PlayerControls.cs

using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.Assertions;

namespace StrategicGame.Client {
    public class PlayerControls : MonoBehaviour {
        const int LMB = 0;
        const int RMB = 1;

        public UnitSelector UnitSelector;
        public WorldRaycaster WorldRaycaster;

        Vector2 _mouseDownPosition;
        bool _mousePressed;
        UnitSelector.IFrameSelecting _frameSelecting;

        public event Action<IEnumerable<Unit>, Vector3> OnSendUnits;

        void Awake() {
            Assert.IsNotNull(UnitSelector);    
            Assert.IsNotNull(WorldRaycaster);  
        }

        void Update() {
            var mousePosition = (Vector2)Input.mousePosition;
            if (Input.GetMouseButtonDown(LMB)) {
                _mouseDownPosition = mousePosition;
                _mousePressed = true;
            } else if (Input.GetMouseButtonUp(LMB)) {
                if (_frameSelecting != null) {
                    _frameSelecting.End();
                    _frameSelecting = null;
                } else
                    UnitSelector.SelectOne(mousePosition);
                _mousePressed = false;
            } else if (Input.GetMouseButtonDown(RMB)) {
                var selection = UnitSelector.CurrentSelection;
                if (selection.Any()) {
                    var units = selection.Select(s => s.GetComponent<Unit>()).Where(s => s != null);
                    if (units.Any()) {
                        var groundPoint =  WorldRaycaster.RaycastGround(mousePosition);
                        OnSendUnits.InvokeSafe(units, groundPoint);
                    }
                }
            } else if (_mousePressed) {
                if (_frameSelecting != null)
                    _frameSelecting.Update(mousePosition);
                else if ((mousePosition - _mouseDownPosition).magnitude > 5)
                    _frameSelecting = UnitSelector.BeginFrameSelection(mousePosition);
            }
        }
    }
}