// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable disable
 
using System.IO.Compression;
using Microsoft.AspNetCore.StaticWebAssets.Tasks.Utils;
using Microsoft.Build.Framework;
 
namespace Microsoft.AspNetCore.StaticWebAssets.Tasks;
 
public class GZipCompress : Task
{
    [Required]
    public ITaskItem[] FilesToCompress { get; set; }
 
    public override bool Execute()
    {
        var outputDirectories = FilesToCompress
            .Select(f => Path.GetDirectoryName(f.ItemSpec))
            .Where(td => !string.IsNullOrWhiteSpace(td))
            .Distinct();
 
        foreach (var outputDirectory in outputDirectories)
        {
            Directory.CreateDirectory(outputDirectory);
            Log.LogMessage(MessageImportance.Low, "Created directory '{0}'.", outputDirectory);
        }
 
        Parallel.For(0, FilesToCompress.Length, i =>
        {
            var file = FilesToCompress[i];
            var outputRelativePath = file.ItemSpec;
 
            if (!AssetToCompress.TryFindInputFilePath(file, Log, out var inputFullPath))
            {
                return;
            }
 
            if (!File.Exists(outputRelativePath))
            {
                Log.LogMessage(MessageImportance.Low, "Compressing '{0}' because compressed file '{1}' does not exist.", inputFullPath, outputRelativePath);
            }
            else if (File.GetLastWriteTimeUtc(inputFullPath) < File.GetLastWriteTimeUtc(outputRelativePath))
            {
                // Incrementalism. If input source doesn't exist or it exists and is not newer than the expected output, do nothing.
                Log.LogMessage(MessageImportance.Low, "Skipping '{0}' because '{1}' is newer than '{2}'.", inputFullPath, outputRelativePath, inputFullPath);
                return;
            }
            else
            {
                Log.LogMessage(MessageImportance.Low, "Compressing '{0}' because file is newer than '{1}'.", inputFullPath, outputRelativePath);
            }
 
            try
            {
                using var sourceStream = File.OpenRead(inputFullPath);
                using var fileStream = File.Create(outputRelativePath);
                using var stream = new GZipStream(fileStream, CompressionLevel.Optimal);
 
                sourceStream.CopyTo(stream);
            }
            catch (Exception e)
            {
                Log.LogErrorFromException(e);
                return;
            }
        });
 
        return !Log.HasLoggedErrors;
    }
}