// 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;
using System.Collections.Immutable;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Diagnostics;
 
namespace Roslyn.Test.Utilities;
 
/// <summary>
/// A simple deriviation of <see cref="AnalyzerReference"/> that returns the source generator
/// passed, for ease in unit tests.
/// </summary>
public class TestGeneratorReference : AnalyzerReference
{
    private readonly ISourceGenerator _generator;
    internal readonly Checksum Checksum;
 
    public TestGeneratorReference(ISourceGenerator generator, string? analyzerFilePath = null)
    {
        _generator = generator;
        Guid = Guid.NewGuid();
 
        // In unit tests, we often simulate OOP interactions by interacting with a in-process remote host, but
        // still going through our serialization pathways. In real OOP cases we only support serializing
        // AnalyzerFileReferences, since we load the file in both places. In unit tests however we often directly
        // create instances of ISourceGenerators so we can test generator support for various features.
        // We'll make up a checksum here so we can "serialize" it to our unit test in-proc "remote" host.
        var checksumArray = Guid.ToByteArray();
        Array.Resize(ref checksumArray, Checksum.HashSize);
        this.Checksum = Checksum.From(checksumArray);
 
        FullPath = analyzerFilePath;
    }
 
    public TestGeneratorReference(IIncrementalGenerator generator, string? analyzerFilePath = null)
        : this(generator.AsSourceGenerator(), analyzerFilePath)
    {
    }
 
    public override string? FullPath { get; }
    public override object Id => this;
    public Guid Guid { get; }
 
    public override ImmutableArray<DiagnosticAnalyzer> GetAnalyzers(string language) => [];
    public override ImmutableArray<DiagnosticAnalyzer> GetAnalyzersForAllLanguages() => [];
    public override ImmutableArray<ISourceGenerator> GetGenerators(string language) => [_generator];
}