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

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;
using NuGet.Frameworks;
using System.Collections.Generic;
using System.Linq;

namespace Microsoft.DotNet.Build.Tasks.TargetFramework
{
    public class ChooseBestTargetFrameworksTask : BuildTask
    {
        [Required]
        public ITaskItem[]? BuildTargetFrameworks { get; set; }

        [Required]
        public string? RuntimeGraph { get; set; }

        [Required]
        public string[]? SupportedTargetFrameworks { get; set; }

        // Returns distinct items only. Compares the include values. Metadata is ignored.
        public bool Distinct { get; set; }

        [Output]
        public ITaskItem[]? BestTargetFrameworks { get; set; }

        public override bool Execute()
        {
            List<ITaskItem> bestTargetFrameworkList = new(BuildTargetFrameworks!.Length);
            TargetFrameworkResolver targetframeworkResolver = TargetFrameworkResolver.CreateOrGet(RuntimeGraph!);
 
            foreach (ITaskItem buildTargetFramework in BuildTargetFrameworks)
            {
                NuGetFramework framework = NuGetFramework.ParseFolder(buildTargetFramework.ItemSpec);
                string? bestTargetFramework = targetframeworkResolver.GetNearest(SupportedTargetFrameworks!, framework);
                if (bestTargetFramework != null && (!Distinct || !bestTargetFrameworkList.Any(b => b.ItemSpec == bestTargetFramework)))
                {
                    TaskItem item = new(bestTargetFramework);
                    buildTargetFramework.CopyMetadataTo(item);
                    bestTargetFrameworkList.Add(item);
                }
            }

            BestTargetFrameworks = bestTargetFrameworkList.ToArray(); 
            return !Log.HasLoggedErrors;
        }
    }
}