import * as Utils from "../../utils";
import { DragSource, DragTarget, DragSourceConfig, DragTargetConfig } from "../../ui/draggables";
import { EventManager, Events } from "../../events";
import { ViewManager, ViewManagerMode } from "../viewManager";
import { Box } from "../../editing/box";


const startDraggingTime = 300;
const frictionCoeff = 0.85;
const bounceCoeff = 0.4;

export class DragManager {
    private pointerX: number;
    private pointerY: number;
    private positionX: number;
    private positionY: number;
    private previousX: number;
    private previousY: number;
    private velocityX: number;
    private velocityY: number;
    private startDraggingTimeout: number;
    private source: DragSource;
    private target: DragTarget;
    private acceptBefore: boolean;
    private initialOffsetX: number;
    private initialOffsetY: number;
    private bounds: Box;

    public sourceData: any;
    public targetData: any;

    public dragged: HTMLElement;
    public isDragged: boolean;
    public draggedClientRect: ClientRect;

    constructor(
        private readonly eventManager: EventManager,
        private readonly viewManager: ViewManager
    ) {
        this.startDragging = this.startDragging.bind(this);
        this.completeDragging = this.completeDragging.bind(this);
        this.onPointerMove = this.onPointerMove.bind(this);
        this.onPointerDown = this.onPointerDown.bind(this);
        this.onPointerUp = this.onPointerUp.bind(this);
        this.setAcceptor = this.setAcceptor.bind(this);
        this.registerDragSource = this.registerDragSource.bind(this);
        this.registerDragTarget = this.registerDragTarget.bind(this);
        this.resetDraggedElementPosition = this.resetDraggedElementPosition.bind(this);
        this.inertia = this.inertia.bind(this);

        this.eventManager.addEventListener("onPointerMove", this.onPointerMove);
        this.eventManager.addEventListener("onPointerUp", this.onPointerUp);
    }

    private onPointerMove(event: MouseEvent): void {
        if (this.viewManager.mode == ViewManagerMode.preview) {
            return;
        }
        if (!this.isDragged) {
            return;
        }

        if (event.which !== 1) {
            this.cancelDragging();
            return;
        }

        this.previousX = this.positionX;
        this.previousY = this.positionY;

        this.pointerX = event.clientX;
        this.pointerY = event.clientY;


        this.positionX = this.pointerX - this.initialOffsetX;
        this.positionY = this.pointerY - this.initialOffsetY;

        if (!this.source.configuration.sticky) {
            if (this.positionX > this.bounds.width - this.draggedClientRect.width) {
                this.positionX = this.bounds.width - this.draggedClientRect.width;
            }

            if (this.positionX < 0) {
                this.positionX = 0;
            }

            if (this.positionY > this.bounds.height - this.draggedClientRect.height) {
                this.positionY = this.bounds.height - this.draggedClientRect.height;
            }

            if (this.positionY < 0) {
                this.positionY = 0;
            }

            this.velocityX = this.positionX - this.previousX;
            this.velocityY = this.positionY - this.previousY;
        }

        if (this.target && this.target.element.classList.contains("accepting")) {
            this.target.element.classList.remove("accepting");
        }

        this.resetDraggedElementPosition();
    }

    private resetDraggedElementPosition(): void {
        this.dragged.style.left = this.positionX + "px";
        this.dragged.style.top = this.positionY + "px";
    }

    public startDragging(source: DragSource): void {
        this.velocityX = 0;
        this.velocityY = 0;
        this.isDragged = true;
        this.dragged = source.element;

        this.sourceData = source.configuration.sourceData;
        this.source = source;
        this.initialOffsetX = this.source.initialOffsetX;
        this.initialOffsetY = this.source.initialOffsetY;
        this.pointerX = this.source.initialPointerX;
        this.pointerY = this.source.initialPointerY;
        this.positionX = this.pointerX - this.initialOffsetX;
        this.positionY = this.pointerY - this.initialOffsetY;

        this.bounds = {
            top: 0,
            left: 0,
            width: document.body.clientWidth,
            height: document.body.clientHeight
        };

        // Fixating the sizes
        if (source.configuration.sticky) {
            const rect = this.dragged.getBoundingClientRect();

            this.dragged.style.width = rect.width + "px";
            this.dragged.style.height = rect.height + "px";
        }

        if (source.configuration.ondragstart) {
            const replacement = source.configuration.ondragstart(source.configuration.sourceData, source.element);

            if (replacement) {
                this.dragged = replacement;
            }
        }

        if (!this.dragged.parentElement) {
            document.body.appendChild(this.dragged);
        }

        this.dragged.classList.add("dragged");
        this.draggedClientRect = source.element.getBoundingClientRect();

        this.resetDraggedElementPosition();

        this.viewManager.mode = ViewManagerMode.dragging;
    }

    private cancelDragging(): void {
        if (this.viewManager.mode == ViewManagerMode.preview) {
            return;
        }
        this.target = null;
        this.completeDragging();
    }

    private completeDragging(): void {
        this.isDragged = false;

        if (this.target) {
            this.target.element.classList.remove("accepting");

            const quadrant = Utils.pointerToClientQuadrant(this.pointerX, this.pointerY, this.target.element);

            if (this.target.config.ondrop) {
                this.target.config.ondrop(this.sourceData, this.target.config.targetData, quadrant);
            }

            if (this.target.config.ondropbefore && this.acceptBefore) {
                this.target.config.ondropbefore(this.source.configuration.sourceData, this.source.element);
            }

            if (this.target.config.ondropafter && !this.acceptBefore) {
                this.target.config.ondropafter(this.source.configuration.sourceData, this.source.element);
            }
        }

        this.dragged.classList.remove("dragged");

        if (this.source.configuration.ondragend) {
            this.source.configuration.ondragend(this.source.configuration.sourceData, this.source.element);
            this.eventManager.dispatchEvent(Events.VirtualDragEnd);
        }

        if (this.source.configuration.sticky) {
            this.dragged.style.removeProperty("left");
            this.dragged.style.removeProperty("top");
            this.dragged.style.removeProperty("width");
            this.dragged.style.removeProperty("height");
        }
        else if (this.source.configuration.inertia) {
            this.inertia();
        }

        this.sourceData = null;
        this.source = null;
        this.target = null;
    }

    private onPointerUp(event: MouseEvent): void {
        if (this.viewManager.mode == ViewManagerMode.preview) {
            return;
        }
        clearTimeout(this.startDraggingTimeout);

        if (!this.isDragged) {
            return;
        }

        this.completeDragging();
    }

    public registerDragSource(element: HTMLElement, config: DragSourceConfig): void {
        new DragSource(element, config, this);
    }

    public registerDragTarget(element: HTMLElement, config: DragTargetConfig): void {
        new DragTarget(element, config, this);
    }

    public onPointerDown(source: DragSource): void {
        if (this.viewManager.mode == ViewManagerMode.preview) {
            return;
        }
        if (source.configuration.sticky) {
            clearTimeout(this.startDraggingTimeout);
            this.startDraggingTimeout = <any>setTimeout(() => this.startDragging(source), startDraggingTime);
        }
        else {
            this.startDragging(source);
        }
    }

    public setAcceptor(acceptor: DragTarget, before: boolean): void {
        this.target = acceptor;

        if (!this.target.element.classList.contains("accepting")) {
            this.target.element.classList.add("accepting");
        }

        this.acceptBefore = before;
    }

    public inertia(): void {
        if (this.isDragged) {
            return;
        }

        if (Math.abs(this.velocityX) > 0.005 || Math.abs(this.velocityY) > 0.005) {
            requestAnimationFrame(this.inertia);
        }

        this.positionX += this.velocityX;
        this.positionY += this.velocityY;
        this.velocityX *= frictionCoeff;
        this.velocityY *= frictionCoeff;

        if (this.positionX > this.bounds.width - this.draggedClientRect.width) {
            this.velocityX *= -bounceCoeff;
            this.positionX = this.bounds.width - this.draggedClientRect.width;
        }

        if (this.positionX < 0) {
            this.velocityX *= -bounceCoeff;
            this.positionX = 0;
        }

        if (this.positionY > this.bounds.height - this.draggedClientRect.height) {
            this.velocityY *= -bounceCoeff;
            this.positionY = this.bounds.height - this.draggedClientRect.height;
        }

        if (this.positionY < 0) {
            this.velocityY *= -bounceCoeff;
            this.positionY = 0;
        }

        this.resetDraggedElementPosition();
    }
}