// 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 System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Text.Json;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.MSBuild;
 
public partial class MSBuildProjectLoader
{
    private static class SolutionFilterReader
    {
        public static bool IsSolutionFilterFilename(string filename)
        {
            return Path.GetExtension(filename).Equals(".slnf", StringComparison.OrdinalIgnoreCase);
        }
 
        public static bool TryRead(string filterFilename, PathResolver pathResolver, [NotNullWhen(true)] out string? solutionFilename, out ImmutableHashSet<string> projectFilter)
        {
            try
            {
                using var document = JsonDocument.Parse(File.ReadAllText(filterFilename));
                var solution = document.RootElement.GetProperty("solution");
                // Convert directory separators to the platform's default, since that is what MSBuild provide us.
                var solutionPath = solution.GetProperty("path").GetString()?.Replace('\\', Path.DirectorySeparatorChar);
                if (solutionPath is null || Path.GetDirectoryName(filterFilename) is not string baseDirectory)
                {
                    solutionFilename = string.Empty;
                    projectFilter = [];
                    return false;
                }
 
                if (!pathResolver.TryGetAbsoluteSolutionPath(solutionPath, baseDirectory, DiagnosticReportingMode.Throw, out solutionFilename))
                {
                    // TryGetAbsoluteSolutionPath should throw before we get here.
                    solutionFilename = string.Empty;
                    projectFilter = [];
                    return false;
                }
 
                if (!File.Exists(solutionFilename))
                {
                    projectFilter = [];
                    return false;
                }
 
                // The base directory for projects is the solution folder.
                baseDirectory = Path.GetDirectoryName(solutionFilename)!;
                RoslynDebug.AssertNotNull(baseDirectory);
 
                var filterProjects = ImmutableHashSet.CreateBuilder<string>(StringComparer.OrdinalIgnoreCase);
                foreach (var project in solution.GetProperty("projects").EnumerateArray())
                {
                    // Convert directory separators to the platform's default, since that is what MSBuild provide us.
                    var projectPath = project.GetString()?.Replace('\\', Path.DirectorySeparatorChar);
                    if (projectPath is null)
                    {
                        continue;
                    }
 
                    // Fill the filter with the absolute project paths.
                    if (pathResolver.TryGetAbsoluteProjectPath(projectPath, baseDirectory, DiagnosticReportingMode.Throw, out var absoluteProjectPath))
                    {
                        filterProjects.Add(absoluteProjectPath);
                    }
                }
 
                projectFilter = filterProjects.ToImmutable();
                return true;
            }
            catch
            {
                solutionFilename = string.Empty;
                projectFilter = [];
                return false;
            }
        }
    }
}