// 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.Composition;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Reflection.Metadata;
using System.Reflection.PortableExecutable;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.MetadataAsSource;
using Microsoft.CodeAnalysis.Shared.Utilities;

namespace Microsoft.CodeAnalysis.PdbSourceDocument;

[Export(typeof(IPdbFileLocatorService)), Shared]
[method: ImportingConstructor]
[SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code")]
internal sealed class PdbFileLocatorService(
    [Import(AllowDefault = true)] IPdbSourceDocumentLogger? logger) : IPdbFileLocatorService
{
    private const int SymbolLocatorTimeout = 2000;

    private readonly IPdbSourceDocumentLogger? _logger = logger;

    public async Task<DocumentDebugInfoReader?> GetDocumentDebugInfoReaderAsync(string dllPath, bool useDefaultSymbolServers, TelemetryMessage telemetry, ISourceLinkService? sourceLinkService, CancellationToken cancellationToken)
    {
        var dllStream = IOUtilities.PerformIO(() => ReadFileIfExists(dllPath));
        if (dllStream is null)
            return null;

        Stream? pdbStream = null;
        DocumentDebugInfoReader? result = null;
        var peReader = new PEReader(dllStream);
        try
        {
            // Try to load the pdb file from disk, or embedded
            if (peReader.TryOpenAssociatedPortablePdb(dllPath, ReadFileIfExists, out var pdbReaderProvider, out var pdbFilePath))
            {
                Contract.ThrowIfNull(pdbReaderProvider);

                if (pdbFilePath is null)
                {
                    telemetry.SetPdbSource("embedded");
                    _logger?.Log(FeaturesResources.Found_embedded_PDB_file);
                }
                else
                {
                    telemetry.SetPdbSource("ondisk");
                    _logger?.Log(FeaturesResources.Found_PDB_file_at_0, pdbFilePath);
                }

                result = new DocumentDebugInfoReader(peReader, pdbReaderProvider);
            }

            if (result is null)
            {
                if (sourceLinkService is null)
                {
                    _logger?.Log(FeaturesResources.Could_not_find_PDB_on_disk_or_embedded);
                }
                else
                {
                    var delay = Task.Delay(SymbolLocatorTimeout, cancellationToken);
                    // Call the debugger to find the PDB from a symbol server etc.
                    var pdbResultTask = sourceLinkService.GetPdbFilePathAsync(dllPath, peReader, useDefaultSymbolServers, cancellationToken);

                    var winner = await Task.WhenAny(pdbResultTask, delay).ConfigureAwait(false);

                    if (winner == pdbResultTask)
                    {
                        var pdbResult = await pdbResultTask.ConfigureAwait(false);
                        if (pdbResult is not null)
                        {
                            pdbStream = IOUtilities.PerformIO(() => File.OpenRead(pdbResult.PdbFilePath));
                            if (pdbStream is not null)
                            {
                                var readerProvider = MetadataReaderProvider.FromPortablePdbStream(pdbStream);
                                telemetry.SetPdbSource("symbolserver");
                                result = new DocumentDebugInfoReader(peReader, readerProvider);
                                _logger?.Log(FeaturesResources.Found_PDB_on_symbol_server);
                            }
                            else
                            {
                                _logger?.Log(FeaturesResources.Found_PDB_on_symbol_server_but_could_not_read_file);
                            }
                        }
                        else
                        {
                            _logger?.Log(FeaturesResources.Could_not_find_PDB_on_disk_or_embedded_or_server);
                        }
                    }
                    else
                    {
                        telemetry.SetPdbSource("timeout");
                        _logger?.Log(FeaturesResources.Timeout_symbol_server);
                    }
                }
            }
        }
        catch (BadImageFormatException ex)
        {
            // If the PDB is corrupt in some way we can just ignore it, and let the system fall through to another provider
            _logger?.Log(FeaturesResources.Error_reading_PDB_0, ex.Message);
            result = null;
        }
        finally
        {
            // If we're returning a result then it will own the disposal of the reader, but if not
            // then we need to do it ourselves.
            if (result is null)
            {
                pdbStream?.Dispose();
                peReader.Dispose();
            }
        }

        return result;

        static FileStream? ReadFileIfExists(string fileName)
        {
            if (File.Exists(fileName))
                return File.OpenRead(fileName);

            return null;
        }
    }
}