import * as fc from 'fast-check';
import { describe, it, expect } from 'vitest';
import { getColor } from '../src/utils/color.js';

/**
 * Feature: ball-block-breaker, Property 17: 颜色计算有效性
 * **Validates: Requirements 8.6**
 *
 * 对于任意正整数 count，getColor(count) 应返回一个有效的7字符十六进制颜色字符串（格式为 #RRGGBB）。
 */
describe('Color Utils', () => {
  it('Property 17: getColor returns a valid 7-character hex color string for any positive integer', () => {
    fc.assert(
      fc.property(
        fc.integer({ min: 1, max: 1_000_000 }),
        (count) => {
          const color = getColor(count);

          // Must be a string of exactly 7 characters
          expect(typeof color).toBe('string');
          expect(color).toHaveLength(7);

          // Must start with '#'
          expect(color[0]).toBe('#');

          // Remaining 6 characters must be valid hex digits [0-9a-f]
          const hexPart = color.slice(1);
          expect(hexPart).toMatch(/^[0-9a-f]{6}$/);
        }
      ),
      { numRuns: 100 }
    );
  });
});