Avalonia/src/Avalonia.Base/Utilities/UriExtensions.cs

using System;

namespace Avalonia.Utilities;

internal static class UriExtensions
{
    public static bool IsAbsoluteResm(this Uri uri) =>
        uri.IsAbsoluteUri && uri.IsResm();

    public static bool IsResm(this Uri uri) => uri.Scheme == "resm";
    
    public static bool IsAvares(this Uri uri) => uri.Scheme == "avares";
    
    public static Uri EnsureAbsolute(this Uri uri, Uri? baseUri)
    {
        if (uri.IsAbsoluteUri)
            return uri;
        if(baseUri == null)
            throw new ArgumentException($"Relative uri {uri} without base url");
        if (!baseUri.IsAbsoluteUri)
            throw new ArgumentException($"Base uri {baseUri} is relative");
        if (baseUri.IsResm())
            throw new ArgumentException(
                $"Relative uris for 'resm' scheme aren't supported; {baseUri} uses resm");
        return new Uri(baseUri, uri);
    }

    public static string GetUnescapeAbsolutePath(this Uri uri) =>
        Uri.UnescapeDataString(uri.AbsolutePath);

    public static string GetUnescapeAbsoluteUri(this Uri uri) =>
        Uri.UnescapeDataString(uri.AbsoluteUri);
    
    public static string GetAssemblyNameFromQuery(this Uri uri)
    {
        const string assembly = "assembly";

        var query = Uri.UnescapeDataString(uri.Query);
        
        // Skip the '?'
        var currentIndex = 1;
        while (currentIndex < query.Length)
        {
            var isFind = false;
            for (var i = 0; i < assembly.Length; ++currentIndex, ++i)
                if (query[currentIndex] == assembly[i])
                {
                    isFind = i == assembly.Length - 1;
                }
                else
                {
                    break;
                }

            // Skip the '='
            ++currentIndex;

            var beginIndex = currentIndex;
            while (currentIndex < query.Length && query[currentIndex] != '&')
                ++currentIndex;

            if (isFind)
                return query.Substring(beginIndex, currentIndex - beginIndex);

            ++currentIndex;
        }

        return "";
    }
}