import { describe, expect, it } from 'vitest';
import type { MergeQueueItem } from './mergeTypes';
import {
  canMergeQueue,
  clampMergeInsertAt,
  createMergedPdfName,
  getReadyMergeQueuePdfs,
  moveMergeQueueItem,
} from './mergeQueueHelpers';

function makeItem(
  id: string,
  status: MergeQueueItem['status']
): MergeQueueItem {
  return {
    id,
    file: new File(['x'], `${id}.pdf`, { type: 'application/pdf' }),
    name: `${id}.pdf`,
    size: 1,
    pageCount: status === 'ready' ? 1 : null,
    pdf:
      status === 'ready'
        ? {
            id: `pdf-${id}`,
            name: `${id}.pdf`,
            // The helper tests never dereference the PDFDocument.
            doc: {} as never,
            pageCount: 1,
            arrayBuffer: new ArrayBuffer(0),
          }
        : null,
    status,
  };
}

describe('merge queue helpers', () => {
  it('moves queued items up and down without mutating the original array', () => {
    const items = [
      makeItem('a', 'ready'),
      makeItem('b', 'ready'),
      makeItem('c', 'ready'),
    ];

    expect(moveMergeQueueItem(items, 'b', 'up').map((item) => item.id)).toEqual(
      ['b', 'a', 'c']
    );
    expect(
      moveMergeQueueItem(items, 'b', 'down').map((item) => item.id)
    ).toEqual(['a', 'c', 'b']);
    expect(items.map((item) => item.id)).toEqual(['a', 'b', 'c']);
  });

  it('only allows merging when every queued item is ready', () => {
    const readyItems = [makeItem('a', 'ready'), makeItem('b', 'ready')];
    const mixedItems = [makeItem('a', 'ready'), makeItem('b', 'loading')];

    expect(canMergeQueue(readyItems)).toBe(true);
    expect(getReadyMergeQueuePdfs(readyItems)).toHaveLength(2);
    expect(canMergeQueue(mixedItems)).toBe(false);
    expect(canMergeQueue([])).toBe(false);
  });

  it('clamps one-based merge positions to zero-based insert slots', () => {
    expect(clampMergeInsertAt('1', 10)).toBe(0);
    expect(clampMergeInsertAt('5', 10)).toBe(4);
    expect(clampMergeInsertAt('99', 10)).toBe(10);
    expect(clampMergeInsertAt('-10', 10)).toBe(0);
    expect(clampMergeInsertAt('not-a-number', 10)).toBe(10);
  });

  it('creates readable merged PDF filenames', () => {
    expect(createMergedPdfName('base.pdf', ['a.pdf', 'b.pdf'], 'append')).toBe(
      'base_plus_2_pdfs.pdf'
    );
    expect(createMergedPdfName('base.pdf', ['a.pdf'], 'overwrite')).toBe(
      'a_merged.pdf'
    );
    expect(createMergedPdfName(null, ['a.pdf', 'b.pdf'], 'overwrite')).toBe(
      'merged_2_pdfs.pdf'
    );
  });
});