<?php

namespace Kirby\Http;

use Kirby\Toolkit\Str;

/**
 * A wrapper around a URL params
 * that converts it into a Kirby Obj for easier
 * access of each param.
 *
 * @package   Kirby Http
 * @author    Bastian Allgeier <bastian@getkirby.com>
 * @link      https://getkirby.com
 * @copyright Bastian Allgeier GmbH
 * @license   https://opensource.org/licenses/MIT
 */
class Params extends Query
{

    /**
     * @var null|string
     */
    public static $separator;

    /**
     * Creates a new params object
     *
     * @param array|string $params
     */
    public function __construct($params)
    {
        if (is_string($params) === true) {
            $params = static::extract($params)['params'];
        }

        parent::__construct($params ?? []);
    }

    /**
     * Extract the params from a string or array
     *
     * @param string|array|null $path
     * @return array
     */
    public static function extract($path = null): array
    {
        if (empty($path) === true) {
            return [
                'path'   => null,
                'params' => null,
                'slash'  => false
            ];
        }

        $slash = false;

        if (is_string($path) === true) {
            $slash = substr($path, -1, 1) === '/';
            $path  = Str::split($path, '/');
        }

        if (is_array($path) === true) {
            $params    = [];
            $separator = static::separator();

            foreach ($path as $index => $p) {
                if (strpos($p, $separator) === false) {
                    continue;
                }

                $paramParts = Str::split($p, $separator);
                $paramKey   = $paramParts[0];
                $paramValue = $paramParts[1] ?? null;

                $params[$paramKey] = $paramValue;
                unset($path[$index]);
            }

            return [
                'path'   => $path,
                'params' => $params,
                'slash'  => $slash
            ];
        }

        return [
            'path'   => null,
            'params' => null,
            'slash'  => false
        ];
    }

    /**
     * Returns the param separator according
     * to the operating system.
     *
     * Unix = ':'
     * Windows = ';'
     *
     * @return string
     */
    public static function separator(): string
    {
        if (static::$separator !== null) {
            return static::$separator;
        }

        if (DIRECTORY_SEPARATOR === '/') {
            return static::$separator = ':';
        } else {
            return static::$separator = ';';
        }
    }

    /**
     * Converts the params object to a params string
     * which can then be used in the URL builder again
     *
     * @param boolean $leadingSlash
     * @param boolean $trailingSlash
     * @return string|null
     */
    public function toString($leadingSlash = false, $trailingSlash = false): string
    {
        if ($this->isEmpty() === true) {
            return '';
        }

        $params    = [];
        $separator = static::separator();

        foreach ($this as $key => $value) {
            if ($value !== null && $value !== '') {
                $params[] = $key . $separator . $value;
            }
        }

        if (empty($params) === true) {
            return '';
        }

        $params = implode('/', $params);

        $leadingSlash  = $leadingSlash  === true ? '/' : null;
        $trailingSlash = $trailingSlash === true ? '/' : null;

        return $leadingSlash . $params . $trailingSlash;
    }
}
