firefly-iii/app/Support/Amount.php

<?php

namespace FireflyIII\Support;

use FireflyIII\Models\Transaction;
/**
 * Class Amount
 *
 * @package FireflyIII\Support
 */
class Amount
{
    /**
     * @param \Transaction $transaction
     * @param bool         $coloured
     *
     * @return string
     */
    public function formatTransaction(Transaction $transaction, $coloured = true)
    {
        $symbol = $transaction->transactionJournal->transactionCurrency->symbol;
        $amount = floatval($transaction->amount);

        return $this->formatWithSymbol($symbol, $amount, $coloured);


    }


    /**
     * @param string $symbol
     * @param float  $amount
     * @param bool   $coloured
     *
     * @return string
     */
    public function formatWithSymbol($symbol, $amount, $coloured = true)
    {
        $amount = floatval($amount);
        $amount = round($amount, 2);
        $string = number_format($amount, 2, ',', '.');

        if ($coloured === true) {
            if ($amount === 0.0) {
                return '<span style="color:#999">' . $symbol . ' ' . $string . '</span>';
            }
            if ($amount > 0) {
                return '<span class="text-success">' . $symbol . ' ' . $string . '</span>';
            }

            return '<span class="text-danger">' . $symbol . ' ' . $string . '</span>';
        }

        // &#8364;
        return $symbol . ' ' . $string;
    }
}