//***********************************************************
// Filename: Visualiser.cs
// Author: Marco Fendrich, Moritz Kolvenbach
// Last changes: Thursday, 9th of August 2018
// Content: A class to render the visual representation of the different teleportConditions
//***********************************************************
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// Handles the rendering of the visual feedback for the different teleportMethods
/// </summary>
public class Visualiser : MonoBehaviour {

    [Header("Parabola Mesh Properties")]
    [Tooltip("Number of points on the parabola mesh.  Greater point counts lead to a higher poly/smoother mesh.")]
    public int PointCount = 50;
    [Tooltip("Approximate spacing between each of the points on the parabola mesh.")]
    public float PointSpacing = 0.5f;
    [Tooltip("Thickness of the parabola mesh")]
    public float GraphicThickness = 0.05f;
    [Tooltip("Material to use to render the parabola mesh")]
    public Material GraphicMaterial;
    [Header("Selection Pad Properties")]
    [SerializeField]
    [Tooltip("Prefab to use as the selection pad when the player is pointing at a valid teleportable surface.")]
    private GameObject SelectionPadPrefab;
    [SerializeField]
    [Tooltip("Prefab to use as the selection pad when the player is pointing at an invalid teleportable surface.")]
    private GameObject InvalidPadPrefab;
    [SerializeField]
    [Tooltip("Prefab to use as the selection pad when using the turn teleport.")]
    private GameObject RotationPadPrefab;

    // The final point, where the player gets teleported to
    private Vector3 SelectedPoint;
    // The mesh used to check for collisions and validate whether the targetPoint is acutually teleportable
    private Mesh ParabolaMesh;
    private float rotation = float.NegativeInfinity;

    // Prefabs for the different kinds of goal markers
    private GameObject SelectionPadObject;
    private GameObject InvalidPadObject;
    private GameObject RotationPadObject;
    
    // Update values based on the information from the different teleportConditions
    public void updateRendering(bool PointOnNavMesh, List<Vector3> ParabolaPoints, Vector3 normal, Vector3 velocity, float rotation)
    {
        this.PointOnNavMesh = PointOnNavMesh;
        this.ParabolaPoints = ParabolaPoints;
        this.normal = normal;
        this.velocity = velocity;
        this.rotation = rotation;
    }

    public void updateRendering(bool PointOnNavMesh, List<Vector3> ParabolaPoints, Vector3 normal, Vector3 velocity)
    {
        this.PointOnNavMesh = PointOnNavMesh;
        this.ParabolaPoints = ParabolaPoints;
        this.normal = normal;
        this.velocity = velocity;
    }

    // True if the final point of parabolaPoints is at a teleportable location
    bool PointOnNavMesh;
    // Normal of selectedPoint
    Vector3 normal;
    Vector3 velocity;
    private List<Vector3> ParabolaPoints;

    void Update () {
        SelectedPoint = ParabolaPoints[ParabolaPoints.Count - 1];
        
        // check which marker to render for each frame

        if (SelectionPadObject != null && rotation == float.NegativeInfinity)
        {
            SelectionPadObject.SetActive(PointOnNavMesh);
            SelectionPadObject.transform.position = SelectedPoint + Vector3.one * 0.005f;
            if (PointOnNavMesh)
            {
                SelectionPadObject.transform.rotation = Quaternion.LookRotation(normal);
                SelectionPadObject.transform.Rotate(90, 0, 0);
            }
        }
        else if (RotationPadObject != null)
        {
            RotationPadObject.SetActive(PointOnNavMesh);
            RotationPadObject.transform.position = SelectedPoint + Vector3.one * 0.005f;
            if (PointOnNavMesh)
            {
                RotationPadObject.transform.rotation = Quaternion.LookRotation(normal);
                RotationPadObject.transform.Rotate(90, 0, 0);

                // rotate selection pad
                Vector2 parabolicVector = new Vector2(velocity.x, velocity.z);
                RotationPadObject.transform.Rotate(0, Vector2.SignedAngle(parabolicVector, Vector2.up) - 90.0F, 0);
                RotationPadObject.transform.Rotate(0, rotation, 0);
            }
        }
        if (InvalidPadObject != null)
        {
            InvalidPadObject.SetActive(!PointOnNavMesh);
            InvalidPadObject.transform.position = SelectedPoint + Vector3.one * 0.005f;
            if (!PointOnNavMesh)
            {
                InvalidPadObject.transform.rotation = Quaternion.LookRotation(normal);
                InvalidPadObject.transform.Rotate(90, 0, 0);
            }
        }

        // Draw parabola (BEFORE the outside faces of the selection pad, to avoid depth issues)
        GenerateMesh(ref ParabolaMesh, ParabolaPoints, velocity, Time.time % 1);
        Graphics.DrawMesh(ParabolaMesh, Matrix4x4.identity, GraphicMaterial, gameObject.layer);
    }

    void Start()
    {
        // populate initial mesh
        ParabolaMesh = new Mesh();
        ParabolaMesh.MarkDynamic();
        ParabolaMesh.name = "Parabolic Pointer";
        ParabolaMesh.vertices = new Vector3[0];
        ParabolaMesh.triangles = new int[0];

        // instantiate target marker prefabs
        if (SelectionPadPrefab != null)
        {
            SelectionPadObject = Instantiate<GameObject>(SelectionPadPrefab);
            SelectionPadObject.SetActive(false);
        }

        if (InvalidPadPrefab != null)
        {
            InvalidPadObject = Instantiate<GameObject>(InvalidPadPrefab);
            InvalidPadObject.SetActive(false);
        }

        if (RotationPadPrefab != null)
        {
            RotationPadObject = Instantiate<GameObject>(RotationPadPrefab);
            RotationPadObject.SetActive(false);
        }
    }

    void OnDisable()
    {
        if (SelectionPadObject != null)
            SelectionPadObject.SetActive(false);
        if (InvalidPadObject != null)
            InvalidPadObject.SetActive(false);
        if (RotationPadObject != null)
            RotationPadObject.SetActive(false);
        rotation = float.NegativeInfinity;
    }

    /// <summary>
    /// Updates the used mesh. Dependent on how the the points list to be visualized is populated
    /// </summary>
    /// <param name="m"> The mesh used for collision detection</param>
    /// <param name="points"> List of Vector3 representing the points to be visualized for the teleport</param>
    /// <param name="forwardVelocity"> Vector3 representing the velocity of the physical throw calculation</param>
    /// <param name="uvOffset"> Offset </param>
    private void GenerateMesh(ref Mesh m, List<Vector3> points, Vector3 forwardVelocity, float uvOffset)
    {
        Vector3[] verts = new Vector3[points.Count * 2];
        Vector2[] uv = new Vector2[points.Count * 2];

        Vector3 right = Vector3.Cross(forwardVelocity, Vector3.up).normalized;

        // calculate new vertices for the mesh
        for (int x = 0; x < points.Count; x++)
        {
            verts[2 * x] = points[x] - right * GraphicThickness / 2;
            verts[2 * x + 1] = points[x] + right * GraphicThickness / 2;

            float uvoffsetMod = uvOffset;
            if (x == points.Count - 1 && x > 1)
            {
                float distLast = (points[x - 2] - points[x - 1]).magnitude;
                float distCur = (points[x] - points[x - 1]).magnitude;
                uvoffsetMod += 1 - distCur / distLast;
            }

            uv[2 * x] = new Vector2(0, x - uvoffsetMod);
            uv[2 * x + 1] = new Vector2(1, x - uvoffsetMod);
        }

        // calculate new triangleArrays for mesh
        int[] indices = new int[2 * 3 * (verts.Length - 2)];
        for (int x = 0; x < verts.Length / 2 - 1; x++)
        {
            int p1 = 2 * x;
            int p2 = 2 * x + 1;
            int p3 = 2 * x + 2;
            int p4 = 2 * x + 3;

            indices[12 * x] = p1;
            indices[12 * x + 1] = p2;
            indices[12 * x + 2] = p3;
            indices[12 * x + 3] = p3;
            indices[12 * x + 4] = p2;
            indices[12 * x + 5] = p4;

            indices[12 * x + 6] = p3;
            indices[12 * x + 7] = p2;
            indices[12 * x + 8] = p1;
            indices[12 * x + 9] = p4;
            indices[12 * x + 10] = p2;
            indices[12 * x + 11] = p3;
        }

        // update mesh with new values
        m.Clear();
        m.vertices = verts;
        m.uv = uv;
        m.triangles = indices;
        m.RecalculateBounds();
        m.RecalculateNormals();
    }
}