<?php

namespace App\Services\Import;

class DecimalNormalizer
{
    /**
     * Normalize a raw decimal string to a standard format (period as decimal separator).
     * Handles European format (comma as decimal) and American format (period as decimal).
     * 
     * Examples:
     * - "958,31" => "958.31"
     * - "1.234,56" => "1234.56"
     * - "1,234.56" => "1234.56"
     * - "1234" => "1234"
     * 
     * Based on ImportProcessor::normalizeDecimal()
     */
    public static function normalize(?string $raw): ?string
    {
        if ($raw === null) {
            return null;
        }

        // Keep digits, comma, dot, and minus to detect separators
        $s = preg_replace('/[^0-9,\.-]/', '', $raw) ?? '';
        $s = trim($s);
        
        if ($s === '') {
            return null;
        }

        $lastComma = strrpos($s, ',');
        $lastDot = strrpos($s, '.');
        
        // Determine decimal separator by last occurrence
        $decimalSep = null;
        if ($lastComma !== false || $lastDot !== false) {
            if ($lastComma === false) {
                $decimalSep = '.';
            } elseif ($lastDot === false) {
                $decimalSep = ',';
            } else {
                $decimalSep = $lastComma > $lastDot ? ',' : '.';
            }
        }

        // Remove all thousand separators and unify decimal to '.'
        if ($decimalSep === ',') {
            // Remove all dots (thousand separators)
            $s = str_replace('.', '', $s);
            // Replace last comma with dot
            $pos = strrpos($s, ',');
            if ($pos !== false) {
                $s[$pos] = '.';
            }
            // Remove any remaining commas (unlikely)
            $s = str_replace(',', '', $s);
        } elseif ($decimalSep === '.') {
            // Remove all commas (thousand separators)
            $s = str_replace(',', '', $s);
            // Dot is already decimal separator
        } else {
            // No decimal separator: remove commas/dots entirely
            $s = str_replace([',', '.'], '', $s);
        }

        // Handle negative numbers
        $s = ltrim($s, '+');
        $neg = false;
        if (str_starts_with($s, '-')) {
            $neg = true;
            $s = ltrim($s, '-');
        }
        // Remove any stray minus signs
        $s = str_replace('-', '', $s);
        if ($neg) {
            $s = '-' . $s;
        }

        return $s;
    }
}