// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable disable warnings
 
using System.Collections.Concurrent;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using Microsoft.AspNetCore.Components.HotReload;
using Microsoft.AspNetCore.Components.Rendering;
 
namespace Microsoft.AspNetCore.Components;
 
/// <summary>
/// Displays the specified page component, rendering it inside its layout
/// and any further nested layouts.
/// </summary>
public class RouteView : IComponent
{
    private RenderHandle _renderHandle;
    private static readonly ConcurrentDictionary<Type, Type?> _layoutAttributeCache = new();
 
    static RouteView()
    {
        if (HotReloadManager.IsSupported)
        {
            HotReloadManager.Default.OnDeltaApplied += _layoutAttributeCache.Clear;
        }
    }
 
    /// <summary>
    /// Gets or sets the route data. This determines the page that will be
    /// displayed and the parameter values that will be supplied to the page.
    /// </summary>
    [Parameter]
    [EditorRequired]
    public RouteData RouteData { get; set; }
 
    /// <summary>
    /// Gets or sets the type of a layout to be used if the page does not
    /// declare any layout. If specified, the type must implement <see cref="IComponent"/>
    /// and accept a parameter named <see cref="LayoutComponentBase.Body"/>.
    /// </summary>
    [Parameter]
    public Type DefaultLayout { get; set; }
 
    /// <inheritdoc />
    public void Attach(RenderHandle renderHandle)
    {
        _renderHandle = renderHandle;
    }
 
    /// <inheritdoc />
    public Task SetParametersAsync(ParameterView parameters)
    {
        parameters.SetParameterProperties(this);
 
        if (RouteData == null)
        {
            throw new InvalidOperationException($"The {nameof(RouteView)} component requires a non-null value for the parameter {nameof(RouteData)}.");
        }
 
        _renderHandle.Render(Render);
        return Task.CompletedTask;
    }
 
    /// <summary>
    /// Renders the component.
    /// </summary>
    /// <param name="builder">The <see cref="RenderTreeBuilder"/>.</param>
    [UnconditionalSuppressMessage("Trimming", "IL2110", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    [UnconditionalSuppressMessage("Trimming", "IL2111", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    [UnconditionalSuppressMessage("Trimming", "IL2118", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    protected virtual void Render(RenderTreeBuilder builder)
    {
        var pageLayoutType = _layoutAttributeCache
            .GetOrAdd(RouteData.PageType, static type => type.GetCustomAttribute<LayoutAttribute>()?.LayoutType)
            ?? DefaultLayout;
 
        builder.OpenComponent<LayoutView>(0);
        builder.AddComponentParameter(1, nameof(LayoutView.Layout), pageLayoutType);
        builder.AddComponentParameter(2, nameof(LayoutView.ChildContent), (RenderFragment)RenderPageWithParameters);
        builder.CloseComponent();
    }
 
    private void RenderPageWithParameters(RenderTreeBuilder builder)
    {
        builder.OpenComponent(0, RouteData.PageType);
 
        foreach (var kvp in RouteData.RouteValues)
        {
            builder.AddComponentParameter(1, kvp.Key, kvp.Value);
        }
 
        builder.CloseComponent();
    }
}