XFESystem

namespace XFESystem.Browser.Tests;

public sealed class BrowserStylesheetMutationTests
{
    private sealed class Transport : IWebTransport
    {
        public readonly List<string> Requests = [];
        public WebResponse Get(Uri address, BrowserLimits limits)
        {
            Requests.Add(address.AbsolutePath);
            var (mime, body) = address.AbsolutePath switch
            {
                "/" => ("text/html", "<style>body{margin:0}</style><link id=Theme rel=stylesheet href=/First.css><div id=Box>Content</div>"),
                "/First.css" => ("text/css", "#Box{width:100px;height:30px;background:blue}"),
                "/Updated.css" => ("text/css", "#Box{width:180px;height:40px;background:green}"),
                _ => throw new InvalidOperationException("Unexpected fixture request")
            };
            return new(address, 200, mime, body);
        }
    }

    [Fact]
    public void RemovingLinkedStylesheetRetractsItsRulesOnNextRealLayout()
    {
        var transport = new Transport(); var browser = new BrowserService(transport); browser.Navigate("http://test/");
        var box = browser.Document!.GetElementById("Box")!;
        var first = browser.Layout(new(600, 400));
        Assert.Equal(100, first.GetBoundingClientRect(box).Width); Assert.Equal(0x0000FFu, first.GetComputedStyle(box)!.Background.Rgb);
        browser.ExecuteJavaScript("document.getElementById('Theme').remove()");
        var removed = browser.Layout(new(600, 400));
        Assert.Equal(600, removed.GetBoundingClientRect(box).Width); Assert.Equal(0, removed.GetComputedStyle(box)!.Background.Alpha);
        Assert.Equal(new[] { "/", "/First.css" }, transport.Requests);
    }

    [Fact]
    public void ReplacingTheSameLinkAtStylesheetLimitLoadsNewRulesWithoutFalseOverflow()
    {
        var transport = new Transport(); var browser = new BrowserService(transport, new() { MaximumStyleSheets = 1 });
        browser.Navigate("http://test/"); var box = browser.Document!.GetElementById("Box")!;
        browser.ExecuteJavaScript("document.getElementById('Theme').setAttribute('href','/Updated.css')");
        var updated = browser.Layout(new(600, 400));
        Assert.Equal(180, updated.GetBoundingClientRect(box).Width); Assert.Equal(40, updated.GetBoundingClientRect(box).Height);
        Assert.Equal(0x008000u, updated.GetComputedStyle(box)!.Background.Rgb);
        Assert.Equal(new[] { "/", "/First.css", "/Updated.css" }, transport.Requests);
        Assert.DoesNotContain("stylesheet count limit", browser.RefreshDocument().Text, StringComparison.Ordinal);
    }
}