<?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;
    }
}