using System;
using System.Collections.Generic;
using Robust.Client.Console;
using Robust.Client.Input;
using Robust.Client.Interfaces.Graphics;
using Robust.Client.Interfaces.Graphics.ClientEye;
using Robust.Client.Interfaces.Input;
using Robust.Client.Interfaces.ResourceManagement;
using Robust.Client.Interfaces.State;
using Robust.Client.Interfaces.UserInterface;
using Robust.Client.Player;
using Robust.Client.UserInterface.Controls;
using Robust.Client.UserInterface.CustomControls;
using Robust.Client.Utility;
using Robust.Shared.Configuration;
using Robust.Shared.Input;
using Robust.Shared.Interfaces.Configuration;
using Robust.Shared.Interfaces.Map;
using Robust.Shared.Interfaces.Network;
using Robust.Shared.Interfaces.Resources;
using Robust.Shared.Interfaces.Timing;
using Robust.Shared.IoC;
using Robust.Shared.Maths;

namespace Robust.Client.UserInterface
{
    internal sealed class UserInterfaceManager : IDisposable, IUserInterfaceManagerInternal, IPostInjectInit
    {
#pragma warning disable 649
        [Dependency] private readonly IInputManager _inputManager;
        [Dependency] private readonly IClyde _displayManager;
        [Dependency] private readonly IClientConsole _console;
        [Dependency] private readonly IResourceManager _resourceManager;
        [Dependency] private readonly IGameTiming _gameTiming;
        [Dependency] private readonly IPlayerManager _playerManager;
        [Dependency] private readonly IEyeManager _eyeManager;
        [Dependency] private readonly IResourceCache _resourceCache;
        [Dependency] private readonly IStateManager _stateManager;
        [Dependency] private readonly IClientNetManager _netManager;
        [Dependency] private readonly IMapManager _mapManager;
        [Dependency] private readonly IConfigurationManager _configurationManager;
#pragma warning restore 649

        public UITheme ThemeDefaults { get; private set; }
        public Stylesheet Stylesheet { get; set; }
        public Control KeyboardFocused { get; private set; }

        // When a control receives a mouse down it must also receive a mouse up and mouse moves, always.
        // So we keep track of which control is "focused" by the mouse.
        private Control _mouseFocused;

        public Control StateRoot { get; private set; }
        public Control ModalRoot { get; private set; }
        public Control CurrentlyHovered { get; private set; }
        public float UIScale { get; private set; } = 1;
        public Control RootControl { get; private set; }
        public Control WindowRoot { get; private set; }
        public DebugConsole DebugConsole { get; private set; }
        public IDebugMonitors DebugMonitors => _debugMonitors;
        private DebugMonitors _debugMonitors;

        public Dictionary<(GodotAsset asset, int resourceId), object> GodotResourceInstanceCache { get; } =
            new Dictionary<(GodotAsset asset, int resourceId), object>();

        private readonly List<Control> _modalStack = new List<Control>();

        private bool _rendering = true;
        private float _tooltipTimer;
        private Tooltip _tooltip;
        private const float TooltipDelay = 1;

        public void Initialize()
        {
            UIScale = _configurationManager.GetCVar<float>("display.uiScale");
            ThemeDefaults = new UIThemeDummy();

            _initializeCommon();

            DebugConsole = new DebugConsole(_console, _resourceManager);
            RootControl.AddChild(DebugConsole);

            _debugMonitors = new DebugMonitors(_gameTiming, _playerManager, _eyeManager, _inputManager,
                _resourceCache, _stateManager, _displayManager, _netManager, _mapManager);
            RootControl.AddChild(_debugMonitors);

            _inputManager.SetInputCommand(EngineKeyFunctions.ShowDebugMonitors,
                InputCmdHandler.FromDelegate(enabled: session => { DebugMonitors.Visible = true; },
                    disabled: session => { DebugMonitors.Visible = false; }));

            _inputManager.SetInputCommand(EngineKeyFunctions.HideUI,
                InputCmdHandler.FromDelegate(
                    enabled: session => _rendering = false,
                    disabled: session => _rendering = true));
        }

        private void _initializeCommon()
        {
            RootControl = new Control("UIRoot")
            {
                MouseFilter = Control.MouseFilterMode.Ignore,
                IsInsideTree = true
            };
            RootControl.SetAnchorPreset(Control.LayoutPreset.Wide);
            RootControl.Size = _displayManager.ScreenSize / UIScale;
            _displayManager.OnWindowResized += args => _updateRootSize();

            StateRoot = new Control("StateRoot")
            {
                MouseFilter = Control.MouseFilterMode.Ignore
            };
            StateRoot.SetAnchorPreset(Control.LayoutPreset.Wide);
            RootControl.AddChild(StateRoot);

            WindowRoot = new Control("WindowRoot")
            {
                MouseFilter = Control.MouseFilterMode.Ignore
            };
            WindowRoot.SetAnchorPreset(Control.LayoutPreset.Wide);
            RootControl.AddChild(WindowRoot);

            ModalRoot = new Control("ModalRoot")
            {
                MouseFilter = Control.MouseFilterMode.Ignore,
            };
            ModalRoot.SetAnchorPreset(Control.LayoutPreset.Wide);
            RootControl.AddChild(ModalRoot);

            _tooltip = new Tooltip();
            RootControl.AddChild(_tooltip);
            _tooltip.Visible = false;
        }

        public void InitializeTesting()
        {
            ThemeDefaults = new UIThemeDummy();

            _initializeCommon();
        }

        public void Dispose()
        {
            RootControl?.Dispose();
        }

        public void Update(ProcessFrameEventArgs args)
        {
            RootControl.DoUpdate(args);
        }

        public void FrameUpdate(RenderFrameEventArgs args)
        {
            RootControl.DoFrameUpdate(args);

            _tooltipTimer -= args.Elapsed;
            if (_tooltipTimer <= 0)
            {
                _showTooltip();
            }
        }

        public void MouseDown(MouseButtonEventArgs args)
        {
            // If we have a modal open and the mouse down was outside it, close said modal.
            if (_modalStack.Count != 0)
            {
                var top = _modalStack[_modalStack.Count - 1];
                var offset = args.Position - top.GlobalPixelPosition;
                if (!top.HasPoint(offset / UIScale))
                {
                    RemoveModal(top);
                    args.Handle();
                    return;
                }
            }

            var control = MouseGetControl(args.Position);
            if (control == null)
            {
                ReleaseKeyboardFocus();
                return;
            }

            _mouseFocused = control;

            if (_mouseFocused.CanKeyboardFocus && _mouseFocused.KeyboardFocusOnClick)
            {
                _mouseFocused.GrabKeyboardFocus();
            }

            var guiArgs = new GUIMouseButtonEventArgs(args.Button, args.DoubleClick, control, Mouse.ButtonMask.None,
                args.Position / UIScale, args.Position, args.Position / UIScale - control.GlobalPosition,
                args.Position - control.GlobalPixelPosition, args.Alt, args.Control, args.Shift,
                args.System);

            _doMouseGuiInput(control, guiArgs, (c, ev) => c.MouseDown(ev));

            // Always mark this as handled.
            // The only case it should not be is if we do not have a control to click on,
            // in which case we never reach this.
            args.Handle();
        }

        public void MouseUp(MouseButtonEventArgs args)
        {
            if (_mouseFocused == null)
            {
                return;
            }

            var guiArgs = new GUIMouseButtonEventArgs(args.Button, args.DoubleClick, _mouseFocused,
                Mouse.ButtonMask.None,
                args.Position / UIScale, args.Position, args.Position / UIScale - _mouseFocused.GlobalPosition,
                args.Position - _mouseFocused.GlobalPixelPosition, args.Alt, args.Control, args.Shift,
                args.System);

            _doMouseGuiInput(_mouseFocused, guiArgs, (c, ev) => c.MouseUp(ev));
            _mouseFocused = null;

            // Always mark this as handled.
            // The only case it should not be is if we do not have a control to click on,
            // in which case we never reach this.
            args.Handle();
        }

        public void MouseMove(MouseMoveEventArgs mouseMoveEventArgs)
        {
            _resetTooltipTimer();
            // Update which control is considered hovered.
            var newHovered = _mouseFocused ?? MouseGetControl(mouseMoveEventArgs.Position);
            if (newHovered != CurrentlyHovered)
            {
                _clearTooltip();
                CurrentlyHovered?.MouseExited();
                CurrentlyHovered = newHovered;
                CurrentlyHovered?.MouseEntered();
            }

            var target = _mouseFocused ?? newHovered;
            if (target != null)
            {
                var guiArgs = new GUIMouseMoveEventArgs(mouseMoveEventArgs.Relative / UIScale,
                    mouseMoveEventArgs.Speed / UIScale, target,
                    mouseMoveEventArgs.ButtonMask, mouseMoveEventArgs.Position / UIScale, mouseMoveEventArgs.Position,
                    mouseMoveEventArgs.Position / UIScale - target.GlobalPosition,
                    mouseMoveEventArgs.Position - target.GlobalPixelPosition,
                    mouseMoveEventArgs.Alt,
                    mouseMoveEventArgs.Control, mouseMoveEventArgs.Shift, mouseMoveEventArgs.System);

                _doMouseGuiInput(target, guiArgs, (c, ev) => c.MouseMove(ev));
            }
        }

        public void MouseWheel(MouseWheelEventArgs args)
        {
            var control = MouseGetControl(args.Position);
            if (control == null)
            {
                return;
            }

            args.Handle();

            var guiArgs = new GUIMouseWheelEventArgs(args.Delta, control, Mouse.ButtonMask.None,
                args.Position / UIScale, args.Position,
                args.Position / UIScale - control.GlobalPosition, args.Position - control.GlobalPixelPosition, args.Alt,
                args.Control, args.Shift, args.System);

            _doMouseGuiInput(control, guiArgs, (c, ev) => c.MouseWheel(ev), true);
        }

        public void TextEntered(TextEventArgs textEvent)
        {
            if (KeyboardFocused == null)
            {
                return;
            }

            var guiArgs = new GUITextEventArgs(KeyboardFocused, textEvent.CodePoint);
            KeyboardFocused.TextEntered(guiArgs);
        }

        public void KeyDown(KeyEventArgs keyEvent)
        {
            // TODO: This is ugly.
            if (keyEvent.Key == Keyboard.Key.Tilde)
            {
                keyEvent.Handle();
                DebugConsole.Toggle();
                return;
            }

            if (KeyboardFocused == null)
            {
                return;
            }

            var guiArgs = new GUIKeyEventArgs(KeyboardFocused, keyEvent.Key, keyEvent.IsRepeat, keyEvent.Alt,
                keyEvent.Control, keyEvent.Shift, keyEvent.System);
            KeyboardFocused.KeyDown(guiArgs);

            if (guiArgs.Handled)
            {
                keyEvent.Handle();
            }
        }

        public void KeyUp(KeyEventArgs keyEvent)
        {
            if (KeyboardFocused == null)
            {
                return;
            }

            var guiArgs = new GUIKeyEventArgs(KeyboardFocused, keyEvent.Key, keyEvent.IsRepeat, keyEvent.Alt,
                keyEvent.Control, keyEvent.Shift, keyEvent.System);
            KeyboardFocused.KeyUp(guiArgs);
        }

        public void DisposeAllComponents()
        {
            RootControl.DisposeAllChildren();
        }

        public void Popup(string contents, string title = "Alert!")
        {
            var popup = new SS14Window
            {
                Title = title
            };

            popup.Contents.AddChild(new Label {Text = contents});
            popup.OpenCenteredMinSize();
        }

        public Control MouseGetControl(Vector2 coordinates)
        {
            return _mouseFindControlAtPos(RootControl, coordinates);
        }

        public void GrabKeyboardFocus(Control control)
        {
            if (control == null)
            {
                throw new ArgumentNullException(nameof(control));
            }

            if (!control.CanKeyboardFocus)
            {
                throw new ArgumentException("Control cannot get keyboard focus.", nameof(control));
            }

            if (control == KeyboardFocused)
            {
                return;
            }

            ReleaseKeyboardFocus();

            KeyboardFocused = control;

            KeyboardFocused.FocusEntered();
        }

        public void ReleaseKeyboardFocus()
        {
            var oldFocused = KeyboardFocused;
            oldFocused?.FocusExited();
            KeyboardFocused = null;
        }

        public void ReleaseKeyboardFocus(Control ifControl)
        {
            if (ifControl == null)
            {
                throw new ArgumentNullException(nameof(ifControl));
            }

            if (ifControl == KeyboardFocused)
            {
                ReleaseKeyboardFocus();
            }
        }

        public void ControlHidden(Control control)
        {
            // Does the same thing but it could later be changed so..
            ControlRemovedFromTree(control);
        }

        public void ControlRemovedFromTree(Control control)
        {
            ReleaseKeyboardFocus(control);
            RemoveModal(control);
            if (control == CurrentlyHovered)
            {
                control.MouseExited();
                CurrentlyHovered = null;
            }

            if (control == _mouseFocused)
            {
                _mouseFocused = null;
            }
        }

        public void PushModal(Control modal)
        {
            _modalStack.Add(modal);
        }

        public void RemoveModal(Control modal)
        {
            if (_modalStack.Remove(modal))
            {
                modal.ModalRemoved();
            }
        }

        public void Render(IRenderHandle renderHandle)
        {
            if (!_rendering)
            {
                return;
            }

            _render(renderHandle, RootControl, Vector2i.Zero, Color.White, null);
        }

        private static void _render(IRenderHandle renderHandle, Control control, Vector2i position, Color modulate,
            UIBox2i? scissorBox)
        {
            if (!control.Visible)
            {
                return;
            }

            // Manual clip test with scissor region as optimization.
            var controlBox = UIBox2i.FromDimensions(position, control.PixelSize);

            if (scissorBox != null)
            {
                var clipMargin = control.RectDrawClipMargin;
                var clipTestBox = new UIBox2i(controlBox.Left - clipMargin, controlBox.Top - clipMargin,
                    controlBox.Right + clipMargin, controlBox.Bottom + clipMargin);

                if (!scissorBox.Value.Intersects(clipTestBox))
                {
                    return;
                }
            }

            var handle = renderHandle.DrawingHandleScreen;
            handle.SetTransform(position, Angle.Zero, Vector2.One);
            modulate *= control.Modulate;
            handle.Modulate = modulate * control.ActualModulateSelf;
            var clip = control.RectClipContent;
            var scissorRegion = scissorBox;
            if (clip)
            {
                scissorRegion = controlBox;
                if (scissorBox != null)
                {
                    // Make the final scissor region a sub region of scissorBox
                    var s = scissorBox.Value;
                    var result = s.Intersection(scissorRegion.Value);
                    if (result == null)
                    {
                        // Uhm... No intersection so... don't draw anything at all?
                        return;
                    }

                    scissorRegion = result.Value;
                }

                renderHandle.SetScissor(scissorRegion);
            }

            control.DrawInternal(renderHandle);
            foreach (var child in control.Children)
            {
                _render(renderHandle, child, position + child.PixelPosition, modulate, scissorRegion);
            }

            if (clip)
            {
                renderHandle.SetScissor(scissorBox);
            }
        }

        private Control _mouseFindControlAtPos(Control control, Vector2 position)
        {
            for (var i = control.ChildCount - 1; i >= 0; i--)
            {
                var child = control.GetChild(i);
                if (!child.Visible || (child.RectClipContent && !child.PixelRect.Contains((Vector2i) position)))
                {
                    continue;
                }

                var maybeFoundOnChild = _mouseFindControlAtPos(child, position - child.PixelPosition);
                if (maybeFoundOnChild != null)
                {
                    return maybeFoundOnChild;
                }
            }

            if (control.MouseFilter != Control.MouseFilterMode.Ignore && control.HasPoint(position / UIScale))
            {
                return control;
            }

            return null;
        }

        private static void _doMouseGuiInput<T>(Control control, T guiEvent, Action<Control, T> action,
            bool ignoreStop = false)
            where T : GUIMouseEventArgs
        {
            while (control != null)
            {
                if (control.MouseFilter != Control.MouseFilterMode.Ignore)
                {
                    action(control, guiEvent);

                    if (guiEvent.Handled || (!ignoreStop && control.MouseFilter == Control.MouseFilterMode.Stop))
                    {
                        break;
                    }
                }

                guiEvent.RelativePosition += control.Position;
                guiEvent.RelativePixelPosition += control.PixelPosition;
                control = control.Parent;
                guiEvent.SourceControl = control;
            }
        }

        private void _clearTooltip()
        {
            _tooltip.Visible = false;
            _resetTooltipTimer();
        }

        private void _resetTooltipTimer()
        {
            _tooltipTimer = TooltipDelay;
        }

        private void _showTooltip()
        {
            var hovered = CurrentlyHovered;
            if (hovered == null || string.IsNullOrWhiteSpace(hovered.ToolTip))
            {
                return;
            }

            _tooltip.Visible = true;
            _tooltip.Text = hovered.ToolTip;
            _tooltip.Position = _inputManager.MouseScreenPosition;
            _tooltip.Size = _tooltip.CustomMinimumSize;

            var (right, bottom) = _tooltip.Position + _tooltip.Size;

            if (right > RootControl.Size.X)
            {
                _tooltip.Position = (RootControl.Size.X - _tooltip.Size.X, _tooltip.Position.Y);
            }

            if (bottom > RootControl.Size.Y)
            {
                _tooltip.Position = (_tooltip.Position.X, RootControl.Size.Y - _tooltip.Size.Y);
            }
        }

        void IPostInjectInit.PostInject()
        {
            _configurationManager.RegisterCVar("display.uiScale", 1f, CVar.ARCHIVE, _uiScaleChanged);
        }

        private void _uiScaleChanged(float newValue)
        {
            UIScale = newValue;

            if (RootControl == null)
            {
                return;
            }

            _propagateUIScaleChanged(RootControl);
            _updateRootSize();
        }

        private static void _propagateUIScaleChanged(Control control)
        {
            control.UIScaleChanged();

            foreach (var child in control.Children)
            {
                _propagateUIScaleChanged(child);
            }
        }

        private void _updateRootSize()
        {
            RootControl.Size = _displayManager.ScreenSize / UIScale;
        }
    }
}