<?php

declare(strict_types=1);

namespace Tests\Unit;

use App\Services\SimulationTaxRuleExpression;
use InvalidArgumentException;
use PHPUnit\Framework\Attributes\Test;
use PHPUnit\Framework\TestCase;

final class SimulationTaxRuleExpressionTest extends TestCase
{
    #[Test]
    public function it_evaluates_a_whitelisted_dag_with_exact_decimal_arithmetic_and_explicit_rounding(): void
    {
        $definition = $this->definition();
        $result = (new SimulationTaxRuleExpression)->evaluate($definition, ['base' => '1234.56'], ['rate' => '0.16']);

        self::assertSame('determinate', $result['status']);
        self::assertSame('19753/100', $result['result']);
        self::assertCount(4, $result['steps']);
    }

    #[Test]
    public function it_reports_missing_values_as_indeterminate_without_defaults(): void
    {
        $result = (new SimulationTaxRuleExpression)->evaluate($this->definition(), [], []);

        self::assertSame('indeterminate', $result['status']);
        self::assertNull($result['result']);
        self::assertSame(['input:base', 'parameter:rate'], $result['missing']);
    }

    #[Test]
    public function it_rejects_cycles_unknown_operations_and_undeclared_fields(): void
    {
        $engine = new SimulationTaxRuleExpression;
        $cycle = ['language' => 'investmoz.tax.v1', 'nodes' => ['a' => ['op' => 'add', 'args' => ['b', 'b']], 'b' => ['op' => 'add', 'args' => ['a', 'a']]], 'result' => 'a'];
        $unknown = ['language' => 'investmoz.tax.v1', 'nodes' => ['a' => ['op' => 'execute', 'code' => 'x']], 'result' => 'a'];
        $extra = ['language' => 'investmoz.tax.v1', 'nodes' => ['a' => ['op' => 'literal', 'value' => '1', 'formula' => 'x']], 'result' => 'a'];

        foreach ([$cycle, $unknown, $extra] as $invalid) {
            try {
                $engine->validate($invalid);
                self::fail('Invalid DSL was accepted.');
            } catch (InvalidArgumentException) {
                self::assertTrue(true);
            }
        }
    }

    /** @return array<string,mixed> */
    private function definition(): array
    {
        return [
            'language' => 'investmoz.tax.v1',
            'nodes' => [
                'base' => ['op' => 'input', 'key' => 'base'],
                'rate' => ['op' => 'parameter', 'key' => 'rate'],
                'raw' => ['op' => 'multiply', 'args' => ['base', 'rate']],
                'tax' => ['op' => 'round', 'args' => ['raw'], 'scale' => 2, 'mode' => 'HALF_UP'],
            ],
            'result' => 'tax',
        ];
    }
}