// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Generic;
using System.Threading;
using Microsoft.AspNetCore.Razor.Language.Extensions;
using Microsoft.AspNetCore.Razor.Language.Intermediate;
using Microsoft.AspNetCore.Razor.PooledObjects;
 
namespace Microsoft.AspNetCore.Razor.Language.Components;
 
internal sealed class ComponentTemplateDiagnosticPass : ComponentIntermediateNodePassBase, IRazorOptimizationPass
{
    // Runs after components/eventhandlers/ref/bind. We need to check for templates in all of those
    // places.
    public override int Order => 150;
 
    protected override void ExecuteCore(
        RazorCodeDocument codeDocument,
        DocumentIntermediateNode documentNode,
        CancellationToken cancellationToken)
    {
        if (!IsComponentDocument(documentNode))
        {
            return;
        }
 
        using var _ = ListPool<IntermediateNodeReference>.GetPooledObject(out var candidates);
 
        var visitor = new Visitor(candidates);
        visitor.Visit(documentNode);
 
        foreach (var candidate in candidates)
        {
            var (node, parent) = candidate;
 
            parent.AddDiagnostic(ComponentDiagnosticFactory.Create_TemplateInvalidLocation(node.Source));
 
            // Remove the offending node since we don't know how to render it. This means that the user won't get C#
            // completion at this location, which is fine because it's inside an HTML attribute.
            candidate.Remove();
        }
    }
 
    private sealed class Visitor(List<IntermediateNodeReference> candidates)
        : IntermediateNodeWalker, IExtensionIntermediateNodeVisitor<TemplateIntermediateNode>
    {
        private readonly List<IntermediateNodeReference> _candidates = candidates;
 
        public void VisitExtension(TemplateIntermediateNode node)
        {
            // We found a template, let's check where it's located.
            foreach (var ancestor in Ancestors)
            {
                if (ancestor is HtmlAttributeIntermediateNode or // Inside markup attribute
                                ComponentAttributeIntermediateNode or // Inside component attribute
                                TagHelperPropertyIntermediateNode or // Inside malformed ref attribute
                                TagHelperDirectiveAttributeIntermediateNode) // Inside a directive attribute
                {
                    _candidates.Add(new IntermediateNodeReference(node, Parent.AssumeNotNull()));
 
                    // We found a candidate and can stop looking. There's no need to report multiple diagnostics for the same node.
                    break;
                }
            }
        }
    }
}