// 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.IO;
using Microsoft.ML.Data;
using Microsoft.ML.Runtime;
 
namespace Microsoft.ML.EntryPoints;
 
/// <summary>
/// Base type for standard predictor model port type.
/// </summary>
[BestFriend]
internal abstract class PredictorModel
{
    [BestFriend]
    private protected PredictorModel()
    {
    }
 
    /// <summary>
    /// Save the model to the given stream.
    /// </summary>
    [BestFriend]
    internal abstract void Save(IHostEnvironment env, Stream stream);
 
    /// <summary>
    /// Extract only the transform portion of the predictor model.
    /// </summary>
    [BestFriend]
    internal abstract TransformModel TransformModel { get; }
 
    /// <summary>
    /// Extract the predictor object out of the predictor model.
    /// </summary>
    [BestFriend]
    internal abstract IPredictor Predictor { get; }
 
    /// <summary>
    /// Apply the predictor model to the transform model and return the resulting predictor model.
    /// </summary>
    [BestFriend]
    internal abstract PredictorModel Apply(IHostEnvironment env, TransformModel transformModel);
 
    /// <summary>
    /// For a given input data, return role mapped data and the predictor object.
    /// The scoring entry point will hopefully know how to construct a scorer out of them.
    /// </summary>
    [BestFriend]
    internal abstract void PrepareData(IHostEnvironment env, IDataView input, out RoleMappedData roleMappedData, out IPredictor predictor);
 
    /// <summary>
    /// Returns a string array containing the label names of the label column type predictor was trained on.
    /// If the training label is a key with text key value annotation, it should return this annotation. The order of the labels should be consistent
    /// with the key values. Otherwise, it returns null.
    /// </summary>
    /// <param name="env"/>
    /// <param name="labelType">The column type of the label the predictor was trained on.</param>
    [BestFriend]
    internal abstract string[] GetLabelInfo(IHostEnvironment env, out DataViewType labelType);
 
    /// <summary>
    /// Returns the <see cref="RoleMappedSchema"/> that was used in training.
    /// </summary>
    [BestFriend]
    internal abstract RoleMappedSchema GetTrainingSchema(IHostEnvironment env);
}