import {
  DEFAULT_MEMOIR_READING_PREFERENCES,
  mergeMemoirReadingPreferences,
  parseMemoirReadingPreferences,
} from '@/core/settings/memoir-reading-settings';

describe('parseMemoirReadingPreferences', () => {
  it('returns defaults for null and empty', () => {
    expect(parseMemoirReadingPreferences(null)).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
    expect(parseMemoirReadingPreferences('')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
    expect(parseMemoirReadingPreferences('   ')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
  });

  it('returns defaults for invalid JSON', () => {
    expect(parseMemoirReadingPreferences('not json')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
  });

  it('returns defaults for non-object JSON', () => {
    expect(parseMemoirReadingPreferences('[]')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
    expect(parseMemoirReadingPreferences('"x"')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
  });

  it('fills missing or invalid fields from defaults', () => {
    expect(parseMemoirReadingPreferences('{}')).toEqual(
      DEFAULT_MEMOIR_READING_PREFERENCES,
    );
    expect(
      parseMemoirReadingPreferences(
        JSON.stringify({
          fontSize: 'huge',
          fontFamily: 'comic',
          background: 'black',
        }),
      ),
    ).toEqual(DEFAULT_MEMOIR_READING_PREFERENCES);
  });

  it('accepts valid partial object', () => {
    expect(
      parseMemoirReadingPreferences(
        JSON.stringify({ fontSize: 'large' }),
      ),
    ).toEqual(
      mergeMemoirReadingPreferences(DEFAULT_MEMOIR_READING_PREFERENCES, {
        fontSize: 'large',
      }),
    );
    expect(
      parseMemoirReadingPreferences(
        JSON.stringify({ background: 'sepia', fontFamily: 'sans' }),
      ),
    ).toEqual({
      ...DEFAULT_MEMOIR_READING_PREFERENCES,
      background: 'sepia',
      fontFamily: 'sans',
    });
  });
});

describe('mergeMemoirReadingPreferences', () => {
  it('applies only defined patch keys', () => {
    const base = {
      fontSize: 'small' as const,
      fontFamily: 'sans' as const,
      background: 'sepia' as const,
    };
    expect(mergeMemoirReadingPreferences(base, { fontSize: 'large' })).toEqual({
      fontSize: 'large',
      fontFamily: 'sans',
      background: 'sepia',
    });
    expect(mergeMemoirReadingPreferences(base, {})).toEqual(base);
  });
});