using System.Numerics;
using AcDream.App.Input;
using AcDream.App.Net;
using AcDream.UI.Abstractions;
using AcDream.UI.Abstractions.Panels.Chat;
using AcDream.UI.Abstractions.Panels.Debug;
using AcDream.UI.Abstractions.Panels.Settings;
using AcDream.UI.Abstractions.Panels.Vitals;
using AcDream.UI.ImGui;
using ImGuiNET;

namespace AcDream.App.Rendering;

internal enum DevToolsPanelLayoutCondition
{
    FirstUseEver,
    Always,
}

internal enum DevToolsPanelKind
{
    Vitals,
    Chat,
    Debug,
    Settings,
}

internal interface IDevToolsFrameLifecycle : IRenderFrameFailureRecovery
{
    void BeginFrame(float deltaSeconds);

    void Render(double deltaSeconds, int viewportWidth, int viewportHeight);
}

internal interface IDevToolsFrameBackend : IDisposable
{
    void BeginFrame(float deltaSeconds);

    void AbortFrame();

    bool BeginMainMenuBar();

    void EndMainMenuBar();

    bool BeginMenu(string label);

    void EndMenu();

    bool MenuItem(string label, string? shortcut = null, bool selected = false);

    void Separator();

    void RenderPanels(PanelContext context);

    void RenderDrawData();

    void SetWindowLayout(
        string title,
        Vector2 position,
        Vector2 size,
        DevToolsPanelLayoutCondition condition);
}

internal interface IDevToolsCameraMenuOperations
{
    bool IsFlyMode { get; }

    bool CollideCamera { get; set; }

    void ToggleFlyOrChase();
}

internal interface IDevToolsCommandBusSource
{
    ICommandBus Current { get; }
}

internal interface IDevToolsPanelSet
{
    bool Contains(DevToolsPanelKind kind);

    string? GetTitle(DevToolsPanelKind kind);

    bool IsVisible(DevToolsPanelKind kind);

    void Toggle(DevToolsPanelKind kind);

    void FocusChatInput();

    void AddDebugToast(string message);
}

/// <summary>Concrete ImGui backend for the developer presentation owner.</summary>
internal sealed class ImGuiDevToolsFrameBackend : IDevToolsFrameBackend, IDisposable
{
    private readonly IImGuiBootstrapper _bootstrap;
    private readonly ImGuiPanelHost _panels;
    private bool _disposed;

    public ImGuiDevToolsFrameBackend(
        IImGuiBootstrapper bootstrap,
        ImGuiPanelHost panels)
    {
        _bootstrap = bootstrap ?? throw new ArgumentNullException(nameof(bootstrap));
        _panels = panels ?? throw new ArgumentNullException(nameof(panels));
    }

    public void BeginFrame(float deltaSeconds) => _bootstrap.BeginFrame(deltaSeconds);

    public void AbortFrame() => _bootstrap.AbortFrame();

    public bool BeginMainMenuBar() => ImGuiNET.ImGui.BeginMainMenuBar();

    public void EndMainMenuBar() => ImGuiNET.ImGui.EndMainMenuBar();

    public bool BeginMenu(string label) => ImGuiNET.ImGui.BeginMenu(label);

    public void EndMenu() => ImGuiNET.ImGui.EndMenu();

    public bool MenuItem(string label, string? shortcut = null, bool selected = false) =>
        ImGuiNET.ImGui.MenuItem(label, shortcut ?? string.Empty, selected);

    public void Separator() => ImGuiNET.ImGui.Separator();

    public void RenderPanels(PanelContext context) => _panels.RenderAll(context);

    public void RenderDrawData() => _bootstrap.Render();

    public void SetWindowLayout(
        string title,
        Vector2 position,
        Vector2 size,
        DevToolsPanelLayoutCondition condition)
    {
        ImGuiCond imguiCondition = condition switch
        {
            DevToolsPanelLayoutCondition.FirstUseEver => ImGuiCond.FirstUseEver,
            DevToolsPanelLayoutCondition.Always => ImGuiCond.Always,
            _ => throw new ArgumentOutOfRangeException(nameof(condition)),
        };
        ImGuiNET.ImGui.SetWindowPos(title, position, imguiCondition);
        ImGuiNET.ImGui.SetWindowSize(title, size, imguiCondition);
    }

    public void Dispose()
    {
        if (_disposed)
            return;

        _bootstrap.Dispose();
        _disposed = true;
    }

}

/// <summary>Mutable late-composition seam for player-mode menu operations.</summary>
internal sealed class DevToolsCameraMenuOperations : IDevToolsCameraMenuOperations
{
    private readonly CameraController _camera;
    private readonly IDevToolsPlayerModeCommands _playerMode;

    public DevToolsCameraMenuOperations(
        CameraController camera,
        IDevToolsPlayerModeCommands playerMode)
    {
        _camera = camera ?? throw new ArgumentNullException(nameof(camera));
        _playerMode = playerMode ?? throw new ArgumentNullException(nameof(playerMode));
    }

    public bool IsFlyMode => _camera.IsFlyMode;

    public bool CollideCamera
    {
        get => AcDream.Core.Rendering.CameraDiagnostics.CollideCamera;
        set => AcDream.Core.Rendering.CameraDiagnostics.CollideCamera = value;
    }

    public void ToggleFlyOrChase() => _playerMode.ToggleFlyOrChase();
}

/// <summary>Resolves the reconnect-safe command bus at draw time.</summary>
internal sealed class DevToolsCommandBusSource : IDevToolsCommandBusSource
{
    private ILiveUiSessionTarget? _session;
    private bool _deactivated;

    public ICommandBus Current =>
        !_deactivated && _session is { } session
            ? session.Commands
            : NullCommandBus.Instance;

    public void Bind(ILiveUiSessionTarget session)
    {
        ArgumentNullException.ThrowIfNull(session);
        ObjectDisposedException.ThrowIf(_deactivated, this);
        if (_session is not null && !ReferenceEquals(_session, session))
            throw new InvalidOperationException(
                "Developer command-bus authority is already bound.");
        _session = session;
    }

    public IDisposable BindOwned(ILiveUiSessionTarget session)
    {
        ArgumentNullException.ThrowIfNull(session);
        ObjectDisposedException.ThrowIf(_deactivated, this);
        if (_session is not null)
        {
            throw new InvalidOperationException(
                "Developer command-bus authority is already bound.");
        }

        _session = session;
        return new Binding(this, session);
    }

    public void Unbind(ILiveUiSessionTarget session)
    {
        ArgumentNullException.ThrowIfNull(session);
        if (ReferenceEquals(_session, session))
            _session = null;
    }

    public void Deactivate()
    {
        _deactivated = true;
        _session = null;
    }

    private sealed class Binding : IDisposable
    {
        private DevToolsCommandBusSource? _owner;
        private readonly ILiveUiSessionTarget _expected;

        public Binding(
            DevToolsCommandBusSource owner,
            ILiveUiSessionTarget expected)
        {
            _owner = owner;
            _expected = expected;
        }

        public void Dispose() =>
            Interlocked.Exchange(ref _owner, null)?.Unbind(_expected);
    }
}

/// <summary>Typed panel operations used by menu and input presentation.</summary>
internal sealed class DevToolsPanelSet : IDevToolsPanelSet
{
    private readonly VitalsPanel _vitals;
    private readonly ChatPanel _chat;
    private readonly DebugPanel _debug;
    private readonly DebugVM _debugViewModel;
    private readonly SettingsPanel? _settings;

    public DevToolsPanelSet(
        VitalsPanel vitals,
        ChatPanel chat,
        DebugPanel debug,
        DebugVM debugViewModel,
        SettingsPanel? settings)
    {
        _vitals = vitals ?? throw new ArgumentNullException(nameof(vitals));
        _chat = chat ?? throw new ArgumentNullException(nameof(chat));
        _debug = debug ?? throw new ArgumentNullException(nameof(debug));
        _debugViewModel = debugViewModel
            ?? throw new ArgumentNullException(nameof(debugViewModel));
        _settings = settings;
    }

    public bool Contains(DevToolsPanelKind kind) =>
        kind != DevToolsPanelKind.Settings || _settings is not null;

    public string? GetTitle(DevToolsPanelKind kind) => GetPanel(kind)?.Title;

    public bool IsVisible(DevToolsPanelKind kind) => GetPanel(kind)?.IsVisible == true;

    public void Toggle(DevToolsPanelKind kind)
    {
        if (GetPanel(kind) is { } panel)
            panel.IsVisible = !panel.IsVisible;
    }

    public void FocusChatInput() => _chat.FocusInput();

    public void AddDebugToast(string message) => _debugViewModel.AddToast(message);

    private IPanel? GetPanel(DevToolsPanelKind kind) => kind switch
    {
        DevToolsPanelKind.Vitals => _vitals,
        DevToolsPanelKind.Chat => _chat,
        DevToolsPanelKind.Debug => _debug,
        DevToolsPanelKind.Settings => _settings,
        _ => throw new ArgumentOutOfRangeException(nameof(kind)),
    };
}

/// <summary>
/// Owns the optional ImGui developer frame, menu policy, panel actions, and
/// reusable default layout. Retained gameplay UI remains a separate earlier
/// presentation phase.
/// </summary>
internal sealed class DevToolsFramePresenter : IDevToolsFrameLifecycle
{
    private readonly IDevToolsFrameBackend _backend;
    private readonly IDevToolsCameraMenuOperations _camera;
    private readonly IDevToolsCommandBusSource _commands;
    private readonly IDevToolsPanelSet _panels;
    private readonly AcDream.App.Diagnostics.FrameProfiler _profiler;
    private bool _frameOpen;

    public DevToolsFramePresenter(
        IDevToolsFrameBackend backend,
        IDevToolsCameraMenuOperations camera,
        IDevToolsCommandBusSource commands,
        AcDream.App.Diagnostics.FrameProfiler profiler,
        IDevToolsPanelSet panels)
    {
        _backend = backend ?? throw new ArgumentNullException(nameof(backend));
        _camera = camera ?? throw new ArgumentNullException(nameof(camera));
        _commands = commands ?? throw new ArgumentNullException(nameof(commands));
        _profiler = profiler ?? throw new ArgumentNullException(nameof(profiler));
        _panels = panels ?? throw new ArgumentNullException(nameof(panels));
    }

    public void BeginFrame(float deltaSeconds)
    {
        if (_frameOpen)
        {
            throw new InvalidOperationException(
                "The previous developer-tools frame must render or abort before a new frame begins.");
        }

        _frameOpen = true;
        _backend.BeginFrame(deltaSeconds);
    }

    public void Render(double deltaSeconds, int viewportWidth, int viewportHeight)
    {
        if (!_frameOpen)
        {
            throw new InvalidOperationException(
                "BeginFrame must open the developer-tools frame before Render.");
        }

        var context = new PanelContext((float)deltaSeconds, _commands.Current);
        DrawMenu(viewportWidth, viewportHeight);
        _backend.RenderPanels(context);
        using var stage = _profiler.BeginStage(AcDream.App.Diagnostics.FrameStage.ImGui);
        _backend.RenderDrawData();
        _frameOpen = false;
    }

    public void AbortFrame()
    {
        if (!_frameOpen)
            return;

        try
        {
            _backend.AbortFrame();
        }
        finally
        {
            _frameOpen = false;
        }
    }

    public void ToggleDebugPanel()
    {
        _panels.Toggle(DevToolsPanelKind.Debug);
        _panels.AddDebugToast(
            $"Debug panel {(_panels.IsVisible(DevToolsPanelKind.Debug) ? "ON" : "OFF")}");
    }

    public void FocusChatInput() => _panels.FocusChatInput();

    public void ToggleSettingsPanel()
    {
        _panels.Toggle(DevToolsPanelKind.Settings);
    }

    public void ResetLayout(
        int viewportWidth,
        int viewportHeight,
        DevToolsPanelLayoutCondition condition)
    {
        float width = Math.Max(viewportWidth, 480);
        float height = Math.Max(viewportHeight, 320);

        SetLayout(
            DevToolsPanelKind.Vitals,
            new Vector2(10f, 30f),
            new Vector2(220f, 110f),
            condition);
        SetLayout(
            DevToolsPanelKind.Chat,
            new Vector2(10f, height - 320f),
            new Vector2(450f, 300f),
            condition);
        SetLayout(
            DevToolsPanelKind.Debug,
            new Vector2(width - 380f, 30f),
            new Vector2(370f, 520f),
            condition);
        if (_panels.Contains(DevToolsPanelKind.Settings))
        {
            SetLayout(
                DevToolsPanelKind.Settings,
                new Vector2((width - 700f) * 0.5f, (height - 500f) * 0.5f),
                new Vector2(700f, 500f),
                condition);
        }
    }

    private void DrawMenu(int viewportWidth, int viewportHeight)
    {
        if (!_backend.BeginMainMenuBar())
            return;

        try
        {
            if (_backend.BeginMenu("View"))
            {
                try
                {
                    if (_panels.Contains(DevToolsPanelKind.Settings)
                        && _backend.MenuItem("Settings", "F11"))
                    {
                        _panels.Toggle(DevToolsPanelKind.Settings);
                    }
                    if (_backend.MenuItem("Vitals"))
                        _panels.Toggle(DevToolsPanelKind.Vitals);
                    if (_backend.MenuItem("Chat"))
                        _panels.Toggle(DevToolsPanelKind.Chat);
                    if (_backend.MenuItem("Debug", "Ctrl+F1"))
                        _panels.Toggle(DevToolsPanelKind.Debug);
                    _backend.Separator();
                    if (_backend.MenuItem("Reset window layout"))
                        ResetLayout(
                            viewportWidth,
                            viewportHeight,
                            DevToolsPanelLayoutCondition.Always);
                }
                finally
                {
                    _backend.EndMenu();
                }
            }

            if (_backend.BeginMenu("Camera"))
            {
                try
                {
                    string flyLabel = _camera.IsFlyMode
                        ? "Exit Free-Fly Mode"
                        : "Enter Free-Fly Mode";
                    if (_backend.MenuItem(flyLabel, "Ctrl+Shift+F"))
                        _camera.ToggleFlyOrChase();

                    bool collide = _camera.CollideCamera;
                    if (_backend.MenuItem(
                        "Collide Camera (spring arm)",
                        selected: collide))
                    {
                        _camera.CollideCamera = !collide;
                    }
                }
                finally
                {
                    _backend.EndMenu();
                }
            }
        }
        finally
        {
            _backend.EndMainMenuBar();
        }
    }

    private void SetLayout(
        DevToolsPanelKind panel,
        Vector2 position,
        Vector2 size,
        DevToolsPanelLayoutCondition condition)
    {
        string? title = _panels.GetTitle(panel);
        if (!string.IsNullOrEmpty(title))
            _backend.SetWindowLayout(title, position, size, condition);
    }
}