import { DynamicTexture, Nullable, Observer, Camera, Engine, KeyboardInfoPre, PointerInfoPre, PointerInfo, Layer, Viewport, Scene, Texture, KeyboardEventTypes, Vector3, Matrix, Vector2, Tools, PointerEventTypes, AbstractMesh, StandardMaterial, Color3 } from "babylonjs";
import { Container } from "./controls/container";
import { Control } from "./controls/control";
import { Style } from "./style";
import { Measure } from "./measure";

/**
 * Interface used to define a control that can receive focus
 */
export interface IFocusableControl {
    /**
     * Function called when the control receives the focus
     */
    onFocus(): void;
    /**
     * Function called when the control loses the focus
     */
    onBlur(): void;
    /**
     * Function called to let the control handle keyboard events
     * @param evt defines the current keyboard event
     */
    processKeyboard(evt: KeyboardEvent): void;

    /**
     * Function called to get the list of controls that should not steal the focus from this control
     * @returns an array of controls
     */
    keepsFocusWith(): Nullable<Control[]>;
}

/**
 * Class used to create texture to support 2D GUI elements
 * @see http://doc.babylonjs.com/how_to/gui
 */
export class AdvancedDynamicTexture extends DynamicTexture {
    private _isDirty = false;
    private _renderObserver: Nullable<Observer<Camera>>;
    private _resizeObserver: Nullable<Observer<Engine>>;
    private _preKeyboardObserver: Nullable<Observer<KeyboardInfoPre>>;
    private _pointerMoveObserver: Nullable<Observer<PointerInfoPre>>;
    private _pointerObserver: Nullable<Observer<PointerInfo>>;
    private _canvasPointerOutObserver: Nullable<Observer<PointerEvent>>;
    private _background: string;
    /** @hidden */
    public _rootContainer = new Container("root");
    /** @hidden */
    public _lastPickedControl: Control;
    /** @hidden */
    public _lastControlOver: { [pointerId: number]: Control } = {};
    /** @hidden */
    public _lastControlDown: { [pointerId: number]: Control } = {};
    /** @hidden */
    public _capturingControl: { [pointerId: number]: Control } = {};
    /** @hidden */
    public _shouldBlockPointer: boolean;
    /** @hidden */
    public _layerToDispose: Nullable<Layer>;
    /** @hidden */
    public _linkedControls = new Array<Control>();
    private _isFullscreen = false;
    private _fullscreenViewport = new Viewport(0, 0, 1, 1);
    private _idealWidth = 0;
    private _idealHeight = 0;
    private _useSmallestIdeal: boolean = false;
    private _renderAtIdealSize = false;
    private _focusedControl: Nullable<IFocusableControl>;
    private _blockNextFocusCheck = false;
    private _renderScale = 1;
    private _rootCanvas: Nullable<HTMLCanvasElement>;

    /**
     * Gets or sets a boolean defining if alpha is stored as premultiplied
     */
    public premulAlpha = false;

    /**
     * Gets or sets a number used to scale rendering size (2 means that the texture will be twice bigger).
     * Useful when you want more antialiasing
     */
    public get renderScale(): number {
        return this._renderScale;
    }

    public set renderScale(value: number) {
        if (value === this._renderScale) {
            return;
        }

        this._renderScale = value;

        this._onResize();
    }

    /** Gets or sets the background color */
    public get background(): string {
        return this._background;
    }

    public set background(value: string) {
        if (this._background === value) {
            return;
        }

        this._background = value;
        this.markAsDirty();
    }

    /**
     * Gets or sets the ideal width used to design controls.
     * The GUI will then rescale everything accordingly
     * @see http://doc.babylonjs.com/how_to/gui#adaptive-scaling
     */
    public get idealWidth(): number {
        return this._idealWidth;
    }

    public set idealWidth(value: number) {
        if (this._idealWidth === value) {
            return;
        }

        this._idealWidth = value;
        this.markAsDirty();
        this._rootContainer._markAllAsDirty();
    }

    /**
     * Gets or sets the ideal height used to design controls.
     * The GUI will then rescale everything accordingly
     * @see http://doc.babylonjs.com/how_to/gui#adaptive-scaling
     */
    public get idealHeight(): number {
        return this._idealHeight;
    }

    public set idealHeight(value: number) {
        if (this._idealHeight === value) {
            return;
        }

        this._idealHeight = value;
        this.markAsDirty();
        this._rootContainer._markAllAsDirty();
    }

    /**
     * Gets or sets a boolean indicating if the smallest ideal value must be used if idealWidth and idealHeight are both set
     * @see http://doc.babylonjs.com/how_to/gui#adaptive-scaling
     */
    public get useSmallestIdeal(): boolean {
        return this._useSmallestIdeal;
    }

    public set useSmallestIdeal(value: boolean) {
        if (this._useSmallestIdeal === value) {
            return;
        }

        this._useSmallestIdeal = value;
        this.markAsDirty();
        this._rootContainer._markAllAsDirty();
    }

    /**
     * Gets or sets a boolean indicating if adaptive scaling must be used
     * @see http://doc.babylonjs.com/how_to/gui#adaptive-scaling
     */
    public get renderAtIdealSize(): boolean {
        return this._renderAtIdealSize;
    }

    public set renderAtIdealSize(value: boolean) {
        if (this._renderAtIdealSize === value) {
            return;
        }

        this._renderAtIdealSize = value;
        this._onResize();
    }

    /**
     * Gets the underlying layer used to render the texture when in fullscreen mode
     */
    public get layer(): Nullable<Layer> {
        return this._layerToDispose;
    }

    /**
     * Gets the root container control
     */
    public get rootContainer(): Container {
        return this._rootContainer;
    }

    /**
     * Gets or sets the current focused control
     */
    public get focusedControl(): Nullable<IFocusableControl> {
        return this._focusedControl;
    }

    public set focusedControl(control: Nullable<IFocusableControl>) {
        if (this._focusedControl == control) {
            return;
        }

        if (this._focusedControl) {
            this._focusedControl.onBlur();
        }

        if (control) {
            control.onFocus();
        }

        this._focusedControl = control;
    }

    /**
     * Gets or sets a boolean indicating if the texture must be rendered in background or foreground when in fullscreen mode
     */
    public get isForeground(): boolean {
        if (!this.layer) {
            return true;
        }
        return (!this.layer.isBackground);
    }

    public set isForeground(value: boolean) {
        if (!this.layer) {
            return;
        }
        if (this.layer.isBackground === !value) {
            return;
        }
        this.layer.isBackground = !value;
    }

    /**
     * Creates a new AdvancedDynamicTexture
     * @param name defines the name of the texture
     * @param width defines the width of the texture
     * @param height defines the height of the texture
     * @param scene defines the hosting scene
     * @param generateMipMaps defines a boolean indicating if mipmaps must be generated (false by default)
     * @param samplingMode defines the texture sampling mode (Texture.NEAREST_SAMPLINGMODE by default)
     */
    constructor(name: string, width = 0, height = 0, scene: Nullable<Scene>, generateMipMaps = false, samplingMode = Texture.NEAREST_SAMPLINGMODE) {
        super(name, { width: width, height: height }, scene, generateMipMaps, samplingMode, Engine.TEXTUREFORMAT_RGBA);

        scene = this.getScene();

        if (!scene || !this._texture) {
            return;
        }

        this._rootCanvas = scene.getEngine()!.getRenderingCanvas()!;

        this._renderObserver = scene.onBeforeCameraRenderObservable.add((camera: Camera) => this._checkUpdate(camera));
        this._preKeyboardObserver = scene.onPreKeyboardObservable.add(info => {
            if (!this._focusedControl) {
                return;
            }

            if (info.type === KeyboardEventTypes.KEYDOWN) {
                this._focusedControl.processKeyboard(info.event);
            }

            info.skipOnPointerObservable = true;
        });

        this._rootContainer._link(null, this);

        this.hasAlpha = true;

        if (!width || !height) {
            this._resizeObserver = scene.getEngine().onResizeObservable.add(() => this._onResize());
            this._onResize();
        }

        this._texture.isReady = true;
    }

    /**
     * Function used to execute a function on all controls
     * @param func defines the function to execute
     * @param container defines the container where controls belong. If null the root container will be used
     */
    public executeOnAllControls(func: (control: Control) => void, container?: Container) {
        if (!container) {
            container = this._rootContainer;
        }

        func(container);

        for (var child of container.children) {
            if ((<any>child).children) {
                this.executeOnAllControls(func, (<Container>child));
                continue;
            }
            func(child);
        }
    }

    /**
     * Marks the texture as dirty forcing a complete update
     */
    public markAsDirty() {
        this._isDirty = true;

        this.executeOnAllControls((control) => {
            if (control._isFontSizeInPercentage) {
                control._resetFontCache();
            }
        });
    }

    /**
     * Helper function used to create a new style
     * @returns a new style
     * @see http://doc.babylonjs.com/how_to/gui#styles
     */
    public createStyle(): Style {
        return new Style(this);
    }

    /**
     * Adds a new control to the root container
     * @param control defines the control to add
     * @returns the current texture
     */
    public addControl(control: Control): AdvancedDynamicTexture {
        this._rootContainer.addControl(control);

        return this;
    }

    /**
     * Removes a control from the root container
     * @param control defines the control to remove
     * @returns the current texture
     */
    public removeControl(control: Control): AdvancedDynamicTexture {
        this._rootContainer.removeControl(control);
        return this;
    }

    /**
     * Release all resources
     */
    public dispose(): void {
        let scene = this.getScene();

        if (!scene) {
            return;
        }

        this._rootCanvas = null;

        scene.onBeforeCameraRenderObservable.remove(this._renderObserver);

        if (this._resizeObserver) {
            scene.getEngine().onResizeObservable.remove(this._resizeObserver);
        }

        if (this._pointerMoveObserver) {
            scene.onPrePointerObservable.remove(this._pointerMoveObserver);
        }

        if (this._pointerObserver) {
            scene.onPointerObservable.remove(this._pointerObserver);
        }

        if (this._preKeyboardObserver) {
            scene.onPreKeyboardObservable.remove(this._preKeyboardObserver);
        }

        if (this._canvasPointerOutObserver) {
            scene.getEngine().onCanvasPointerOutObservable.remove(this._canvasPointerOutObserver);
        }

        if (this._layerToDispose) {
            this._layerToDispose.texture = null;
            this._layerToDispose.dispose();
            this._layerToDispose = null;
        }

        this._rootContainer.dispose();

        super.dispose();
    }

    private _onResize(): void {
        let scene = this.getScene();

        if (!scene) {
            return;
        }

        // Check size
        var engine = scene.getEngine();
        var textureSize = this.getSize();
        var renderWidth = engine.getRenderWidth() * this._renderScale;
        var renderHeight = engine.getRenderHeight() * this._renderScale;

        if (this._renderAtIdealSize) {
            if (this._idealWidth) {
                renderHeight = (renderHeight * this._idealWidth) / renderWidth;
                renderWidth = this._idealWidth;
            } else if (this._idealHeight) {
                renderWidth = (renderWidth * this._idealHeight) / renderHeight;
                renderHeight = this._idealHeight;
            }
        }

        if (textureSize.width !== renderWidth || textureSize.height !== renderHeight) {
            this.scaleTo(renderWidth, renderHeight);

            this.markAsDirty();

            if (this._idealWidth || this._idealHeight) {
                this._rootContainer._markAllAsDirty();
            }
        }
    }

    /** @hidden */
    public _getGlobalViewport(scene: Scene): Viewport {
        var engine = scene.getEngine();
        return this._fullscreenViewport.toGlobal(engine.getRenderWidth(), engine.getRenderHeight());
    }

    /**
     * Get screen coordinates for a vector3
     * @param position defines the position to project
     * @param worldMatrix defines the world matrix to use
     * @returns the projected position
     */
    public getProjectedPosition(position: Vector3, worldMatrix: Matrix): Vector2 {
        var scene = this.getScene();

        if (!scene) {
            return Vector2.Zero();
        }

        var globalViewport = this._getGlobalViewport(scene);
        var projectedPosition = Vector3.Project(position, worldMatrix, scene.getTransformMatrix(), globalViewport);

        projectedPosition.scaleInPlace(this.renderScale);

        return new Vector2(projectedPosition.x, projectedPosition.y);
    }

    private _checkUpdate(camera: Camera): void {
        if (this._layerToDispose) {
            if ((camera.layerMask & this._layerToDispose.layerMask) === 0) {
                return;
            }
        }

        if (this._isFullscreen && this._linkedControls.length) {
            var scene = this.getScene();

            if (!scene) {
                return;
            }

            var globalViewport = this._getGlobalViewport(scene);

            for (var control of this._linkedControls) {
                if (!control.isVisible) {
                    continue;
                }

                var mesh = control._linkedMesh;

                if (!mesh || mesh.isDisposed()) {
                    Tools.SetImmediate(() => {
                        control.linkWithMesh(null);
                    });

                    continue;
                }

                var position = mesh.getBoundingInfo().boundingSphere.center;
                var projectedPosition = Vector3.Project(position, mesh.getWorldMatrix(), scene.getTransformMatrix(), globalViewport);

                if (projectedPosition.z < 0 || projectedPosition.z > 1) {
                    control.notRenderable = true;
                    continue;
                }
                control.notRenderable = false;
                // Account for RenderScale.
                projectedPosition.scaleInPlace(this.renderScale);
                control._moveToProjectedPosition(projectedPosition);
            }
        }

        if (!this._isDirty && !this._rootContainer.isDirty) {
            return;
        }
        this._isDirty = false;

        this._render();
        this.update(true, this.premulAlpha);
    }

    private _render(): void {
        var textureSize = this.getSize();
        var renderWidth = textureSize.width;
        var renderHeight = textureSize.height;

        // Clear
        var context = this.getContext();
        context.clearRect(0, 0, renderWidth, renderHeight);
        if (this._background) {
            context.save();
            context.fillStyle = this._background;
            context.fillRect(0, 0, renderWidth, renderHeight);
            context.restore();
        }

        // Render
        context.font = "18px Arial";
        context.strokeStyle = "white";
        var measure = new Measure(0, 0, renderWidth, renderHeight);
        this._rootContainer._draw(measure, context);
    }

    /** @hidden */
    public _changeCursor(cursor: string) {
        if (this._rootCanvas) {
            this._rootCanvas.style.cursor = cursor;
        }
    }

    private _doPicking(x: number, y: number, type: number, pointerId: number, buttonIndex: number): void {
        var scene = this.getScene();

        if (!scene) {
            return;
        }

        var engine = scene.getEngine();
        var textureSize = this.getSize();

        if (this._isFullscreen) {
            x = x * (textureSize.width / engine.getRenderWidth());
            y = y * (textureSize.height / engine.getRenderHeight());
        }

        if (this._capturingControl[pointerId]) {
            this._capturingControl[pointerId]._processObservables(type, x, y, pointerId, buttonIndex);
            return;
        }

        if (!this._rootContainer._processPicking(x, y, type, pointerId, buttonIndex)) {
            this._changeCursor("");
            if (type === PointerEventTypes.POINTERMOVE) {
                if (this._lastControlOver[pointerId]) {
                    this._lastControlOver[pointerId]._onPointerOut(this._lastControlOver[pointerId]);
                }

                delete this._lastControlOver[pointerId];
            }
        }

        this._manageFocus();
    }

    /** @hidden */
    public _cleanControlAfterRemovalFromList(list: { [pointerId: number]: Control }, control: Control) {
        for (var pointerId in list) {
            if (!list.hasOwnProperty(pointerId)) {
                continue;
            }

            var lastControlOver = list[pointerId];
            if (lastControlOver === control) {
                delete list[pointerId];
            }
        }
    }

    /** @hidden */
    public _cleanControlAfterRemoval(control: Control) {
        this._cleanControlAfterRemovalFromList(this._lastControlDown, control);
        this._cleanControlAfterRemovalFromList(this._lastControlOver, control);
    }

    /** Attach to all scene events required to support pointer events */
    public attach(): void {
        var scene = this.getScene();
        if (!scene) {
            return;
        }

        this._pointerMoveObserver = scene.onPrePointerObservable.add((pi, state) => {
            if (scene!.isPointerCaptured((<PointerEvent>(pi.event)).pointerId)) {
                return;
            }

            if (pi.type !== PointerEventTypes.POINTERMOVE
                && pi.type !== PointerEventTypes.POINTERUP
                && pi.type !== PointerEventTypes.POINTERDOWN) {
                return;
            }

            if (!scene) {
                return;
            }

            let camera = scene.cameraToUseForPointers || scene.activeCamera;

            if (!camera) {
                return;
            }
            let engine = scene.getEngine();
            let viewport = camera.viewport;
            let x = (scene.pointerX / engine.getHardwareScalingLevel() - viewport.x * engine.getRenderWidth()) / viewport.width;
            let y = (scene.pointerY / engine.getHardwareScalingLevel() - viewport.y * engine.getRenderHeight()) / viewport.height;

            this._shouldBlockPointer = false;
            // Do picking modifies _shouldBlockPointer
            this._doPicking(x, y, pi.type, (pi.event as PointerEvent).pointerId || 0, pi.event.button);
            
            // Avoid overwriting a true skipOnPointerObservable to false 
            if(this._shouldBlockPointer){
                pi.skipOnPointerObservable = this._shouldBlockPointer;
            }
        });

        this._attachToOnPointerOut(scene);
    }

    /**
     * Connect the texture to a hosting mesh to enable interactions
     * @param mesh defines the mesh to attach to
     * @param supportPointerMove defines a boolean indicating if pointer move events must be catched as well
     */
    public attachToMesh(mesh: AbstractMesh, supportPointerMove = true): void {
        var scene = this.getScene();
        if (!scene) {
            return;
        }
        this._pointerObserver = scene.onPointerObservable.add((pi, state) => {
            if (pi.type !== PointerEventTypes.POINTERMOVE
                && pi.type !== PointerEventTypes.POINTERUP
                && pi.type !== PointerEventTypes.POINTERDOWN) {
                return;
            }
            var pointerId = (pi.event as PointerEvent).pointerId || 0;
            if (pi.pickInfo && pi.pickInfo.hit && pi.pickInfo.pickedMesh === mesh) {
                var uv = pi.pickInfo.getTextureCoordinates();

                if (uv) {
                    let size = this.getSize();

                    this._doPicking(uv.x * size.width, (1.0 - uv.y) * size.height, pi.type, pointerId, pi.event.button);
                }
            } else if (pi.type === PointerEventTypes.POINTERUP) {
                if (this._lastControlDown[pointerId]) {
                    this._lastControlDown[pointerId]._forcePointerUp(pointerId);
                }
                delete this._lastControlDown[pointerId];

                if (this.focusedControl) {
                    const friendlyControls = this.focusedControl.keepsFocusWith();
                    
                    let canMoveFocus = true;

                    if (friendlyControls) {
                        for (var control of friendlyControls) {
                            // Same host, no need to keep the focus
                            if (this === control._host) {
                                continue;
                            }

                            // Different hosts
                            const otherHost = control._host;

                            if (otherHost._lastControlOver[pointerId] && otherHost._lastControlOver[pointerId].isAscendant(control)) {
                                canMoveFocus = false;
                                break;
                            }
                        }
                    }

                    if (canMoveFocus) {
                        this.focusedControl = null;
                    }
                }
            } else if (pi.type === PointerEventTypes.POINTERMOVE) {
                if (this._lastControlOver[pointerId]) {
                    this._lastControlOver[pointerId]._onPointerOut(this._lastControlOver[pointerId]);
                }
                delete this._lastControlOver[pointerId];
            }
        });

        mesh.enablePointerMoveEvents = supportPointerMove;
        this._attachToOnPointerOut(scene);
    }

    /**
     * Move the focus to a specific control
     * @param control defines the control which will receive the focus
     */
    public moveFocusToControl(control: IFocusableControl): void {
        this.focusedControl = control;
        this._lastPickedControl = <any>control;
        this._blockNextFocusCheck = true;
    }

    private _manageFocus(): void {
        if (this._blockNextFocusCheck) {
            this._blockNextFocusCheck = false;
            this._lastPickedControl = <any>this._focusedControl;
            return;
        }

        // Focus management
        if (this._focusedControl) {
            if (this._focusedControl !== (<any>this._lastPickedControl)) {
                if (this._lastPickedControl.isFocusInvisible) {
                    return;
                }

                this.focusedControl = null;
            }
        }
    }

    private _attachToOnPointerOut(scene: Scene): void {
        this._canvasPointerOutObserver = scene.getEngine().onCanvasPointerOutObservable.add((pointerEvent) => {
            if (this._lastControlOver[pointerEvent.pointerId]) {
                this._lastControlOver[pointerEvent.pointerId]._onPointerOut(this._lastControlOver[pointerEvent.pointerId]);
            }
            delete this._lastControlOver[pointerEvent.pointerId];

            if (this._lastControlDown[pointerEvent.pointerId]) {
                this._lastControlDown[pointerEvent.pointerId]._forcePointerUp();
            }
            delete this._lastControlDown[pointerEvent.pointerId];
        });
    }

    // Statics
    /**
     * Creates a new AdvancedDynamicTexture in projected mode (ie. attached to a mesh)
     * @param mesh defines the mesh which will receive the texture
     * @param width defines the texture width (1024 by default)
     * @param height defines the texture height (1024 by default)
     * @param supportPointerMove defines a boolean indicating if the texture must capture move events (true by default)
     * @param onlyAlphaTesting defines a boolean indicating that alpha blending will not be used (only alpha testing) (false by default)
     * @returns a new AdvancedDynamicTexture
     */
    public static CreateForMesh(mesh: AbstractMesh, width = 1024, height = 1024, supportPointerMove = true, onlyAlphaTesting = false): AdvancedDynamicTexture {
        var result = new AdvancedDynamicTexture(mesh.name + " AdvancedDynamicTexture", width, height, mesh.getScene(), true, Texture.TRILINEAR_SAMPLINGMODE);

        var material = new StandardMaterial("AdvancedDynamicTextureMaterial", mesh.getScene());
        material.backFaceCulling = false;
        material.diffuseColor = Color3.Black();
        material.specularColor = Color3.Black();

        if (onlyAlphaTesting) {
            material.diffuseTexture = result;
            material.emissiveTexture = result;
            result.hasAlpha = true;    
        } else {
            material.emissiveTexture = result;
            material.opacityTexture = result;   
        }

        mesh.material = material;

        result.attachToMesh(mesh, supportPointerMove);

        return result;
    }

    /**
     * Creates a new AdvancedDynamicTexture in fullscreen mode.
     * In this mode the texture will rely on a layer for its rendering.
     * This allows it to be treated like any other layer.
     * As such, if you have a multi camera setup, you can set the layerMask on the GUI as well.
     * LayerMask is set through advancedTexture.layer.layerMask
     * @param name defines name for the texture
     * @param foreground defines a boolean indicating if the texture must be rendered in foreground (default is true)
     * @param scene defines the hsoting scene
     * @param sampling defines the texture sampling mode (Texture.BILINEAR_SAMPLINGMODE by default)
     * @returns a new AdvancedDynamicTexture
     */
    public static CreateFullscreenUI(name: string, foreground: boolean = true, scene: Nullable<Scene> = null, sampling = Texture.BILINEAR_SAMPLINGMODE): AdvancedDynamicTexture {
        var result = new AdvancedDynamicTexture(name, 0, 0, scene, false, sampling);

        // Display
        var layer = new Layer(name + "_layer", null, scene, !foreground);
        layer.texture = result;

        result._layerToDispose = layer;
        result._isFullscreen = true;

        // Attach
        result.attach();

        return result;
    }
}