Use historic BTC rate for expense items; allow BTC as currency

app/components/add-expense-item/component.js

@@ -18,7 +18,8 @@ export default class AddExpenseItemComponent extends Component {
 
   currencies = [
     { code: 'EUR' },
-    { code: 'USD' }
+    { code: 'USD' },
+    { code: 'BTC' }
   ];
 
   get isValidAmount () {

app/components/add-reimbursement/component.js

@@ -5,7 +5,9 @@ import { inject as service } from '@ember/service';
 import { action } from '@ember/object';
 import { A } from '@ember/array';
 import { scheduleOnce } from '@ember/runloop';
+import { btcToSats, satsToBtc } from 'kredits-web/utils/btc-conversions';
 import isValidAmount from 'kredits-web/utils/is-valid-amount';
+import isoDateIsToday from 'kredits-web/utils/iso-date-is-today';
 import readFileContent from 'kredits-web/utils/read-file-content';
 import config from 'kredits-web/config/environment';
 
@@ -73,22 +75,6 @@ export default class AddReimbursementComponent extends Component {
     anchor.scrollIntoView();
   }
 
-  updateTotalAmountFromFiat() {
-    let btcAmount = 0;
-
-    if (this.exchangeRates.btceur > 0 && this.totalEUR > 0) {
-      btcAmount += (this.totalEUR / this.exchangeRates.btceur);
-    }
-    if (this.exchangeRates.btcusd > 0 && this.totalUSD > 0) {
-      btcAmount += (this.totalUSD / this.exchangeRates.btcusd);
-    }
-    if (this.totalUSD === 0 && this.totalEUR === 0) {
-      btcAmount = 0;
-    }
-
-    this.total = btcAmount.toFixed(8);
-  }
-
   // TODO use ember-concurrency here
   // https://github.com/67P/kredits-web/pull/209#discussion_r1064234421
   @action
@@ -118,16 +104,38 @@ export default class AddReimbursementComponent extends Component {
   }
 
   @action
-  addExpenseItem (expenseItem) {
-    this.expenses.pushObject(expenseItem);
-    this.updateTotalAmountFromFiat();
+  async addExpenseItem (expense) {
+    let totalBTC = parseFloat(this.total);
+
+    if (expense.currency === "BTC") {
+      expense.amountSats = btcToSats(expense.amount);
+      totalBTC += expense.amount;
+    } else {
+      let amountSats;
+      if (isoDateIsToday(expense.date)) {
+        amountSats = btcToSats(expense.amount / this.exchangeRates[expense.currency]);
+      } else {
+        const rates = await this.exchangeRates.fetchHistoricRates(expense.date);
+        amountSats = btcToSats(expense.amount / rates[expense.currency]);
+      }
+      expense.amountSats = amountSats;
+      totalBTC += satsToBtc(amountSats);
+    }
+    console.debug("Adding expense:", expense);
+
+    this.total = totalBTC.toFixed(8);
+    this.expenses.pushObject(expense);
     this.expenseFormVisible = false;
   }
 
   @action
-  removeExpenseItem (expenseItem) {
-    this.expenses.removeObject(expenseItem);
-    this.updateTotalAmountFromFiat();
+  async removeExpenseItem (expense) {
+    let totalBTC = parseFloat(this.total);
+    let amountBTC = satsToBtc(expense.amountSats);
+    totalBTC = totalBTC - amountBTC;
+    this.total = totalBTC.toFixed(8);
+
+    this.expenses.removeObject(expense);
 
     if (this.expenses.length === 0) {
       this.expenseFormVisible = true;
@@ -143,7 +151,7 @@ export default class AddReimbursementComponent extends Component {
     const contributor = this.contributors.findBy('id', this.contributorId);
 
     const attributes = {
-      amount: parseInt(parseFloat(this.total) * 100000000), // convert to sats
+      amount: btcToSats(this.total),
       token: config.tokens['BTC'],
       recipientId: this.contributorId,
       title: `Expenses covered by ${contributor.name}`,

app/helpers/fmt-fiat-currency.js

@@ -2,10 +2,14 @@ import { helper } from '@ember/component/helper';
 
 export default helper(function fmtFiatCurrency(params) {
   const lang = navigator.language || navigator.userLanguage;
+  const value = params[0];
+  const currency = params[1] || 'EUR';
+
+  if (currency === 'BTC') return `BTC ${value}`;
+
   const formatter = new Intl.NumberFormat(lang, {
-    style: 'currency',
-    currency: params[1] || 'EUR',
-    currencyDisplay: 'code'
+    style: 'currency', currency, currencyDisplay: 'code'
   })
+
   return formatter.format(params[0]);
 });

app/services/community-funds.js

@@ -42,7 +42,7 @@ export default class CommunityFundsService extends Service {
 
     // Format and round the approximate USD value
     const lang = navigator.language || navigator.userLanguage;
-    const balanceUSD = (res.confirmed_balance / 100000000) * this.exchangeRates.btcusd;
+    const balanceUSD = (res.confirmed_balance / 100000000) * this.exchangeRates.USD;
     res.balanceUSD = Math.round(balanceUSD).toLocaleString(lang);
 
     this.balances.pushObject({

app/services/exchange-rates.js

@@ -4,6 +4,7 @@ import config from 'kredits-web/config/environment';
 
 // Need to go through proxy for CORS headers
 const bitstampBaseUrl = `${config.corsProxy}https://www.bitstamp.net/api/v2`;
+const kosmosBtcPriceBaseUrl = "https://storage.kosmos.org/kosmos/public/btc-price";
 
 async function fetchFromBitstamp(currencyPair) {
   try {
@@ -16,11 +17,12 @@ async function fetchFromBitstamp(currencyPair) {
 }
 
 export default class ExchangeRatesService extends Service {
-  @tracked btceur = 0;
-  @tracked btcusd = 0;
+  @tracked EUR = 0;
+  @tracked USD = 0;
+  @tracked historic = {};
 
   get exchangeRatesLoaded () {
-    return (this.btceur !== 0) && (this.btcusd !== 0);
+    return (this.EUR !== 0) && (this.USD !== 0);
   }
 
   async fetchRates (source='bitstamp') {
@@ -28,8 +30,24 @@ export default class ExchangeRatesService extends Service {
 
     switch(source) {
       case 'bitstamp':
-        this.btceur = await fetchFromBitstamp('btceur');
-        this.btcusd = await fetchFromBitstamp('btcusd');
+        this.EUR = await fetchFromBitstamp('btceur');
+        this.USD = await fetchFromBitstamp('btcusd');
+    }
+  }
+
+  async fetchHistoricRates (isoDate) {
+    if (typeof this.historic[isoDate] === "object") {
+      return this.historic[isoDate];
+    } else {
+      const url = `${kosmosBtcPriceBaseUrl}/${isoDate}`;
+      try {
+        const rates = await fetch(url).then(res => res.json());
+        this.historic[isoDate] = rates;
+        return rates;
+      } catch(e) {
+        console.error(e);
+        Promise.reject(e);
+      }
     }
   }
 }

tests/integration/helpers/fmt-fiat-currency-test.js

@@ -18,5 +18,12 @@ module('Integration | Helper | fmt-fiat-currency', function(hooks) {
     await render(hbs`{{fmt-fiat-currency this.amount 'USD'}}`);
     assert.ok(this.element.textContent.trim().match(/USD/),
               'using defined currency when given');
+
+    await render(hbs`{{fmt-fiat-currency 0.00123 'BTC'}}`);
+    assert.ok(this.element.textContent.trim().match(/0.00123/),
+              'allows more decimals');
+    assert.ok(this.element.textContent.trim().match(/BTC/),
+              'using defined currency when given');
   });
+
 });

tests/unit/components/add-reimbursement-test.js

@@ -39,12 +39,4 @@ module('Unit | Component | add-reimbursement', function(hooks) {
     assert.equal(component.totalEUR, '71');
     assert.equal(component.totalUSD, '59');
   });
-
-  test('#updateTotalAmountFromFiat', async function(assert) {
-    let component = createComponent('component:add-reimbursement');
-    component.expenses = expenses;
-    await component.exchangeRates.fetchRates();
-    component.updateTotalAmountFromFiat();
-    assert.equal(component.total, '0.01323322', 'converts EUR and USD totals to BTC and rounds to 8 decimals');
-  });
 });

tests/unit/services/exchange-rates-test.js

@@ -7,7 +7,7 @@ module('Unit | Service | exchange-rates', function(hooks) {
   test('#fetchRates', async function(assert) {
     let service = this.owner.lookup('service:exchange-rates');
     await service.fetchRates();
-    assert.equal(service.btceur, 9167.57, 'fetches BTCEUR from Bitstamp');
-    assert.equal(service.btcusd, 10749.70, 'fetches BTCUSD from Bitstamp');
+    assert.equal(service.EUR, 9167.57, 'fetches BTCEUR from Bitstamp');
+    assert.equal(service.USD, 10749.70, 'fetches BTCUSD from Bitstamp');
   });
 });