using UnityEngine;
using System.Collections;

public class PolarToGeographical : MonoBehaviour {

    public Transform planet;
    float planetRadius {
        get {
            return planet.gameObject.GetComponent<SphereCollider>().radius;
        }
    }
    Vector3 relPos {
        get {
            return this.transform.position - planet.position;
        }
    }

    struct Directionality {
        public Vector3 up;
        public Vector3 north;
        public Vector3 east;
        public Vector3 west {
            get {
                return east * -1f;
            }
        }
        public Vector3 south {
            get {
                return north * -1f;
            }
        }
        public Vector3 down {
            get {
                return up * -1f;
            }
        }
    }

    struct Geographical {
        public float latitude;
        public float longitude;
        public float height;
    }

    //returns current directionality
    Directionality getDirectionality() {
        Directionality direction = new Directionality ();
        direction.up = relPos.normalized * -1f;
        direction.east = Vector3.Cross (Vector3.up, direction.up).normalized;
        direction.north = Vector3.Cross (direction.up, direction.east).normalized;

        return direction;
    }

    Geographical getGeographical() {
        Geographical geo = new Geographical ();
        //Use a more complicated solution for vMod if the planet will move or rotate.
            //goal is to project onto planet's xz-plane
            //I recommend this transform's worldToLocalMatrix method
            //docs.unity3d.com/ScriptReference/Transform-worldToLocalMatrix.html
        Vector3 vMod = relPos;
        vMod.y = 0f;

        geo.latitude = Vector3.Angle (vMod, relPos);
        if (relPos.y < 0f)
            geo.latitude *= -1f;

        geo.longitude = Vector3.Angle (vMod, planet.forward);
        if (relPos.x < 0f)
            geo.longitude *= -1f;

        geo.height = (relPos.magnitude - planetRadius) * -1f;

        return geo;
    }

    void OnDrawGizmos() {
        //unnecessary, but reads better
        Vector3 pos = this.transform.position;
        Directionality direction = getDirectionality ();

        Gizmos.color = Color.green;
        Gizmos.DrawLine (pos, pos + direction.up);


        Gizmos.color = Color.red;
        Gizmos.DrawLine (pos, pos + direction.east);

        Gizmos.color = Color.blue;
        Gizmos.DrawLine (pos, pos + direction.north);


        Geographical geo = getGeographical ();
        this.gameObject.name = (
            "Lon: "
            + geo.longitude.ToString("N")
            + ", Lat: "
            + geo.latitude.ToString("N")
            + ". Ht: "
            + geo.height.ToString("N")
        );
    }
}