// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Composition;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem;
using Microsoft.VisualStudio.LanguageServices.Implementation.Venus;
using Microsoft.VisualStudio.Shell;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation;
 
[ExportWorkspaceService(typeof(IHierarchyItemToProjectIdMap), ServiceLayer.Host), Shared]
internal sealed class HierarchyItemToProjectIdMap : IHierarchyItemToProjectIdMap
{
    private readonly VisualStudioWorkspaceImpl _workspace;
 
    [ImportingConstructor]
    [SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
    public HierarchyItemToProjectIdMap(VisualStudioWorkspaceImpl workspace)
        => _workspace = workspace;
 
    public bool TryGetProjectId(IVsHierarchyItem hierarchyItem, string? targetFrameworkMoniker, [NotNullWhen(true)] out ProjectId? projectId)
    {
        // A project node is represented in two different hierarchies: the solution's IVsHierarchy (where it is a leaf node)
        // and the project's own IVsHierarchy (where it is the root node). The IVsHierarchyItem joins them together for the
        // purpose of creating the tree displayed in Solution Explorer. The project's hierarchy is what is passed from the
        // project system to the language service, so that's the one the one to query here. To do that we need to get
        // the "nested" hierarchy from the IVsHierarchyItem.
        var nestedHierarchy = hierarchyItem.HierarchyIdentity.NestedHierarchy;
 
        // First filter the projects by matching up properties on the input hierarchy against properties on each
        // project's hierarchy.
        var candidateProjects = _workspace.CurrentSolution.Projects
            .Where(p =>
            {
                // We're about to access various properties of the IVsHierarchy associated with the project.
                // The properties supported and the interpretation of their values varies from one project system
                // to another. This code is designed with C# and VB in mind, so we need to filter out everything
                // else.
                if (p.Language is not LanguageNames.CSharp
                    and not LanguageNames.VisualBasic)
                {
                    return false;
                }
 
                var hierarchy = _workspace.GetHierarchy(p.Id);
 
                return hierarchy == nestedHierarchy;
            })
            .ToArray();
 
        // If we only have one candidate then no further checks are required.
        if (candidateProjects.Length == 1)
        {
            projectId = candidateProjects[0].Id;
            return true;
        }
 
        // For CPS projects, we may have a string we extracted from a $TFM-prefixed capability; compare that to the string we're given
        // from CPS to see if this matches.
        if (targetFrameworkMoniker != null)
        {
            var matchingProject = candidateProjects.FirstOrDefault(p => _workspace.TryGetDependencyNodeTargetIdentifier(p.Id) == targetFrameworkMoniker);
 
            if (matchingProject != null)
            {
                projectId = matchingProject.Id;
                return true;
            }
        }
 
        // If we have multiple candidates then we might be dealing with Web Application Projects. In this case
        // there will be one main project plus one project for each open aspx/cshtml/vbhtml file, all with
        // identical properties on their hierarchies. We can find the main project by taking the first project
        // without a ContainedDocument.
        foreach (var candidateProject in candidateProjects)
        {
            if (!candidateProject.DocumentIds.Any(id => ContainedDocument.TryGetContainedDocument(id) != null))
            {
                projectId = candidateProject.Id;
                return true;
            }
        }
 
        projectId = null;
        return false;
    }
}