using System.Reflection;
using System.Xml.Linq;
using AcDream.Plugin.Abstractions;

namespace AcDream.Plugins.MossTank.Tests;

public sealed class MossTankMarkupContractTests
{
    [Fact]
    public void VtankTabOrderAndEveryBindingResolveAgainstTheLivePanel()
    {
        XDocument document = XDocument.Load(
            Path.Combine(AppContext.BaseDirectory, "mosstank.xml"));
        XElement root = Assert.IsType<XElement>(document.Root);

        Assert.Equal(
            [
                "Options", "Profiles", "Vitals", "Monsters", "Items",
                "Consumables", "Buffs", "Route", "Meta",
            ],
            root.Elements("tab")
                .Select(static tab => (string?)tab.Attribute("text")));

        PropertyInfo[] properties = typeof(MossTankPanel).GetProperties(
            BindingFlags.Instance | BindingFlags.Public);
        var byName = properties.ToDictionary(
            static property => property.Name,
            StringComparer.Ordinal);

        foreach (XAttribute attribute in root.DescendantsAndSelf().Attributes())
        {
            string value = attribute.Value;
            if (!value.Contains('{', StringComparison.Ordinal))
                continue;
            Assert.Matches("^\\{[^{}]+\\}$", value);
            string name = value[1..^1];
            Assert.True(
                byName.ContainsKey(name),
                $"Markup binding {value} on <{attribute.Parent?.Name}> has no "
                + $"public MossTankPanel property.");
        }
    }

    [Fact]
    public void EveryInteractiveBindingMatchesTheRetainedUiDelegateShape()
    {
        XDocument document = XDocument.Load(
            Path.Combine(AppContext.BaseDirectory, "mosstank.xml"));
        XElement root = Assert.IsType<XElement>(document.Root);
        PropertyInfo[] properties = typeof(MossTankPanel).GetProperties(
            BindingFlags.Instance | BindingFlags.Public);
        var byName = properties.ToDictionary(
            static property => property.Name,
            StringComparer.Ordinal);

        foreach (XElement element in root.DescendantsAndSelf())
        {
            AssertBindingType(element, "onclick", typeof(Action), byName);
            AssertBindingType(
                element,
                "onsubmit",
                typeof(Action<string>),
                byName);

            Type? changeType = element.Name.LocalName switch
            {
                "field" or "menu" => typeof(Action<string>),
                "slider" => typeof(Action<float>),
                "list" => typeof(Action<int>),
                _ => null,
            };
            if (changeType is not null)
                AssertBindingType(element, "onchange", changeType, byName);
        }
    }

    [Fact]
    public void EveryInteractiveControlDeclaresARealHandlerBinding()
    {
        XDocument document = XDocument.Load(
            Path.Combine(AppContext.BaseDirectory, "mosstank.xml"));
        XElement root = Assert.IsType<XElement>(document.Root);
        HashSet<string> interactive = new(
        [
            "tab", "button", "toggle", "slider", "field", "menu", "list",
        ], StringComparer.Ordinal);

        XElement[] controls = root.Descendants()
            .Where(element => interactive.Contains(element.Name.LocalName))
            .ToArray();
        Assert.Equal(190, controls.Length);

        foreach (XElement control in controls)
        {
            XAttribute? handler = control.Attribute("onclick")
                ?? control.Attribute("onchange")
                ?? control.Attribute("onsubmit");
            Assert.NotNull(handler);
            Assert.NotEqual("false", (string?)control.Attribute("enabled"));
        }
    }

    [Fact]
    public void EveryVtankTabIsBackedByALivePanelSurface()
    {
        var panel = new MossTankPanel(new StubHost());

        Assert.True(panel.OptionsTabEnabled);
        Assert.True(panel.VitalsTabEnabled);
        Assert.True(panel.MonstersTabEnabled);
        Assert.True(panel.BuffsTabEnabled);
        Assert.True(panel.ProfilesTabEnabled);
        Assert.True(panel.ItemsTabEnabled);
        Assert.True(panel.ConsumablesTabEnabled);
        Assert.True(panel.RouteTabEnabled);
        Assert.True(panel.MetaTabEnabled);
    }

    [Fact]
    public void AuthoredShellFitsTheMinimumCanvasAndEverySizedChildFitsItsParent()
    {
        XDocument document = XDocument.Load(
            Path.Combine(AppContext.BaseDirectory, "mosstank.xml"));
        XElement root = Assert.IsType<XElement>(document.Root);

        Assert.Equal(800f, Number(root, "w"));
        Assert.Equal(244f, Number(root, "h"));
        AssertWithinParent(root);
    }

    [Fact]
    public void TextlessAndAbbreviatedControlsHaveAccessibleRetailTooltips()
    {
        XDocument document = XDocument.Load(
            Path.Combine(AppContext.BaseDirectory, "mosstank.xml"));
        XElement root = Assert.IsType<XElement>(document.Root);
        string[] interactive =
        [
            "tab", "button", "toggle", "slider", "field", "menu", "list",
        ];
        HashSet<string> terse = new(
        [
            "+", "-", "↑", "↓", "F", "B", "G", "I", "Y", "V", "A",
            "R", "S", "W", "FC", "Cp", "DC", "Cs",
        ], StringComparer.Ordinal);

        foreach (XElement element in root.Descendants()
                     .Where(element => interactive.Contains(
                         element.Name.LocalName,
                         StringComparer.Ordinal)))
        {
            string? text = (string?)element.Attribute("text");
            if (!string.IsNullOrWhiteSpace(text) && !terse.Contains(text))
                continue;
            Assert.False(
                string.IsNullOrWhiteSpace((string?)element.Attribute("tooltip")),
                $"<{element.Name}> text='{text}' needs a tooltip.");
        }
    }

    private static void AssertBindingType(
        XElement element,
        string attributeName,
        Type expectedType,
        IReadOnlyDictionary<string, PropertyInfo> properties)
    {
        string? expression = (string?)element.Attribute(attributeName);
        if (expression is null)
            return;
        Assert.StartsWith("{", expression, StringComparison.Ordinal);
        Assert.EndsWith("}", expression, StringComparison.Ordinal);
        string name = expression[1..^1];
        Assert.True(
            properties.TryGetValue(name, out PropertyInfo? property),
            $"Markup binding {expression} on <{element.Name}> has no public "
            + "MossTankPanel property.");
        Assert.Equal(expectedType, property.PropertyType);
    }

    private static void AssertWithinParent(XElement parent)
    {
        float parentWidth = Number(parent, "w");
        float parentHeight = Number(parent, "h");
        foreach (XElement child in parent.Elements())
        {
            float width = Number(child, "w");
            float height = Number(child, "h");
            if (width > 0f)
            {
                Assert.True(
                    Number(child, "x") + width <= parentWidth,
                    $"<{child.Name}> crosses the right edge of <{parent.Name}>.");
            }
            if (height > 0f)
            {
                Assert.True(
                    Number(child, "y") + height <= parentHeight,
                    $"<{child.Name}> crosses the bottom edge of <{parent.Name}>.");
            }
            AssertWithinParent(child);
        }
    }

    private static float Number(XElement element, string attribute) =>
        float.TryParse(
            (string?)element.Attribute(attribute),
            System.Globalization.NumberStyles.Float,
            System.Globalization.CultureInfo.InvariantCulture,
            out float value)
            ? value
            : 0f;

    private sealed class StubHost : IPluginHost
    {
        public bool HasUi => false;
        public IPluginLogger Log { get; } = new StubLogger();
        public IGameState State { get; } = new StubState();
        public IEvents Events { get; } = new StubEvents();
        public ISelectionService Selection { get; } = new StubSelection();
        public IUiRegistry Ui => NoOpUiRegistry.Instance;
        public IAutomationSurface Automation => NoOpAutomationSurface.Instance;
    }

    private sealed class StubLogger : IPluginLogger
    {
        public void Info(string message) { }
        public void Warn(string message) { }
        public void Error(string message, Exception? exception = null) { }
    }

    private sealed class StubState : IGameState
    {
        public IReadOnlyList<WorldEntitySnapshot> Entities => [];
    }

    private sealed class StubEvents : IEvents
    {
        public event Action<WorldEntitySnapshot> EntitySpawned
        {
            add { }
            remove { }
        }
        public event Action<double> Tick
        {
            add { }
            remove { }
        }
    }

    private sealed class StubSelection : ISelectionService
    {
        public uint? SelectedObjectId => null;
        public uint? PreviousObjectId => null;
        public event Action<SelectionChangedEvent> Changed
        {
            add { }
            remove { }
        }
        public bool Select(uint objectId) => false;
        public bool Clear() => false;
    }
}