import { ScrollEventData } from "ui/scroll-view";
import { View, layout, ScrollViewBase, orientationProperty } from "./scroll-view-common";

export * from "./scroll-view-common";

class UIScrollViewDelegateImpl extends NSObject implements UIScrollViewDelegate {
    private _owner: WeakRef<ScrollView>;

    public static initWithOwner(owner: WeakRef<ScrollView>): UIScrollViewDelegateImpl {
        let impl = <UIScrollViewDelegateImpl>UIScrollViewDelegateImpl.new();
        impl._owner = owner;
        return impl;
    }

    public scrollViewDidScroll(sv: UIScrollView): void {
        let owner = this._owner.get();
        if (owner) {
            owner.notify(<ScrollEventData>{
                object: owner,
                eventName: ScrollViewBase.scrollEvent,
                scrollX: owner.horizontalOffset / layout.getDisplayDensity(),
                scrollY: owner.verticalOffset / layout.getDisplayDensity()
            });
        }
    }

    public static ObjCProtocols = [UIScrollViewDelegate];
}

export class ScrollView extends ScrollViewBase {
    private _scroll: UIScrollView;
    private _contentMeasuredWidth: number = 0;
    private _contentMeasuredHeight: number = 0;
    private _delegate: UIScrollViewDelegateImpl;

    constructor() {
        super();
        this._scroll = UIScrollView.new();
    }

    protected attachNative() {
        this._delegate = UIScrollViewDelegateImpl.initWithOwner(new WeakRef(this));
        this._scroll.delegate = this._delegate;
    }

    protected dettachNative() {
        this._scroll.delegate = null;
    }

    get horizontalOffset(): number {
        return this._scroll.contentOffset.x;
    }

    get verticalOffset(): number {
        return this._scroll.contentOffset.y;
    }

    get scrollableWidth(): number {
        if (this.orientation !== "horizontal") {
            return 0;
        }

        return Math.max(0, this._scroll.contentSize.width - this._scroll.bounds.size.width) / layout.getDisplayDensity();
    }

    get scrollableHeight(): number {
        if (this.orientation !== "vertical") {
            return 0;
        }

        return Math.max(0, this._scroll.contentSize.height - this._scroll.bounds.size.height) / layout.getDisplayDensity();
    }

    get ios(): UIView {
        return this._scroll;
    }

    get _nativeView(): UIView {
        return this._scroll;
    }

    public scrollToVerticalOffset(value: number, animated: boolean) {
        if (this.orientation === "vertical") {
            const bounds = this._scroll.bounds.size;
            this._scroll.scrollRectToVisibleAnimated(CGRectMake(0, value, bounds.width, bounds.height), animated);
        }
    }

    public scrollToHorizontalOffset(value: number, animated: boolean) {
        if (this.orientation === "horizontal") {
            const bounds = this._scroll.bounds.size;
            this._scroll.scrollRectToVisibleAnimated(CGRectMake(value, 0, bounds.width, bounds.height), animated);
        }
    }

    public onMeasure(widthMeasureSpec: number, heightMeasureSpec: number): void {
        // Don't call measure because it will measure content twice.
        const width = layout.getMeasureSpecSize(widthMeasureSpec);
        const widthMode = layout.getMeasureSpecMode(widthMeasureSpec);

        const height = layout.getMeasureSpecSize(heightMeasureSpec);
        const heightMode = layout.getMeasureSpecMode(heightMeasureSpec);

        const density = layout.getDisplayDensity();
        const child = this.layoutView;
        const style = this.style;
        if (!child) {
            this._contentMeasuredWidth = style.effectiveMinWidth * density;
            this._contentMeasuredHeight = style.effectiveMinHeight * density;
        }
        else {
            let childSize: { measuredWidth: number; measuredHeight: number };
            if (this.orientation === "vertical") {
                childSize = View.measureChild(this, child, widthMeasureSpec, layout.makeMeasureSpec(0, layout.UNSPECIFIED));
            }
            else {
                childSize = View.measureChild(this, child, layout.makeMeasureSpec(0, layout.UNSPECIFIED), heightMeasureSpec);
            }

            this._scroll.contentSize = CGSizeMake(childSize.measuredWidth, childSize.measuredHeight);
            this._contentMeasuredWidth = Math.max(childSize.measuredWidth, style.effectiveMinWidth * density);
            this._contentMeasuredHeight = Math.max(childSize.measuredHeight, style.effectiveMinHeight * density);
        }

        const widthAndState = View.resolveSizeAndState(this._contentMeasuredWidth, width, widthMode, 0);
        const heightAndState = View.resolveSizeAndState(this._contentMeasuredHeight, height, heightMode, 0);

        this.setMeasuredDimension(widthAndState, heightAndState);
    }

    public onLayout(left: number, top: number, right: number, bottom: number): void {

        const width = (right - left);
        const height = (bottom - top);

        if (this.orientation === "horizontal") {
            View.layoutChild(this, this.layoutView, 0, 0, Math.max(this._contentMeasuredWidth, width), height);
        }
        else {
            View.layoutChild(this, this.layoutView, 0, 0, width, Math.max(this._contentMeasuredHeight, height));
        }
    }
}