src/Finance/BalanceCalculator.php

@@ -0,0 +1,90 @@
+<?php namespace RVR\Finance;
+
+use RVR\PersistentData\Model\Community;
+use RVR\Repository\CommunityMemberRepository;
+use RVR\Repository\TransactionRepository;
+
+class BalanceCalculator
+{
+    private Community $community;
+
+    private TransactionRepository $transactionRepository;
+
+    private CommunityMemberRepository $communityMemberRepository;
+
+    private ExchangeRateCalculator $exchangeRateCalculator;
+
+    private array $members;
+
+    private array $payments;
+
+    public function __construct(Community $community)
+    {
+        $this->community = $community;
+        $this->transactionRepository = new TransactionRepository();
+        $this->communityMemberRepository = new CommunityMemberRepository();
+        $this->exchangeRateCalculator = new ExchangeRateCalculator($this->community->getMainCurrency());
+    }
+
+    public function calculate(): array
+    {
+        $this->collectMembers();
+        $this->createPaymentsMatrix();
+        $this->sumTransactions();
+        return $this->calculateActualDebts();
+    }
+
+    private function collectMembers(): void
+    {
+        $this->members = [];
+        foreach ($this->communityMemberRepository->getAllByCommunity($this->community, true, ['user']) as $member) {
+            $this->members[$member->getUserId()] = $member;
+        }
+    }
+
+    private function createPaymentsMatrix(): void
+    {
+        $this->payments = [];
+        foreach ($this->members as $payerUserId => $member) {
+            $this->payments[$payerUserId] = [];
+            foreach ($this->members as $payeeUserId => $member) {
+                $this->payments[$payerUserId][$payeeUserId] = 0;
+            }
+        }
+    }
+
+    private function sumTransactions(): void
+    {
+        $membersCount = count($this->members);
+        $transactions = $this->transactionRepository->getAllByCommunity($this->community, true, ['currency']);
+
+        foreach ($transactions as $transaction) {
+            $sum = $this->exchangeRateCalculator->calculate($transaction->getSum(), $transaction->getCurrency(), $transaction->getTimeDate());
+
+            if ($transaction->getPayeeUserId()) {
+                $this->payments[$transaction->getPayerUserId()][$transaction->getPayeeUserId()] += $sum;
+            } else {
+                foreach ($this->members as $payeeUserId => $member) {
+                    $this->payments[$transaction->getPayerUserId()][$payeeUserId] += $sum / $membersCount;
+                }
+            }
+        }
+    }
+
+    private function calculateActualDebts(): array
+    {
+        $actualDebts = [];
+
+        foreach ($this->payments as $payerUserId => $paymentsOfPayer) {
+            foreach ($paymentsOfPayer as $payeeUserId => $sum) {
+                $actualDebt = $this->payments[$payeeUserId][$payerUserId] - $sum;
+
+                if (round($actualDebt, $this->community->getMainCurrency()->getRoundDigits()) > 0.0) {
+                    $actualDebts[] = ['payer' => $this->members[$payerUserId], 'payee' => $this->members[$payeeUserId], 'amount' => $actualDebt];
+                }
+            }
+        }
+
+        return $actualDebts;
+    }
+}