import { describe, expect, it } from 'vitest';

import {
  closeDocument,
  noDocuments,
  openedIds,
  pinDocument,
  previewDocument,
  selectDocument,
} from './documents';

// The owner's complaint (2) in executable form: five single clicks must leave ONE tab in the row.
describe('the VS Code tab model', () => {
  it('five single clicks give exactly one preview tab', () => {
    let documents = noDocuments;
    for (const id of ['ch_1', 'ch_2', 'ch_3', 'ch_4', 'ch_5']) {
      documents = previewDocument(documents, id);
    }
    expect(openedIds(documents)).toEqual(['ch_5']);
    expect(documents.active).toBe('ch_5');
  });

  it('pinning makes the preview permanent, the next click opens a new one beside it', () => {
    let documents = previewDocument(noDocuments, 'ch_1');
    documents = pinDocument(documents, 'ch_1');
    expect(documents.preview).toBeNull();

    documents = previewDocument(documents, 'ch_2');
    expect(openedIds(documents)).toEqual(['ch_1', 'ch_2']);
    expect(documents.preview).toBe('ch_2');

    // And the next single click replaces ONLY the preview, leaving the pinned one alone.
    documents = previewDocument(documents, 'ch_3');
    expect(openedIds(documents)).toEqual(['ch_1', 'ch_3']);
  });

  it('a click on an already pinned tab selects it and does not start a preview', () => {
    let documents = pinDocument(previewDocument(noDocuments, 'ch_1'), 'ch_1');
    documents = previewDocument(documents, 'ch_2');
    documents = previewDocument(documents, 'ch_1');
    expect(documents.active).toBe('ch_1');
    expect(documents.preview).toBe('ch_2');
  });

  it('closing the selected tab moves the selection to the neighbour on the right', () => {
    let documents = noDocuments;
    for (const id of ['a', 'b', 'c']) documents = pinDocument(documents, id);
    documents = selectDocument(documents, 'b');
    documents = closeDocument(documents, 'b');
    expect(documents.active).toBe('c');
    expect(openedIds(documents)).toEqual(['a', 'c']);
  });

  it('closing the last tab leaves the centre empty rather than selected into nowhere', () => {
    const documents = closeDocument(previewDocument(noDocuments, 'ch_1'), 'ch_1');
    expect(openedIds(documents)).toEqual([]);
    expect(documents.active).toBe('');
  });

  it('closing a tab that is NOT selected does not move the selection', () => {
    let documents = noDocuments;
    for (const id of ['a', 'b']) documents = pinDocument(documents, id);
    const after = closeDocument(documents, 'a');
    expect(after.active).toBe('b');
  });
});