misuzu/src/Pagination.php

<?php
namespace Misuzu;

use Index\Http\HttpRequest;

final class Pagination {
    public private(set) bool $validOffset;

    public function __construct(
        public private(set) int $count = 0,
        public private(set) int $range = 0,
        public private(set) int $offset = 0
    ) {
        $this->count = max(0, $count);
        if($range < 1)
            $this->range = $count;

        $this->validOffset = $offset >= 0 && $offset < $count;
        $this->offset = max(0, $offset);
    }

    public int $pages {
        get => (int)ceil($this->count / $this->range);
    }

    public int $page {
        get => (int)floor($this->offset / $this->range) + 1;
    }

    public static function fromPage(
        int $count,
        int $page,
        int $range = 0,
        int $firstPage = 1
    ): self {
        if($range < 1)
            $range = $count;

        $offset = $range * ($page - $firstPage);
        if($offset < 0 || $offset >= $count)
            $offset = -1;

        return new Pagination($count, $range, $offset);
    }

    public static function fromInput(
        int $count,
        int $range = 0,
        string $pageParam = 'p',
        int $firstPage = 1
    ): self {
        return self::fromPage(
            $count,
            (int)(filter_input(INPUT_GET, $pageParam, FILTER_SANITIZE_NUMBER_INT) ?? $firstPage),
            $range,
            $firstPage
        );
    }

    public static function fromRequest(
        HttpRequest $request,
        int $count,
        int $range = 0,
        string $pageParam = 'page',
        int $firstPage = 1
    ): Pagination {
        return self::fromPage(
            $count,
            (int)($request->getParam($pageParam, FILTER_SANITIZE_NUMBER_INT) ?? $firstPage),
            $range,
            $firstPage
        );
    }
}