// 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 Microsoft.Build.Graph;
using Microsoft.DotNet.HotReload;
using Microsoft.Extensions.Logging;

namespace Microsoft.DotNet.Watch;

internal sealed class StaticFileHandler(ILogger logger, LoadedProjectGraph projectGraph, BrowserRefreshServerFactory browserConnector)
{
    public async ValueTask<bool> HandleFileChangesAsync(IReadOnlyList<ChangedFile> files, CancellationToken cancellationToken)
    {
        var stopwatch = Stopwatch.StartNew();
        var allFilesHandled = true;
        var refreshRequests = new Dictionary<BrowserRefreshServer, List<string>>();
        var projectsWithoutRefreshServer = new HashSet<ProjectGraphNode>();

        for (int i = 0; i < files.Count; i++)
        {
            var file = files[i].Item;

            if (file.StaticWebAssetRelativeUrl is null)
            {
                allFilesHandled = false;
                continue;
            }

            logger.LogDebug("Handling file change event for static content {FilePath}.", file.FilePath);

            foreach (var containingProjectPath in file.ContainingProjectPaths)
            {
                foreach (var projectNode in projectGraph.GetProjectNodes(containingProjectPath))
                {
                    if (browserConnector.TryGetRefreshServer(projectNode, out var refreshServer))
                    {
                        if (!refreshRequests.TryGetValue(refreshServer, out var filesPerServer))
                        {
                            logger.LogDebug("[{ProjectName}] Refreshing browser.", projectNode.GetDisplayName());
                            refreshRequests.Add(refreshServer, filesPerServer = []);
                        }

                        filesPerServer.Add(StaticWebAsset.WebRoot + "/" + file.StaticWebAssetRelativeUrl);
                    }
                    else if (projectsWithoutRefreshServer.Add(projectNode))
                    {
                        logger.LogDebug("[{ProjectName}] No refresh server.", projectNode.GetDisplayName());
                    }
                }
            }
        }

        if (refreshRequests.Count == 0)
        {
            return allFilesHandled;
        }

        var tasks = refreshRequests.Select(request => request.Key.UpdateStaticAssetsAsync(request.Value, cancellationToken).AsTask());

        await Task.WhenAll(tasks).WaitAsync(cancellationToken);

        logger.Log(MessageDescriptor.StaticAssetsChangesApplied, stopwatch.ElapsedMilliseconds);

        return allFilesHandled;
    }

    private readonly struct UpdateStaticFileMessage
    {
        public string Type => "UpdateStaticFile";
        public string Path { get; init; }
    }
}