using UnityEngine;
using System.Collections;
using System.Collections.Generic;

namespace WPM
{
	public class GlobePosAnimator : MonoBehaviour
	{

		public bool auto;

		/// <summary>
		/// Array with latitude/longitude positions
		/// </summary>
		public List<Vector2> latLon;
		List<GameObject>pathLines = new List<GameObject> ();
		WorldMapGlobe map;
		float[] stepLengths;
		float totalLength;
		float currentProgress = 0;

		void Awake ()
		{
			map = WorldMapGlobe.instance;
		}

		void OnDestroy ()
		{
			RemovePath ();
		}

		public void DrawPath ()
		{
			RemovePath ();
			for (int k=0; k<latLon.Count-1; k++) {
				Vector2 latLonStart = latLon [k];
				Vector2 latLonEnd = latLon [k + 1];
				LineMarkerAnimator line = map.AddLine (latLonStart, latLonEnd, Color.white, 0f, 0f, 0.05f, 0);
				pathLines.Add (line.gameObject);
			}

			// Compute path length
			int steps = latLon.Count;
			stepLengths = new float[steps];
		
			// Calculate total travel length
			totalLength = 0;
			for (int k=0; k<steps-1; k++) {
				stepLengths [k] = map.calc.Distance (latLon [k], latLon [k + 1]);
				totalLength += stepLengths [k];
			}
		
			Debug.Log ("Total path length = " + totalLength / 1000 + " km.");
		}

		void RemovePath ()
		{
			if (pathLines.Count > 0) {
				while (pathLines.Count>0) {
					if (pathLines [0] != null) {
						Destroy (pathLines [0]);
					}
					pathLines.RemoveAt (0);
				}
			}
		}

		/// <summary>
		/// Moves the gameobject obj onto the globe at the path given by latlon array and progress factor.
		/// </summary>
		/// <param name="obj">Object.</param>
		/// <param name="progress">Progress expressed in 0..1.</param>
		public void MoveTo (float progress)
		{
			currentProgress = progress;

			// Iterate again until we reach progress
			int steps = latLon.Count;
			float acum = 0, acumPrev = 0;
			for (int k=0; k<steps-1; k++) {
				acumPrev = acum;
				acum += stepLengths [k] / totalLength;
				if (acum > progress) {
					// This is the step where "progress" is contained.
					if (k > 0) {
						progress = (progress - acumPrev) / (acum - acumPrev);
					}
					Vector3 pos0 = Conversion.GetSpherePointFromLatLon (latLon [k]);
					Vector3 pos1 = Conversion.GetSpherePointFromLatLon (latLon [k + 1]);
					Vector3 pos = Vector3.Lerp (pos0, pos1, progress);
					pos = pos.normalized * 0.5f;
					map.AddMarker (gameObject, pos, 0.01f, false);

					// Make it look towards destination
					Vector3 dir = (pos1 - pos0).normalized;
					Vector3 proj = Vector3.ProjectOnPlane (dir, pos0);
					transform.LookAt (map.transform.TransformPoint(proj + pos0), map.transform.TransformDirection(pos0));

					// Follow object
					map.FlyToLocation (pos, 0f);
					break;
				}
			}
		}

		public void Update() {
			if (auto) {
				currentProgress += Time.deltaTime * 0.1f;
				if (currentProgress > 1f)
					currentProgress = 0;
				MoveTo (currentProgress);
			}

		}

	}
}