Umbraco-CMS/src/Umbraco.Core/Routing/UriUtility.cs

using System.Text;
using Umbraco.Cms.Core.Configuration.Models;
using Umbraco.Cms.Core.Hosting;
using Umbraco.Extensions;

namespace Umbraco.Cms.Core.Routing;

public sealed class UriUtility
{
    private static string? _appPath;
    private static string? _appPathPrefix;

    public UriUtility(IHostingEnvironment hostingEnvironment)
    {
        if (hostingEnvironment is null)
        {
            throw new ArgumentNullException(nameof(hostingEnvironment));
        }

        ResetAppDomainAppVirtualPath(hostingEnvironment);
    }

    // will be "/" or "/foo"
    public string? AppPath => _appPath;

    // will be "" or "/foo"
    public string? AppPathPrefix => _appPathPrefix;

    // adds the virtual directory if any
    // see also VirtualPathUtility.ToAbsolute
    // TODO: Does this do anything differently than IHostingEnvironment.ToAbsolute? Seems it does less, maybe should be removed?
    public string ToAbsolute(string url)
    {
        // return ResolveUrl(url);
        url = url.TrimStart(Constants.CharArrays.Tilde);
        return _appPathPrefix + url;
    }

    // internal for unit testing only
    internal void SetAppDomainAppVirtualPath(string appPath)
    {
        _appPath = appPath ?? "/";
        _appPathPrefix = _appPath;
        if (_appPathPrefix == "/")
        {
            _appPathPrefix = string.Empty;
        }
    }

    internal void ResetAppDomainAppVirtualPath(IHostingEnvironment hostingEnvironment) =>
        SetAppDomainAppVirtualPath(hostingEnvironment.ApplicationVirtualPath);

    // strips the virtual directory if any
    // see also VirtualPathUtility.ToAppRelative
    public string ToAppRelative(string virtualPath)
    {
        if (_appPathPrefix is not null && virtualPath.InvariantStartsWith(_appPathPrefix)
                                       && (virtualPath.Length == _appPathPrefix.Length ||
                                           virtualPath[_appPathPrefix.Length] == '/'))
        {
            virtualPath = virtualPath[_appPathPrefix.Length..];
        }

        if (virtualPath.Length == 0)
        {
            virtualPath = "/";
        }

        return virtualPath;
    }

    // maps an internal umbraco uri to a public uri
    // ie with virtual directory, .aspx if required...
    public Uri UriFromUmbraco(Uri uri, RequestHandlerSettings requestConfig)
    {
        var path = uri.GetSafeAbsolutePath();

        if (path != "/" && requestConfig.AddTrailingSlash)
        {
            path = path.EnsureEndsWith("/");
        }

        path = ToAbsolute(path);

        return uri.Rewrite(path);
    }

    // maps a media umbraco uri to a public uri
    // ie with virtual directory - that is all for media
    public Uri MediaUriFromUmbraco(Uri uri)
    {
        var path = uri.GetSafeAbsolutePath();
        path = ToAbsolute(path);
        return uri.Rewrite(path);
    }

    // maps a public uri to an internal umbraco uri
    // ie no virtual directory, no .aspx, lowercase...
    public Uri UriToUmbraco(Uri uri)
    {
        // TODO: This is critical code that executes on every request, we should
        // look into if all of this is necessary? not really sure we need ToLower?

        // note: no need to decode uri here because we're returning a uri
        // so it will be re-encoded anyway
        var path = uri.GetSafeAbsolutePath();

        path = path.ToLower();
        path = ToAppRelative(path); // strip vdir if any

        if (path != "/")
        {
            path = path.TrimEnd(Constants.CharArrays.ForwardSlash);

            // perform fallback to root if the path was all slashes (i.e. https://some.where//////)
            if (path == string.Empty)
            {
                path = "/";
            }
        }

        return uri.Rewrite(path);
    }

    #region ResolveUrl

    // http://www.codeproject.com/Articles/53460/ResolveUrl-in-ASP-NET-The-Perfect-Solution
    // note
    // if browsing http://example.com/sub/page1.aspx then
    // ResolveUrl("page2.aspx") returns "/page2.aspx"
    // Page.ResolveUrl("page2.aspx") returns "/sub/page2.aspx" (relative...)
    public string ResolveUrl(string relativeUrl)
    {
        if (relativeUrl == null)
        {
            throw new ArgumentNullException("relativeUrl");
        }

        if (relativeUrl.Length == 0 || relativeUrl[0] == '/' || relativeUrl[0] == '\\')
        {
            return relativeUrl;
        }

        var idxOfScheme = relativeUrl.IndexOf(@"://", StringComparison.Ordinal);
        if (idxOfScheme != -1)
        {
            var idxOfQM = relativeUrl.IndexOf('?', StringComparison.Ordinal);
            if (idxOfQM == -1 || idxOfQM > idxOfScheme)
            {
                return relativeUrl;
            }
        }

        var sbUrl = new StringBuilder();
        sbUrl.Append(_appPathPrefix);
        if (sbUrl.Length == 0 || sbUrl[^1] != '/')
        {
            sbUrl.Append('/');
        }

        // found question mark already? query string, do not touch!
        var foundQM = false;
        bool foundSlash; // the latest char was a slash?
        if (relativeUrl.Length > 1
            && relativeUrl[0] == '~'
            && (relativeUrl[1] == '/' || relativeUrl[1] == '\\'))
        {
            relativeUrl = relativeUrl[2..];
            foundSlash = true;
        }
        else
        {
            foundSlash = false;
        }

        foreach (var c in relativeUrl)
        {
            if (!foundQM)
            {
                if (c == '?')
                {
                    foundQM = true;
                }
                else
                {
                    if (c == '/' || c == '\\')
                    {
                        if (foundSlash)
                        {
                            continue;
                        }

                        sbUrl.Append('/');
                        foundSlash = true;
                        continue;
                    }

                    if (foundSlash)
                    {
                        foundSlash = false;
                    }
                }
            }

            sbUrl.Append(c);
        }

        return sbUrl.ToString();
    }

    #endregion

    /// <summary>
    ///     Returns an full URL with the host, port, etc...
    /// </summary>
    /// <param name="absolutePath">An absolute path (i.e. starts with a '/' )</param>
    /// <param name="curentRequestUrl"> </param>
    /// <returns></returns>
    /// <remarks>
    ///     Based on http://stackoverflow.com/questions/3681052/get-absolute-url-from-relative-path-refactored-method
    /// </remarks>
    internal Uri ToFullUrl(string absolutePath, Uri curentRequestUrl)
    {
        if (string.IsNullOrEmpty(absolutePath))
        {
            throw new ArgumentNullException(nameof(absolutePath));
        }

        if (!absolutePath.StartsWith("/", StringComparison.Ordinal))
        {
            throw new FormatException("The absolutePath specified does not start with a '/'");
        }

        return new Uri(absolutePath, UriKind.Relative).MakeAbsolute(curentRequestUrl);
    }
}