module BABYLON {
    /**
     * This represents a set of one or more post processes in Babylon.
     * A post process can be used to apply a shader to a texture after it is rendered.
     * @example https://doc.babylonjs.com/how_to/how_to_use_postprocessrenderpipeline
     */
    export class PostProcessRenderEffect {
        private _postProcesses: { [Key: string]: Array<PostProcess> };
        private _getPostProcesses: () => Nullable<PostProcess | Array<PostProcess>>;

        private _singleInstance: boolean;

        private _cameras: { [key: string]: Nullable<Camera> };
        private _indicesForCamera: { [key: string]: number[] };

        /**
         * Name of the effect
         * @hidden
         */
        public _name: string;

        /**
         * Instantiates a post process render effect.
         * A post process can be used to apply a shader to a texture after it is rendered.
         * @param engine The engine the effect is tied to
         * @param name The name of the effect
         * @param getPostProcesses A function that returns a set of post processes which the effect will run in order to be run.
         * @param singleInstance False if this post process can be run on multiple cameras. (default: true)
         */
        constructor(engine: Engine, name: string, getPostProcesses: () => Nullable<PostProcess | Array<PostProcess>>, singleInstance?: boolean) {
            this._name = name;
            this._singleInstance = singleInstance || true;

            this._getPostProcesses = getPostProcesses;

            this._cameras = {};
            this._indicesForCamera = {};

            this._postProcesses = {};
        }

        /**
         * Checks if all the post processes in the effect are supported.
         */
        public get isSupported(): boolean {
            for (var index in this._postProcesses) {
                if (this._postProcesses.hasOwnProperty(index)) {
                    let pps = this._postProcesses[index];
                    for (var ppIndex = 0; ppIndex < pps.length; ppIndex++) {
                        if (!pps[ppIndex].isSupported) {
                            return false;
                        }
                    }
                }
            }
            return true;
        }

        /**
         * Updates the current state of the effect
         * @hidden
         */
        public _update(): void {
        }

        /**
         * Attaches the effect on cameras
         * @param cameras The camera to attach to.
         * @hidden
         */
        public _attachCameras(cameras: Camera): void;
        /**
         * Attaches the effect on cameras
         * @param cameras The camera to attach to.
         * @hidden
         */
        public _attachCameras(cameras: Camera[]): void;
        /**
         * Attaches the effect on cameras
         * @param cameras The camera to attach to.
         * @hidden
         */
        public _attachCameras(cameras: any): void {
            var cameraKey;

            var cams = Tools.MakeArray(cameras || this._cameras);

            if (!cams) {
                return;
            }

            for (var i = 0; i < cams.length; i++) {
                var camera = cams[i];
                var cameraName = camera.name;

                if (this._singleInstance) {
                    cameraKey = 0;
                }
                else {
                    cameraKey = cameraName;
                }

                if (!this._postProcesses[cameraKey]) {
                    var postProcess = this._getPostProcesses();
                    if (postProcess) {
                        this._postProcesses[cameraKey] = Array.isArray(postProcess) ? postProcess : [postProcess];
                    }
                }

                if (!this._indicesForCamera[cameraName]) {
                    this._indicesForCamera[cameraName] = [];
                }

                this._postProcesses[cameraKey].forEach((postProcess: PostProcess) => {
                    var index = camera.attachPostProcess(postProcess);

                    this._indicesForCamera[cameraName].push(index);
                });

                if (!this._cameras[cameraName]) {
                    this._cameras[cameraName] = camera;
                }

            }
        }

        /**
         * Detatches the effect on cameras
         * @param cameras The camera to detatch from.
         * @hidden
         */
        public _detachCameras(cameras: Camera): void;
        /**
         * Detatches the effect on cameras
         * @param cameras The camera to detatch from.
         * @hidden
         */
        public _detachCameras(cameras: Camera[]): void;
        /**
         * Detatches the effect on cameras
         * @param cameras The camera to detatch from.
         * @hidden
         */
        public _detachCameras(cameras: any): void {
            var cams = Tools.MakeArray(cameras || this._cameras);

            if (!cams) {
                return;
            }

            for (var i = 0; i < cams.length; i++) {
                var camera: Camera = cams[i];
                var cameraName: string = camera.name;
                this._postProcesses[this._singleInstance ? 0 : cameraName].forEach((postProcess: PostProcess) => {
                    camera.detachPostProcess(postProcess);
                })

                if (this._cameras[cameraName]) {
                    //this._indicesForCamera.splice(index, 1);
                    this._cameras[cameraName] = null;
                }
            }
        }

        /**
         * Enables the effect on given cameras
         * @param cameras The camera to enable.
         * @hidden
         */
        public _enable(cameras: Camera): void;
        /**
         * Enables the effect on given cameras
         * @param cameras The camera to enable.
         * @hidden
         */
        public _enable(cameras: Nullable<Camera[]>): void;
        /**
         * Enables the effect on given cameras
         * @param cameras The camera to enable.
         * @hidden
         */
        public _enable(cameras: any): void {
            var cams: Nullable<Array<Camera>> = Tools.MakeArray(cameras || this._cameras);

            if (!cams) {
                return;
            }

            for (var i = 0; i < cams.length; i++) {
                var camera = cams[i];
                var cameraName = camera.name;

                for (var j = 0; j < this._indicesForCamera[cameraName].length; j++) {
                    if (camera._postProcesses[this._indicesForCamera[cameraName][j]] === undefined || camera._postProcesses[this._indicesForCamera[cameraName][j]] === null) {
                        this._postProcesses[this._singleInstance ? 0 : cameraName].forEach((postProcess) => {
                            cams![i].attachPostProcess(postProcess, this._indicesForCamera[cameraName][j]);
                        });
                    }
                }
            }
        }

        /**
         * Disables the effect on the given cameras
         * @param cameras The camera to disable.
         * @hidden
         */
        public _disable(cameras: Camera): void;
        /**
         * Disables the effect on the given cameras
         * @param cameras The camera to disable.
         * @hidden
         */
        public _disable(cameras: Nullable<Camera[]>): void;
        /**
         * Disables the effect on the given cameras
         * @param cameras The camera to disable.
         * @hidden
         */
        public _disable(cameras: any): void {
            var cams: Nullable<Array<Camera>> = Tools.MakeArray(cameras || this._cameras);

            if (!cams) {
                return;
            }

            for (var i = 0; i < cams.length; i++) {
                var camera = cams[i];
                var cameraName = camera.name;
                this._postProcesses[this._singleInstance ? 0 : cameraName].forEach((postProcess) => {
                    camera.detachPostProcess(postProcess);
                });
            }
        }

        /**
         * Gets a list of the post processes contained in the effect.
         * @param camera The camera to get the post processes on.
         * @returns The list of the post processes in the effect.
         */
        public getPostProcesses(camera?: Camera): Nullable<Array<PostProcess>> {
            if (this._singleInstance) {
                return this._postProcesses[0];
            }
            else {
                if (!camera) {
                    return null;
                }
                return this._postProcesses[camera.name];
            }
        }
    }
}