// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;
using System.Runtime.Serialization.Json;
using Microsoft.Build.Framework;
using Microsoft.DotNet.Watch;
using Task = Microsoft.Build.Utilities.Task;

namespace DotNetWatchTasks;

public class FileSetSerializer : Task
{
    [Required]
    public ITaskItem[] WatchFiles { get; set; } = null!;

    [Required]
    public string OutputPath { get; set; } = null!;

    public override bool Execute()
    {
        var projectItems = new Dictionary<string, ProjectItems>();
        var fileSetResult = new MSBuildFileSetResult
        {
            Projects = projectItems
        };

        foreach (var item in WatchFiles)
        {
            var fullPath = item.GetMetadata("FullPath");
            var staticWebAssetPath = item.GetMetadata("StaticWebAssetPath");

            // containing project path:
            var projectFullPath = item.GetMetadata("ProjectFullPath");

            if (!projectItems.TryGetValue(projectFullPath, out var project))
            {
                projectItems.Add(projectFullPath, project = new ProjectItems());
            }

            // The following eliminates duplicate entries originating from diamond dependencies.
            // Each project evaluates _CollectWatchItems target once and the result is reused.
            // The resulting items are then merged into items of the referencing project.
            // If a single project is referenced from two different projects their common ancestor
            // will see multiple entries for the files.

            // Note: We don't track files per TFM.

            if (string.IsNullOrEmpty(staticWebAssetPath))
            {
                project.FileSetBuilder.Add(fullPath);
            }
            else if (!project.StaticFileSetBuilder.TryGetValue(fullPath, out var existingStaticWebAssetPath))
            {
                project.StaticFileSetBuilder.Add(fullPath, staticWebAssetPath);
            }
            else
            {
                Debug.Assert(existingStaticWebAssetPath == staticWebAssetPath);
            }
        }

        foreach (var projectItem in projectItems)
        {
            projectItem.Value.PrepareForSerialization();
        }

        var serializer = new DataContractJsonSerializer(fileSetResult.GetType(), new DataContractJsonSerializerSettings
        {
            UseSimpleDictionaryFormat = true,
        });

        using var fileStream = File.Create(OutputPath);
        using var writer = JsonReaderWriterFactory.CreateJsonWriter(fileStream, Encoding.UTF8, ownsStream: false, indent: true);
        serializer.WriteObject(writer, fileSetResult);

        return !Log.HasLoggedErrors;
    }
}