<?php

namespace App\Yr\Forecast\Tabular;

/**
 * Removes superfluous forecast data in an Time-object
 * only storing changes.
 *
 * @author Joachim M. Giæver (joachim[]giaever.org)
 */
class Variations {

    private $data = [];

    /**
     * @param array $t Array of Time-objects
     */
    public function __construct(array $t) {
        if (!current($t) instanceof Time)
            return;

        foreach ($t as $time)
            $this->determineVariance($time);
    }

    private function determineVariance(Time $t) {
        $var = [
            'time' => $t,
            'entities' => iterator_to_array($t->getIterator())
        ];

        if (empty($this->data))
            $this->data[] = $var;
        else {
            foreach (array_reverse($this->data) as $entry) {
                foreach ($entry['entities'] as $entity) {
                    foreach ($var['entities'] as $key => $ventity)
                        if ($ventity instanceof $entity && !$ventity->diff($entity))
                            unset($var['entities'][$key]);
                }
            }
            if (!empty($var['entities']))
                $this->data[] = $var;
        }
    }

    /**
     * Returns the changes in the forecast
     *
     * @return array 
     */
    public function getData(callable $filterFn = null): array {
        return $this->data;
    }
}