<?php

namespace App\Http\Controllers;

use App\CMS\Contracts\Repositories\Content;
use App\Http\Requests;

class Sitemap extends Controller
{
    /**
     * @var Content
     */
    private $content;

    /**
     * Sitemap constructor.
     *
     * @param Content $content
     */
    public function __construct(Content $content)
    {
        $this->content = $content;
    }

    /**
     * Get sitemap for all content pages
     *
     * @return mixed
     */
    public function getMap()
    {
        // load all public pages
        $pages = $this->content->all();

        // iterate over all pages and add tag for each of them
        foreach ($pages as $page) {

            // is this page a homepage? because of URL
            if ($page->isHomepage) {
                $route = route('page.index');
                $priority = 1;
            } else {
                $route = route('page.content', ['url' => $page->url]);
                $priority = 0.8;
            }

            // compute update frequency
            $updateFrequency = $this->getUpdateFrequency($page->updated_at);

            // add to all pages
            \Sitemap::addTag($route, $page->updated_at, $updateFrequency, $priority);
        }

        // print sitemap
        return \Sitemap::render();
    }

    /**
     * Based on updatedAt compute "changefreq" for sitemap
     *
     * @param $updatedAt
     */
    private function getUpdateFrequency($updatedAt)
    {
        // shortcuts for times
        $day = 24 * 60 * 60;
        $week = 7 * $day;
        $month = 4 * $week;
        $year = 12 * $month;

        // change frequencies in format "name" => maximum age of last editation
        $changeFrequencies = [
            'always'  => 300,
            'hourly'  => 3600,
            'daily'   => $day,
            'weekly'  => $week,
            'monthly' => $month,
            'yearly'  => $year,
            'never'   => PHP_INT_MAX,
        ];

        // get time difference
        $timeDiffInMinutes = time() - strtotime($updatedAt);

        // iterate over array with all change frequencies and break when time of edit is smaller than maximum time
        do {
            $changeFrequency = key($changeFrequencies);
            $changeFreqMinTime = next($changeFrequencies);
        } while ($timeDiffInMinutes > $changeFreqMinTime);

        if ($changeFrequency != 'never') {
            $changeFrequency = key($changeFrequencies);
        }

        return $changeFrequency;
    }
}