using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class AugmentedScript : MonoBehaviour
{
  private float originalLatitude;
  private float originalLongitude;
  private float currentLongitude;
  private float currentLatitude;

  private GameObject distanceTextObject;
  private double distance;

  private bool setOriginalValues = true;

  private Vector3 targetPosition;
  private Vector3 originalPosition;

  private float speed = .1f;

  IEnumerator GetCoordinates()
  {
    // update/get device‘s gps coordinates
  }

  public void Calc(float lat1, float lon1, float lat2, float lon2)
  {// calculates distance between two sets of coordinates, taking into account the curvature of the earth
  }

  void Start(){
    // initialization
  }

  void Update(){
    // update each frame
  }
}

void Start(){
    // get the reference to UIText distance to get the user gps coordinates
    distanceTextObject = GameObject.FindGameObjectWithTag ("distanceText");
    // keep getting the gps coordinates from the phone
    StartCoroutine ("GetCoordinates");
    // initialize target and original position, transform refers to the flying disk
    targetPosition = transform.position;
    originalPosition = transform.position;
}

void Update(){
    // linearly interpolate from current position to target position
    transform.position = Vector3.Lerp(transform.position, targetPosition, speed);
    // rotate by 1 degree about the y axis every frame
    transform.eulerAngles += new Vector3 (0, 1f, 0);
}

IEnumerator GetCoordinates()
{
    // while true so this function keeps running once started.
    while (true) {
        // code from LocationService.Start documentation sample 
        // https://docs.unity3d.com/ScriptReference/LocationService.Start.html
        
        // check if user has location service enabled
        if (!Input.location.isEnabledByUser)
            yield break;
        // Start service before querying location
        Input.location.Start (1f, 0.1f);
        // Wait until service initializes
        int maxWait = 20;
        while (Input.location.status == LocationServiceStatus.Initializing && maxWait > 0) {
            yield return new WaitForSeconds (1);
            maxWait--;
        }
        // Service didn‘t initialize in 20 seconds
        if (maxWait < 1) {
            print ("Timed out");
            yield break;
        }
        // Connection has failed
        if (Input.location.status == LocationServiceStatus.Failed) {
            print ("Unable to determine device location");
            yield break;
        } else {
            // start doing the device‘s coordinates processing
            
            // Access granted and location value could be retrieved
            print ("Location: " + Input.location.lastData.latitude + " " + Input.location.lastData.longitude + " " + Input.location.lastData.altitude + " " + Input.location.lastData.horizontalAccuracy + " " + Input.location.lastData.timestamp);

            // if original value has not yet been set, then save player‘s coordinates when app starts
            if (setOriginalValues) {
                // "private bool setOriginalValues = true;" at the start 
                originalLatitude = Input.location.lastData.latitude;
                originalLongitude = Input.location.lastData.longitude;
                setOriginalValues = false;
            }
            //overwrite current lat and lon everytime
            currentLatitude = Input.location.lastData.latitude;
            currentLongitude = Input.location.lastData.longitude;
            //calculate the distance between where the player was when the app started and where they are now.
            Calc (originalLatitude, originalLongitude, currentLatitude, currentLongitude);
        }
        Input.location.Stop();
    }
}

public void Calc(float lat1, float lon1, float lat2, float lon2)
{
    var R = 6378.137; // Radius of earth in KM
    var dLat = lat2 * Mathf.PI / 180 - lat1 * Mathf.PI / 180;
    var dLon = lon2 * Mathf.PI / 180 - lon1 * Mathf.PI / 180;
    float a = Mathf.Sin(dLat / 2) * Mathf.Sin(dLat / 2) + 
            Mathf.Cos(lat1 * Mathf.PI / 180) * Mathf.Cos(lat2 * Mathf.PI / 180) * Mathf.Sin(dLon / 2) * Mathf.Sin(dLon / 2);
    var c = 2 * Mathf.Atan2(Mathf.Sqrt(a), Mathf.Sqrt(1 - a));
    distance = R * c;
    distance = distance * 1000f; // meters
    //set the distance text on the canvas
    distanceTextObject.GetComponent<Text> ().text = "Distance: " + distance;
    //convert distance from double to float
    float distanceFloat = (float)distance;
    //set the target position of the ufo, this is where we lerp to in the update function
    targetPosition = originalPosition - new Vector3 (0, 0, distanceFloat * 12);
    //distance was multiplied by 12 so I didn‘t have to walk that far to get the UFO to show up closer
}