// 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 Microsoft.ML.Data;
using Microsoft.ML.Runtime;
using Microsoft.ML.Transforms;

namespace Microsoft.ML
{
 /// <summary>
 /// Class used to create instances of preview objects for debugging.
 /// Note: this class and all methods should only be used for debugging and not in production code.
 /// </summary>
 public static class DebuggerExtensions
 {
 /// <summary>
 /// Extract a 'head' of the data view in a view that is convenient to debug.
 /// </summary>
 /// <param name="data">The data view to preview</param>
 /// <param name="maxRows">Maximum number of rows to pull</param>
 public static DataDebuggerPreview Preview(this IDataView data, int maxRows = DataDebuggerPreview.Defaults.MaxRows)
 => new DataDebuggerPreview(data, maxRows);

 /// <summary>
 /// Preview an effect of the <paramref name="transformer"/> on a given <paramref name="data"/>.
 /// </summary>
 /// <param name="transformer">The transformer which effect we are previewing</param>
 /// <param name="data">The data view to use for preview</param>
 /// <param name="maxRows">Maximum number of rows to pull</param>
 public static DataDebuggerPreview Preview(this ITransformer transformer, IDataView data, int maxRows = DataDebuggerPreview.Defaults.MaxRows)
 => new DataDebuggerPreview(transformer.Transform(data), maxRows);

 /// <summary>
 /// Preview an effect of the <paramref name="estimator"/> on a given <paramref name="data"/>.
 /// </summary>
 /// <param name="estimator">The estimnator which effect we are previewing</param>
 /// <param name="data">The data view to use for preview</param>
 /// <param name="maxRows">Maximum number of rows to show in preview</param>
 /// <param name="maxTrainingRows">Maximum number of rows to fit the estimator</param>
 public static DataDebuggerPreview Preview(this IEstimator<ITransformer> estimator, IDataView data, int maxRows = DataDebuggerPreview.Defaults.MaxRows,
 int maxTrainingRows = DataDebuggerPreview.Defaults.MaxRows)
 {
 Contracts.CheckValue(estimator, nameof(estimator));
 Contracts.CheckValue(data, nameof(data));
 Contracts.CheckParam(maxRows >= 0, nameof(maxRows));
 Contracts.CheckParam(maxTrainingRows >= 0, nameof(maxTrainingRows));

 var env = new LocalEnvironment();
 var trainData = SkipTakeFilter.Create(env, new SkipTakeFilter.TakeOptions { Count = maxTrainingRows }, data);
 return new DataDebuggerPreview(estimator.Fit(trainData).Transform(data), maxRows);
 }

 /// <summary>
 /// Preview an effect of the <paramref name="loader"/> on a given <paramref name="source"/>.
 /// </summary>
 /// <param name="loader">The data loader to preview</param>
 /// <param name="source">The source to pull the data from</param>
 /// <param name="maxRows">Maximum number of rows to pull</param>
 public static DataDebuggerPreview Preview<TSource>(this IDataLoader<TSource> loader, TSource source, int maxRows = DataDebuggerPreview.Defaults.MaxRows)
 => new DataDebuggerPreview(loader.Load(source), maxRows);
 }
}