XFESystem

using System.Security.Cryptography;
using System.Text;

namespace XFESystem.Browser.Tests;

public sealed class PackagedResourceCacheTests
{
    [Fact]
    public void PrewarmKeepsOriginalEmbeddedTextAndSharesItAcrossCatalogInstances()
    {
        int warmed = PackagedBrowserResources.PrewarmTextResources();
        var first = new PackagedBrowserResources(); var second = new PackagedBrowserResources();
        int checkedResources = 0;
        foreach (string name in typeof(PackagedBrowserResources).Assembly.GetManifestResourceNames())
        {
            string normalized = name.Replace('\\', '/');
            string? path = normalized.StartsWith("MonacoCore/", StringComparison.Ordinal) ? PackagedBrowserResources.MonacoCoreRoot + normalized[11..] :
                normalized.StartsWith("WebsiteCode/", StringComparison.Ordinal) ? PackagedBrowserResources.WebsiteCodeRoot + normalized[12..] : null;
            if (path is null || Path.GetExtension(path) is not (".js" or ".css" or ".json")) continue;
            using var original = typeof(PackagedBrowserResources).Assembly.GetManifestResourceStream(name)!;
            using var reader = new StreamReader(original, Encoding.UTF8, true);
            string expected = reader.ReadToEnd();
            Assert.True(first.TryGet(new(path), out var a)); Assert.True(second.TryGet(new(path), out var b));
            Assert.NotSame(a, b); Assert.Same(a.Body, b.Body);
            Assert.Equal(expected, a.Body);
            Assert.Equal(SHA256.HashData(Encoding.UTF8.GetBytes(expected)), SHA256.HashData(Encoding.UTF8.GetBytes(a.Body)));
            Assert.Equal(Path.GetExtension(path) switch { ".css" => "text/css", ".json" => "application/json", _ => "application/javascript" }, a.ContentType);
            checkedResources++;
        }
        Assert.True(checkedResources > 5);
        Assert.Equal(checkedResources, warmed);
        Assert.Equal(warmed, PackagedBrowserResources.PrewarmTextResources());
    }

    [Fact]
    public void LargeCoreCacheIsConcurrentAndRepeatedHitsDoNotDecodeAnotherLargeString()
    {
        PackagedBrowserResources.PrewarmTextResources();
        var resources = new PackagedBrowserResources();
        var address = new Uri(PackagedBrowserResources.MonacoCoreRoot + "EditorCore.js");
        Assert.True(resources.TryGet(address, out var original));
        var strings = new string[32];
        Parallel.For(0, strings.Length, index =>
        {
            Assert.True(new PackagedBrowserResources().TryGet(address, out var response)); strings[index] = response.Body;
        });
        Assert.All(strings, value => Assert.Same(original.Body, value));
        long characters = 0;
        long allocatedBefore = GC.GetAllocatedBytesForCurrentThread();
        for (int index = 0; index < 64; index++)
        {
            if (!resources.TryGet(address, out var response)) throw new IOException("The cached core disappeared.");
            characters += response.Body.Length;
        }
        long allocated = GC.GetAllocatedBytesForCurrentThread() - allocatedBefore;
        Assert.Equal((long)original.Body.Length * 64, characters);
        Assert.InRange(allocated, 0, 1_048_576);
    }

    [Fact]
    public void CachedScriptStillConsumesTheFullNavigationBudgetOnEveryFetch()
    {
        var resources = new PackagedBrowserResources();
        string path = PackagedBrowserResources.WebsiteCodeRoot + "CodePalette.js";
        Assert.True(resources.TryGet(new(path), out var script));
        var browser = new BrowserService(new PageTransport(path), new BrowserLimits { MaximumTotalResourceCharacters = script.Body.Length * 2 - 1 }, resources);
        var page = browser.Navigate("http://cache-budget.test/Index.html");
        var receipt = Assert.Single(browser.LoadedResources, resource => resource.Kind == "script");
        Assert.Equal(script.Body.Length, receipt.Characters);
        Assert.Contains("character budget", page.Text, StringComparison.Ordinal);
        Assert.Equal("object", browser.ExecuteJavaScript("typeof xfeWebsiteCodePalette"));
    }

    [Fact]
    public void CacheRetainsOriginAllowlistAndReturnsTheCurrentRequestAddress()
    {
        var resources = new PackagedBrowserResources();
        var address = new Uri(PackagedBrowserResources.MonacoCoreRoot + "EditorCore.js?first=1");
        Assert.True(resources.TryGet(address, out var first));
        var other = new Uri(PackagedBrowserResources.MonacoCoreRoot + "EditorCore.js?second=2");
        Assert.True(resources.TryGet(other, out var second));
        Assert.Same(first.Body, second.Body); Assert.Equal(address, first.Address); Assert.Equal(other, second.Address);
        Assert.False(resources.TryGet(new("file:///C:/Secret.js"), out _));
        Assert.False(resources.TryGet(new("http://foreign.test/Browser/Monaco/0.52.2/Core/EditorCore.js"), out _));
        Assert.False(resources.TryGet(new(PackagedBrowserResources.MonacoCoreRoot + "Missing.js"), out _));
    }

    private sealed class PageTransport(string script) : IWebTransport
    {
        public WebResponse Get(Uri address, BrowserLimits limits) => new(address, 200, "text/html",
            "<body>Cache budget test</body><script src='" + script + "'></script><script src='" + script + "'></script>");
    }
}