using System;
using Godot;

public partial class CameraController : Camera2D
{
    [Export] public float ZoomStep = 0.1f;
    [Export] public float MinZoom = 0.5f;
    [Export] public float MaxZoom = 3.0f;

    [Export] private float minX = 0f;
    [Export] private float maxX = 0f;
    [Export] private float minY = 0f;
    [Export] private float maxY = 0f;
    
    private bool _dragging;
    private Vector2 _grabWorldPos;

    public override void _Input(InputEvent @event)
    {
        // Middle mouse drag
        if (@event is InputEventMouseButton mb)
        {
            if (mb.ButtonIndex == MouseButton.Middle)
            {
                _dragging = mb.Pressed;

                if (_dragging)
                    _grabWorldPos = GetGlobalMousePosition();
            }

            // Scroll zoom
            if (mb.Pressed &&
                (mb.ButtonIndex == MouseButton.WheelUp ||
                 mb.ButtonIndex == MouseButton.WheelDown))
            {
                Vector2 mouseBeforeZoom = GetGlobalMousePosition();

                float zoomFactor = mb.ButtonIndex == MouseButton.WheelUp
                    ? -ZoomStep
                    : ZoomStep;

                float newZoom = Mathf.Clamp(Zoom.X + zoomFactor, MinZoom, MaxZoom);
                Zoom = new Vector2(newZoom, newZoom);

                // keep cursor locked to same world point
                Vector2 mouseAfterZoom = GetGlobalMousePosition();
                GlobalPosition += mouseBeforeZoom - mouseAfterZoom;
                ClampPos();
            }
        }

        if (_dragging && @event is InputEventMouseMotion)
        {
            Vector2 currentWorld = GetGlobalMousePosition();
            GlobalPosition += _grabWorldPos - currentWorld;
            ClampPos();
        }
    }

    private void ClampPos()
    {
        var t = GetCanvasTransform();
        var camrect = t.AffineInverse().BasisXform(GetViewportRect().Size);
        GlobalPosition = new Vector2(
            Mathf.Clamp(GlobalPosition.X, LimitLeft + camrect.X / 2, LimitRight - camrect.X / 2),
            Mathf.Clamp(GlobalPosition.Y, LimitTop + camrect.Y / 2, LimitBottom - camrect.Y / 2)
        );
    }
}