import { Vector3, Matrix, TmpVectors } from "../Maths/math.vector";
import { Color3 } from '../Maths/math.color';
import { Scene } from "../scene";
import { Nullable } from "../types";
import { Bone } from "../Bones/bone";
import { Skeleton } from "../Bones/skeleton";
import { AbstractMesh } from "../Meshes/abstractMesh";
import { Mesh } from "../Meshes/mesh";
import { LinesMesh } from "../Meshes/linesMesh";
import { LinesBuilder } from "../Meshes/Builders/linesBuilder";
import { UtilityLayerRenderer } from "../Rendering/utilityLayerRenderer";
import { StandardMaterial } from '../Materials/standardMaterial';
import { VertexBuffer } from '../Meshes/buffer';

import { ISkeletonViewerOptions } from './ISkeletonViewer';
import { Observer } from '../Misc/observable';

import { SphereBuilder } from '../Meshes/Builders/sphereBuilder';
import { ShapeBuilder } from '../Meshes/Builders/shapeBuilder';

/**
 * Class used to render a debug view of a given skeleton
 * @see http://www.babylonjs-playground.com/#1BZJVJ#8
 */
export class SkeletonViewer {
    /** public Display constants BABYLON.SkeletonViewer.DISPLAY_LINES */
    public static readonly DISPLAY_LINES = 0;
    /** public Display constants BABYLON.SkeletonViewer.DISPLAY_SPHERES */
    public static readonly DISPLAY_SPHERES = 1;
    /** public Display constants BABYLON.SkeletonViewer.DISPLAY_SPHERE_AND_SPURS */
    public static readonly DISPLAY_SPHERE_AND_SPURS = 2;

    /** If SkeletonViewer scene scope. */
    private _scene : Scene;

    /** Gets or sets the color used to render the skeleton */
    public color: Color3 = Color3.White();

    /** Array of the points of the skeleton fo the line view. */
    private _debugLines = new Array<Array<Vector3>>();

    /** The SkeletonViewers Mesh. */
    private _debugMesh: Nullable<LinesMesh>;

    /** If SkeletonViewer is enabled. */
    private _isEnabled = false;

    /** If SkeletonViewer is ready. */
    private _ready : boolean;

    /** SkeletonViewer render observable. */
    private _obs: Nullable<Observer<Scene>> = null;

     /** The Utility Layer to render the gizmos in. */
    private _utilityLayer: Nullable<UtilityLayerRenderer>;

    /** Gets the Scene. */
    get scene(): Scene {
        return this._scene;
    }
    /** Gets the utilityLayer. */
    get utilityLayer(): Nullable<UtilityLayerRenderer> {
        return this._utilityLayer;
    }
    /** Checks Ready Status. */
    get isReady(): Boolean {
        return this._ready;
    }
    /** Sets Ready Status. */
    set ready(value: boolean) {
        this._ready = value;
    }
    /** Gets the debugMesh */
    get debugMesh(): Nullable<AbstractMesh> | Nullable<LinesMesh> {
        return this._debugMesh;
    }
    /** Sets the debugMesh */
    set debugMesh(value: Nullable<AbstractMesh> | Nullable<LinesMesh>) {
         this._debugMesh = (value as any);
    }
    /** Gets the material */
    get material(): StandardMaterial {
        return this.material;
    }
    /** Sets the material */
    set material(value: StandardMaterial) {
         this.material = value;
    }

    /**
     * Creates a new SkeletonViewer
     * @param skeleton defines the skeleton to render
     * @param mesh defines the mesh attached to the skeleton
     * @param scene defines the hosting scene
     * @param autoUpdateBonesMatrices defines a boolean indicating if bones matrices must be forced to update before rendering (true by default)
     * @param renderingGroupId defines the rendering group id to use with the viewer
     * @param options All of the extra constructor options for the SkeletonViewer
     */
    constructor(
        /** defines the skeleton to render */
        public skeleton: Skeleton,
        /** defines the mesh attached to the skeleton */
        public mesh: AbstractMesh,
        /** The Scene scope*/
        scene: Scene,
        /** defines a boolean indicating if bones matrices must be forced to update before rendering (true by default)  */
        public autoUpdateBonesMatrices: boolean = true,
        /** defines the rendering group id to use with the viewer */
        public renderingGroupId: number = 3,
        /** is the options for the viewer */
        public options: Partial<ISkeletonViewerOptions> = {}
        ) {

        this._scene = scene;
        this._ready = false;

        //Defaults
        options.pauseAnimations = options.pauseAnimations ?? true;
        options.returnToRest = options.returnToRest ?? true;
        options.displayMode = options.displayMode ?? SkeletonViewer.DISPLAY_LINES;
        options.displayOptions = options.displayOptions ?? {};
        options.displayOptions.midStep = options.displayOptions.midStep ?? 0.235;
        options.displayOptions.midStepFactor = options.displayOptions.midStepFactor ?? 0.155;
        options.displayOptions.sphereBaseSize = options.displayOptions.sphereBaseSize ?? 0.15;
        options.displayOptions.sphereScaleUnit = options.displayOptions.sphereScaleUnit ?? 2;
        options.displayOptions.sphereFactor = options.displayOptions.sphereFactor ?? 0.865;
        options.computeBonesUsingShaders = options.computeBonesUsingShaders ?? true;

        /* Create Utility Layer */
        this._utilityLayer = new UtilityLayerRenderer(this._scene, false);
        this._utilityLayer.pickUtilitySceneFirst = false;
        this._utilityLayer.utilityLayerScene.autoClearDepthAndStencil = true;

        let displayMode = this.options.displayMode || 0;
        if (displayMode > SkeletonViewer.DISPLAY_SPHERE_AND_SPURS) {
            displayMode = SkeletonViewer.DISPLAY_LINES;
        }
        this.options.displayMode = displayMode;
        //Prep the Systems
        this.update();
        this._bindObs();
    }

    /** The Dynamic bindings for the update functions */
    private _bindObs(): void {
        switch (this.options.displayMode){
            case SkeletonViewer.DISPLAY_LINES: {
                    this._obs = this.scene.onBeforeRenderObservable.add(() => {
                        this._displayLinesUpdate();
                    });
                break;
            }
        }
    }

    /** Update the viewer to sync with current skeleton state, only used to manually update. */
    public update(): void {
        switch (this.options.displayMode){
            case SkeletonViewer.DISPLAY_LINES: {
                this._displayLinesUpdate();
                break;
            }
            case SkeletonViewer.DISPLAY_SPHERES: {
                this._buildSpheresAndSpurs(true);
                break;
            }
            case SkeletonViewer.DISPLAY_SPHERE_AND_SPURS: {
                this._buildSpheresAndSpurs(false);
                break;
            }
        }
    }

    /** Gets or sets a boolean indicating if the viewer is enabled */
    public set isEnabled(value: boolean) {
        if (this.isEnabled === value) {
            return;
        }

        this._isEnabled = value;

        if (this.debugMesh) {
            this.debugMesh.setEnabled(value);
        }

        if (value && !this._obs) {
            this._bindObs();
        } else if (!value && this._obs) {
            this.scene.onBeforeRenderObservable.remove(this._obs);
            this._obs = null;
        }
    }

    public get isEnabled(): boolean {
        return this._isEnabled;
    }

    private _getBonePosition(position: Vector3, bone: Bone, meshMat: Matrix, x = 0, y = 0, z = 0): void {
        var tmat = TmpVectors.Matrix[0];
        var parentBone = bone.getParent();
        tmat.copyFrom(bone.getLocalMatrix());

        if (x !== 0 || y !== 0 || z !== 0) {
            var tmat2 = TmpVectors.Matrix[1];
            Matrix.IdentityToRef(tmat2);
            tmat2.setTranslationFromFloats(x, y, z);
            tmat2.multiplyToRef(tmat, tmat);
        }

        if (parentBone) {
            tmat.multiplyToRef(parentBone.getAbsoluteTransform(), tmat);
        }

        tmat.multiplyToRef(meshMat, tmat);

        position.x = tmat.m[12];
        position.y = tmat.m[13];
        position.z = tmat.m[14];
    }

    private _getLinesForBonesWithLength(bones: Bone[], meshMat: Matrix): void {
        var len = bones.length;

        let mesh = this.mesh._effectiveMesh;
        var meshPos = mesh.position;
        for (var i = 0; i < len; i++) {
            var bone = bones[i];
            var points = this._debugLines[i];
            if (!points) {
                points = [Vector3.Zero(), Vector3.Zero()];
                this._debugLines[i] = points;
            }
            this._getBonePosition(points[0], bone, meshMat);
            this._getBonePosition(points[1], bone, meshMat, 0, bone.length, 0);
            points[0].subtractInPlace(meshPos);
            points[1].subtractInPlace(meshPos);
        }
    }

    private _getLinesForBonesNoLength(bones: Bone[]): void {
        var len = bones.length;
        var boneNum = 0;

        let mesh = this.mesh._effectiveMesh;
        var meshPos = mesh.position;
        for (var i = len - 1; i >= 0; i--) {
            var childBone = bones[i];
            var parentBone = childBone.getParent();
            if (!parentBone) {
                continue;
            }
            var points = this._debugLines[boneNum];
            if (!points) {
                points = [Vector3.Zero(), Vector3.Zero()];
                this._debugLines[boneNum] = points;
            }
            childBone.getAbsolutePositionToRef(mesh, points[0]);
            parentBone.getAbsolutePositionToRef(mesh, points[1]);
            points[0].subtractInPlace(meshPos);
            points[1].subtractInPlace(meshPos);
            boneNum++;
        }
    }

    /** function to revert the mesh and scene back to the initial state. */
    private _revert(): void {
        if (this.options.pauseAnimations) {
            this.scene.animationsEnabled = true;
        }
    }

    /** function to build and bind sphere joint points and spur bone representations. */
    private _buildSpheresAndSpurs(spheresOnly = true): Promise<void> {
        this.dispose();

        this._ready = false;
        let scene = this.scene;
        let bones: Bone[] = this.skeleton.bones;
        let spheres: Mesh[] = [];
        let spurs: Mesh[] = [];

        return new Promise((resolve, reject) => {
            try {
                if (this.options.pauseAnimations) {
                    scene.animationsEnabled = false;
                }

                if (this.options.returnToRest) {
                    this.skeleton.returnToRest();
                }

                if (this.autoUpdateBonesMatrices) {
                    this.skeleton.computeAbsoluteTransforms();
                }

                let longestBoneLength = Number.NEGATIVE_INFINITY;
                let getAbsoluteRestPose = function(bone: Nullable<Bone>, matrix: Matrix) {
                    if (bone == null) {
                        matrix.copyFrom(Matrix.Identity());
                        return;
                    }
                    getAbsoluteRestPose(bone.getParent(), matrix);
                    bone.getRestPose().multiplyToRef(matrix, matrix);
                    return;
                };

                let displayOptions = this.options.displayOptions || {};

                for (let i = 0; i < bones.length; i++) {
                    let bone: Bone = bones[i];

                    if (bone._index === null) {
                        bone._index = i;
                    }
                    if (bone._index === -1) {
                        continue;
                    }

                    let boneAbsoluteRestTransform = new Matrix();
                    getAbsoluteRestPose(bone, boneAbsoluteRestTransform);

                    let anchorPoint = new Vector3();
                    boneAbsoluteRestTransform.decompose(undefined, undefined, anchorPoint);

                    bone.children.forEach((bc, i) => {
                        let childAbsoluteRestTransform : Matrix = new Matrix();
                        bc.getRestPose().multiplyToRef(boneAbsoluteRestTransform, childAbsoluteRestTransform);
                        let childPoint = new Vector3();
                        childAbsoluteRestTransform.decompose(undefined, undefined, childPoint);

                        let distanceFromParent = Vector3.Distance(anchorPoint, childPoint);

                        if (distanceFromParent > longestBoneLength) {
                            longestBoneLength = distanceFromParent;
                        }
                        if (spheresOnly) {
                            return;
                        }

                        let dir = childPoint.clone().subtract(anchorPoint.clone());
                        let h = dir.length();
                        let up = dir.normalize().scale(h);

                        let midStep = displayOptions.midStep || 0.165;
                        let midStepFactor = displayOptions.midStepFactor || 0.215;

                        let up0 = up.scale(midStep);

                        let spur = ShapeBuilder.ExtrudeShapeCustom(bc.name + ':spur',
                        {
                            shape:  [
                                        new Vector3(1, -1,  0),
                                        new Vector3(1,  1,  0),
                                        new Vector3(-1,  1,  0),
                                        new Vector3(-1, -1,  0),
                                        new Vector3(1, -1,  0)
                                    ],
                            path:   [ Vector3.Zero(), up0, up ],
                            scaleFunction:
                                    (i: number) => {
                                        switch (i){
                                            case 0:
                                            case 2:
                                            return 0;
                                            case 1:
                                            return h * midStepFactor;
                                        }
                                        return 0;
                                    },
                            sideOrientation: Mesh.DEFAULTSIDE,
                            updatable: true
                        },  scene);

                        let ind = spur.getIndices() || [];
                        let mwk: number[] = [], mik: number[] = [];

                        for (let i = 0; i < ind.length; i++) {
                            mwk.push(1, 0, 0, 0);
                            mik.push(bone.getIndex(), 0, 0, 0);
                        }
                        spur.convertToFlatShadedMesh();
                        spur.position = anchorPoint.clone();

                        spur.setVerticesData(VertexBuffer.MatricesWeightsKind, mwk, false);
                        spur.setVerticesData(VertexBuffer.MatricesIndicesKind, mik, false);
                        spurs.push(spur);

                    });

                    let sphereBaseSize = displayOptions.sphereBaseSize || 0.2;

                    let sphere = SphereBuilder.CreateSphere(bone.name + ':sphere', {
                        segments: 6,
                        diameter: sphereBaseSize,
                        updatable: true
                    }, scene);

                    let ind = sphere.getIndices() || [];
                    let mwk: number[] = [], mik: number[] = [];

                    for (let i = 0; i < ind.length; i++) {
                        mwk.push(1, 0, 0, 0);
                        mik.push(bone.getIndex(), 0, 0, 0);
                    }

                    sphere.setVerticesData(VertexBuffer.MatricesWeightsKind, mwk, false);
                    sphere.setVerticesData(VertexBuffer.MatricesIndicesKind, mik, false);
                    sphere.position = anchorPoint.clone();
                    spheres.push(sphere);
                }

                let skip = 0;
                let sphereScaleUnit = displayOptions.sphereScaleUnit || 2;
                let sphereFactor = displayOptions.sphereFactor || 0.85;

                for (let i = 0; i < bones.length; i++) {
                    let bone: Nullable<Bone> = bones[i];
                    if (bone.getIndex() === -1) {
                        skip++;
                        continue;
                    }
                    let sphere = spheres[i - skip];
                    let scale = 1 / (sphereScaleUnit / longestBoneLength);

                    let _stepsOut = 0;
                    let _b: Bone = (bone as Bone) || {};

                    while ((_b.getParent()) && (_b.getParent() as Bone).getIndex() !== -1) {
                        _stepsOut++;
                        _b = (_b.getParent() as Bone);
                    }
                    sphere.scaling.scaleInPlace(scale * Math.pow(sphereFactor, _stepsOut));
                }

                this.debugMesh = Mesh.MergeMeshes(spheres.concat(spurs), true, true);
                if (this.debugMesh) {
                    this.debugMesh.renderingGroupId = this.renderingGroupId;
                    this.debugMesh.skeleton = this.skeleton;
                    this.debugMesh.parent = this.mesh;
                    this.debugMesh.computeBonesUsingShaders = this.options.computeBonesUsingShaders ?? true;
                }

                resolve();
            } catch (err) {
                console.log(err);
                this._revert();
                this.dispose();
            }
        }).then(() => {
            this._revert();
            this.ready = true;
        }).catch((err) => {
            console.log(err);
            this.dispose();
        });        
    }

    /** Update the viewer to sync with current skeleton state, only used for the line display. */
    private  _displayLinesUpdate() {
        if (!this._utilityLayer) {
            return;
        }

        if (this.autoUpdateBonesMatrices) {
            this.skeleton.computeAbsoluteTransforms();
        }

        let mesh = this.mesh._effectiveMesh;

        if (this.skeleton.bones[0].length === undefined) {
            this._getLinesForBonesNoLength(this.skeleton.bones);
        } else {
            this._getLinesForBonesWithLength(this.skeleton.bones, mesh.getWorldMatrix());
        }

        const targetScene = this._utilityLayer.utilityLayerScene;

        if (targetScene) {
            if (!this._debugMesh) {
                this._debugMesh = LinesBuilder.CreateLineSystem("", { lines: this._debugLines, updatable: true, instance: null }, targetScene);
                this._debugMesh.renderingGroupId = this.renderingGroupId;
            } else {
                LinesBuilder.CreateLineSystem("", { lines: this._debugLines, updatable: true, instance: this._debugMesh }, targetScene);
            }
            this._debugMesh.position.copyFrom(this.mesh.position);
            this._debugMesh.color = this.color;
        }
    }

    /** Release associated resources */
    public dispose() {
        this.isEnabled = false;
        if (this._debugMesh) {
            this._debugMesh.dispose();
            this._debugMesh = null;
        }

        if (this._utilityLayer) {
            this._utilityLayer.dispose();
            this._utilityLayer = null;
        }
    }
}