// 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.Immutable;
using Microsoft.CodeAnalysis.CodeStyle;
using Microsoft.CodeAnalysis.CSharp.CodeGeneration;
using Microsoft.CodeAnalysis.CSharp.CodeStyle;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
 
namespace Microsoft.CodeAnalysis.CSharp.UseExpressionBody
{
    internal class UseExpressionBodyForIndexersHelper :
        UseExpressionBodyHelper<IndexerDeclarationSyntax>
    {
        public static readonly UseExpressionBodyForIndexersHelper Instance = new();
 
        private UseExpressionBodyForIndexersHelper()
            : base(IDEDiagnosticIds.UseExpressionBodyForIndexersDiagnosticId,
                   EnforceOnBuildValues.UseExpressionBodyForIndexers,
                   new LocalizableResourceString(nameof(CSharpAnalyzersResources.Use_expression_body_for_indexer), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)),
                   new LocalizableResourceString(nameof(CSharpAnalyzersResources.Use_block_body_for_indexer), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)),
                   CSharpCodeStyleOptions.PreferExpressionBodiedIndexers,
                   ImmutableArray.Create(SyntaxKind.IndexerDeclaration))
        {
        }
 
        public override CodeStyleOption2<ExpressionBodyPreference> GetExpressionBodyPreference(CSharpCodeGenerationOptions options)
            => options.PreferExpressionBodiedIndexers;
 
        protected override BlockSyntax GetBody(IndexerDeclarationSyntax declaration)
            => GetBodyFromSingleGetAccessor(declaration.AccessorList);
 
        protected override ArrowExpressionClauseSyntax GetExpressionBody(IndexerDeclarationSyntax declaration)
            => declaration.ExpressionBody;
 
        protected override SyntaxToken GetSemicolonToken(IndexerDeclarationSyntax declaration)
            => declaration.SemicolonToken;
 
        protected override IndexerDeclarationSyntax WithSemicolonToken(IndexerDeclarationSyntax declaration, SyntaxToken token)
            => declaration.WithSemicolonToken(token);
 
        protected override IndexerDeclarationSyntax WithExpressionBody(IndexerDeclarationSyntax declaration, ArrowExpressionClauseSyntax expressionBody)
            => declaration.WithExpressionBody(expressionBody);
 
        protected override IndexerDeclarationSyntax WithAccessorList(IndexerDeclarationSyntax declaration, AccessorListSyntax accessorList)
            => declaration.WithAccessorList(accessorList);
 
        protected override IndexerDeclarationSyntax WithBody(IndexerDeclarationSyntax declaration, BlockSyntax body)
        {
            if (body == null)
            {
                return declaration.WithAccessorList(null);
            }
 
            throw new InvalidOperationException();
        }
 
        protected override IndexerDeclarationSyntax WithGenerateBody(SemanticModel semanticModel, IndexerDeclarationSyntax declaration)
            => WithAccessorList(semanticModel, declaration);
 
        protected override bool CreateReturnStatementForExpression(SemanticModel semanticModel, IndexerDeclarationSyntax declaration) => true;
 
        protected override bool TryConvertToExpressionBody(
            IndexerDeclarationSyntax declaration,
            ExpressionBodyPreference conversionPreference,
            out ArrowExpressionClauseSyntax arrowExpression,
            out SyntaxToken semicolonToken)
        {
            return TryConvertToExpressionBodyForBaseProperty(declaration, conversionPreference, out arrowExpression, out semicolonToken);
        }
 
        protected override Location GetDiagnosticLocation(IndexerDeclarationSyntax declaration)
        {
            var body = GetBody(declaration);
            if (body != null)
            {
                return body.Statements[0].GetLocation();
            }
 
            var getAccessor = GetSingleGetAccessor(declaration.AccessorList);
            return getAccessor.ExpressionBody.GetLocation();
        }
    }
}