// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using Microsoft.AspNetCore.Testing;
using Xunit;

namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
{
    public class SourceLocationTest
    {
        [Fact]
        public void ConstructorWithLineAndCharacterIndexSetsAssociatedProperties()
        {
            // Act
            var loc = new SourceLocation(0, 42, 24);

            // Assert
            Assert.Null(loc.FilePath);
            Assert.Equal(0, loc.AbsoluteIndex);
            Assert.Equal(42, loc.LineIndex);
            Assert.Equal(24, loc.CharacterIndex);
        }

        [Fact]
        public void Constructor_SetsFilePathAndIndexes()
        {
            // Arrange
            var filePath = "some-file-path";
            var absoluteIndex = 133;
            var lineIndex = 23;
            var characterIndex = 12;

            // Act
            var sourceLocation = new SourceLocation(filePath, absoluteIndex, lineIndex, characterIndex);

            // Assert
            Assert.Equal(filePath, sourceLocation.FilePath);
            Assert.Equal(absoluteIndex, sourceLocation.AbsoluteIndex);
            Assert.Equal(lineIndex, sourceLocation.LineIndex);
            Assert.Equal(characterIndex, sourceLocation.CharacterIndex);
        }

        [Theory]
        [InlineData(null)]
        [InlineData("some-file")]
        public void GetHashCode_ReturnsSameValue_WhenEqual(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 10, 3, 4);
            var sourceLocationB = new SourceLocation(path, 10, 3, 4);
            var sourceLocationC = new SourceLocation(path, 10, 45, 8754);

            // Act
            var hashCodeA = sourceLocationA.GetHashCode();
            var hashCodeB = sourceLocationB.GetHashCode();
            var hashCodeC = sourceLocationC.GetHashCode();

            // Assert
            Assert.Equal(hashCodeA, hashCodeB);
            Assert.Equal(hashCodeA, hashCodeC);
        }

        [Fact]
        public void Equals_ReturnsTrue_FilePathsNullAndAbsoluteIndicesMatch()
        {
            // Arrange
            var sourceLocationA = new SourceLocation(10, 3, 4);
            var sourceLocationB = new SourceLocation(10, 45, 8754);

            // Act
            var result = sourceLocationA.Equals(sourceLocationB);

            // Assert
            Assert.True(result);
        }

        [Fact]
        public void Equals_ReturnsFalse_IfFilePathIsDifferent()
        {
            // Arrange
            var sourceLocationA = new SourceLocation(10, 3, 4);
            var sourceLocationB = new SourceLocation("different-file", 10, 3, 4);

            // Act
            var result = sourceLocationA.Equals(sourceLocationB);

            // Assert
            Assert.False(result);
        }

        [Theory]
        [InlineData(null)]
        [InlineData("some-file")]
        public void Equals_ReturnsTrue_IfFilePathAndIndexesAreSame(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 10, 3, 4);
            var sourceLocationB = new SourceLocation(path, 10, 3, 4);
            var sourceLocationC = new SourceLocation("different-path", 10, 3, 4);

            // Act
            var result1 = sourceLocationA.Equals(sourceLocationB);
            var result2 = sourceLocationA.Equals(sourceLocationC);

            // Assert
            Assert.True(result1);
            Assert.False(result2);
        }

        [Fact]
        public void Add_Throws_IfFilePathsDoNotMatch()
        {
            // Arrange
            var sourceLocationA = new SourceLocation("a-path", 1, 1, 1);
            var sourceLocationB = new SourceLocation("b-path", 1, 1, 1);

            // Act and Assert
            ExceptionAssert.ThrowsArgument(
                () => { var result = sourceLocationA + sourceLocationB; },
                "right",
                $"Cannot perform '+' operations on 'SourceLocation' instances with different file paths.");
        }

        [Theory]
        [InlineData(null)]
        [InlineData("same-path")]
        public void Add_IgnoresCharacterIndexIfRightLineIndexIsNonZero(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 1, 2, 3);
            var sourceLocationB = new SourceLocation(path, 4, 5, 6);

            // Act
            var result = sourceLocationA + sourceLocationB;

            // Assert
            Assert.Equal(path, result.FilePath);
            Assert.Equal(5, result.AbsoluteIndex);
            Assert.Equal(7, result.LineIndex);
            Assert.Equal(6, result.CharacterIndex);
        }

        [Theory]
        [InlineData(null)]
        [InlineData("same-path")]
        public void Add_UsesCharacterIndexIfRightLineIndexIsZero(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 2, 5, 3);
            var sourceLocationB = new SourceLocation(path, 4, 0, 6);

            // Act
            var result = sourceLocationA + sourceLocationB;

            // Assert
            Assert.Equal(path, result.FilePath);
            Assert.Equal(6, result.AbsoluteIndex);
            Assert.Equal(5, result.LineIndex);
            Assert.Equal(9, result.CharacterIndex);
        }

        [Fact]
        public void Add_AllowsRightFilePathToBeNull_WhenLeftFilePathIsNonNull()
        {
            // Arrange
            var left = new SourceLocation("left-path", 7, 1, 7);
            var right = new SourceLocation(13, 1, 4);

            // Act
            var result = left + right;

            // Assert
            Assert.Equal(left.FilePath, result.FilePath);
            Assert.Equal(20, result.AbsoluteIndex);
            Assert.Equal(2, result.LineIndex);
            Assert.Equal(4, result.CharacterIndex);
        }

        [Fact]
        public void Add_AllowsLeftFilePathToBeNull_WhenRightFilePathIsNonNull()
        {
            // Arrange
            var left = new SourceLocation(4, 5, 6);
            var right = new SourceLocation("right-path", 7, 8, 9);

            // Act
            var result = left + right;

            // Assert
            Assert.Equal(right.FilePath, result.FilePath);
            Assert.Equal(11, result.AbsoluteIndex);
            Assert.Equal(13, result.LineIndex);
            Assert.Equal(9, result.CharacterIndex);
        }

        [Fact]
        public void Subtract_Throws_IfFilePathsDoNotMatch()
        {
            // Arrange
            var sourceLocationA = new SourceLocation("a-path", 1, 1, 1);
            var sourceLocationB = new SourceLocation("b-path", 1, 1, 1);

            // Act and Assert
            ExceptionAssert.ThrowsArgument(
                () => { var result = sourceLocationA - sourceLocationB; },
                "right",
                "Cannot perform '-' operations on 'SourceLocation' instances with different file paths.");
        }

        [Theory]
        [InlineData(null)]
        [InlineData("same-path")]
        public void Subtract_UsesDifferenceOfCharacterIndexesIfLineIndexesAreSame(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 1, 5, 3);
            var sourceLocationB = new SourceLocation(path, 5, 5, 6);

            // Act
            var result = sourceLocationB - sourceLocationA;

            // Assert
            Assert.Null(result.FilePath);
            Assert.Equal(4, result.AbsoluteIndex);
            Assert.Equal(0, result.LineIndex);
            Assert.Equal(3, result.CharacterIndex);
        }

        [Theory]
        [InlineData(null)]
        [InlineData("same-path")]
        public void Subtract_UsesLeftCharacterIndexIfLineIndexesAreDifferent(string path)
        {
            // Arrange
            var sourceLocationA = new SourceLocation(path, 2, 0, 3);
            var sourceLocationB = new SourceLocation(path, 4, 5, 6);

            // Act
            var result = sourceLocationB - sourceLocationA;

            // Assert
            Assert.Null(result.FilePath);
            Assert.Equal(2, result.AbsoluteIndex);
            Assert.Equal(5, result.LineIndex);
            Assert.Equal(6, result.CharacterIndex);
        }

        [Theory]
        [InlineData(null)]
        [InlineData("path-to-file")]
        public void Advance_PreservesSourceLocationFilePath(string path)
        {
            // Arrange
            var sourceLocation = new SourceLocation(path, 15, 2, 8);

            // Act
            var result = SourceLocation.Advance(sourceLocation, "Hello world");

            // Assert
            Assert.Equal(path, result.FilePath);
            Assert.Equal(26, result.AbsoluteIndex);
            Assert.Equal(2, result.LineIndex);
            Assert.Equal(19, result.CharacterIndex);
        }
    }
}