// 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.Threading;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Xunit;

namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Extensions
{
    public class SyntaxTreeExtensionsTests
    {
        private static void VerifyWholeLineIsActive(SyntaxTree tree, int lineNumber)
        {
            var line = tree.GetText().Lines[lineNumber];
            for (var pos = line.Start; pos < line.EndIncludingLineBreak; pos++)
            {
                Assert.False(tree.IsInInactiveRegion(pos, CancellationToken.None));
            }
        }

        private static void VerifyWholeLineIsInactive(SyntaxTree tree, int lineNumber)
        {
            var line = tree.GetText().Lines[lineNumber];
            for (var pos = line.Start; pos < line.EndIncludingLineBreak; pos++)
            {
                Assert.True(tree.IsInInactiveRegion(pos, CancellationToken.None));
            }
        }

        [Fact]
        public void SimpleInactive()
        {
            var code = """
                #if false
                This is inactive
                #else
                // This is active
                #endif
                """;
            var tree = CSharpSyntaxTree.ParseText(code);
            VerifyWholeLineIsActive(tree, 0);
            VerifyWholeLineIsInactive(tree, 1);
            VerifyWholeLineIsActive(tree, 2);
            VerifyWholeLineIsActive(tree, 3);
            VerifyWholeLineIsActive(tree, 4);
        }

        [Fact]
        public void InactiveEof()
        {
            var code = """
                #if false
                This is inactive
                """;
            var tree = CSharpSyntaxTree.ParseText(code);
            VerifyWholeLineIsActive(tree, 0);
            VerifyWholeLineIsInactive(tree, 1);
        }

        [Fact]
        public void InactiveEof2()
        {
            var code = """
                #if false
                This is inactive
                #endif
                // This is active
                """;

            var tree = CSharpSyntaxTree.ParseText(code);
            VerifyWholeLineIsActive(tree, 0);
            VerifyWholeLineIsInactive(tree, 1);
            VerifyWholeLineIsActive(tree, 2);
            VerifyWholeLineIsActive(tree, 3);
        }
    }
}
