<?php

namespace App\Yr\Forecast\Tabular\Variation;

use App\Yr\Forecast\Tabular\Time;
use App\Yr\Forecast\Tabular\Time\DiffInterface;

if (!function_exists('array_key_last')) {
    function array_key_last(array $args): ?int {
        $keys = array_keys($args);
        return array_pop($keys);
    }
}

class Variation implements \IteratorAggregate {

    private $time;
    private $entities = [];
    private $intersects = [];

    public function __construct(Time $t) {
        $this->time = $t;
    }

    public function addEntity(DiffInterface $entity, ?DiffInterface $intersects): self {
        $this->entities[] = $entity;

        if ($intersects != null)
            $this->intersects[array_key_last($this->entities)] = $intersects;

        return $this;
    }

    public function getTime(): Time {
        return $this->time;
    }

    public function getIntersection(DiffInterface $entity): ?DiffInterface {
        $key = (function() use ($entity) : int {
            foreach ($this->entities as $key => $ent)
                if ($ent == $entity)
                    return $key;
        })();

        if (isset($this->intersects[$key]))
            return $this->intersects[$key];

        return null;
    }

    public function isEmpty(): bool {
        return empty($this->entities);
    }

    public function getIterator(): \Generator {
        foreach ($this->entities as $entity)
            yield $entity;
    }

}