import { test } from 'node:test';
import assert from 'node:assert/strict';
import { CrawlFrontier } from './frontier.js';

test('CrawlFrontier: BFS dequeues in FIFO order, identical to a plain array shift()', () => {
  const f = new CrawlFrontier('BFS', ['https://a.com/1', 'https://a.com/2']);
  f.push('https://a.com/3');
  assert.equal(f.shift(), 'https://a.com/1');
  assert.equal(f.shift(), 'https://a.com/2');
  assert.equal(f.shift(), 'https://a.com/3');
  assert.equal(f.shift(), undefined);
});

test('CrawlFrontier: DFS dequeues in LIFO order', () => {
  const f = new CrawlFrontier('DFS', ['https://a.com/1', 'https://a.com/2']);
  f.push('https://a.com/3');
  assert.equal(f.shift(), 'https://a.com/3');
  assert.equal(f.shift(), 'https://a.com/2');
  assert.equal(f.shift(), 'https://a.com/1');
});

test('CrawlFrontier: BEST_FIRST prefers shallower paths over deeper ones', () => {
  const f = new CrawlFrontier('BEST_FIRST', [
    'https://a.com/products/electronics/phones/model-x',
    'https://a.com/about',
  ]);
  assert.equal(f.shift(), 'https://a.com/about');
  assert.equal(f.shift(), 'https://a.com/products/electronics/phones/model-x');
});

test('CrawlFrontier: BEST_FIRST boosts URLs matching keywords ahead of shallower non-matching ones', () => {
  const f = new CrawlFrontier('BEST_FIRST', ['https://a.com/'], ['pricing']);
  f.push('https://a.com/deep/nested/pricing/plans');
  // "/" has depth 0 (score 0); the pricing URL has depth 4 (score -4) but +10 for the
  // keyword match, netting +6 — the keyword-matching page should win despite depth.
  assert.equal(f.shift(), 'https://a.com/deep/nested/pricing/plans');
  assert.equal(f.shift(), 'https://a.com/');
});

test('CrawlFrontier: length reflects push/shift correctly across all strategies', () => {
  for (const strategy of ['BFS', 'DFS', 'BEST_FIRST'] as const) {
    const f = new CrawlFrontier(strategy, ['https://a.com/1']);
    assert.equal(f.length, 1);
    f.push('https://a.com/2');
    assert.equal(f.length, 2);
    f.shift();
    assert.equal(f.length, 1);
  }
});

test('CrawlFrontier: filter returns URLs matching the predicate without mutating the frontier', () => {
  const f = new CrawlFrontier('BFS', ['https://a.com/1', 'https://a.com/2', 'https://a.com/3']);
  const matched = f.filter((u) => u.endsWith('/2'));
  assert.deepEqual(matched, ['https://a.com/2']);
  assert.equal(f.length, 3); // unchanged
});

test('CrawlFrontier: malformed URLs never throw when scored under BEST_FIRST', () => {
  assert.doesNotThrow(() => {
    const f = new CrawlFrontier('BEST_FIRST', ['not-a-valid-url', 'https://a.com/ok']);
    f.shift();
    f.shift();
  });
});