groupByType functionality for transactions (#22)

src/lib/manager/reportmanager.ts

@@ -9,9 +9,38 @@ import * as Utils from '../utils';
 import moment from 'moment';
 import { BreakdownFormatted, Breakdown } from '../../types/breakdown';
 
+type TransactionGroups = { [key: string]: { transactions: Transaction[], seen: { [key: string]: number } } };
+
 export const reportManager = {
-  countByType: (txns: Transaction[]) => {
+  /**
+   * groups transactions by type if their type is within the given types
+   * transactions should be ordered by ascending date order
+   */
+  groupByType: (transactions: Transaction[], types: string[]): TransactionGroups => {
+    const groups: TransactionGroups = { };
+    let idx = 0;
+
+    transactions.forEach(txn => {
+      if (types.indexOf(txn.type) !== -1) {
+        if (!groups[txn.type]) {
+          groups[txn.type] = {
+            transactions: [],
+            seen: {},
+          };
+        }
+
+        let group = groups[txn.type];
+
+        if (group.seen[txn.description] === undefined) {
+          group.transactions.push(txn);
+          group.seen[txn.description] = idx++;
+        } else {
+          group.transactions[group.seen[txn.description]] = txn;
+        }
+      }
+    });
 
+    return groups;
   },
 
   generateWebFrontendReport: (txns: Transaction[]): FormattedTransaction[] => {

test/manager/reportmanager.spec.ts

@@ -0,0 +1,63 @@
+import { reportManager } from '../../src/lib/manager/reportmanager';
+import { Transaction } from '../../src/lib/transaction';
+import { expect } from 'chai';
+
+describe('report manager', () => {
+  it('groups by type', () => {
+    const transactions: Transaction[] = [
+      {
+        description: 'Virgin Media',
+        debitAmount: 40,
+        type: 'DD',
+        date: '2018-01-01T00:00:00Z',
+      },
+      {
+        description: 'Virgin Media',
+        debitAmount: 77,
+        type: 'DD',
+        date: '2018-02-01T00:00:00Z',
+      },
+      {
+        description: 'Virgin Media',
+        debitAmount: 77,
+        type: 'DD',
+        date: '2018-02-02T00:00:00Z',
+      },
+      {
+        description: 'TFL',
+        debitAmount: 130,
+        type: 'DD',
+        date: '2018-03-01T00:00:00Z',
+      },
+      {
+        description: 'Rent',
+        debitAmount: 1000,
+        type: 'SO',
+        date: '2018-03-07T00:00:00Z',
+      },
+      {
+        description: 'Salary',
+        creditAmount: 2000,
+        type: 'FPI',
+        date: '2018-03-30T00:00:00Z',
+      },
+      {
+        description: 'Some random spends',
+        debitAmount: 12,
+        type: 'DEB',
+        date: '2018-04-01T00:00:00Z'
+      },
+    ].map(t => new Transaction(t));
+
+    let groups = reportManager.groupByType(transactions, ['DD',  'SO']);
+    expect(Object.keys(groups)).to.deep.equal(['DD', 'SO']);
+    expect(groups['DD']).to.have.property('transactions').with.lengthOf(2);
+    expect(groups['DD'].transactions[0].description).to.equal('Virgin Media');
+    expect(groups['DD'].transactions[0].debitAmount).to.equal(77);
+    expect(groups['DD'].transactions[1].description).to.equal('TFL');
+    expect(groups['DD'].transactions[1].debitAmount).to.equal(130);
+    expect(groups['SO']).to.have.property('transactions').with.lengthOf(1);
+    expect(groups['SO'].transactions[0].description).to.equal('Rent');
+    expect(groups['SO'].transactions[0].debitAmount).to.equal(1000);
+  });
+});