using ChatAgent.Client.Services;

namespace ChatAgent.Client.Tests;

/// <summary>
/// Tests for MarkdownService covering markdown rendering and HTML sanitization.
/// Each test verifies a specific markdown element or sanitization rule from the
/// rich-text-display spec.
/// </summary>
public class MarkdownServiceTests
{
    private readonly MarkdownService _sut = new();

    // --- Markdown rendering tests ---

    [Fact]
    public void ConvertToHtml_BoldText_RendersStrong()
    {
        var result = _sut.ConvertToHtml("**bold text**");
        Assert.Contains("<strong>bold text</strong>", result);
    }

    [Fact]
    public void ConvertToHtml_ItalicText_RendersEm()
    {
        var result = _sut.ConvertToHtml("*italic text*");
        Assert.Contains("<em>italic text</em>", result);
    }

    [Fact]
    public void ConvertToHtml_FencedCodeBlock_RendersPreCode()
    {
        var result = _sut.ConvertToHtml("```\nvar x = 1;\n```");
        Assert.Contains("<pre>", result);
        Assert.Contains("<code>", result);
        Assert.Contains("var x = 1;", result);
    }

    [Fact]
    public void ConvertToHtml_InlineCode_RendersCode()
    {
        var result = _sut.ConvertToHtml("Use `Console.WriteLine` here");
        Assert.Contains("<code>Console.WriteLine</code>", result);
    }

    [Fact]
    public void ConvertToHtml_UnorderedList_RendersUlLi()
    {
        var result = _sut.ConvertToHtml("- item one\n- item two");
        Assert.Contains("<ul>", result);
        Assert.Contains("<li>item one</li>", result);
        Assert.Contains("<li>item two</li>", result);
    }

    [Fact]
    public void ConvertToHtml_OrderedList_RendersOlLi()
    {
        var result = _sut.ConvertToHtml("1. first\n2. second");
        Assert.Contains("<ol>", result);
        Assert.Contains("<li>first</li>", result);
    }

    [Fact]
    public void ConvertToHtml_Heading_RendersH2()
    {
        var result = _sut.ConvertToHtml("## My Heading");
        Assert.Contains("<h2>My Heading</h2>", result);
    }

    [Fact]
    public void ConvertToHtml_Table_RendersTableElements()
    {
        var markdown = "| Name | Value |\n|------|-------|\n| A    | 1     |";
        var result = _sut.ConvertToHtml(markdown);
        Assert.Contains("<table>", result);
        Assert.Contains("<th>", result);
        Assert.Contains("<td>", result);
    }

    [Fact]
    public void ConvertToHtml_Link_RendersAnchorWithHref()
    {
        var result = _sut.ConvertToHtml("[click here](https://example.com)");
        Assert.Contains("<a", result);
        Assert.Contains("href=\"https://example.com\"", result);
        Assert.Contains("click here</a>", result);
    }

    [Fact]
    public void ConvertToHtml_EmptyString_ReturnsEmpty()
    {
        Assert.Equal(string.Empty, _sut.ConvertToHtml(""));
        Assert.Equal(string.Empty, _sut.ConvertToHtml(null!));
    }

    // --- Sanitization tests ---

    [Fact]
    public void ConvertToHtml_ScriptTag_IsStripped()
    {
        var result = _sut.ConvertToHtml("Hello <script>alert('xss')</script> world");
        Assert.DoesNotContain("<script>", result);
        Assert.DoesNotContain("alert", result);
    }

    [Fact]
    public void ConvertToHtml_EventHandler_IsStripped()
    {
        var result = _sut.ConvertToHtml("<div onclick=\"alert('xss')\">test</div>");
        Assert.DoesNotContain("onclick", result);
        Assert.DoesNotContain("alert", result);
    }

    [Fact]
    public void ConvertToHtml_ImgTag_IsStripped()
    {
        var result = _sut.ConvertToHtml("<img src=\"x\" onerror=\"alert('xss')\">");
        Assert.DoesNotContain("<img", result);
        Assert.DoesNotContain("onerror", result);
    }

    [Fact]
    public void ConvertToHtml_SafeTagsPreserved()
    {
        var result = _sut.ConvertToHtml("**bold** and *italic* and `code`");
        Assert.Contains("<strong>", result);
        Assert.Contains("<em>", result);
        Assert.Contains("<code>", result);
    }

    [Fact]
    public void ConvertToHtml_AnchorOnlyKeepsHref()
    {
        // Markdig generates links from markdown — verify only href survives
        var result = _sut.ConvertToHtml("[test](https://example.com)");
        Assert.Contains("href=", result);
        Assert.DoesNotContain("onclick", result);
        Assert.DoesNotContain("style", result);
    }
}