<?php
require_once('FacilityDataSet.php');
class Paginator {
    protected $_pages, $_totalPages, $_rowLimit, $_offset, $_pageMatrix, $_rowCount;

    public function __construct($rowLimit, $offset, $dataset) {
        $this->_rowLimit = $rowLimit;
        $this->_offset = $offset;
        $this->_totalPages = $this->calculateTotalPages($dataset['count']);
        $this->_rowCount = $dataset['count'];
        $this->_pages = $dataset['dataset'];
        $this->_pageMatrix = $this->Paginate();
    }

    private function calculateTotalPages(int $count): int {
        return $count > 0 ? ceil($count / $this->_rowLimit) : 0;
    }

    public function Paginate(): array {
        $pageMatrix = [];
        for ($i = 0; $i < $this->_totalPages; $i++) {
            $page = [];
            $start = $i * $this->_rowLimit;
            $end = min($start + $this->_rowLimit, $this->_rowCount); // Ensure within bounds

            for ($j = $start; $j < $end; $j++) {
                $page[] = $this->_pages[$j];
            }

            $pageMatrix[$i] = $page;
        }
        return $pageMatrix;
    }

    function getPageFromUri(): int {
        // Retrieve 'page' parameter and default to 0 if missing or invalid
        return filter_input(INPUT_GET, 'page', FILTER_VALIDATE_INT, [
            'options' => ['default' => 0, 'min_range' => 0] // Default to 0 if invalid or missing
        ]);
    }

    public function setPageUri(int $page): void
    {
        $uri = $_SERVER['REQUEST_URI'];
        $uriComp = parse_url($uri);
        $params = [];

        // Parse existing query parameters
        if (isset($uriComp['query'])) {
            parse_str($uriComp['query'], $params);
        }

        // Avoid unnecessary redirection if the page is already correct
        if (isset($params['page']) && (int)$params['page'] === $page) {
            return; // Do nothing if already on the correct page
        }

        // Update the 'page' parameter
        $params['page'] = $page;

        // Rebuild the query string
        $newUri = http_build_query($params);

        // Redirect to the updated URI
        $path = $uriComp['path'] ?? '/'; // Use the current path or root
        header("Location: $path?$newUri");
        exit;
    }

    public function getPage(int $pageNumber): array {

        if ($pageNumber < 0 || $pageNumber >= $this->_totalPages) {
            return []; // Return an empty array if the page number is invalid
        }
        return $this->_pageMatrix[$pageNumber];
    }

    public function countPageResults(int $pageNumber): int {
        if ($pageNumber < 0 || $pageNumber >= $this->_totalPages) {
            return 0; // Return 0 if the page number is invalid
        }
        return count($this->_pageMatrix[$pageNumber]);
    }
}