startPayment static method

Implementation

static Future<PhonePePaymentResult> startPayment({
  required BuildContext context,
  required PhonePeConfig config,
  required int amountPaise, // ₹ * 100
  required String returnDeepLink, // e.g. myapp://payment-return
  String? merchantUserId,
  String? merchantTransactionId,
  String? appBarTitle,
}) async {
  final base = config.environment.baseUrl;

  final txnId =
      merchantTransactionId ?? 'TXN_${DateTime.now().millisecondsSinceEpoch}';
  final userId =
      merchantUserId ?? 'user_${DateTime.now().millisecondsSinceEpoch}';

  if (config.enableLogs) {
    // ignore: avoid_print
    print(
      '[PhonePe] Env=${config.environment.label} Amount=$amountPaise Txn=$txnId',
    );
  }

  // 1) Build payload for /pg/v1/pay
  final payload = {
    'merchantId': config.merchantId,
    'merchantTransactionId': txnId,
    'merchantUserId': userId,
    'amount': amountPaise,
    'redirectUrl': returnDeepLink,
    'callbackUrl': returnDeepLink, // sandbox ok; use server webhook in prod
    'paymentInstrument': {'type': 'PAY_PAGE'},
  };

  final jsonPayload = jsonEncode(payload);
  final base64Payload = base64.encode(utf8.encode(jsonPayload));

  String xVerifyForPay() {
    const path = '/pg/v1/pay';
    final toSign = base64Payload + path + config.saltKey;
    final digest = sha256.convert(utf8.encode(toSign)).toString();
    return '$digest###${config.saltIndex}';
  }

  // 2) Create payment
  final payRes = await http.post(
    Uri.parse('$base/pg/v1/pay'),
    headers: {
      'Content-Type': 'application/json',
      'X-VERIFY': xVerifyForPay(),
      if (config.headers.isNotEmpty) ...config.headers,
    },
    body: jsonEncode({'request': base64Payload}),
  );

  if (config.enableLogs) {
    // ignore: avoid_print
    print('[PhonePe] /pay status=${payRes.statusCode} body=${payRes.body}');
  }

  if (payRes.statusCode != 200 && payRes.statusCode != 201) {
    throw PhonePeCheckoutException(
      'Create payment failed: ${payRes.statusCode} ${payRes.body}',
    );
  }

  final payBody = jsonDecode(payRes.body) as Map<String, dynamic>;
  final redirectUrl = payBody['data']?['instrumentResponse']?['redirectInfo']
      ?['url'] as String?;
  if (redirectUrl == null) {
    throw PhonePeCheckoutException('Missing redirect URL in create response');
  }

  // 3) Open WebView and intercept the deep link

  String interimStatus = 'pending';
  if (context.mounted) {
    await Navigator.of(context).push(
      MaterialPageRoute(
        builder: (_) => CheckoutWebView(
          returnDeepLink: returnDeepLink,
          checkoutUrl: redirectUrl,
          onReturn: (uri) {
            final statusId = uri.queryParameters['status_id'];
            // 1=success, 2=pending, 3=failed
            if (statusId == '1') {
              interimStatus = 'success';
            } else if (statusId == '3') {
              interimStatus = 'failed';
            } else {
              interimStatus = 'pending';
            }
          },
          appBarTitle: appBarTitle ?? 'PhonePe Checkout',
        ),
      ),
    );
  }

  // 4) Verify via Status API
  String xVerifyForStatus() {
    final path = '/pg/v1/status/${config.merchantId}/$txnId';
    final toSign = path + config.saltKey;
    final digest = sha256.convert(utf8.encode(toSign)).toString();
    return '$digest###${config.saltIndex}';
  }

  final statusRes = await http.get(
    Uri.parse('$base/pg/v1/status/${config.merchantId}/$txnId'),
    headers: {
      'Content-Type': 'application/json',
      'X-VERIFY': xVerifyForStatus(),
      'X-MERCHANT-ID': config.merchantId,
      if (config.headers.isNotEmpty) ...config.headers,
    },
  );

  if (config.enableLogs) {
    // ignore: avoid_print
    print(
      '[PhonePe] /status code=${statusRes.statusCode} body=${statusRes.body}',
    );
  }

  if (statusRes.statusCode != 200) {
    throw PhonePeCheckoutException(
      'Status check failed: ${statusRes.statusCode} ${statusRes.body}',
    );
  }

  final statusBody = jsonDecode(statusRes.body) as Map<String, dynamic>;
  final code = (statusBody['code'] ?? '').toString().toUpperCase();

  String finalStatus = interimStatus;
  if (code.contains('SUCCESS')) {
    finalStatus = 'SUCCESS';
  } else if (code.contains('ERROR') || code.contains('FAIL')) {
    finalStatus = 'FAILED';
  }

  return PhonePePaymentResult(
    merchantTransactionId: txnId,
    status: finalStatus,
    raw: {
      'flowId': config.flowId,
      'request': payload,
      'createResponse': payBody,
      'statusResponse': statusBody,
    },
  );
}