import { describe, it, expect } from 'vitest';
import crypto from 'crypto';
import { generateSign, verifySign } from '@/lib/easy-pay/sign';

const TEST_PKEY = 'test-merchant-secret-key';

describe('EasyPay MD5 Sign', () => {
  const testParams: Record<string, string> = {
    pid: '1001',
    type: 'alipay',
    out_trade_no: 'order-001',
    notify_url: 'https://pay.example.com/api/easy-pay/notify',
    return_url: 'https://pay.example.com/pay/result',
    name: 'Test Product',
    money: '10.00',
    clientip: '127.0.0.1',
  };

  describe('generateSign', () => {
    it('should generate a valid MD5 hex string', () => {
      const sign = generateSign(testParams, TEST_PKEY);
      expect(sign).toBeTruthy();
      expect(sign).toMatch(/^[0-9a-f]{32}$/);
    });

    it('should produce consistent signatures for same input', () => {
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(testParams, TEST_PKEY);
      expect(sign1).toBe(sign2);
    });

    it('should sort parameters alphabetically', () => {
      const reversed: Record<string, string> = {};
      const keys = Object.keys(testParams).reverse();
      for (const key of keys) {
        reversed[key] = testParams[key];
      }
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(reversed, TEST_PKEY);
      expect(sign1).toBe(sign2);
    });

    it('should filter out empty values', () => {
      const paramsWithEmpty = { ...testParams, empty_field: '' };
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(paramsWithEmpty, TEST_PKEY);
      expect(sign1).toBe(sign2);
    });

    it('should exclude sign field from signing', () => {
      const paramsWithSign = { ...testParams, sign: 'old_sign' };
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(paramsWithSign, TEST_PKEY);
      expect(sign1).toBe(sign2);
    });

    it('should exclude sign_type field from signing', () => {
      const paramsWithSignType = { ...testParams, sign_type: 'MD5' };
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(paramsWithSignType, TEST_PKEY);
      expect(sign1).toBe(sign2);
    });

    it('should produce correct MD5 hash for known input', () => {
      // Manually compute expected: sorted keys → query string → append pkey → MD5
      const sorted = Object.entries(testParams)
        .filter(([, v]) => v !== '')
        .sort(([a], [b]) => a.localeCompare(b));
      const queryString = sorted.map(([k, v]) => `${k}=${v}`).join('&');
      const expected = crypto
        .createHash('md5')
        .update(queryString + TEST_PKEY)
        .digest('hex');

      const sign = generateSign(testParams, TEST_PKEY);
      expect(sign).toBe(expected);
    });

    it('should produce different signatures for different pkeys', () => {
      const sign1 = generateSign(testParams, TEST_PKEY);
      const sign2 = generateSign(testParams, 'different-key');
      expect(sign1).not.toBe(sign2);
    });

    it('should produce different signatures for different params', () => {
      const sign1 = generateSign(testParams, TEST_PKEY);
      const modified = { ...testParams, money: '99.99' };
      const sign2 = generateSign(modified, TEST_PKEY);
      expect(sign1).not.toBe(sign2);
    });
  });

  describe('verifySign', () => {
    it('should return true for a valid signature', () => {
      const sign = generateSign(testParams, TEST_PKEY);
      const valid = verifySign(testParams, TEST_PKEY, sign);
      expect(valid).toBe(true);
    });

    it('should return false for an invalid signature', () => {
      const valid = verifySign(testParams, TEST_PKEY, 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');
      expect(valid).toBe(false);
    });

    it('should return false for tampered params', () => {
      const sign = generateSign(testParams, TEST_PKEY);
      const tampered = { ...testParams, money: '999.99' };
      const valid = verifySign(tampered, TEST_PKEY, sign);
      expect(valid).toBe(false);
    });

    it('should return false for wrong pkey', () => {
      const sign = generateSign(testParams, TEST_PKEY);
      const valid = verifySign(testParams, 'wrong-key', sign);
      expect(valid).toBe(false);
    });

    it('should return false when sign length differs (timing-safe guard)', () => {
      const valid = verifySign(testParams, TEST_PKEY, 'short');
      expect(valid).toBe(false);
    });

    it('should use timing-safe comparison (same length, different content)', () => {
      const sign = generateSign(testParams, TEST_PKEY);
      // Flip the first character to create a same-length but different sign
      const flipped = (sign[0] === 'a' ? 'b' : 'a') + sign.slice(1);
      const valid = verifySign(testParams, TEST_PKEY, flipped);
      expect(valid).toBe(false);
    });
  });
});