// Copyright HTC Corporation All Rights Reserved.

using System.Text;
using UnityEngine;

namespace VIVE.OpenXR.Raycast
{
    /// <summary>
    /// To draw a ring pointer to indicate the gazed space.
    /// </summary>
    [RequireComponent(typeof(MeshRenderer), typeof(MeshFilter))]
    public class RaycastRing : RaycastImpl
    {
        const string LOG_TAG = "VIVE.OpenXR.Raycast.RaycastRing";
        void DEBUG(StringBuilder msg) { Debug.LogFormat("{0} {1}", LOG_TAG, msg); }

        public enum GazeEvent
        {
            Down = 0,
            Submit = 1
        }

        #region Inspector
        // ----------- Width of ring -----------
        const float kRingWidthDefault = 0.005f;
        const float kRingWidthMinimal = 0.001f;
        [Tooltip("Set the width of the pointer's ring.")]
        [SerializeField]
        private float m_PointerRingWidth = kRingWidthDefault;
        public float PointerRingWidth { get { return m_PointerRingWidth; } set { m_PointerRingWidth = value; } }

        // ----------- Radius of inner circle -----------
        const float kInnerCircleRadiusDefault = 0.005f;
        const float kInnerCircleRadiusMinimal = 0.001f;
        [Tooltip("Set the radius of the pointer's inner circle.")]
        [SerializeField]
        private float m_PointerCircleRadius = kInnerCircleRadiusDefault;
        public float PointerCircleRadius { get { return m_PointerCircleRadius; } set { m_PointerCircleRadius = value; } }

        // ----------- Z distance of ring -----------
        const float kPointerDistanceDefault = 1;
        const float kPointerDistanceMinimal = 0.1f;
        [Tooltip("Set the z-coordinate of the pointer.")]
        [SerializeField]
        private float m_PointerDistance = kPointerDistanceDefault;
        public float PointerDistance { get { return m_PointerDistance; } set { m_PointerDistance = value; } }

        /// The offset from the pointer to the pointer-mounted object.
        private Vector3 ringOffset = Vector3.zero;
        /// The offset from the pointer to the pointer-mounted object in every frame.
        private Vector3 ringFrameOffset = Vector3.zero;
        /// The pointer world position.
        private Vector3 ringWorldPosition = Vector3.zero;

        // ----------- Color of ring -----------
        /// Color of ring background.
        [Tooltip("Set the ring background color.")]
        [SerializeField]
        private Color m_PointerColor = Color.white;
        public Color PointerColor { get { return m_PointerColor; } set { m_PointerColor = value; } }

        /// Color of ring foreground
        [Tooltip("Set the ring foreground progess color.")]
        [SerializeField]
        private Color m_ProgressColor = new Color(0, 245, 255);
        public Color ProgressColor { get { return m_ProgressColor; } set { m_ProgressColor = value; } }

        // ----------- Material and Mesh -----------
        private Mesh m_Mesh = null;

        const string kPointerMaterial = "Materials/GazePointerDef";
        [Tooltip("Empty for using the default material or set a customized material.")]
        [SerializeField]
        private Material m_PointerMaterial = null;
        public Material PointerMaterial { get { return m_PointerMaterial; } set { m_PointerMaterial = value; } }
        private Material pointerMaterialInstance = null;

        private MeshFilter m_MeshFilter = null;
        private MeshRenderer m_MeshRenderer = null;

        const int kMaterialRenderQueueMin = 1000;
        const int kMaterialRenderQueueMax = 5000;
        /// The material's renderQueue.
        [Tooltip("Set the Material's renderQueue.")]
        [SerializeField]
        private int m_PointerRenderQueue = kMaterialRenderQueueMax;
        public int PointerRenderQueue { get { return m_PointerRenderQueue; } set { m_PointerRenderQueue = value; } }

        /// The MeshRenderer's sortingOrder.
        [Tooltip("Set the MeshRenderer's sortingOrder.")]
        [SerializeField]
        private int m_PointerSortingOrder = 32767;
        public int PointerSortingOrder { get { return m_PointerSortingOrder; } set { m_PointerSortingOrder = value; } }

        protected int m_RingPercent = 0;
        public int RingPercent { get { return m_RingPercent; } set { m_RingPercent = value; } }

        [Tooltip("Gaze timer to trigger gaze events.")]
        [SerializeField]
        private float m_TimeToGaze = 1.5f;
        public float TimeToGaze { get { return m_TimeToGaze; } set { m_TimeToGaze = value; } }

        private void ValidateParameters()
        {
            if (m_PointerRingWidth < kRingWidthMinimal)
                m_PointerRingWidth = kRingWidthDefault;

            if (m_PointerCircleRadius < kInnerCircleRadiusMinimal)
                m_PointerCircleRadius = kInnerCircleRadiusDefault;

            if (m_PointerDistance < kPointerDistanceMinimal)
                m_PointerDistance = kPointerDistanceDefault;

            if (m_PointerRenderQueue < kMaterialRenderQueueMin || m_PointerRenderQueue > kMaterialRenderQueueMax)
                m_PointerRenderQueue = kMaterialRenderQueueMax;
        }
        #endregion

        #region MonoBehaviour overrides
        private bool mEnabled = false;
        protected override void OnEnable()
        {
            base.OnEnable();

            if (!mEnabled)
            {
                sb.Clear().Append("OnEnable()"); DEBUG(sb);
                // 1. Texture or Mesh < Material < < MeshFilter < MeshRenderer, we don't use the texture.
                if (m_Mesh == null)
                    m_Mesh = new Mesh();
                if (m_Mesh != null)
                    m_Mesh.name = gameObject.name + " Mesh";

                // 2. Load the Material RingUnlitTransparentMat.
                if (m_PointerMaterial == null)
                    m_PointerMaterial = Resources.Load(kPointerMaterial) as Material;
                if (m_PointerMaterial != null)
                {
                    pointerMaterialInstance = Instantiate(m_PointerMaterial);
                    sb.Clear().Append("OnEnable() Loaded resource ").Append(pointerMaterialInstance.name); DEBUG(sb);
                }

                // 3. Get the MeshFilter.
                m_MeshFilter = GetComponent<MeshFilter>();

                // 4. Get the MeshRenderer.
                m_MeshRenderer = GetComponent<MeshRenderer>();
                m_MeshRenderer.sortingOrder = m_PointerSortingOrder;
                m_MeshRenderer.material = pointerMaterialInstance;
                m_MeshRenderer.material.renderQueue = PointerRenderQueue;

                mEnabled = true;
            }
        }

        protected override void OnDisable()
        {
            base.OnDisable();

            if (mEnabled)
            {
                sb.Clear().Append("OnDisable()"); DEBUG(sb);
                if (m_MeshFilter != null)
                {
                    Mesh mesh = m_MeshFilter.mesh;
                    mesh.Clear();
                }
                Destroy(pointerMaterialInstance);

                mEnabled = false;
            }
        }

        protected override void Update()
        {
            base.Update();

            if (!IsInteractable()) { return; }

            ValidateParameters();
            UpdatePointerOffset();

            ringFrameOffset = ringOffset;
            ringFrameOffset.z = ringFrameOffset.z < kPointerDistanceMinimal ? kPointerDistanceDefault : ringFrameOffset.z;

            // Calculate the pointer world position
            Vector3 rotated_direction = transform.rotation * ringFrameOffset;
            ringWorldPosition = transform.position + rotated_direction;
            //DEBUG("ringWorldPosition: " + ringWorldPosition.x + ", " + ringWorldPosition.y + ", " + ringWorldPosition.z);

            float calcRingWidth = m_PointerRingWidth * (ringFrameOffset.z / kPointerDistanceDefault);
            float calcInnerCircleRadius = m_PointerCircleRadius * (ringFrameOffset.z / kPointerDistanceDefault);

            UpdateRingPercent();
            DrawRingRoll(calcRingWidth + calcInnerCircleRadius, calcInnerCircleRadius, ringFrameOffset, m_RingPercent);

            if (printIntervalLog)
            {
                sb.Clear().Append("Update() ")
                    .Append(gameObject.name).Append(" is ").Append(m_MeshRenderer.enabled ? "shown" : "hidden")
                    .Append(", ringFrameOffset (").Append(ringFrameOffset.x).Append(", ").Append(ringFrameOffset.y).Append(", ").Append(ringFrameOffset.z).Append(")");
                DEBUG(sb);
            }
        }
        #endregion

        private bool IsInteractable()
        {
            ActivatePointer(m_Interactable);
            return m_Interactable;
        }
        private void ActivatePointer(bool active)
        {
            if (m_MeshRenderer == null)
                return;

            if (m_MeshRenderer.enabled != active)
            {
                m_MeshRenderer.enabled = active;
                sb.Clear().Append("ActivatePointer() ").Append(m_MeshRenderer.enabled); DEBUG(sb);
                if (m_MeshRenderer.enabled)
                {
                    m_MeshRenderer.sortingOrder = m_PointerSortingOrder;
                    if (pointerMaterialInstance != null)
                    {
                        m_MeshRenderer.material = pointerMaterialInstance;
                        m_MeshRenderer.material.renderQueue = PointerRenderQueue;
                    }
                    // The MeshFilter's mesh is updated in DrawRingRoll(), not here.
                }
            }
        }

        private void UpdatePointerOffset()
        {
            ringOffset = pointerLocalOffset;
            // Moves the pointer onto the gazed object.
            if (raycastObject != null)
            {
                Vector3 rotated_direction = pointerData.pointerCurrentRaycast.worldPosition - gameObject.transform.position;
                ringOffset = Quaternion.Inverse(transform.rotation) * rotated_direction;
            }
        }

        protected float m_GazeOnTime = 0;
        private void UpdateRingPercent()
        {
            if (raycastObject != raycastObjectEx)
            {
                m_RingPercent = 0;
                if (raycastObject != null)
                    m_GazeOnTime = Time.unscaledTime;
            }
            else
            {
                // Hovering
                if (raycastObject != null)
                    m_RingPercent = (int)(((Time.unscaledTime - m_GazeOnTime) / m_TimeToGaze) * 100);
            }
        }

        const int kRingVertexCount = 400;       // 100 percents * 2 + 2, ex: 80% ring -> 80 * 2 + 2
        private Vector3[] ringVert = new Vector3[kRingVertexCount];
        private Color[] ringColor = new Color[kRingVertexCount];

        const int kRingTriangleCount = 100 * 6; // 100 percents * 6, ex: 80% ring -> 80 * 6
        private int[] ringTriangle = new int[kRingTriangleCount];
        private Vector2[] ringUv = new Vector2[kRingVertexCount];

        const float kPercentAngle = 3.6f;    // 100% = 100 * 3.6f = 360 degrees.

        private void DrawRingRoll(float radius, float innerRadius, Vector3 offset, int percent)
        {
            if (m_MeshFilter == null)
                return;

            percent = percent >= 100 ? 100 : percent;

            // vertices and colors
            float start_angle = 90;             // Start angle of drawing ring.
            for (int i = 0; i < kRingVertexCount; i += 2)
            {
                float radian_cur = start_angle * Mathf.Deg2Rad;
                float cosA = Mathf.Cos(radian_cur);
                float sinA = Mathf.Sin(radian_cur);

                ringVert[i].x = offset.x + radius * cosA;
                ringVert[i].y = offset.y + radius * sinA;
                ringVert[i].z = offset.z;

                ringColor[i] = (i <= (percent * 2) && i > 0) ? m_ProgressColor : m_PointerColor;

                ringVert[i + 1].x = offset.x + innerRadius * cosA;
                ringVert[i + 1].y = offset.y + innerRadius * sinA;
                ringVert[i + 1].z = offset.z;

                ringColor[i + 1] = (i <= (percent * 2) && i > 0) ? m_ProgressColor : m_PointerColor;

                start_angle -= kPercentAngle;
            }

            // triangles
            for (int i = 0, vi = 0; i < kRingTriangleCount; i += 6, vi += 2)
            {
                ringTriangle[i] = vi;
                ringTriangle[i + 1] = vi + 3;
                ringTriangle[i + 2] = vi + 1;

                ringTriangle[i + 3] = vi + 2;
                ringTriangle[i + 4] = vi + 3;
                ringTriangle[i + 5] = vi;
            }

            // uv
            for (int i = 0; i < kRingVertexCount; i++)
            {
                ringUv[i].x = ringVert[i].x / radius / 2 + 0.5f;
                ringUv[i].y = ringVert[i].z / radius / 2 + 0.5f;
            }

            m_Mesh.Clear();

            m_Mesh.vertices = ringVert;
            m_Mesh.colors = ringColor;
            m_Mesh.triangles = ringTriangle;
            m_Mesh.uv = ringUv;
            m_MeshFilter.mesh = m_Mesh;
        }

        #region External Functions
        public Vector3 GetPointerPosition()
        {
            return ringWorldPosition;
        }
        #endregion
    }
}