using System; using System.Collections.Generic; using Microsoft.AspNetCore.Components; using Microsoft.AspNetCore.Components.Rendering; using Microsoft.AspNetCore.Components.Routing; namespace AntDesign { public class MenuLink : AntDomComponentBase { private const string DefaultActiveClass = "active"; private bool _isActive; private string _hrefAbsolute; private string _class; /// /// Gets or sets the CSS class name applied to the NavLink when the /// current route matches the NavLink href. /// [Parameter] public string ActiveClass { get; set; } [Parameter] public string Href { get; set; } /// /// Gets or sets the child content of the component. /// [Parameter] public RenderFragment ChildContent { get; set; } [Parameter(CaptureUnmatchedValues = true)] public Dictionary Attributes { get; set; } /// /// Gets or sets a value representing the URL matching behavior. /// [Parameter] public NavLinkMatch Match { get; set; } = NavLinkMatch.All; [CascadingParameter] public MenuItem MenuItem { get; set; } [CascadingParameter] public Menu Menu { get; set; } [CascadingParameter] public Button Button { get; set; } [Inject] private NavigationManager NavigationManger { get; set; } /// protected override void OnInitialized() { // We'll consider re-rendering on each location change NavigationManger.LocationChanged += OnLocationChanged; ClassMapper.If(ActiveClass, () => _isActive) .If(DefaultActiveClass, () => _isActive && string.IsNullOrWhiteSpace(ActiveClass)); } /// /// protected override void OnParametersSet() { if (Match != NavLinkMatch.All && Href == "/") { Match = NavLinkMatch.All; } // Update computed state _hrefAbsolute = Href == null ? null : NavigationManger.ToAbsoluteUri(Href).AbsoluteUri; if (MenuItem.FirstRun) { _isActive = ShouldMatch(NavigationManger.Uri); if (MenuItem != null && _isActive && !MenuItem.IsSelected) { Menu?.SelectItem(MenuItem); Menu?.SelectSubmenu(MenuItem.ParentMenu); } } } /// protected override void Dispose(bool disposing) { // To avoid leaking memory, it's important to detach any event handlers in Dispose() NavigationManger.LocationChanged -= OnLocationChanged; base.Dispose(disposing); } private void OnLocationChanged(object sender, LocationChangedEventArgs args) { // We could just re-render always, but for this component we know the // only relevant state change is to the _isActive property. bool shouldBeActiveNow = ShouldMatch(args.Location); if (shouldBeActiveNow != _isActive) { _isActive = shouldBeActiveNow; if (MenuItem != null) { if (_isActive && !MenuItem.IsSelected) { Menu.SelectItem(MenuItem); } else if (!_isActive && MenuItem.IsSelected) { MenuItem.Deselect(); } } Menu.MarkStateHasChanged(); } } private bool ShouldMatch(string currentUriAbsolute) { if (EqualsHrefExactlyOrIfTrailingSlashAdded(currentUriAbsolute)) { return true; } if (Match == NavLinkMatch.Prefix && IsStrictlyPrefixWithSeparator(currentUriAbsolute, _hrefAbsolute)) { return true; } return false; } private bool EqualsHrefExactlyOrIfTrailingSlashAdded(string currentUriAbsolute) { if (string.Equals(currentUriAbsolute, _hrefAbsolute, StringComparison.OrdinalIgnoreCase)) { return true; } if (currentUriAbsolute.Length == _hrefAbsolute.Length - 1) { // Special case: highlight links to http://host/path/ even if you're // at http://host/path (with no trailing slash) // // This is because the router accepts an absolute URI value of "same // as base URI but without trailing slash" as equivalent to "base URI", // which in turn is because it's common for servers to return the same page // for http://host/vdir as they do for host://host/vdir/ as it's no // good to display a blank page in that case. if (_hrefAbsolute[^1] == '/' && _hrefAbsolute.StartsWith(currentUriAbsolute, StringComparison.OrdinalIgnoreCase)) { return true; } } return false; } protected override void BuildRenderTree(RenderTreeBuilder builder) { if (builder != null) { builder.OpenElement(0, "a"); builder.AddAttribute(1, "href", Href); builder.AddAttribute(2, "class", ClassMapper.Class); builder.AddAttribute(3, "style", Style); builder.SetKey(MenuItem.Key); builder.AddMultipleAttributes(5, Attributes); builder.AddContent(6, ChildContent); builder.CloseElement(); } } private static bool IsStrictlyPrefixWithSeparator(string value, string prefix) { int prefixLength = prefix.Length; if (value.Length > prefixLength) { return value.StartsWith(prefix, StringComparison.OrdinalIgnoreCase) && ( // Only match when there's a separator character either at the end of the // prefix or right after it. // Example: "/abc" is treated as a prefix of "/abc/def" but not "/abcdef" // Example: "/abc/" is treated as a prefix of "/abc/def" but not "/abcdef" prefixLength == 0 || !char.IsLetterOrDigit(prefix[prefixLength - 1]) || !char.IsLetterOrDigit(value[prefixLength]) ); } else { return false; } } } }