module BABYLON {
    /**
     * A multi-material is used to apply different materials to different parts of the same object without the need of
     * separate meshes. This can be use to improve performances.
     * @see http://doc.babylonjs.com/how_to/multi_materials
     */
    export class MultiMaterial extends Material {
        private _subMaterials: Nullable<Material>[];

        /**
         * Gets or Sets the list of Materials used within the multi material.
         * They need to be ordered according to the submeshes order in the associated mesh
         */
        public get subMaterials(): Nullable<Material>[] {
            return this._subMaterials;
        }

        public set subMaterials(value: Nullable<Material>[]) {
            this._subMaterials = value;
            this._hookArray(value);
        }

        /**
         * Instantiates a new Multi Material
         * A multi-material is used to apply different materials to different parts of the same object without the need of
         * separate meshes. This can be use to improve performances.
         * @see http://doc.babylonjs.com/how_to/multi_materials
         * @param name Define the name in the scene
         * @param scene Define the scene the material belongs to
         */
        constructor(name: string, scene: Scene) {
            super(name, scene, true);

            scene.multiMaterials.push(this);

            this.subMaterials = new Array<Material>();

            this._storeEffectOnSubMeshes = true; // multimaterial is considered like a push material
        }

        private _hookArray(array: Nullable<Material>[]): void {
            var oldPush = array.push;
            array.push = (...items: Nullable<Material>[]) => {
                var result = oldPush.apply(array, items);

                this._markAllSubMeshesAsTexturesDirty();

                return result;
            };

            var oldSplice = array.splice;
            array.splice = (index: number, deleteCount?: number) => {
                var deleted = oldSplice.apply(array, [index, deleteCount]);

                this._markAllSubMeshesAsTexturesDirty();

                return deleted;
            };
        }

        /**
         * Get one of the submaterial by its index in the submaterials array
         * @param index The index to look the sub material at
         * @returns The Material if the index has been defined
         */
        public getSubMaterial(index: number): Nullable<Material> {
            if (index < 0 || index >= this.subMaterials.length) {
                return this.getScene().defaultMaterial;
            }

            return this.subMaterials[index];
        }

        /**
         * Get the list of active textures for the whole sub materials list.
         * @returns All the textures that will be used during the rendering
         */
        public getActiveTextures(): BaseTexture[] {
            return super.getActiveTextures().concat(...this.subMaterials.map((subMaterial) => {
                if (subMaterial) {
                    return subMaterial.getActiveTextures();
                } else {
                    return [];
                }
            }));
        }

        /**
         * Gets the current class name of the material e.g. "MultiMaterial"
         * Mainly use in serialization.
         * @returns the class name
         */
        public getClassName(): string {
            return "MultiMaterial";
        }

        /**
         * Checks if the material is ready to render the requested sub mesh
         * @param mesh Define the mesh the submesh belongs to
         * @param subMesh Define the sub mesh to look readyness for
         * @param useInstances Define whether or not the material is used with instances
         * @returns true if ready, otherwise false
         */
        public isReadyForSubMesh(mesh: AbstractMesh, subMesh: BaseSubMesh, useInstances?: boolean): boolean {
            for (var index = 0; index < this.subMaterials.length; index++) {
                var subMaterial = this.subMaterials[index];
                if (subMaterial) {
                    if (subMaterial._storeEffectOnSubMeshes) {
                        if (!subMaterial.isReadyForSubMesh(mesh, subMesh, useInstances)) {
                            return false;
                        }
                        continue;
                    }

                    if (!subMaterial.isReady(mesh)) {
                        return false;
                    }
                }
            }

            return true;
        }

        /**
         * Clones the current material and its related sub materials
         * @param name Define the name of the newly cloned material
         * @param cloneChildren Define if submaterial will be cloned or shared with the parent instance
         * @returns the cloned material
         */
        public clone(name: string, cloneChildren?: boolean): MultiMaterial {
            var newMultiMaterial = new MultiMaterial(name, this.getScene());

            for (var index = 0; index < this.subMaterials.length; index++) {
                var subMaterial: Nullable<Material> = null;
                let current = this.subMaterials[index];
                if (cloneChildren && current) {
                    subMaterial = current.clone(name + "-" + current.name);
                } else {
                    subMaterial = this.subMaterials[index];
                }
                newMultiMaterial.subMaterials.push(subMaterial);
            }

            return newMultiMaterial;
        }

        /**
         * Serializes the materials into a JSON representation.
         * @returns the JSON representation
         */
        public serialize(): any {
            var serializationObject: any = {};

            serializationObject.name = this.name;
            serializationObject.id = this.id;
            if (Tags) {
                serializationObject.tags = Tags.GetTags(this);
            }
            serializationObject.materials = [];

            for (var matIndex = 0; matIndex < this.subMaterials.length; matIndex++) {
                var subMat = this.subMaterials[matIndex];

                if (subMat) {
                    serializationObject.materials.push(subMat.id);
                } else {
                    serializationObject.materials.push(null);
                }
            }

            return serializationObject;
        }

        /**
         * Dispose the material and release its associated resources
         * @param forceDisposeEffect Define if we want to force disposing the associated effect (if false the shader is not released and could be reuse later on)
         * @param forceDisposeTextures Define if we want to force disposing the associated textures (if false, they will not be disposed and can still be use elsewhere in the app)
         */
        public dispose(forceDisposeEffect?: boolean, forceDisposeTextures?: boolean): void {
            var scene = this.getScene();
            if (!scene) {
                return;
            }

            var index = scene.multiMaterials.indexOf(this);
            if (index >= 0) {
                scene.multiMaterials.splice(index, 1);
            }

            super.dispose(forceDisposeEffect, forceDisposeTextures);
        }
    }
}