fix(hub): compensate minter-hub validation of amount not considering …

…discount

components/HubWithdrawForm.vue

@@ -2,6 +2,7 @@
 import Big from '~/assets/big.js';
 import {validationMixin} from 'vuelidate';
 import required from 'vuelidate/lib/validators/required.js';
+import minValue from 'vuelidate/lib/validators/minValue.js';
 import maxValue from 'vuelidate/lib/validators/maxValue.js';
 import minLength from 'vuelidate/lib/validators/minLength.js';
 import autosize from 'v-autosize';
@@ -139,9 +140,11 @@ export default {
  const inverseRate = new Big(this.hubFeeRate).div(new Big(1).minus(this.hubFeeRate));
  return amount.times(inverseRate).toString();
  },
+ /*
  totalFee() {
  return new Big(this.coinFee).plus(this.hubFee).toString();
  },
+ */
  amountToSend() {
  return new Big(this.form.amount || 0).plus(this.coinFee).plus(this.hubFee).toString();
  },
@@ -170,6 +173,9 @@ export default {
  return maxAmount.toString();
  }
  },
+ minAmount() {
+ return getHubMinAmount(this.coinFee, this.hubFeeRate);
+ },
  suggestionList() {
  return this.hubCoinList
  // show only available coins for selected network
@@ -224,7 +230,7 @@ export default {
  amount: {
  required,
  // validAmount: isValidAmount,
- minValue: (value) => value > 0,
+ minValue: minValue(this.minAmount),
  maxValue: maxValue(this.maxAmount || 0),
  },
  },
@@ -375,6 +381,48 @@ export default {
  },
  },
 };
+
+/**
+ * // Minter Hub not consider discount in amount validation, so we need compensate amount for discount difference
+ * @param {number|string} destinationNetworkFee
+ * @param {number|string} hubFeeRate
+ * @param {number|string} hubFeeBaseRate - hub fee rate without discount (0.01)
+ * @return {number|string}
+ */
+function getHubMinAmount(destinationNetworkFee, hubFeeRate, hubFeeBaseRate = 0.01) {
+ // minAmount = hubFeeBase - hubFee
+ // But while form.amount increase hubFee increase too, so we need to find such formAmount which will be equal minAmount, it will be maximum minAmount
+
+ // Some 7 grade math below
+ // hubFeeBase = (destinationNetworkFee + formAmount) * (0.01 / (1 - 0.01));
+ // hubFee = (destinationNetworkFee + formAmount) * (hubFeeRate / (1 - hubFeeRate))
+ // define (a = hubFeeBaseRate; b = hubFeeRate)
+ // minAmount = (destinationNetworkFee + formAmount) * (a / (1 - a)) - (destinationNetworkFee + formAmount) * (b / (1 - b))
+ // minAmount = (destinationNetworkFee + formAmount) * ((a / (1 - a) - (b / (1 - b));
+ // minAmount = (destinationNetworkFee + formAmount) * x;
+
+ // Let's calculate factor x
+ // x = a / (1 - a) - b / (1 - b)
+ // x = a * (1-b) / ((1-a)*(1-b)) - b * (1-a) / ((1-a)*(1-b))
+ // x = (a * (1-b) - b * (1-a)) / ((1-a)*(1-b))
+ // x = (a - ab - b + ab) / ((1-a)*(1-b))
+ // x = (a - b) / ((1-a)*(1-b))
+ // const factor = (hubFeeBaseRate - hubFeeRate) / ((1 - hubFeeBaseRate) * (1 - hubFeeRate));
+ const factor = new Big(hubFeeBaseRate).minus(hubFeeRate).div(new Big(1).minus(hubFeeBaseRate).times(new Big(1).minus(hubFeeRate))).toString();
+
+ // We are finding formAmount equal to minAmount (fa = formAmount, dnf = destinationNetworkFee)
+ // fa = minAmount
+ // fa = (fa + dnf) * x
+ // fa = fa * x + dnf * x
+ // fa - fa * x = dnf * x
+ // fa * 1 - fa * x = dnf * x
+ // fa * (1 -x) = dnf * x
+ // fa = dnf * x / (1 - x)
+ // const minAmount = destinationNetworkFee * factor / (1 - factor);
+ const minAmount = new Big(destinationNetworkFee).times(factor).div(new Big(1).minus(factor)).toString();
+ // add 1 pip because 0 will not pass validation too
+ return new Big(minAmount).plus(1e-18).toString();
+}
 </script>
 
 <template>
@@ -426,7 +474,7 @@ export default {
  :max-value="maxAmount"
  />
  <span class="form-field__error" v-if="$v.form.amount.$dirty && !$v.form.amount.required">{{ $td('Enter amount', 'form.amount-error-required') }}</span>
- <span class="form-field__error" v-else-if="$v.form.amount.$dirty && (!$v.form.amount.minValue)">{{ $td('Invalid amount', 'form.amount-error-invalid') }}</span>
+ <span class="form-field__error" v-else-if="$v.form.amount.$dirty && (!$v.form.amount.minValue)">{{ $td(`Minimum ${minAmount}`, 'form.amount-error-min', {min: minAmount}) }}</span>
  <span class="form-field__error" v-else-if="$v.form.amount.$dirty && !$v.form.amount.maxValue">{{ $td('Not enough', 'form.amount-error-not-enough') }} {{ form.coin }} ({{ $td('max.', 'hub.max') }} {{ pretty(maxAmount) }})</span>
  </div>
  <div class="u-cell u-cell--large--1-2 u-cell--large-down--order-minus">

lang/ru.js

@@ -392,6 +392,7 @@ export default {
  'amount': 'Количество',
  'amount-error-required': 'Укажите количество',
  'amount-error-invalid': 'Некорректное количество',
+ 'amount-error-min': 'Минимум {min}',
  'amount-error-not-enough': 'Недостаточно',
  'number-invalid': 'Укажите положительное целое число',
  'fee': 'Монета для оплаты комиссии',