import { CompositeMemoryBackend } from '../compositeBackend';
import { MockMemoryBackend } from './mockBackend';
import type { MemoryBackend, MemoryEntry } from '../types';

class FakeGraphBackend implements MemoryBackend {
  readonly kind = 'graph' as const;
  private data: MemoryEntry[] = [];
  constructor(seed: Array<{ content: string; score: number }>) {
    this.data = seed.map((s, i) => ({
      id: `g${i}`,
      path: 'graph/node.md',
      content: s.content,
      score: s.score,
      createdAt: new Date(),
      source: 'graph',
    }));
  }
  async search() {
    return this.data;
  }
  async get() {
    return null;
  }
  async append() {}
  async health() {
    return { ok: true, backend: 'graph' as const };
  }
}

describe('CompositeMemoryBackend', () => {
  const scope = { agentId: 'A', userId: '1' };

  it('merges and ranks results from every backend', async () => {
    const vector = new MockMemoryBackend();
    await vector.append(scope, {
      path: 'memory/agent/playbook.md',
      content: 'decision about X',
    });
    const graph = new FakeGraphBackend([
      { content: 'graph node about X', score: 0.95 },
    ]);
    const composite = new CompositeMemoryBackend([vector, graph]);

    const results = await composite.search(scope, 'X', { maxResults: 5 });
    expect(results.length).toBeGreaterThanOrEqual(2);
    expect(results[0].score).toBeGreaterThanOrEqual(
      results[results.length - 1].score
    );
    expect(results.map((r) => r.source)).toEqual(
      expect.arrayContaining(['vector', 'graph'])
    );
  });

  it('fan-out append stops on first failure', async () => {
    const ok = new MockMemoryBackend();
    const broken: MemoryBackend = {
      kind: 'graph',
      async search() {
        return [];
      },
      async get() {
        return null;
      },
      async append() {
        throw new Error('graph down');
      },
      async health() {
        return { ok: false, backend: 'graph', error: 'down' };
      },
    };
    const composite = new CompositeMemoryBackend([ok, broken]);
    await expect(
      composite.append(scope, {
        path: 'memory/agent/pitfalls.md',
        content: 'test',
      })
    ).rejects.toThrow('graph down');
  });
});