.1"', size: 90 }, 40, t), 0, 'size changed');
  assert.strictEqual(R.resumeFrom(null, 40, t), 0, 'no sidecar');
  assert.strictEqual(R.resumeFrom({ etag: '"a.1"', size: 100 }, 150, t), 100, 'never past the end');
});