<?php
namespace WP_Statistics\Utils;

class Url
{
    /**
     * Retrieves the protocol from a given URL.
     *
     * @param string $url The URL from which to extract the scheme.
     * @return string The scheme extracted from the URL, or an empty string if the URL is invalid.
     */
    public static function getProtocol($url)
    {
        $parsedUrl = wp_parse_url($url);

        return $parsedUrl['scheme'] ?? '';
    }

    /**
     * Retrieves the domain from a given URL without www.
     *
     * @param string $url The URL from which to extract the domain.
     * @param bool $protocol (Optional) Whether to include the protocol in the domain. Default is false.
     * @return string The domain extracted from the URL, or an empty string if the URL is invalid.
     */
    public static function getDomain($url, $protocol = false)
    {
        // Make url lower case
        $url = strtolower($url);

        // Sanitize url
        $url = sanitize_url($url);

        // Parse URL
        $parsedUrl = wp_parse_url($url);

        // If host is empty, return early
        if (empty($parsedUrl['host'])) return '';

        // Get domain name
        $domain = $parsedUrl['host'];

        // Remove www if present
        $domain = preg_replace('/^www\./', '', $domain);

        // Remove trailing slash
        $domain = rtrim($domain, '/');

        // Add protocol
        if ($protocol && !empty($parsedUrl['scheme'])) {
            $domain = $parsedUrl['scheme'] . '://' . $domain;
        }

        return $domain;
    }

    /**
     * Formats a given URL by removing trailing slashes and adding a protocol if missing.
     *
     * @param string $url The URL to be formatted.
     * @return string The formatted URL.
     */
    public static function formatUrl($url) {
        if (empty($url)) return '';

        // Remove trailing slash
        $url = rtrim($url, '/');

        // Add https protocol if missing
        if (empty(self::getProtocol($url))) {
            $url = "https://$url";
        }

        return $url;
    }

    /**
     * Checks if a specified query parameter exists in a given URL and returns its value.
     *
     * @param string $url The URL to check.
     * @param string $param The query parameter to search for.
     * @return mixed The value of the query parameter if found, or null if not.
     */
    public static function getParam($url, $param)
    {
        // Parse URL
        $parsedUrl = wp_parse_url($url);

        // If query param is empty, return early
        if (empty($parsedUrl['query'])) return null;

        // Parse query string
        parse_str($parsedUrl['query'], $params);

        // Return the query parameter value. A single parameter is expected to be
        // scalar, so ignore array-style values (e.g. param[]=x) to avoid warnings.
        $value = $params[$param] ?? null;

        return is_array($value) ? null : $value;
    }

    /**
     * Get query parameters of a given URL.
     *
     * @param string $url The URL to check.
     * @param string $format The format to return the value in. Could be 'string' or 'array'.
     * @return mixed The value of the query parameter if found.
     */
    public static function getParams($url, $format = 'string')
    {
        // Parse URL
        $parsedUrl = wp_parse_url($url);

        // Get query params
        $query = $parsedUrl['query'] ?? '';

        // Parse query string
        parse_str($query, $params);

        return $format === 'string' ? $query : $params;
    }

    /**
     * Checks if a given URL is internal by comparing its domain to the current website domain.
     *
     * @param string $url The URL to check.
     * @return bool True if the URL's domain matches the current domain, false otherwise.
     */
    public static function isInternal($url)
    {
        $url        = Url::getDomain($url);
        $homeUrl    = Url::getDomain(home_url());

        return $url === $homeUrl;
    }

    /**
     * Clean a URL by removing the protocol and www.
     *
     * @param string $url The URL to clean.
     * @return string The cleaned URL.
     */
    public static function cleanUrl($url)
    {
        $url = trim($url); // remove whitespaces
        $url = rtrim($url, '/'); // remove trailing slash
        $url = preg_replace('/^(https?:\/\/)?(www\.)?/i', '', $url); // remove protocol and www

        return $url;
    }

    /**
     * Get relative path of urls
     *
     * @param string $url
     * @return string Relative path or empty string
     */
    public static function getPath($url)
    {
        return wp_parse_url($url, PHP_URL_PATH) ?? '';
    }
}
