//***********************************************************
// Filename: TargetManager.cs
// Author: Niclas
// Last changes: 08 August 2018
// Content: This file generates new targets with several parameters
//***********************************************************
using System.Collections;
using System.Collections.Generic;
using UnityEngine;


/// <summary>
/// This class is responsible for generating new targets with various constrains on button press and tracking the experiment progress
/// </summary>
public class TargetManager : MonoBehaviour, IButton {

    // true if the experiment is ongoing
    public bool isExpActive = false;

    // Area in which new targets can be generated
    private GameObject area;
    // Bounds of the area
    private Bounds areaBounds;

    // The number of targets that will be spawned in this experiment
    public int numberOfTargets = 0;

    // Prefab used to generate a new target
    public GameObject targetPrefab;

    // The gameobject of prefab instance which is already placed in the scene
    public GameObject lastTarget;

    // Constrains for generating the next target
    // The maximum rotation of the direction of targets in either way
    public float maxAngle = 10;
    // minimum and maximum distance of the next target to the current one
    public float minDistance = 1;
    public float maxDistance = 3;
    // The maximum y rotation of the next target
    public float maxTargetRotation = 360;
    // Directional Vector from which the direction in which the next target spawns will be calculated
    private Vector3 dirOfNextPos = Vector3.right;

    // 0 for starting target, >0 for "true" targets; doubles as target count
    private int currentTargetId = 0;


    // Use this for initialization
    void Start() {

        // Set base Target which only used to calculate the postion of the first "real" Target
        if (lastTarget == null) {
            lastTarget = new GameObject();
        }

        area = GameObject.FindGameObjectWithTag("ExpPlane");
        areaBounds = area.GetComponent<MeshFilter>().mesh.bounds;

    }

    // Update is called once per frame
    void Update() {
        // Debug Listener for KeyPress
        if (Input.GetKeyDown(KeyCode.Space)) {
            OnButtonUp();
        }
    }


    /// <summary>
    /// Spawns Target at desired position and rotation as child of area
    /// </summary>
    private void SpawnTarget() {
        currentTargetId++;

        GameObject target = Instantiate(targetPrefab);
        target.transform.SetParent(area.transform, false);

        target.transform.localPosition = RandomRestrictedPosition();
        target.transform.rotation = RandomYRotation();

        target.GetComponent<TestTarget>().id = currentTargetId;
        lastTarget = target;

        // Fire event that a new target has been spawned
        TargetSpawnedEvent tse = new TargetSpawnedEvent();
        tse.targetId = currentTargetId;
        tse.targetTransform = target.transform;
        tse.FireEvent();
    }


    /// <summary>
    /// Generates a random rotation with nullvector as base, is separate to allow possible restrictions in rotation
    /// </summary>
    /// <returns>Returns a Quaternion containing a random rotation within constrains</returns>
    private Quaternion RandomYRotation() {
        Vector3 euler = Vector3.zero;
        euler.y = Random.Range((-maxTargetRotation / 2) - 90, (maxTargetRotation / 2) - 90);
        return Quaternion.Euler(euler);
    }

    /// <summary>
    /// Returns a randomly selected position in the area and calls for a check if it is valid
    /// </summary>
    /// <returns>Returns a within constrains random and valid position</returns>
    private Vector3 RandomRestrictedPosition() {
        Vector3 nextPos = lastTarget.transform.localPosition;
        float rot = Random.Range(-maxAngle, maxAngle);

        Vector3 moveTarget = Quaternion.AngleAxis(rot, Vector3.up) * dirOfNextPos;
        // TODO: improve so it rotates based on lastTarget rotation
        moveTarget = moveTarget.normalized * Random.Range(minDistance, maxDistance);

        nextPos += moveTarget;
        nextPos.y = 0;

        return ValidatePosition(nextPos);
    }

    /// <summary>
    /// Checks if next Position is in the areas bounds and set it inside if needed
    /// </summary>
    /// <param name="position">The position that should be checked if it lies within constrains</param>
    /// <returns>Returns the position with, if necessary, corrections</returns>
    private Vector3 ValidatePosition(Vector3 position) {
        if (!areaBounds.Contains(position)) {
            Debug.Log("OutOfBounds! ClosestPos: " + areaBounds.ClosestPoint(position));
            position = areaBounds.ClosestPoint(position) + ((areaBounds.ClosestPoint(position) - position).normalized * maxDistance);
            dirOfNextPos = dirOfNextPos * -1;
        }

        return position;
    }

    /// <summary>
    /// Called when the corresponding button on the controller this script is put into, is released
    /// </summary>
    public void OnButtonUp() {

        if (isExpActive) {
            Destroy(lastTarget);

            if (currentTargetId == numberOfTargets) {
                isExpActive = false;
                ExperimentEndEvent eee = new ExperimentEndEvent();
                eee.FireEvent();
            } else {
                SpawnTarget();
            }
        }
    }

    // unused; necessary to match signature
    public void OnButtonDown(GameObject controllerObject, int controllerIdentificator) {

    }
}