// 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.
 
#nullable disable
 
using System;
using System.IO;
using System.Reflection;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Scripting.Hosting
{
    internal sealed class DesktopAssemblyLoaderImpl : AssemblyLoaderImpl
    {
        private readonly Func<string, Assembly, Assembly> _assemblyResolveHandlerOpt;
 
        public DesktopAssemblyLoaderImpl(InteractiveAssemblyLoader loader)
            : base(loader)
        {
            _assemblyResolveHandlerOpt = loader.ResolveAssembly;
            CoreLightup.Desktop.AddAssemblyResolveHandler(_assemblyResolveHandlerOpt);
        }
 
        public override void Dispose()
        {
            if (_assemblyResolveHandlerOpt != null)
            {
                CoreLightup.Desktop.RemoveAssemblyResolveHandler(_assemblyResolveHandlerOpt);
            }
        }
 
        public override Assembly LoadFromStream(Stream peStream, Stream pdbStream)
        {
            byte[] peImage = new byte[peStream.Length];
            peStream.TryReadAll(peImage, 0, peImage.Length);
 
            if (pdbStream != null)
            {
                byte[] pdbImage = new byte[pdbStream.Length];
                pdbStream.TryReadAll(pdbImage, 0, pdbImage.Length);
 
                return Assembly.Load(peImage, pdbImage);
            }
 
            return Assembly.Load(peImage);
        }
 
        public override AssemblyAndLocation LoadFromPath(string path)
        {
            // An assembly is loaded into CLR's Load Context if it is in the GAC, otherwise it's loaded into No Context via Assembly.LoadFile(string).
            // Assembly.LoadFile(string) automatically redirects to GAC if the assembly has a strong name and there is an equivalent assembly in GAC. 
 
            var assembly = Assembly.LoadFile(path);
            var location = assembly.Location;
            var fromGac = CoreLightup.Desktop.IsAssemblyFromGlobalAssemblyCache(assembly);
            return new AssemblyAndLocation(assembly, location, fromGac);
        }
    }
}