<?php

namespace App\Domain\Reports\Calculators;

use App\Domain\Reports\Models\MetricAggregate;
use App\Domain\Reports\Models\OperationInterval;

final class PreoperativeDaysCalculator
{
    /**
     * @param  iterable<OperationInterval>  $intervals
     */
    public function calculate(iterable $intervals): MetricAggregate
    {
        $totalDays = 0;
        $patientCount = 0;

        foreach ($intervals as $interval) {
            if ($interval->operationAt < $interval->admittedAt) {
                continue;
            }

            $totalDays += $interval->admittedAt->setTime(0, 0)->diff($interval->operationAt->setTime(0, 0))->days;
            $patientCount++;
        }

        return new MetricAggregate(
            total: $totalDays,
            count: $patientCount,
            average: $patientCount > 0 ? round($totalDays / $patientCount, 1) : 0.0,
        );
    }
}