<?php

namespace App\Casts;

use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
use Illuminate\Support\Facades\Crypt;
use InvalidArgumentException;

/**
 * Encrypted decimal stored as ciphertext (string) with fixed scale.
 * Works with string or numeric inputs. Always returns string with fixed scale.
 */
class EncryptedDecimal implements CastsAttributes
{
    private int $scale;

    public function __construct(int $scale = 4)
    {
        if ($scale < 0 || $scale > 18) {
            throw new InvalidArgumentException('Invalid scale for EncryptedDecimal.');
        }
        $this->scale = $scale;
    }

    public function get($model, string $key, $value, array $attributes)
    {
        if ($value === null || $value === '') {
            // Treat null as zero but do not mutate DB implicitly
            return number_format(0, $this->scale, '.', '');
        }
        try {
            $plain = Crypt::decryptString((string) $value);
        } catch (\Throwable $e) {
            // If value is not decryptable (legacy/plain), try to normalize as plain string
            $plain = (string) $value;
        }
        return $this->normalize($plain);
    }

    public function set($model, string $key, $value, array $attributes)
    {
        if ($value === null || $value === '') {
            return [$key => null];
        }
        $normalized = $this->normalize($value);
        return [$key => Crypt::encryptString($normalized)];
    }

    private function normalize($value): string
    {
        // Accept numeric, string with comma/dot; normalize to string with fixed scale
        $s = is_string($value) ? trim($value) : (string) $value;
        $s = str_replace([',', ' '], ['', ''], $s);
        if (!preg_match('/^-?\d*(?:\.\d+)?$/', $s)) {
            throw new InvalidArgumentException('Invalid decimal value.');
        }
        if ($s === '' || $s === '-') {
            $s = '0';
        }
        // Use integer math on scaled value to avoid float precision
        $scale = $this->scale;
        // Split integer and fractional part
        $neg = str_starts_with($s, '-') ? '-' : '';
        if ($neg) $s = substr($s, 1);
        [$int, $frac] = array_pad(explode('.', $s, 2), 2, '');
        $frac = substr($frac . str_repeat('0', $scale), 0, $scale);
        $intPart = ltrim($int === '' ? '0' : $int, '0');
        if ($intPart === '') { $intPart = '0'; }
        $out = ($neg ? '-' : '') . $intPart;
        if ($scale > 0) {
            $out .= '.' . $frac;
        }
        return $out;
    }
}