// 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.
 
#nullable disable
 
using System;
using System.Collections.Generic;
using System.Composition;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Options;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.CSharp
{
    [ExportLanguageService(typeof(ISyntaxTreeFactoryService), LanguageNames.CSharp), Shared]
    internal partial class CSharpSyntaxTreeFactoryService : AbstractSyntaxTreeFactoryService
    {
        private static readonly CSharpParseOptions _parseOptionWithLatestLanguageVersion = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.Preview);
 
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public CSharpSyntaxTreeFactoryService()
        {
        }
 
        public override ParseOptions GetDefaultParseOptions()
            => CSharpParseOptions.Default;
 
        public override ParseOptions GetDefaultParseOptionsWithLatestLanguageVersion()
            => _parseOptionWithLatestLanguageVersion;
 
        public override ParseOptions TryParsePdbParseOptions(IReadOnlyDictionary<string, string> metadata)
        {
            if (!metadata.TryGetValue("language-version", out var langVersionString) ||
                !LanguageVersionFacts.TryParse(langVersionString, out var langVersion))
            {
                langVersion = LanguageVersion.Default;
            }
 
            return new CSharpParseOptions(
                languageVersion: langVersion,
                preprocessorSymbols: metadata.TryGetValue("define", out var defines) ? defines.Split(',') : null);
        }
 
        public override bool OptionsDifferOnlyByPreprocessorDirectives(ParseOptions options1, ParseOptions options2)
        {
            var csharpOptions1 = (CSharpParseOptions)options1;
            var csharpOptions2 = (CSharpParseOptions)options2;
 
            // The easy way to figure out if these only differ by a single field is to update one with the preprocessor symbols of the
            // other, and then do an equality check from there; this is future proofed if another value is ever added.
            return csharpOptions1.WithPreprocessorSymbols(csharpOptions2.PreprocessorSymbolNames) == csharpOptions2;
        }
 
        public override SyntaxTree CreateSyntaxTree(string filePath, ParseOptions options, Encoding encoding, SourceHashAlgorithm checksumAlgorithm, SyntaxNode root)
        {
            options ??= GetDefaultParseOptions();
            return new ParsedSyntaxTree(lazyText: null, (CSharpSyntaxNode)root, (CSharpParseOptions)options, filePath, encoding, checksumAlgorithm);
        }
 
        public override SyntaxTree ParseSyntaxTree(string filePath, ParseOptions options, SourceText text, CancellationToken cancellationToken)
        {
            options ??= GetDefaultParseOptions();
            return SyntaxFactory.ParseSyntaxTree(text, options, filePath, cancellationToken: cancellationToken);
        }
    }
}