using Microsoft.CodeAnalysis.CSharp;

using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace JavaToCSharp.Statements;

/// <summary>

/// Lowers Java's labeled <c>break</c>/<c>continue</c> into C#.

/// </summary>

/// <remarks>

/// Two shapes are supported, selected by <see cref="JavaConversionOptions.UseLabeledBreakAndContinue"/>:

/// <list type="bullet">

/// <item>C# 15 labeled jumps (<c>break outer;</c>), which map one-to-one onto the Java syntax.</item>

/// <item>A <c>goto</c> to a generated target label, which is valid in every C# version.</item>

/// </list>

/// </remarks>

internal static class LabeledJumpHelper

{

/// <summary>

/// The label a <c>goto</c> jumps to in order to leave the loop labeled <paramref name="label"/>.

/// Emitted immediately after the loop.

/// </summary>

internal static string BreakTargetLabel(string label) => $"{label}_break";

/// <summary>

/// The label a <c>goto</c> jumps to in order to start the next iteration of the loop labeled

/// <paramref name="label"/>. Emitted as the last statement of the loop body.

/// </summary>

internal static string ContinueTargetLabel(string label) => $"{label}_continue";

/// <summary>

/// Creates the statement for a labeled <c>break</c> or <c>continue</c>, recording on the context which

/// target labels the <c>goto</c> fallback must emit.

/// </summary>

internal static StatementSyntax CreateJump(ConversionContext context, string label, bool isBreak)

{

if (context.Options.UseLabeledBreakAndContinue)

{

var name = SyntaxFactory.IdentifierName(label);

// The labeled break/continue factory overloads are still marked experimental in Roslyn.

#pragma warning disable RSEXPERIMENTAL006

return isBreak

? SyntaxFactory.BreakStatement(name)

: SyntaxFactory.ContinueStatement(name);

#pragma warning restore RSEXPERIMENTAL006

}

var target = isBreak ? BreakTargetLabel(label) : ContinueTargetLabel(label);

if (isBreak)

{

context.LabelsNeedingBreakTarget.Add(label);

}

else

{

context.LabelsNeedingContinueTarget.Add(label);

}

return SyntaxFactory.GotoStatement(

SyntaxKind.GotoStatement,

SyntaxFactory.IdentifierName(target));

}

}