// Traffic Simulation
// https://github.com/mchrbn/unity-traffic-simulation

using System.Collections.Generic;
using UnityEngine;

namespace TrafficSimulation{
    public enum IntersectionType{
        STOP,
        TRAFFIC_LIGHT
    }

    public class Intersection : MonoBehaviour
    {   
        public IntersectionType intersectionType;
        public int id;  

        //For stop only
        public List<Segment> prioritySegments;

        //For traffic lights only
        public float lightsDuration = 8;
        public float orangeLightDuration = 2;
        public List<Segment> lightsNbr1;
        public List<Segment> lightsNbr2;

        private List<GameObject> vehiclesQueue;
        private List<GameObject> vehiclesInIntersection;
        private TrafficSystem trafficSystem;
        
        [HideInInspector] public int currentRedLightsGroup = 1;

        void Start(){
            vehiclesQueue = new List<GameObject>();
            vehiclesInIntersection = new List<GameObject>();
            if(intersectionType == IntersectionType.TRAFFIC_LIGHT)
                InvokeRepeating("SwitchLights", lightsDuration, lightsDuration);
        }

        void SwitchLights(){

            if(currentRedLightsGroup == 1) currentRedLightsGroup = 2;
            else if(currentRedLightsGroup == 2) currentRedLightsGroup = 1;            
            //Wait few seconds after light transition before making the other car move (= orange light)
            Invoke("MoveVehiclesQueue", orangeLightDuration);
        }

        void OnTriggerEnter(Collider _other) {
            //Check if vehicle is already in the list if yes abort
            //Also abort if we just started the scene (if vehicles inside colliders at start)
            if(IsAlreadyInIntersection(_other.gameObject) || Time.timeSinceLevelLoad < .5f) return;

            if(_other.tag == "AutonomousVehicle" && intersectionType == IntersectionType.STOP){
                //Debug.Log("Trigger Stop!");
                TriggerStop(_other.gameObject);
            }else if(_other.tag == "AutonomousVehicle" && intersectionType == IntersectionType.TRAFFIC_LIGHT){
                //Debug.Log("Trigger Light!");
                TriggerLight(_other.gameObject);
            }
        }

        void OnTriggerExit(Collider _other) {
            if(_other.tag == "AutonomousVehicle" && intersectionType == IntersectionType.STOP)
                ExitStop(_other.gameObject);
            else if(_other.tag == "AutonomousVehicle" && intersectionType == IntersectionType.TRAFFIC_LIGHT)
                ExitLight(_other.gameObject);
        }

        void TriggerStop(GameObject _vehicle){
            VehicleAI vehicleAI = _vehicle.GetComponent<VehicleAI>();
            
            //Depending on the waypoint threshold, the car can be either on the target segment or on the past segment
            int vehicleSegment = vehicleAI.GetSegmentVehicleIsIn();

            if(!IsPrioritySegment(vehicleSegment)){
                if(vehiclesQueue.Count > 0 || vehiclesInIntersection.Count > 0){
                    vehicleAI.vehicleStatus = Status.STOP;
                    vehiclesQueue.Add(_vehicle);
                }
                else{
                    vehiclesInIntersection.Add(_vehicle);
                    vehicleAI.vehicleStatus = Status.SLOW_DOWN;
                }
            }
            else{
                vehicleAI.vehicleStatus = Status.SLOW_DOWN;
                vehiclesInIntersection.Add(_vehicle);
            }
        }

        void ExitStop(GameObject _vehicle){

            _vehicle.GetComponent<VehicleAI>().vehicleStatus = Status.GO;
            vehiclesInIntersection.Remove(_vehicle);
            vehiclesQueue.Remove(_vehicle);

            if(vehiclesQueue.Count > 0 && vehiclesInIntersection.Count == 0){
                vehiclesQueue[0].GetComponent<VehicleAI>().vehicleStatus = Status.GO;
            }
        }

        void TriggerLight(GameObject _vehicle){
            VehicleAI vehicleAI = _vehicle.GetComponent<VehicleAI>();
            int vehicleSegment = vehicleAI.GetSegmentVehicleIsIn();
            if(IsRedLightSegment(vehicleSegment)){
                //Debug.Log("Stop Vehicle");
                vehicleAI.vehicleStatus = Status.STOP;
                vehiclesQueue.Add(_vehicle);
            }
            else{
                //Debug.Log("Go Vehicle");
                vehicleAI.vehicleStatus = Status.GO;
            }
        }

        void ExitLight(GameObject _vehicle){
            _vehicle.GetComponent<VehicleAI>().vehicleStatus = Status.GO;
        }

        bool IsRedLightSegment(int _vehicleSegment){
            if(currentRedLightsGroup == 1){
                foreach(Segment segment in lightsNbr1){
                    if(segment.id == _vehicleSegment)
                        return true;
                }
            }
            else{
                foreach(Segment segment in lightsNbr2){
                    if(segment.id == _vehicleSegment)
                        return true;
                }
            }
            return false;
        }

        void MoveVehiclesQueue(){
            //Move all vehicles in queue
            List<GameObject> nVehiclesQueue = new List<GameObject>(vehiclesQueue);
            foreach(GameObject vehicle in vehiclesQueue){
                int vehicleSegment = vehicle.GetComponent<VehicleAI>().GetSegmentVehicleIsIn();
                if(!IsRedLightSegment(vehicleSegment)){
                    vehicle.GetComponent<VehicleAI>().vehicleStatus = Status.GO;
                    nVehiclesQueue.Remove(vehicle);
                }
            }
            vehiclesQueue = nVehiclesQueue;
        }

        bool IsPrioritySegment(int _vehicleSegment){
            foreach(Segment s in prioritySegments){
                if(_vehicleSegment == s.id)
                    return true;
            }
            return false;
        }

        bool IsAlreadyInIntersection(GameObject _target){
            foreach(GameObject vehicle in vehiclesInIntersection){
                if(vehicle.GetInstanceID() == _target.GetInstanceID()) return true;
            }
            foreach(GameObject vehicle in vehiclesQueue){
                if(vehicle.GetInstanceID() == _target.GetInstanceID()) return true;
            }

            return false;
        } 


        private List<GameObject> memVehiclesQueue = new List<GameObject>();
        private List<GameObject> memVehiclesInIntersection = new List<GameObject>();

        public void SaveIntersectionStatus(){
            memVehiclesQueue = vehiclesQueue;
            memVehiclesInIntersection = vehiclesInIntersection;
        }

        public void ResumeIntersectionStatus(){
            foreach(GameObject v in vehiclesInIntersection){
                foreach(GameObject v2 in memVehiclesInIntersection){
                    if(v.GetInstanceID() == v2.GetInstanceID()){
                        v.GetComponent<VehicleAI>().vehicleStatus = v2.GetComponent<VehicleAI>().vehicleStatus;
                        break;
                    }
                }
            }
            foreach(GameObject v in vehiclesQueue){
                foreach(GameObject v2 in memVehiclesQueue){
                    if(v.GetInstanceID() == v2.GetInstanceID()){
                        v.GetComponent<VehicleAI>().vehicleStatus = v2.GetComponent<VehicleAI>().vehicleStatus;
                        break;
                    }
                }
            }
        }
    }
}