<?php

declare(strict_types=1);

namespace App\Services;

use App\Models\InvestmentLegalSource;
use App\Models\User;
use App\Support\IsolatedQaDatabase;
use Brick\Math\BigRational;
use Illuminate\Support\Facades\DB;

/** Exact operation-level IVA calculation against an explicit QA draft; never a payment/return total. */
final class SimulationFiscalQaPreview
{
    public function create(User $actor, string $ruleId, array $input, string $key): array
    {
        abort_unless(IsolatedQaDatabase::allowsSchemaChanges(), 404);

        return DB::transaction(function () use ($actor, $ruleId, $input, $key): array {
            $rule = app(SimulationTaxRuleGovernance::class)->show($actor, $ruleId);
            abort_unless($rule->status === 'draft' && $rule->rule_code === 'IVA-GERAL-BASE-LIQUIDA', 422,
                'Seleccione o rascunho do primeiro lote fiscal.');
            abort_if(collect($rule->rule_definition['nodes'] ?? [])->contains(fn (array $node): bool => ($node['op'] ?? null) === 'round'), 422,
                'Este percurso preserva o valor exacto e não aplica arredondamento automático.');
            $source = InvestmentLegalSource::findOrFail($rule->legal_source_id);
            $version = $rule->attributesToArray();
            $version['source'] = $source->attributesToArray();
            $date = $input['reference_date'];
            $context = ['operation' => $input['operation'], 'currency' => $input['currency']];
            $missing = [];
            $resolution = [];
            $evaluation = null;
            if ($date < '2026-01-01' || $date > '2026-12-31') {
                $missing[] = 'demonstrated_coverage';
            } else {
                $resolution = app(SimulationTaxParameterResolver::class)->resolveDraftForQa([$version], 'IVA', $date, $date, $context);
                $rate = collect($resolution)->firstWhere('parameter_code', 'IVA_GENERAL_RATE');
                if (($rate['status'] ?? null) !== 'resolved' || ($rate['unit'] ?? null) !== 'percent') {
                    $missing[] = 'eligible_parameter';
                } else {
                    $evaluation = app(SimulationTaxRuleExpression::class)->evaluate($rule->rule_definition,
                        ['base_tributavel' => $input['base']], ['iva_general_rate' => $rate['value']]);
                }
            }
            $exact = ($evaluation['status'] ?? null) === 'determinate'
                ? (string) BigRational::of($evaluation['result'])->toBigDecimal()
                : null;
            if ($exact === null && $missing === []) {
                $missing = $evaluation['missing'] ?? ['eligible_parameter'];
            }
            $snapshot = [
                'contract_version' => 1, 'scenario_kind' => 'fiscal_rule_qa_preview',
                'base' => $input['base'], 'currency' => $input['currency'], 'indicative_total' => $exact,
                'legal_interpretation' => false, 'formula_version' => 'investmoz.tax.v1',
                'context' => [
                    'reference_date' => $date, 'currency' => $input['currency'], 'currency_fraction_digits' => 2,
                    'scenario_id' => null, 'scenario_version' => 1, 'engine_version' => 'fiscal-draft-preview-v1',
                    'ruleset_version' => $rule->rule_code.':'.$rule->rule_version,
                ],
                'result' => [
                    'status' => $exact === null ? 'indeterminate' : 'calculated', 'value' => $exact, 'unit' => 'MZN',
                    'explanation' => $exact === null
                        ? 'IVA indeterminado: o contexto, a fonte ou o período não permitem resolver o parâmetro deste lote QA.'
                        : 'IVA calculado com precisão decimal exacta, sem arredondamento. Ensaio QA de regra em rascunho; enquadramento declarado, não validado. Não é saldo de declaração nem valor a pagar.',
                    'missing_inputs' => $missing, 'source_ids' => [(string) $source->id],
                ],
                'presentation' => ['value' => $exact, 'currency' => $input['currency'], 'rounding_applied' => false, 'purpose' => 'operation_tax_not_payment'],
                // Exact rational steps supplement the decimal result; no float conversion.
                'intermediate' => $evaluation,
                'fiscal_provenance' => [
                    'mode' => 'qa_draft_only', 'scope_status' => 'user_declared', 'context' => $context,
                    'rounding_policy' => $rule->rounding_policy, 'resolution' => $resolution,
                    'rule' => $version, 'source_acceptance' => 'Fonte oficial aceite pela decisão Tempo de 08/10/2026; não constitui aprovação jurídica desta operação ou publicação da regra.',
                ],
            ];

            return app(SimulationExecution::class)->createFiscalQaPreview($snapshot, $actor->id, $key);
        });
    }
}