import { Nullable, IndicesArray, DeepImmutable, FloatArray } from "../types";
import { Matrix, Vector3 } from "../Maths/math.vector";
import { Engine } from "../Engines/engine";
import { VertexBuffer } from "./buffer";
import { IntersectionInfo } from "../Collisions/intersectionInfo";
import { ICullable, BoundingInfo } from "../Culling/boundingInfo";
import { Effect } from "../Materials/effect";
import { Constants } from "../Engines/constants";
import { DataBuffer } from './dataBuffer';
import { extractMinAndMaxIndexed } from '../Maths/math.functions';
import { Plane } from '../Maths/math.plane';

declare type Collider = import("../Collisions/collider").Collider;
declare type Material = import("../Materials/material").Material;
declare type MaterialDefines = import("../Materials/materialDefines").MaterialDefines;
declare type MultiMaterial = import("../Materials/multiMaterial").MultiMaterial;
declare type AbstractMesh = import("./abstractMesh").AbstractMesh;
declare type Mesh = import("./mesh").Mesh;
declare type Ray = import("../Culling/ray").Ray;
declare type TrianglePickingPredicate = import("../Culling/ray").TrianglePickingPredicate;

/**
 * Base class for submeshes
 */
export class BaseSubMesh {
    /** @hidden */
    public _materialDefines: Nullable<MaterialDefines> = null;
    /** @hidden */
    public _materialEffect: Nullable<Effect> = null;
    /** @hidden */
    public _effectOverride: Nullable<Effect> = null;

    /**
     * Gets material defines used by the effect associated to the sub mesh
     */
    public get materialDefines(): Nullable<MaterialDefines> {
        return this._materialDefines;
    }

    /**
     * Sets material defines used by the effect associated to the sub mesh
     */
    public set materialDefines(defines: Nullable<MaterialDefines>) {
        this._materialDefines = defines;
    }

    /**
     * Gets associated effect
     */
    public get effect(): Nullable<Effect> {
        return this._effectOverride ?? this._materialEffect;
    }

    /**
     * Sets associated effect (effect used to render this submesh)
     * @param effect defines the effect to associate with
     * @param defines defines the set of defines used to compile this effect
     */
    public setEffect(effect: Nullable<Effect>, defines: Nullable<MaterialDefines> = null) {
        if (this._materialEffect === effect) {
            if (!effect) {
                this._materialDefines = null;
            }
            return;
        }
        this._materialDefines = defines;
        this._materialEffect = effect;
    }
}

/**
 * Defines a subdivision inside a mesh
 */
export class SubMesh extends BaseSubMesh implements ICullable {
    /** @hidden */
    public _linesIndexCount: number = 0;
    private _mesh: AbstractMesh;
    private _renderingMesh: Mesh;
    private _boundingInfo: BoundingInfo;
    private _linesIndexBuffer: Nullable<DataBuffer> = null;
    /** @hidden */
    public _lastColliderWorldVertices: Nullable<Vector3[]> = null;
    /** @hidden */
    public _trianglePlanes: Plane[];
    /** @hidden */
    public _lastColliderTransformMatrix: Nullable<Matrix> = null;

    /** @hidden */
    public _renderId = 0;
    /** @hidden */
    public _alphaIndex: number = 0;
    /** @hidden */
    public _distanceToCamera: number = 0;
    /** @hidden */
    public _id: number;

    private _currentMaterial: Nullable<Material> = null;

    /**
     * Add a new submesh to a mesh
     * @param materialIndex defines the material index to use
     * @param verticesStart defines vertex index start
     * @param verticesCount defines vertices count
     * @param indexStart defines index start
     * @param indexCount defines indices count
     * @param mesh defines the parent mesh
     * @param renderingMesh defines an optional rendering mesh
     * @param createBoundingBox defines if bounding box should be created for this submesh
     * @returns the new submesh
     */
    public static AddToMesh(materialIndex: number, verticesStart: number, verticesCount: number, indexStart: number, indexCount: number, mesh: AbstractMesh, renderingMesh?: Mesh, createBoundingBox: boolean = true): SubMesh {
        return new SubMesh(materialIndex, verticesStart, verticesCount, indexStart, indexCount, mesh, renderingMesh, createBoundingBox);
    }

    /**
     * Creates a new submesh
     * @param materialIndex defines the material index to use
     * @param verticesStart defines vertex index start
     * @param verticesCount defines vertices count
     * @param indexStart defines index start
     * @param indexCount defines indices count
     * @param mesh defines the parent mesh
     * @param renderingMesh defines an optional rendering mesh
     * @param createBoundingBox defines if bounding box should be created for this submesh
     */
    constructor(
        /** the material index to use */
        public materialIndex: number,
        /** vertex index start */
        public verticesStart: number,
        /** vertices count */
        public verticesCount: number,
        /** index start */
        public indexStart: number,
        /** indices count */
        public indexCount: number, mesh: AbstractMesh, renderingMesh?: Mesh, createBoundingBox: boolean = true) {
        super();
        this._mesh = mesh;
        this._renderingMesh = renderingMesh || <Mesh>mesh;
        mesh.subMeshes.push(this);

        this._trianglePlanes = [];

        this._id = mesh.subMeshes.length - 1;

        if (createBoundingBox) {
            this.refreshBoundingInfo();
            mesh.computeWorldMatrix(true);
        }
    }

    /**
     * Returns true if this submesh covers the entire parent mesh
     * @ignorenaming
     */
    public get IsGlobal(): boolean {
        return (this.verticesStart === 0 && this.verticesCount === this._mesh.getTotalVertices());
    }

    /**
     * Returns the submesh BoudingInfo object
     * @returns current bounding info (or mesh's one if the submesh is global)
     */
    public getBoundingInfo(): BoundingInfo {
        if (this.IsGlobal) {
            return this._mesh.getBoundingInfo();
        }

        return this._boundingInfo;
    }

    /**
     * Sets the submesh BoundingInfo
     * @param boundingInfo defines the new bounding info to use
     * @returns the SubMesh
     */
    public setBoundingInfo(boundingInfo: BoundingInfo): SubMesh {
        this._boundingInfo = boundingInfo;
        return this;
    }

    /**
     * Returns the mesh of the current submesh
     * @return the parent mesh
     */
    public getMesh(): AbstractMesh {
        return this._mesh;
    }

    /**
     * Returns the rendering mesh of the submesh
     * @returns the rendering mesh (could be different from parent mesh)
     */
    public getRenderingMesh(): Mesh {
        return this._renderingMesh;
    }

    /**
     * Returns the submesh material
     * @returns null or the current material
     */
    public getMaterial(): Nullable<Material> {
        var rootMaterial = this._renderingMesh.material;

        if (rootMaterial === null || rootMaterial === undefined) {
            return this._mesh.getScene().defaultMaterial;
        } else if ((<MultiMaterial>rootMaterial).getSubMaterial) {
            var multiMaterial = <MultiMaterial>rootMaterial;
            var effectiveMaterial = multiMaterial.getSubMaterial(this.materialIndex);

            if (this._currentMaterial !== effectiveMaterial) {
                this._currentMaterial = effectiveMaterial;
                this._materialDefines = null;
            }

            return effectiveMaterial;
        }

        return rootMaterial;
    }

    // Methods

    /**
     * Sets a new updated BoundingInfo object to the submesh
     * @param data defines an optional position array to use to determine the bounding info
     * @returns the SubMesh
     */
    public refreshBoundingInfo(data: Nullable<FloatArray> = null): SubMesh {
        this._lastColliderWorldVertices = null;

        if (this.IsGlobal || !this._renderingMesh || !this._renderingMesh.geometry) {
            return this;
        }

        if (!data) {
            data = this._renderingMesh.getVerticesData(VertexBuffer.PositionKind);
        }

        if (!data) {
            this._boundingInfo = this._mesh.getBoundingInfo();
            return this;
        }

        var indices = <IndicesArray>this._renderingMesh.getIndices();
        var extend: { minimum: Vector3, maximum: Vector3 };

        //is this the only submesh?
        if (this.indexStart === 0 && this.indexCount === indices.length) {
            let boundingInfo = this._renderingMesh.getBoundingInfo();

            //the rendering mesh's bounding info can be used, it is the standard submesh for all indices.
            extend = { minimum: boundingInfo.minimum.clone(), maximum: boundingInfo.maximum.clone() };
        } else {
            extend = extractMinAndMaxIndexed(data, indices, this.indexStart, this.indexCount, this._renderingMesh.geometry.boundingBias);
        }

        if (this._boundingInfo) {
            this._boundingInfo.reConstruct(extend.minimum, extend.maximum);
        }
        else {
            this._boundingInfo = new BoundingInfo(extend.minimum, extend.maximum);
        }
        return this;
    }

    /** @hidden */
    public _checkCollision(collider: Collider): boolean {
        let boundingInfo = this.getBoundingInfo();

        return boundingInfo._checkCollision(collider);
    }

    /**
     * Updates the submesh BoundingInfo
     * @param world defines the world matrix to use to update the bounding info
     * @returns the submesh
     */
    public updateBoundingInfo(world: DeepImmutable<Matrix>): SubMesh {
        let boundingInfo = this.getBoundingInfo();

        if (!boundingInfo) {
            this.refreshBoundingInfo();
            boundingInfo = this.getBoundingInfo();
        }
        if (boundingInfo) {
            (<BoundingInfo>boundingInfo).update(world);
        }
        return this;
    }

    /**
     * True is the submesh bounding box intersects the frustum defined by the passed array of planes.
     * @param frustumPlanes defines the frustum planes
     * @returns true if the submesh is intersecting with the frustum
     */
    public isInFrustum(frustumPlanes: Plane[]): boolean {
        let boundingInfo = this.getBoundingInfo();

        if (!boundingInfo) {
            return false;
        }
        return boundingInfo.isInFrustum(frustumPlanes, this._mesh.cullingStrategy);
    }

    /**
     * True is the submesh bounding box is completely inside the frustum defined by the passed array of planes
     * @param frustumPlanes defines the frustum planes
     * @returns true if the submesh is inside the frustum
     */
    public isCompletelyInFrustum(frustumPlanes: Plane[]): boolean {
        let boundingInfo = this.getBoundingInfo();

        if (!boundingInfo) {
            return false;
        }
        return boundingInfo.isCompletelyInFrustum(frustumPlanes);
    }

    /**
     * Renders the submesh
     * @param enableAlphaMode defines if alpha needs to be used
     * @returns the submesh
     */
    public render(enableAlphaMode: boolean): SubMesh {
        this._renderingMesh.render(this, enableAlphaMode, this._mesh._internalAbstractMeshDataInfo._actAsRegularMesh ? this._mesh : undefined);
        return this;
    }

    /**
     * @hidden
     */
    public _getLinesIndexBuffer(indices: IndicesArray, engine: Engine): DataBuffer {
        if (!this._linesIndexBuffer) {
            var linesIndices = [];

            for (var index = this.indexStart; index < this.indexStart + this.indexCount; index += 3) {
                linesIndices.push(indices[index], indices[index + 1],
                    indices[index + 1], indices[index + 2],
                    indices[index + 2], indices[index]);
            }

            this._linesIndexBuffer = engine.createIndexBuffer(linesIndices);
            this._linesIndexCount = linesIndices.length;
        }
        return this._linesIndexBuffer;
    }

    /**
     * Checks if the submesh intersects with a ray
     * @param ray defines the ray to test
     * @returns true is the passed ray intersects the submesh bounding box
     */
    public canIntersects(ray: Ray): boolean {
        let boundingInfo = this.getBoundingInfo();

        if (!boundingInfo) {
            return false;
        }
        return ray.intersectsBox(boundingInfo.boundingBox);
    }

    /**
     * Intersects current submesh with a ray
     * @param ray defines the ray to test
     * @param positions defines mesh's positions array
     * @param indices defines mesh's indices array
     * @param fastCheck defines if the first intersection will be used (and not the closest)
     * @param trianglePredicate defines an optional predicate used to select faces when a mesh intersection is detected
     * @returns intersection info or null if no intersection
     */
    public intersects(ray: Ray, positions: Vector3[], indices: IndicesArray,
        fastCheck?: boolean, trianglePredicate?: TrianglePickingPredicate): Nullable<IntersectionInfo> {
        const material = this.getMaterial();
        if (!material) {
            return null;
        }
        let step = 3;
        let checkStopper = false;

        switch (material.fillMode) {
            case Constants.MATERIAL_PointListDrawMode:
            case Constants.MATERIAL_LineListDrawMode:
            case Constants.MATERIAL_LineLoopDrawMode:
            case Constants.MATERIAL_LineStripDrawMode:
            case Constants.MATERIAL_TriangleFanDrawMode:
                return null;
            case Constants.MATERIAL_TriangleStripDrawMode:
                step = 1;
                checkStopper = true;
                break;
            default:
                break;
        }

        // LineMesh first as it's also a Mesh...
        if (this._mesh.getClassName() === "InstancedLinesMesh" || this._mesh.getClassName() === "LinesMesh") {
            // Check if mesh is unindexed
            if (!indices.length) {
                return this._intersectUnIndexedLines(ray, positions, indices, (this._mesh as any).intersectionThreshold, fastCheck);
            }
            return this._intersectLines(ray, positions, indices, (this._mesh as any).intersectionThreshold, fastCheck);
        }
        else {
            // Check if mesh is unindexed
            if (!indices.length && this._mesh._unIndexed) {
                return this._intersectUnIndexedTriangles(ray, positions, indices, fastCheck, trianglePredicate);
            }

            return this._intersectTriangles(ray, positions, indices, step, checkStopper, fastCheck, trianglePredicate);
        }
    }

    /** @hidden */
    private _intersectLines(ray: Ray, positions: Vector3[], indices: IndicesArray, intersectionThreshold: number, fastCheck?: boolean): Nullable<IntersectionInfo> {
        var intersectInfo: Nullable<IntersectionInfo> = null;

        // Line test
        for (var index = this.indexStart; index < this.indexStart + this.indexCount; index += 2) {
            var p0 = positions[indices[index]];
            var p1 = positions[indices[index + 1]];

            var length = ray.intersectionSegment(p0, p1, intersectionThreshold);
            if (length < 0) {
                continue;
            }

            if (fastCheck || !intersectInfo || length < intersectInfo.distance) {
                intersectInfo = new IntersectionInfo(null, null, length);
                intersectInfo.faceId = index / 2;
                if (fastCheck) {
                    break;
                }
            }
        }
        return intersectInfo;
    }

    /** @hidden */
    private _intersectUnIndexedLines(ray: Ray, positions: Vector3[], indices: IndicesArray, intersectionThreshold: number, fastCheck?: boolean): Nullable<IntersectionInfo> {
        var intersectInfo: Nullable<IntersectionInfo> = null;

        // Line test
        for (var index = this.verticesStart; index < this.verticesStart + this.verticesCount; index += 2) {
            var p0 = positions[index];
            var p1 = positions[index + 1];

            var length = ray.intersectionSegment(p0, p1, intersectionThreshold);
            if (length < 0) {
                continue;
            }

            if (fastCheck || !intersectInfo || length < intersectInfo.distance) {
                intersectInfo = new IntersectionInfo(null, null, length);
                intersectInfo.faceId = index / 2;
                if (fastCheck) {
                    break;
                }
            }
        }

        return intersectInfo;
    }

    /** @hidden */
    private _intersectTriangles(ray: Ray, positions: Vector3[], indices: IndicesArray,
        step: number, checkStopper: boolean,
        fastCheck?: boolean, trianglePredicate?: TrianglePickingPredicate): Nullable<IntersectionInfo> {
        var intersectInfo: Nullable<IntersectionInfo> = null;

        // Triangles test
        let faceID = -1;
        for (var index = this.indexStart; index < this.indexStart + this.indexCount; index += step) {
            faceID++;
            const indexA = indices[index];
            const indexB = indices[index + 1];
            const indexC = indices[index + 2];

            if (checkStopper && indexC === 0xFFFFFFFF) {
                index += 2;
                continue;
            }

            var p0 = positions[indexA];
            var p1 = positions[indexB];
            var p2 = positions[indexC];

            if (trianglePredicate && !trianglePredicate(p0, p1, p2, ray)) {
                continue;
            }

            var currentIntersectInfo = ray.intersectsTriangle(p0, p1, p2);

            if (currentIntersectInfo) {
                if (currentIntersectInfo.distance < 0) {
                    continue;
                }

                if (fastCheck || !intersectInfo || currentIntersectInfo.distance < intersectInfo.distance) {
                    intersectInfo = currentIntersectInfo;
                    intersectInfo.faceId = faceID;

                    if (fastCheck) {
                        break;
                    }
                }
            }
        }
        return intersectInfo;
    }

    /** @hidden */
    private _intersectUnIndexedTriangles(ray: Ray, positions: Vector3[], indices: IndicesArray,
        fastCheck?: boolean, trianglePredicate?: TrianglePickingPredicate): Nullable<IntersectionInfo> {
        var intersectInfo: Nullable<IntersectionInfo> = null;
        // Triangles test
        for (var index = this.verticesStart; index < this.verticesStart + this.verticesCount; index += 3) {
            var p0 = positions[index];
            var p1 = positions[index + 1];
            var p2 = positions[index + 2];

            if (trianglePredicate && !trianglePredicate(p0, p1, p2, ray)) {
                continue;
            }

            var currentIntersectInfo = ray.intersectsTriangle(p0, p1, p2);

            if (currentIntersectInfo) {
                if (currentIntersectInfo.distance < 0) {
                    continue;
                }

                if (fastCheck || !intersectInfo || currentIntersectInfo.distance < intersectInfo.distance) {
                    intersectInfo = currentIntersectInfo;
                    intersectInfo.faceId = index / 3;

                    if (fastCheck) {
                        break;
                    }
                }
            }
        }
        return intersectInfo;
    }

    /** @hidden */
    public _rebuild(): void {
        if (this._linesIndexBuffer) {
            this._linesIndexBuffer = null;
        }
    }

    // Clone
    /**
     * Creates a new submesh from the passed mesh
     * @param newMesh defines the new hosting mesh
     * @param newRenderingMesh defines an optional rendering mesh
     * @returns the new submesh
     */
    public clone(newMesh: AbstractMesh, newRenderingMesh?: Mesh): SubMesh {
        var result = new SubMesh(this.materialIndex, this.verticesStart, this.verticesCount, this.indexStart, this.indexCount, newMesh, newRenderingMesh, false);

        if (!this.IsGlobal) {
            let boundingInfo = this.getBoundingInfo();

            if (!boundingInfo) {
                return result;
            }

            result._boundingInfo = new BoundingInfo(boundingInfo.minimum, boundingInfo.maximum);
        }

        return result;
    }

    // Dispose

    /**
     * Release associated resources
     */
    public dispose(): void {
        if (this._linesIndexBuffer) {
            this._mesh.getScene().getEngine()._releaseBuffer(this._linesIndexBuffer);
            this._linesIndexBuffer = null;
        }

        // Remove from mesh
        var index = this._mesh.subMeshes.indexOf(this);
        this._mesh.subMeshes.splice(index, 1);
    }

    /**
     * Gets the class name
     * @returns the string "SubMesh".
     */
    public getClassName(): string {
        return "SubMesh";
    }

    // Statics
    /**
     * Creates a new submesh from indices data
     * @param materialIndex the index of the main mesh material
     * @param startIndex the index where to start the copy in the mesh indices array
     * @param indexCount the number of indices to copy then from the startIndex
     * @param mesh the main mesh to create the submesh from
     * @param renderingMesh the optional rendering mesh
     * @returns a new submesh
     */
    public static CreateFromIndices(materialIndex: number, startIndex: number, indexCount: number, mesh: AbstractMesh, renderingMesh?: Mesh): SubMesh {
        var minVertexIndex = Number.MAX_VALUE;
        var maxVertexIndex = -Number.MAX_VALUE;

        const whatWillRender = (renderingMesh || mesh);
        var indices = whatWillRender!.getIndices()!;

        for (var index = startIndex; index < startIndex + indexCount; index++) {
            var vertexIndex = indices[index];

            if (vertexIndex < minVertexIndex) {
                minVertexIndex = vertexIndex;
            }
            if (vertexIndex > maxVertexIndex) {
                maxVertexIndex = vertexIndex;
            }
        }

        return new SubMesh(materialIndex, minVertexIndex, maxVertexIndex - minVertexIndex + 1, startIndex, indexCount, mesh, renderingMesh);
    }
}