<?php
function convert_csv($inputPath, $outputPath) {
    if (!is_readable($inputPath)) {
        throw new RuntimeException("Input file not readable: $inputPath");
    }

    $in = fopen($inputPath, 'rb');
    if ($in === false) {
        throw new RuntimeException("Failed to open input file: $inputPath");
    }

    $out = fopen($outputPath, 'wb');
    if ($out === false) {
        fclose($in);
        throw new RuntimeException("Failed to open output file: $outputPath");
    }

    // Read header and build index map
    $headers = fgetcsv($in);
    if ($headers === false) {
        fclose($in);
        fclose($out);
        throw new RuntimeException("Input CSV appears to be empty.");
    }

    // Handle potential BOM
    if (isset($headers[0])) {
        $headers[0] = preg_replace('/^\xEF\xBB\xBF/', '', $headers[0]);
    }

    // Build a map of header name (trimmed) to index
    $idx = [];
    foreach ($headers as $i => $name) {
        $norm = trim($name);
        $idx[$norm] = $i;
    }

    // Helper to fetch a cell by header name, with fallbacks
    $get = function(array $row, array $candidates) use ($idx) {
        foreach ($candidates as $cand) {
            if (isset($idx[$cand])) {
                $val = isset($row[$idx[$cand]]) ? $row[$idx[$cand]] : '';
                $val = is_string($val) ? trim($val) : $val;
                if ($val !== '' && $val !== null) {
                    return $val;
                }
            }
        }
        return '';
    };

    // Helper to normalize date to YYYY-MM-DD
    $normDate = function($s) {
        $s = trim($s);
        if ($s === '') {
            return '';
        }
        // Try to extract date part
        // Accept formats: YYYY-MM-DD, YYYY-MM-DDTHH:MM:SSZ, etc.
        if (preg_match('/^\d{4}-\d{2}-\d{2}/', $s, $m)) {
            return $m[0];
        }
        // Try strtotime
        $ts = strtotime($s);
        if ($ts !== false) {
            return date('Y-m-d', $ts);
        }
        return $s;
    };

    // Helper to normalize amount (use dot as decimal separator, keep sign)
    $normAmount = function($s) {
        $s = trim((string)$s);
        if ($s === '') return '0';
        // Replace comma decimal to dot, remove spaces
        $s = str_replace([' ', ','], ['', '.'], $s);
        // If it's a plain numeric string, keep as-is
        if (is_numeric($s)) {
            // Keep as minimally formatted string
            // Avoid scientific notation
            $f = (float)$s;
            // Preserve sign and decimals without trailing zeros if possible
            // Format with high precision then trim
            $str = rtrim(rtrim(number_format($f, 8, '.', ''), '0'), '.');
            return $str === '' ? '0' : $str;
        }
        return $s;
    };

    // Write output header (semicolon-separated)
    $outputHeader = [
        'Data księgowania',
        'Nadawca / Odbiorca',
        'Adres nadawcy / odbiorcy',
        'Rachunek źródłowy',
        'Rachunek docelowy',
        'Tytuł',
        'Kwota',
    ];
    // Use fputcsv with semicolon delimiter
    fputcsv($out, $outputHeader, ';');

    while (($row = fgetcsv($in)) !== false) {
        // Skip entirely empty rows
        if (count($row) === 1 && trim((string)$row[0]) === '') {
            continue;
        }

        // Extract fields using common header names
        $date = $get($row, ['Date completed (UTC)', 'Date started (UTC)', 'Date', 'Completed Date']);
        $date = $normDate($date);

        $description = $get($row, ['Description', 'Narrative', 'Details']);
        $payer = $get($row, ['Payer', 'Counterparty', 'Merchant']);
        $account = $get($row, ['Account', 'From', 'Source account']);

        $benefIban = $get($row, ['Beneficiary IBAN', 'Beneficiary account IBAN', 'IBAN']);
        $benefAccNo = $get($row, ['Beneficiary account number', 'Beneficiary account', 'Account number']);
        $benefRouting = $get($row, ['Beneficiary sort code or routing number', 'Routing number', 'Sort code']);

        $amount = $get($row, ['Amount', 'Total amount', 'Payment amount', 'Paid amount', 'Value']);
        if ($amount === '') {
            // Fallback to original amount if needed
            $amount = $get($row, ['Orig amount', 'Original amount']);
        }
        $amount = $normAmount($amount);

        $counterparty = $description !== '' ? $description : ($payer !== '' ? $payer : '');
        $title = $description !== '' ? $description : ($counterparty !== '' ? $counterparty : '');

        $destAccount = '';
        if ($benefIban !== '') {
            $destAccount = $benefIban;
        } elseif ($benefAccNo !== '') {
            $destAccount = $benefAccNo;
        } elseif ($benefRouting !== '') {
            $destAccount = $benefRouting;
        }

        $outRow = [
            $date,
            $counterparty,
            '',              // Adres nadawcy / odbiorcy (not provided in input)
            $account,
            $destAccount,
            $title,
            $amount,
        ];

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

    fclose($in);
    fclose($out);
}
?>