// 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.Generic;
using System.Collections.Immutable;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using Microsoft.CodeAnalysis.FileBasedPrograms;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.MSBuild;

internal sealed class ProjectFileExtensionRegistry
{
    private readonly DiagnosticReporter _diagnosticReporter;
    private readonly IFileBasedProgramService? _fileBasedProgramService;
    private readonly Dictionary<string, string> _extensionToLanguageMap;
    private readonly NonReentrantLock _dataGuard;

    public ProjectFileExtensionRegistry(DiagnosticReporter diagnosticReporter, IFileBasedProgramService? fileBasedProgramService)
    {
        _diagnosticReporter = diagnosticReporter;
        _fileBasedProgramService = fileBasedProgramService;

        _extensionToLanguageMap = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
        {
            { ".csproj", LanguageNames.CSharp },
            { ".vbproj", LanguageNames.VisualBasic },
            { ".fsproj", LanguageNames.FSharp }
        };

        _dataGuard = new NonReentrantLock();
    }

    /// <summary>
    /// Associates a project file extension with a language name.
    /// </summary>
    public void AssociateFileExtensionWithLanguage(string fileExtension, string language)
    {
        using (_dataGuard.DisposableWait())
        {
            _extensionToLanguageMap[AddLeadingDot(fileExtension)] = language;
        }
    }

    /// <summary>
    /// Gets the registered project file extensions. Non-empty extensions have a leading '.'.
    /// </summary>
    public ImmutableArray<string> GetRegisteredProjectFileExtensions()
    {
        using (_dataGuard.DisposableWait())
        {
            return [.. _extensionToLanguageMap.Keys];
        }
    }

    /// <summary>
    /// Tries to get the language registered for an extension, with or without a leading '.'.
    /// </summary>
    public bool TryGetLanguageNameFromExtension(string extension, [NotNullWhen(true)] out string? languageName)
    {
        using (_dataGuard.DisposableWait())
        {
            return _extensionToLanguageMap.TryGetValue(AddLeadingDot(extension), out languageName);
        }
    }

    private static string AddLeadingDot(string extension)
        => extension.Length == 0 || extension[0] == '.' ? extension : "." + extension;

    public bool TryGetLanguageNameFromProjectPath(string? projectFilePath, DiagnosticReportingMode mode, [NotNullWhen(true)] out string? languageName)
        => TryGetLanguageNameFromProjectPath(projectFilePath, mode, out languageName, out _);

    public bool TryGetLanguageNameFromProjectPath(
        string? projectFilePath,
        DiagnosticReportingMode mode,
        [NotNullWhen(true)] out string? languageName,
        out bool isFileBasedApp)
    {
        if (projectFilePath is null)
        {
            languageName = null;
            isFileBasedApp = false;
            _diagnosticReporter.Report(mode, "Project file path is null.");
            return false;
        }

        var projectFileExtension = Path.GetExtension(projectFilePath);

        if (TryGetLanguageNameFromExtension(projectFileExtension, out languageName))
        {
            isFileBasedApp = false;
            return true;
        }

        if (_fileBasedProgramService?.IsValidEntryPointPath(projectFilePath) == true)
        {
            languageName = LanguageNames.CSharp;
            isFileBasedApp = true;
            return true;
        }

        isFileBasedApp = false;
        _diagnosticReporter.Report(mode, string.Format(WorkspacesResources.Cannot_open_project_0_because_the_file_extension_1_is_not_associated_with_a_language, projectFilePath, projectFileExtension));
        return false;
    }
}