// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using Microsoft.ML;
using Microsoft.ML.CommandLine;
using Microsoft.ML.Data;
using Microsoft.ML.EntryPoints;
using Microsoft.ML.Internal.Internallearn;
using Microsoft.ML.Runtime;
using Microsoft.ML.Trainers.Ensemble;
 
[assembly: LoadableClass(typeof(MultiWeightedAverage), typeof(MultiWeightedAverage.Options), typeof(SignatureCombiner),
    MultiWeightedAverage.UserName, MultiWeightedAverage.LoadName)]
 
[assembly: LoadableClass(typeof(MultiWeightedAverage), null, typeof(SignatureLoadModel),
    MultiWeightedAverage.UserName, MultiWeightedAverage.LoaderSignature)]
 
namespace Microsoft.ML.Trainers.Ensemble
{
    /// <summary>
    /// Generic interface for combining outputs of multiple models
    /// </summary>
    internal sealed class MultiWeightedAverage : BaseMultiAverager, IWeightedAverager
    {
        public const string UserName = "Multi Weighted Average";
        public const string LoadName = "MultiWeightedAverage";
        public const string LoaderSignature = "MultiWeightedAverageComb";
 
        private static VersionInfo GetVersionInfo()
        {
            return new VersionInfo(
                modelSignature: "MWAVCOMB",
                verWrittenCur: 0x00010001,
                verReadableCur: 0x00010001,
                verWeCanReadBack: 0x00010001,
                loaderSignature: LoaderSignature,
                loaderAssemblyName: typeof(MultiWeightedAverage).Assembly.FullName);
        }
 
        [TlcModule.Component(Name = LoadName, FriendlyName = UserName)]
        public sealed class Options : OptionsBase, ISupportMulticlassOutputCombinerFactory
        {
            IMulticlassOutputCombiner IComponentFactory<IMulticlassOutputCombiner>.CreateComponent(IHostEnvironment env) => new MultiWeightedAverage(env, this);
 
            [Argument(ArgumentType.AtMostOnce, HelpText = "The metric type to be used to find the weights for each model", ShortName = "wn", SortOrder = 50)]
            [TGUI(Label = "Metric Name", Description = "The weights are calculated according to the selected metric")]
            public MultiWeightageKind WeightageName = MultiWeightageKind.AccuracyMicroAvg;
        }
 
        private readonly MultiWeightageKind _weightageKind;
        public string WeightageMetricName { get { return _weightageKind.ToString(); } }
 
        public MultiWeightedAverage(IHostEnvironment env, Options options)
            : base(env, LoaderSignature, options)
        {
            _weightageKind = options.WeightageName;
            Host.CheckUserArg(Enum.IsDefined(typeof(MultiWeightageKind), _weightageKind), nameof(options.WeightageName));
        }
 
        private MultiWeightedAverage(IHostEnvironment env, ModelLoadContext ctx)
            : base(env, LoaderSignature, ctx)
        {
            // *** Binary format ***
            // int: _weightageKind
 
            _weightageKind = (MultiWeightageKind)ctx.Reader.ReadInt32();
            Host.CheckDecode(Enum.IsDefined(typeof(MultiWeightageKind), _weightageKind));
        }
 
        public static MultiWeightedAverage Create(IHostEnvironment env, ModelLoadContext ctx)
        {
            Contracts.CheckValue(env, nameof(env));
            env.CheckValue(ctx, nameof(ctx));
            ctx.CheckAtModel(GetVersionInfo());
            return new MultiWeightedAverage(env, ctx);
        }
 
        protected override void SaveCore(ModelSaveContext ctx)
        {
            base.SaveCore(ctx);
            ctx.SetVersionInfo(GetVersionInfo());
            // *** Binary format ***
            // int: _weightageKind
 
            Host.Assert(Enum.IsDefined(typeof(MultiWeightageKind), _weightageKind));
            ctx.Writer.Write((int)_weightageKind);
        }
 
        public override Combiner<VBuffer<Single>> GetCombiner()
        {
            return CombineCore;
        }
    }
 
    // These values are serialized, so should not be changed.
    internal enum MultiWeightageKind
    {
        [TGUI(Label = MulticlassClassificationEvaluator.AccuracyMicro)]
        AccuracyMicroAvg = 0,
        [TGUI(Label = MulticlassClassificationEvaluator.AccuracyMacro)]
        AccuracyMacroAvg = 1
    }
}