// 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.Collections.Immutable;
using System.Linq;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editor.EditorConfigSettings.Data;
using Microsoft.CodeAnalysis.Editor.EditorConfigSettings.Extensions;
using Microsoft.CodeAnalysis.Editor.EditorConfigSettings.Updater;
using Microsoft.CodeAnalysis.EditorConfig;
using Microsoft.CodeAnalysis.Shared.Extensions;
using RoslynEnumerableExtensions = Microsoft.CodeAnalysis.Editor.EditorConfigSettings.Extensions.EnumerableExtensions;

namespace Microsoft.CodeAnalysis.Editor.EditorConfigSettings.DataProvider.Analyzer
{
    internal sealed class AnalyzerSettingsProvider : SettingsProviderBase<AnalyzerSetting, AnalyzerSettingsUpdater, AnalyzerSetting, ReportDiagnostic>
    {
        private readonly IDiagnosticAnalyzerService _analyzerService;

        public AnalyzerSettingsProvider(string fileName, AnalyzerSettingsUpdater settingsUpdater, Workspace workspace, IDiagnosticAnalyzerService analyzerService)
            : base(fileName, settingsUpdater, workspace, analyzerService.GlobalOptions)
        {
            _analyzerService = analyzerService;
            Update();
        }

        protected override void UpdateOptions(TieredAnalyzerConfigOptions options, ImmutableArray<Project> projectsInScope)
        {
            var analyzerReferences = RoslynEnumerableExtensions.DistinctBy(projectsInScope.SelectMany(p => p.AnalyzerReferences), a => a.Id).ToImmutableArray();
            foreach (var analyzerReference in analyzerReferences)
            {
                var configSettings = GetSettings(analyzerReference, options.EditorConfigOptions);
                AddRange(configSettings);
            }
        }

        private IEnumerable<AnalyzerSetting> GetSettings(AnalyzerReference analyzerReference, AnalyzerConfigOptions editorConfigOptions)
        {
            IEnumerable<DiagnosticAnalyzer> csharpAnalyzers = analyzerReference.GetAnalyzers(LanguageNames.CSharp);
            IEnumerable<DiagnosticAnalyzer> visualBasicAnalyzers = analyzerReference.GetAnalyzers(LanguageNames.VisualBasic);
            var dotnetAnalyzers = csharpAnalyzers.Intersect(visualBasicAnalyzers, DiagnosticAnalyzerComparer.Instance);
            csharpAnalyzers = csharpAnalyzers.Except(dotnetAnalyzers, DiagnosticAnalyzerComparer.Instance);
            visualBasicAnalyzers = visualBasicAnalyzers.Except(dotnetAnalyzers, DiagnosticAnalyzerComparer.Instance);

            var csharpSettings = ToAnalyzerSetting(csharpAnalyzers, Language.CSharp);
            var csharpAndVisualBasicSettings = csharpSettings.Concat(ToAnalyzerSetting(visualBasicAnalyzers, Language.VisualBasic));
            return csharpAndVisualBasicSettings.Concat(ToAnalyzerSetting(dotnetAnalyzers, Language.CSharp | Language.VisualBasic));

            IEnumerable<AnalyzerSetting> ToAnalyzerSetting(IEnumerable<DiagnosticAnalyzer> analyzers,
                                                                   Language language)
            {
                return analyzers
                    .SelectMany(a => _analyzerService.AnalyzerInfoCache.GetDiagnosticDescriptors(a))
                    .GroupBy(d => d.Id)
                    .OrderBy(g => g.Key, StringComparer.CurrentCulture)
                    .Select(g =>
                    {
                        var selectedDiagnostic = g.First();
                        var isEditorconfig = selectedDiagnostic.IsDefinedInEditorConfig(editorConfigOptions);
                        var settingLocation = new SettingLocation(isEditorconfig ? LocationKind.EditorConfig : LocationKind.VisualStudio, FileName);
                        var severity = selectedDiagnostic.GetEffectiveSeverity(editorConfigOptions);
                        return new AnalyzerSetting(selectedDiagnostic, severity, SettingsUpdater, language, settingLocation);
                    });
            }
        }

        private class DiagnosticAnalyzerComparer : IEqualityComparer<DiagnosticAnalyzer>
        {
            public static readonly DiagnosticAnalyzerComparer Instance = new();

            public bool Equals(DiagnosticAnalyzer? x, DiagnosticAnalyzer? y)
            {
                if (x is null && y is null)
                    return true;

                if (x is null || y is null)
                    return false;

                return x.GetAnalyzerIdAndVersion().GetHashCode() == y.GetAnalyzerIdAndVersion().GetHashCode();
            }

            public int GetHashCode(DiagnosticAnalyzer obj) => obj.GetAnalyzerIdAndVersion().GetHashCode();
        }
    }
}
