import { getHistoryCompletionItems, readHistory, saveHistory } from '../history';

describe('LogQL query history', () => {
  const historyKey = 'logql-history-test';

  beforeEach(() => {
    window.localStorage.clear();
  });

  it('does not read or write history without a key', () => {
    expect(saveHistory(undefined, 'service:api', 1)).toEqual([]);
    expect(window.localStorage.length).toBe(0);
    expect(readHistory(undefined)).toEqual([]);
  });

  it('does not save blank queries', () => {
    expect(saveHistory(historyKey, '   ', 1)).toEqual([]);
    expect(window.localStorage.getItem(historyKey)).toBeNull();
  });

  it('increments the usage count for an existing query', () => {
    saveHistory(historyKey, 'service:api', 1);
    saveHistory(historyKey, 'service:api', 2);

    expect(readHistory(historyKey)).toEqual([{ query: 'service:api', usageCount: 2, lastUsedAt: 2 }]);
  });

  it('evicts the least-used and then oldest query after 20 items', () => {
    for (let index = 0; index < 20; index += 1) {
      saveHistory(historyKey, `query-${index}`, index + 1);
    }
    saveHistory(historyKey, 'query-19', 30);
    saveHistory(historyKey, 'query-new', 31);

    const history = readHistory(historyKey);
    expect(history).toHaveLength(20);
    expect(history.find((item) => item.query === 'query-0')).toBeUndefined();
    expect(history.find((item) => item.query === 'query-19')?.usageCount).toBe(2);
  });

  it('returns only the ten most-used records for completion', () => {
    for (let index = 0; index < 12; index += 1) {
      for (let count = 0; count <= index; count += 1) {
        saveHistory(historyKey, `query-${index}`, index * 100 + count);
      }
    }

    const completions = getHistoryCompletionItems(historyKey);
    expect(completions).toHaveLength(10);
    expect(completions[0].query).toBe('query-11');
    expect(completions[9].query).toBe('query-2');
  });

  it('silently ignores invalid cached data', () => {
    window.localStorage.setItem(historyKey, '{not json');
    expect(readHistory(historyKey)).toEqual([]);
    expect(() => saveHistory(historyKey, 'service:api', 1)).not.toThrow();
  });

  it('silently handles unavailable localStorage', () => {
    const getItem = jest.spyOn(Storage.prototype, 'getItem').mockImplementation(() => {
      throw new Error('unavailable');
    });
    const setItem = jest.spyOn(Storage.prototype, 'setItem').mockImplementation(() => {
      throw new Error('unavailable');
    });

    expect(() => saveHistory(historyKey, 'service:api', 1)).not.toThrow();

    getItem.mockRestore();
    setItem.mockRestore();
  });
});