using System.Linq;
using System.Numerics;
using Content.Shared._CP14.Skill;
using Content.Shared._CP14.Skill.Components;
using Content.Shared._CP14.Skill.Prototypes;
using Content.Shared._CP14.Skill.Restrictions;
using Robust.Client.AutoGenerated;
using Robust.Client.Graphics;
using Robust.Client.UserInterface;
using Robust.Client.UserInterface.Controls;
using Robust.Client.UserInterface.XAML;
using Robust.Client.Utility;
using Robust.Shared.Input;
using Robust.Shared.Prototypes;

namespace Content.Client._CP14.Skill.Ui;

[GenerateTypedNameReferences]
public sealed partial class CP14SkillTreeGraphControl : BoxContainer
{
    [Dependency] private readonly IEntityManager _entManager = default!;
    [Dependency] private readonly IPrototypeManager _proto = default!;
    private readonly CP14SharedSkillSystem _skillSystem;

    private Entity<CP14SkillStorageComponent>? _player;

    private IEnumerable<CP14SkillPrototype> _allSkills;

    private CP14SkillPrototype? _hoveredNode;
    private CP14SkillPrototype? _selectedNode;
    public CP14SkillTreePrototype? Tree;

    private bool dragging = false;
    private Vector2 _previousMousePosition = Vector2.Zero;
    private Vector2 _globalOffset = new (60,60);

    private const float GridSize = 25f;

    public event Action<CP14SkillPrototype?>? OnNodeSelected;
    public event Action<Vector2>? OnOffsetChanged;

    public CP14SkillTreeGraphControl()
    {
        IoCManager.InjectDependencies(this);
        RobustXamlLoader.Load(this);

        _skillSystem = _entManager.System<CP14SharedSkillSystem>();

        _allSkills = _proto.EnumeratePrototypes<CP14SkillPrototype>();
        _proto.PrototypesReloaded += _ => _allSkills = _proto.EnumeratePrototypes<CP14SkillPrototype>().OrderBy(skill => _skillSystem.GetSkillName(skill)).ToList();
        OnOffsetChanged?.Invoke(_globalOffset);
    }

    public void UpdateState(Entity<CP14SkillStorageComponent>? player)
    {
        _player = player;
        OnOffsetChanged?.Invoke(_globalOffset);
    }

    protected override void KeyBindDown(GUIBoundKeyEventArgs args)
    {
        base.KeyBindDown(args);

        if (args.Handled)
            return;

        if (args.Function == EngineKeyFunctions.UIClick)
        {
            dragging = true;

            if (_hoveredNode == null)
                return;

            OnNodeSelected?.Invoke(_hoveredNode);
            UserInterfaceManager.ClickSound();
            _selectedNode = _hoveredNode;
        }

        if (args.Function == EngineKeyFunctions.UIRightClick)
        {
            _globalOffset = new Vector2(60, 60); // Reset offset on right click
            OnOffsetChanged?.Invoke(_globalOffset);
        }
    }

    protected override void KeyBindUp(GUIBoundKeyEventArgs args)
    {
        base.KeyBindUp(args);

        if (args.Handled || args.Function != EngineKeyFunctions.UIClick)
            return;

        dragging = false;
    }

    protected override void ExitedTree()
    {
        base.ExitedTree();

        OnNodeSelected?.Invoke(null);
    }

    protected override void Draw(DrawingHandleScreen handle)
    {
        base.Draw(handle);

        _hoveredNode = null;
        if (_player == null || Tree == null)
        {
            return;
        }

        var cursor = (UserInterfaceManager.MousePositionScaled.Position * UIScale) - GlobalPixelPosition;

        if (dragging)
        {
            var delta = cursor - _previousMousePosition;
            _globalOffset += delta;
            OnOffsetChanged?.Invoke(_globalOffset);
        }

        _previousMousePosition = cursor;

        var playerSkills = _player.Value.Comp.LearnedSkills;

        //Draw connection lines
        foreach (var skill in _allSkills)
        {
            if (skill.Tree != Tree)
                continue;

            var fromPos = skill.SkillUiPosition * GridSize * UIScale + _globalOffset;

            foreach (var req in skill.Restrictions)
            {
                switch (req)
                {
                    case NeedPrerequisite prerequisite:
                        if (!_proto.TryIndex(prerequisite.Prerequisite, out var prerequisiteSkill))
                            continue;

                        if (prerequisiteSkill.Tree != Tree)
                            continue;

                        var learned = playerSkills.Contains(skill.ID);

                        var toPos = prerequisiteSkill.SkillUiPosition * GridSize * UIScale + _globalOffset;
                        var color = learned ? Color.White : Color.FromSrgb(new Color(0.7f, 0.7f, 0.7f));
                        handle.DrawLine(fromPos, toPos, color);

                        break;
                }
            }
        }

        //Draw skill icons over lines
        foreach (var skill in _allSkills)
        {
            if (skill.Tree != Tree)
                continue;

            //TODO: Not optimized, recalculates every frame. Needs to be calculated on state update and cached.
            var canBeLearned = _skillSystem.CanLearnSkill(_player.Value, skill, _player.Value.Comp);
            var pos = skill.SkillUiPosition * GridSize * UIScale + _globalOffset;

            // Base skill icon
            var baseTexture = skill.Icon.Frame0();
            var baseSize = new Vector2(baseTexture.Width, baseTexture.Height) * 2;
            var baseQuad = new UIBox2(pos - baseSize / 2, pos + baseSize / 2);

            var hovered = (cursor - pos).LengthSquared() <= (baseSize.X / 2) * (baseSize.X / 2);

            // Frame
            var frameTexture = Tree.FrameIcon.Frame0();
            var frameSize = new Vector2(frameTexture.Width, frameTexture.Height) * 2;
            var frameQuad = new UIBox2(pos - frameSize / 2, pos + frameSize / 2);
            handle.DrawTextureRect(frameTexture, frameQuad, canBeLearned ? Color.White : Color.FromSrgb(new Color(0.7f, 0.7f, 0.7f)));

            // Selected Skill
            if (_selectedNode == skill)
            {
                var selectedTexture = Tree.SelectedIcon.Frame0();
                var selectedSize = new Vector2(selectedTexture.Width, selectedTexture.Height) * 2;
                var selectedQuad = new UIBox2(pos - selectedSize / 2, pos + selectedSize / 2);
                handle.DrawTextureRect(selectedTexture, selectedQuad, Color.White);
            }

            // Hovered Skill
            if (hovered)
            {
                _hoveredNode = skill;
                var hoveredTexture = Tree.HoveredIcon.Frame0();
                var hoveredSize = new Vector2(hoveredTexture.Width, hoveredTexture.Height) * 2;
                var hoveredQuad = new UIBox2(pos - hoveredSize / 2, pos + hoveredSize / 2);
                handle.DrawTextureRect(hoveredTexture, hoveredQuad, Color.White);
            }

            var learned = playerSkills.Contains(skill.ID);
            var allowedToLearn = _skillSystem.AllowedToLearn(_player.Value, skill, _player.Value.Comp);

            // Learned Skill
            if (learned)
            {
                var learnedTexture = Tree.LearnedIcon.Frame0();
                var learnedSize = new Vector2(learnedTexture.Width, learnedTexture.Height) * 2;
                var learnedQuad = new UIBox2(pos - learnedSize / 2, pos + learnedSize / 2);
                handle.DrawTextureRect(learnedTexture, learnedQuad, Color.White);
            }
            else if (canBeLearned)
            {
                var availableTexture = Tree.AvailableIcon.Frame0();
                var availableSize = new Vector2(availableTexture.Width, availableTexture.Height) * 2;
                var availableQuad = new UIBox2(pos - availableSize / 2, pos + availableSize / 2);
                handle.DrawTextureRect(availableTexture, availableQuad, Color.White);
            }

            var iconColor = allowedToLearn switch
            {
                true when !learned => Color.FromSrgb(new Color(0.7f, 0.7f, 0.7f)),
                false when !learned => Color.FromSrgb(new Color(0f, 0f, 0f)),
                _ => Color.White
            };

            handle.DrawTextureRect(baseTexture, baseQuad, iconColor);
        }
    }
}