#nullable enable

using System;
using Demo2.Domain;
using UnityEngine;
using UnityEngine.UIElements;

namespace Demo2.Runtime
{
    public sealed class Demo2GridInput : IDisposable
    {
        private readonly VisualElement _surface;
        private readonly Camera _worldCamera;
        private bool _middleDragging;
        public event Action<int, int, int>? GridClicked;

        public Demo2GridInput(VisualElement surface, Camera worldCamera)
        {
            _surface = surface;
            _worldCamera = worldCamera;
            _surface.RegisterCallback<PointerDownEvent>(OnPointerDown);
            _surface.RegisterCallback<PointerUpEvent>(OnPointerUp);
            _surface.RegisterCallback<PointerMoveEvent>(OnPointerMove);
            _surface.RegisterCallback<WheelEvent>(OnWheel);
        }

        public void Dispose()
        {
            _surface.UnregisterCallback<PointerDownEvent>(OnPointerDown);
            _surface.UnregisterCallback<PointerUpEvent>(OnPointerUp);
            _surface.UnregisterCallback<PointerMoveEvent>(OnPointerMove);
            _surface.UnregisterCallback<WheelEvent>(OnWheel);
        }

        private void OnPointerDown(PointerDownEvent eventData)
        {
            if (eventData.button == 2)
            {
                _middleDragging = true;
                _surface.CapturePointer(eventData.pointerId);
                eventData.StopPropagation();
                return;
            }
            if (eventData.button is not (0 or 1)) return;
            var world = _worldCamera.ScreenToWorldPoint(PanelToScreen(eventData.position));
            var x = Mathf.FloorToInt(world.x);
            var y = Demo2Protocol.GridHeight - 1 - Mathf.FloorToInt(world.y);
            if (x >= 0 && x < Demo2Protocol.GridWidth && y >= 0 && y < Demo2Protocol.GridHeight) GridClicked?.Invoke(x, y, eventData.button);
            eventData.StopPropagation();
        }

        private void OnPointerUp(PointerUpEvent eventData)
        {
            if (eventData.button != 2) return;
            _middleDragging = false;
            if (_surface.HasPointerCapture(eventData.pointerId)) _surface.ReleasePointer(eventData.pointerId);
            eventData.StopPropagation();
        }

        private void OnPointerMove(PointerMoveEvent eventData)
        {
            if (!_middleDragging) return;
            var scale = _worldCamera.orthographicSize * 2f / Mathf.Max(1, _surface.resolvedStyle.height);
            var position = _worldCamera.transform.position;
            position -= new Vector3(eventData.deltaPosition.x, -eventData.deltaPosition.y) * scale;
            position.x = Mathf.Clamp(position.x, 4f, Demo2Protocol.GridWidth - 4f);
            position.y = Mathf.Clamp(position.y, 3f, Demo2Protocol.GridHeight - 3f);
            _worldCamera.transform.position = position;
            eventData.StopPropagation();
        }

        private void OnWheel(WheelEvent eventData)
        {
            _worldCamera.orthographicSize = Mathf.Clamp(_worldCamera.orthographicSize + eventData.delta.y * 0.7f, 5f, 15f);
            eventData.StopPropagation();
        }

        private Vector3 PanelToScreen(Vector3 panelPosition)
        {
            var root = _surface.panel?.visualTree;
            var width = Mathf.Max(1, root?.resolvedStyle.width ?? Screen.width);
            var height = Mathf.Max(1, root?.resolvedStyle.height ?? Screen.height);
            return new Vector3(panelPosition.x / width * Screen.width, Screen.height - panelPosition.y / height * Screen.height, 0);
        }
    }
}