import { Observer, Observable } from "../Misc/observable";
import { Nullable } from "../types";
import { PointerInfo } from "../Events/pointerEvents";
import { Quaternion, Matrix, Vector3, Color3 } from "../Maths/math";
import { AbstractMesh } from "../Meshes/abstractMesh";
import { Mesh } from "../Meshes/mesh";
import { LinesMesh } from "../Meshes/linesMesh";
import { PointerDragBehavior } from "../Behaviors/Meshes/pointerDragBehavior";
import { _TimeToken } from "../Instrumentation/timeToken";
import { _DepthCullingState, _StencilState, _AlphaState } from "../States/index";
import { Gizmo } from "./gizmo";
import { UtilityLayerRenderer } from "../Rendering/utilityLayerRenderer";
import { StandardMaterial } from "../Materials/standardMaterial";

import "../Meshes/Builders/linesBuilder";

/**
 * Single plane rotation gizmo
 */
export class PlaneRotationGizmo extends Gizmo {
    /**
     * Drag behavior responsible for the gizmos dragging interactions
     */
    public dragBehavior: PointerDragBehavior;
    private _pointerObserver: Nullable<Observer<PointerInfo>> = null;

    /**
     * Rotation distance in radians that the gizmo will snap to (Default: 0)
     */
    public snapDistance = 0;
    /**
     * Event that fires each time the gizmo snaps to a new location.
     * * snapDistance is the the change in distance
     */
    public onSnapObservable = new Observable<{ snapDistance: number }>();

    /**
     * Creates a PlaneRotationGizmo
     * @param gizmoLayer The utility layer the gizmo will be added to
     * @param planeNormal The normal of the plane which the gizmo will be able to rotate on
     * @param color The color of the gizmo
     * @param tessellation Amount of tessellation to be used when creating rotation circles
     */
    constructor(planeNormal: Vector3, color: Color3 = Color3.Gray(), gizmoLayer: UtilityLayerRenderer = UtilityLayerRenderer.DefaultUtilityLayer, tessellation = 32) {
        super(gizmoLayer);

        // Create Material
        var coloredMaterial = new StandardMaterial("", gizmoLayer.utilityLayerScene);
        coloredMaterial.diffuseColor = color;
        coloredMaterial.specularColor = color.subtract(new Color3(0.1, 0.1, 0.1));

        var hoverMaterial = new StandardMaterial("", gizmoLayer.utilityLayerScene);
        hoverMaterial.diffuseColor = color.add(new Color3(0.3, 0.3, 0.3));

        // Build mesh on root node
        var parentMesh = new AbstractMesh("", gizmoLayer.utilityLayerScene);

        let drag = Mesh.CreateTorus("", 0.6, 0.03, tessellation, gizmoLayer.utilityLayerScene);
        drag.visibility = 0;
        let rotationMesh = Mesh.CreateTorus("", 0.6, 0.005, tessellation, gizmoLayer.utilityLayerScene);
        rotationMesh.material = coloredMaterial;

        // Position arrow pointing in its drag axis
        rotationMesh.rotation.x = Math.PI / 2;
        drag.rotation.x = Math.PI / 2;
        parentMesh.addChild(rotationMesh);
        parentMesh.addChild(drag);
        parentMesh.lookAt(this._rootMesh.position.add(planeNormal));

        this._rootMesh.addChild(parentMesh);
        parentMesh.scaling.scaleInPlace(1 / 3);
        // Add drag behavior to handle events when the gizmo is dragged
        this.dragBehavior = new PointerDragBehavior({ dragPlaneNormal: planeNormal });
        this.dragBehavior.moveAttached = false;
        this.dragBehavior.maxDragAngle = Math.PI * 9 / 20;
        this.dragBehavior._useAlternatePickedPointAboveMaxDragAngle = true;
        this._rootMesh.addBehavior(this.dragBehavior);

        var lastDragPosition = new Vector3();

        this.dragBehavior.onDragStartObservable.add((e) => {
            if (this.attachedMesh) {
                lastDragPosition.copyFrom(e.dragPlanePoint);
            }
        });

        var rotationMatrix = new Matrix();
        var planeNormalTowardsCamera = new Vector3();
        var localPlaneNormalTowardsCamera = new Vector3();

        var tmpSnapEvent = { snapDistance: 0 };
        var currentSnapDragDistance = 0;
        var tmpMatrix = new Matrix();
        var tmpVector = new Vector3();
        var amountToRotate = new Quaternion();
        this.dragBehavior.onDragObservable.add((event) => {
            if (this.attachedMesh) {
                if (!this.attachedMesh.rotationQuaternion) {
                    this.attachedMesh.rotationQuaternion = Quaternion.RotationYawPitchRoll(this.attachedMesh.rotation.y, this.attachedMesh.rotation.x, this.attachedMesh.rotation.z);
                }
                // Calc angle over full 360 degree (https://stackoverflow.com/questions/43493711/the-angle-between-two-3d-vectors-with-a-result-range-0-360)
                var newVector = event.dragPlanePoint.subtract(this.attachedMesh.absolutePosition).normalize();
                var originalVector = lastDragPosition.subtract(this.attachedMesh.absolutePosition).normalize();
                var cross = Vector3.Cross(newVector, originalVector);
                var dot = Vector3.Dot(newVector, originalVector);
                var angle = Math.atan2(cross.length(), dot);
                planeNormalTowardsCamera.copyFrom(planeNormal);
                localPlaneNormalTowardsCamera.copyFrom(planeNormal);
                if (this.updateGizmoRotationToMatchAttachedMesh) {
                    this.attachedMesh.rotationQuaternion.toRotationMatrix(rotationMatrix);
                    localPlaneNormalTowardsCamera = Vector3.TransformCoordinates(planeNormalTowardsCamera, rotationMatrix);
                }
                // Flip up vector depending on which side the camera is on
                if (gizmoLayer.utilityLayerScene.activeCamera) {
                    var camVec = gizmoLayer.utilityLayerScene.activeCamera.position.subtract(this.attachedMesh.position);
                    if (Vector3.Dot(camVec, localPlaneNormalTowardsCamera) > 0) {
                        planeNormalTowardsCamera.scaleInPlace(-1);
                        localPlaneNormalTowardsCamera.scaleInPlace(-1);
                    }
                }
                var halfCircleSide = Vector3.Dot(localPlaneNormalTowardsCamera, cross) > 0.0;
                if (halfCircleSide) { angle = -angle; }

                // Snapping logic
                var snapped = false;
                if (this.snapDistance != 0) {
                    currentSnapDragDistance += angle;
                    if (Math.abs(currentSnapDragDistance) > this.snapDistance) {
                        var dragSteps = Math.floor(Math.abs(currentSnapDragDistance) / this.snapDistance);
                        if (currentSnapDragDistance < 0) {
                            dragSteps *= -1;
                        }
                        currentSnapDragDistance = currentSnapDragDistance % this.snapDistance;
                        angle = this.snapDistance * dragSteps;
                        snapped = true;
                    } else {
                        angle = 0;
                    }
                }

                // If the mesh has a parent, convert needed world rotation to local rotation
                tmpMatrix.reset();
                if (this.attachedMesh.parent) {
                    this.attachedMesh.parent.computeWorldMatrix().invertToRef(tmpMatrix);
                    tmpMatrix.getRotationMatrixToRef(tmpMatrix);
                    Vector3.TransformCoordinatesToRef(planeNormalTowardsCamera, tmpMatrix, planeNormalTowardsCamera);
                }

                // Convert angle and axis to quaternion (http://www.euclideanspace.com/maths/geometry/rotations/conversions/angleToQuaternion/index.htm)
                var quaternionCoefficient = Math.sin(angle / 2);
                amountToRotate.set(planeNormalTowardsCamera.x * quaternionCoefficient, planeNormalTowardsCamera.y * quaternionCoefficient, planeNormalTowardsCamera.z * quaternionCoefficient, Math.cos(angle / 2));

                // If the meshes local scale is inverted (eg. loaded gltf file parent with z scale of -1) the rotation needs to be inverted on the y axis
                if (tmpMatrix.determinant() > 0) {
                    amountToRotate.toEulerAnglesToRef(tmpVector);
                    Quaternion.RotationYawPitchRollToRef(tmpVector.y, -tmpVector.x, -tmpVector.z, amountToRotate);
                }

                if (this.updateGizmoRotationToMatchAttachedMesh) {
                    // Rotate selected mesh quaternion over fixed axis
                    this.attachedMesh.rotationQuaternion.multiplyToRef(amountToRotate, this.attachedMesh.rotationQuaternion);
                } else {
                    // Rotate selected mesh quaternion over rotated axis
                    amountToRotate.multiplyToRef(this.attachedMesh.rotationQuaternion, this.attachedMesh.rotationQuaternion);
                }

                lastDragPosition.copyFrom(event.dragPlanePoint);
                if (snapped) {
                    tmpSnapEvent.snapDistance = angle;
                    this.onSnapObservable.notifyObservers(tmpSnapEvent);
                }
            }
        });

        this._pointerObserver = gizmoLayer.utilityLayerScene.onPointerObservable.add((pointerInfo) => {
            if (this._customMeshSet) {
                return;
            }
            var isHovered = pointerInfo.pickInfo && (this._rootMesh.getChildMeshes().indexOf(<Mesh>pointerInfo.pickInfo.pickedMesh) != -1);
            var material = isHovered ? hoverMaterial : coloredMaterial;
            this._rootMesh.getChildMeshes().forEach((m) => {
                m.material = material;
                if ((<LinesMesh>m).color) {
                    (<LinesMesh>m).color = material.diffuseColor;
                }
            });
        });

        var light = gizmoLayer._getSharedGizmoLight();
        light.includedOnlyMeshes = light.includedOnlyMeshes.concat(this._rootMesh.getChildMeshes(false));
    }

    protected _attachedMeshChanged(value: Nullable<AbstractMesh>) {
        if (this.dragBehavior) {
            this.dragBehavior.enabled = value ? true : false;
        }
    }

    /**
     * Disposes of the gizmo
     */
    public dispose() {
        this.onSnapObservable.clear();
        this.gizmoLayer.utilityLayerScene.onPointerObservable.remove(this._pointerObserver);
        this.dragBehavior.detach();
        super.dispose();
    }
}