<?php

namespace App\Application\Reports;

use App\Application\Reports\DTO\GenerateReportInput;
use App\Application\Reports\DTO\ReportComparisonResult;
use App\Domain\Reports\Contracts\ReportRepository;
use App\Infrastructure\Reports\Adapters\LegacyReportServiceAdapter;
use RuntimeException;

final readonly class CompareLegacyAndNewReportUseCase
{
    public function __construct(
        private ReportRepository $reportRepository,
        private LegacyReportServiceAdapter $legacyAdapter,
    ) {}

    public function handle(GenerateReportInput $input): ReportComparisonResult
    {
        $startedAt = microtime(true);
        $expected = $this->legacyAdapter->buildSnapshotFromInput($input);

        if ($input->persistedReportId === null) {
            throw new RuntimeException('persistedReportId is required for report comparison.');
        }

        $actual = $this->reportRepository->findSnapshot($input->persistedReportId);

        if ($actual === null) {
            throw new RuntimeException('Saved report snapshot was not found for comparison.');
        }

        $diff = $this->buildDiff($expected->toComparableArray(), $actual->toComparableArray());
        $status = empty($diff) ? 'matched' : 'diff';

        return new ReportComparisonResult(
            reportType: $input->reportType,
            path: 'new',
            status: $status,
            diff: $diff,
            departmentId: $input->departmentId,
            userId: $input->userId,
            periodStart: $input->periodStart->format('Y-m-d H:i:s'),
            periodEnd: $input->periodEnd->format('Y-m-d H:i:s'),
            reportId: $input->persistedReportId,
            durationMs: round((microtime(true) - $startedAt) * 1000, 2),
        );
    }

    /**
     * @param  array<string, mixed>  $expected
     * @param  array<string, mixed>  $actual
     * @return array<string, mixed>
     */
    private function buildDiff(array $expected, array $actual): array
    {
        $diff = [];

        foreach ($expected as $key => $value) {
            $actualValue = $actual[$key] ?? null;

            if ($actualValue !== $value) {
                $diff[$key] = [
                    'expected' => $value,
                    'actual' => $actualValue,
                ];
            }
        }

        return $diff;
    }
}