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

using System.Linq;
using Microsoft.Extensions.DependencyModel;

namespace System.Collections.Generic
{
    public static partial class CollectionExtensions
    {
        public static RuntimeAssetGroup? GetDefaultGroup(this IEnumerable<RuntimeAssetGroup> self) => GetGroup(self, string.Empty);

        public static RuntimeAssetGroup? GetRuntimeGroup(this IEnumerable<RuntimeAssetGroup> self, string runtime)
        {
            if (string.IsNullOrEmpty(runtime))
            {
                throw new ArgumentNullException(nameof(runtime));
            }
            return GetGroup(self, runtime);
        }

        private static RuntimeAssetGroup? GetGroup(IEnumerable<RuntimeAssetGroup> groups, string runtime)
        {
            return groups.FirstOrDefault(g => g.Runtime == runtime);
        }

        public static IEnumerable<string> GetDefaultAssets(this IEnumerable<RuntimeAssetGroup> self) => GetAssets(self, string.Empty);
        public static IEnumerable<string> GetRuntimeAssets(this IEnumerable<RuntimeAssetGroup> self, string runtime)
        {
            if (string.IsNullOrEmpty(runtime))
            {
                throw new ArgumentNullException(nameof(runtime));
            }
            return GetAssets(self, runtime);
        }

        private static IEnumerable<string> GetAssets(IEnumerable<RuntimeAssetGroup> groups, string runtime)
        {
            foreach (RuntimeAssetGroup group in groups)
            {
                if (group.Runtime == runtime)
                {
                    foreach (string path in group.AssetPaths)
                    {
                        yield return path;
                    }
                }
            }
        }

        public static IEnumerable<RuntimeFile> GetDefaultRuntimeFileAssets(this IEnumerable<RuntimeAssetGroup> self) => GetRuntimeFiles(self, string.Empty);
        public static IEnumerable<RuntimeFile> GetRuntimeFileAssets(this IEnumerable<RuntimeAssetGroup> self, string runtime)
        {
            if (string.IsNullOrEmpty(runtime))
            {
                throw new ArgumentNullException(nameof(runtime));
            }
            return GetRuntimeFiles(self, runtime);
        }

        private static IEnumerable<RuntimeFile> GetRuntimeFiles(IEnumerable<RuntimeAssetGroup> groups, string runtime)
        {
            foreach (RuntimeAssetGroup group in groups)
            {
                if (group.Runtime == runtime)
                {
                    foreach (RuntimeFile file in group.RuntimeFiles)
                    {
                        yield return file;
                    }
                }
            }
        }
    }
}