import { pool } from '../../src/db';
import { cutoutPathFor, restoreOriginalsForItem } from '../../src/intake/backgroundRemoval';

// The database module is replaced outright rather than spied on. This has to
// be a unit test: the only failure `restoreOriginalsForItem` can report is a
// database fault, and the only way to inject one is to make a query fail on
// command. Doing that in the integration suite means interfering with the
// single pool every suite in the same `--runInBand` process shares, and that
// `afterAll` calls `pool.end()` on — which made the whole suite unrunnable.
// Here no `Pool` is ever constructed: jest gives this file its own module
// registry, so there is nothing shared to break.
jest.mock('../../src/db', () => ({ pool: { query: jest.fn(), connect: jest.fn() } }));

const mockPool = pool as unknown as { query: jest.Mock; connect: jest.Mock };

/** The distinctive text of the swap that puts one photo back. */
const SWAP_SQL = 'SET image_path = original_image_path';

/**
 * A pool over `imageIds` whose nth restore swap fails.
 *
 * Matching on the swap's SQL rather than counting queries: `restoreImageOriginal`
 * also issues BEGIN, the `item_drafts` update and COMMIT on the same client, so
 * a bare call counter would break whichever query happened to land nth.
 */
function poolWhoseSwapFailsOn(imageIds: number[], failOnSwap: number): void {
  mockPool.query.mockResolvedValue({ rows: imageIds.map((id) => ({ id })) });
  let swaps = 0;
  mockPool.connect.mockImplementation(async () => ({
    query: jest.fn(async (sql: string) => {
      if (!String(sql).includes(SWAP_SQL)) return { rows: [] };
      swaps += 1;
      if (swaps === failOnSwap) throw new Error('database is down');
      return { rows: [{ item_id: 1 }] };
    }),
    release: jest.fn()
  }));
}

describe('where a cut-out is written', () => {
  // A new file rather than a rewrite of the original, which is what makes the
  // original restorable at all — and what makes the JPEG-to-PNG change free,
  // since no existing path is renamed.
  it('sits beside the original with a -cutout suffix and a .png extension', () => {
    expect(cutoutPathFor('/uploads/abc-123.jpg')).toBe('/uploads/abc-123-cutout.png');
  });

  // image_path is a contract, not a string: #103 made the stored value the
  // path uploadUrl joins an origin onto.
  it('keeps the /uploads/ prefix', () => {
    expect(cutoutPathFor('/uploads/x.webp')).toBe('/uploads/x-cutout.png');
  });

  // The extension is replaced rather than appended, so a second pass cannot
  // produce `.png.png`.
  it('replaces the extension rather than appending to it', () => {
    expect(cutoutPathFor('/uploads/x.png')).toBe('/uploads/x-cutout.png');
  });
});

describe('when a restore fails partway through an item', () => {
  // Logged rather than thrown, so the log line is expected here; silenced to
  // keep it out of the suite's output rather than because it does not matter.
  let logged: jest.SpyInstance;

  beforeEach(() => {
    jest.clearAllMocks();
    logged = jest.spyOn(console, 'error').mockImplementation(() => {});
  });

  afterEach(() => {
    logged.mockRestore();
  });

  // The case the summary's `failed` field exists for: a genuine database
  // failure partway through must not turn into a bare 500 that discards how
  // far the restore got. It has to stop, report the count, and let the caller
  // decide whether to retry — the same contract removeBackgroundsForItem has.
  it('stops at the first genuine failure and reports how far it got', async () => {
    poolWhoseSwapFailsOn([11, 22, 33], 2);

    await expect(restoreOriginalsForItem(4)).resolves.toEqual({
      total: 3,
      restored: 1,
      failed: true
    });
  });

  // The third photo is never attempted, which is what makes pressing Restore
  // again worth something: it resumes rather than starting over.
  it('does not go on to the photos after the one that failed', async () => {
    poolWhoseSwapFailsOn([11, 22, 33], 2);

    await restoreOriginalsForItem(4);

    expect(mockPool.connect).toHaveBeenCalledTimes(2);
  });
});