// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable disable
 
using System;
using Xunit;
 
namespace Microsoft.AspNetCore.Razor.Language.Intermediate;
 
public class DefaultRazorIntermediateNodeBuilderTest
{
    [Fact]
    public void Ctor_CreatesEmptyBuilder()
    {
        // Arrange & Act
        var builder = new DefaultRazorIntermediateNodeBuilder();
        var current = builder.Current;
 
        // Assert
        Assert.Null(current);
    }
 
    [Fact]
    public void Push_WhenEmpty_AddsNode()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Push(node);
 
        // Assert
        Assert.Same(node, builder.Current);
    }
 
    [Fact]
    public void Push_WhenNonEmpty_SetsUpChild()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Push(node);
 
        // Assert
        Assert.Same(node, builder.Current);
        Assert.Collection(parent.Children, n => Assert.Same(node, n));
    }
 
    [Fact]
    public void Pop_ThrowsWhenEmpty()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        // Act & Assert
        var ex = Assert.Throws<InvalidOperationException>(
            () => builder.Pop());
        Assert.Equal(
            "The 'Pop' operation is not valid when the builder is empty.",
            ex.Message);
    }
 
    [Fact]
    public void Pop_SingleNodeDepth_RemovesAndReturnsNode()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var node = new BasicIntermediateNode();
        builder.Push(node);
 
        // Act
        var result = builder.Pop();
 
        // Assert
        Assert.Same(node, result);
        Assert.Null(builder.Current);
    }
 
    [Fact]
    public void Pop_MultipleNodeDepth_RemovesAndReturnsNode()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var node = new BasicIntermediateNode();
        builder.Push(node);
 
        // Act
        var result = builder.Pop();
 
        // Assert
        Assert.Same(node, result);
        Assert.Same(parent, builder.Current);
    }
 
    [Fact]
    public void Add_AddsToChildrenAndSetsParent()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Add(node);
 
        // Assert
        Assert.Same(parent, builder.Current);
        Assert.Collection(parent.Children, n => Assert.Same(node, n));
    }
 
    [Fact]
    public void Insert_AddsToChildren_EmptyCollection()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Insert(0, node);
 
        // Assert
        Assert.Same(parent, builder.Current);
        Assert.Collection(parent.Children, n => Assert.Same(node, n));
    }
 
    [Fact]
    public void Insert_AddsToChildren_NonEmpyCollection()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var child = new BasicIntermediateNode();
        builder.Add(child);
 
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Insert(0, node);
 
        // Assert
        Assert.Same(parent, builder.Current);
        Assert.Collection(parent.Children, n => Assert.Same(node, n), n => Assert.Same(child, n));
    }
 
    [Fact]
    public void Insert_AddsToChildren_NonEmpyCollection_AtEnd()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var parent = new BasicIntermediateNode();
        builder.Push(parent);
 
        var child = new BasicIntermediateNode();
        builder.Add(child);
 
        var node = new BasicIntermediateNode();
 
        // Act
        builder.Insert(1, node);
 
        // Assert
        Assert.Same(parent, builder.Current);
        Assert.Collection(parent.Children, n => Assert.Same(child, n), n => Assert.Same(node, n));
    }
 
    [Fact]
    public void Build_PopsMultipleLevels()
    {
        // Arrange
        var builder = new DefaultRazorIntermediateNodeBuilder();
 
        var document = new DocumentIntermediateNode();
        builder.Push(document);
 
        var node = new BasicIntermediateNode();
        builder.Push(node);
 
        // Act
        var result = builder.Build();
 
        // Assert
        Assert.Same(document, result);
        Assert.Null(builder.Current);
    }
 
    private class BasicIntermediateNode : IntermediateNode
    {
        public override IntermediateNodeCollection Children { get; } = [];
 
        public override void Accept(IntermediateNodeVisitor visitor)
        {
            throw new NotImplementedException();
        }
    }
}