<?php
function convert_csv($inputFile, $outputFile) {
    $strip_bom = function ($s) {
        if ($s === null) return '';
        if (strncmp($s, "\xEF\xBB\xBF", 3) === 0) {
            return substr($s, 3);
        }
        return $s;
    };

    $in = @fopen($inputFile, 'r');
    if ($in === false) {
        return false;
    }

    // Read header
    $header = fgetcsv($in, 0, ',', '"', '\\');
    if ($header === false) {
        fclose($in);
        return false;
    }

    // Normalize header names and build index map
    $index = [];
    foreach ($header as $i => $name) {
        $name = trim($strip_bom($name));
        $index[$name] = $i;
    }

    $get = function ($row, $name) use ($index) {
        if (!isset($index[$name])) return '';
        $i = $index[$name];
        return isset($row[$i]) ? trim($row[$i]) : '';
    };

    $out = @fopen($outputFile, 'w');
    if ($out === false) {
        fclose($in);
        return false;
    }

    // Output header using semicolon separator
    $outHeader = [
        'Data księgowania',
        'Nadawca / Odbiorca',
        'Adres nadawcy / odbiorcy',
        'Rachunek źródłowy',
        'Rachunek docelowy',
        'Tytuł',
        'Kwota'
    ];
    fputcsv($out, $outHeader, ';');

    while (($row = fgetcsv($in, 0, ',', '"', '\\')) !== false) {
        // Skip completely empty rows
        $nonEmpty = false;
        foreach ($row as $v) {
            if ($v !== null && $v !== '') { $nonEmpty = true; break; }
        }
        if (!$nonEmpty) continue;

        $date = $get($row, 'Date completed (UTC)');
        if ($date === '') {
            $date = $get($row, 'Date started (UTC)');
        }

        $description = $get($row, 'Description');
        $payer = $get($row, 'Payer');
        $counterparty = $description !== '' ? $description : $payer;

        $sourceAccount = $get($row, 'Account');

        $benefIban = $get($row, 'Beneficiary IBAN');
        $benefAccNo = $get($row, 'Beneficiary account number');
        $destAccount = $benefIban !== '' ? $benefIban : $benefAccNo;

        $reference = $get($row, 'Reference');
        $type = $get($row, 'Type');
        $title = $reference !== '' ? $reference : str_replace('_', ' ', $type);
        if ($title === '' && $counterparty !== '') {
            $title = $counterparty;
        }

        // Prefer Amount, then Total amount, then Orig amount
        $amount = $get($row, 'Amount');
        if ($amount === '') $amount = $get($row, 'Total amount');
        if ($amount === '') $amount = $get($row, 'Orig amount');

        // Normalize decimal separator just in case
        $amount = str_replace(',', '.', $amount);

        $outputRow = [
            $date,
            $counterparty,
            '',
            $sourceAccount,
            $destAccount,
            $title,
            $amount
        ];

        fputcsv($out, $outputRow, ';');
    }

    fclose($in);
    fclose($out);
    return true;
}