// 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 System.Collections.Generic;
using System.Linq;
using System.Text;
using FluentAssertions;
using Microsoft.ML.SearchSpace;
using Microsoft.ML.TestFramework;
using Xunit;
using Xunit.Abstractions;

namespace Microsoft.ML.AutoML.Test
{
    public class GridSearchTunerTests : BaseTestClass
    {
        public GridSearchTunerTests(ITestOutputHelper output)
            : base(output)
        {
        }

        [Fact]
        public void GridSearchTuner_should_search_entire_naive_search_space()
        {
            // the behavior of a grid search tuner is it will exhaustively generate 
            // candidates from a grid of parameter value. And once exhausted, it will start
            // over again.
            // So we use the following way to test a grid search tuner: we go through the grid search
            // twice, and check if all candidates are repeated twice. By doing so we know if grid search
            // tuner either search grid of parameter value exhaustively or or generate candidates exactly one
            // time in each search.

            // default step is used when an option is continous, like double option or single option.
            var defaultStep = 10;
            var searchSpace = new SearchSpace<NaiveSearchSpace>();
            var tuner = new GridSearchTuner(searchSpace, defaultStep);
            var parameters = new List<Parameter>();

            // calculate the total steps, which is the sum of all grid points.
            var steps = 1;
            foreach (var step in searchSpace.Step)
            {
                steps *= step ?? defaultStep;
            }

            foreach (var i in Enumerable.Range(0, steps * 2))
            {
                var settings = new TrialSettings();
                parameters.Add(tuner.Propose(settings));
            }

            steps.Should().Be(600);
            parameters.Distinct().Count().Should().Be(steps);
        }

        private class NaiveSearchSpace
        {
            [Range((int)-10, 10, 0, false)]
            public int IntProperty { get; set; }

            [Range(-10f, 10, 0, false)]
            public float SingleProperty { get; set; }

            [Choice("a", "b", "c")]
            public string TextProperty { get; set; }

            [BooleanChoice]
            public bool BooleanProperty { get; set; }
        }
    }
}