import { Feature } from '../Feature.mjs';
import { observeIntersection } from './observers.mjs';

const thresholdNames = {
    some: 0,
    all: 1,
};
class InViewFeature extends Feature {
    constructor() {
        super(...arguments);
        this.hasEnteredView = false;
        this.isInView = false;
    }
    startObserver() {
        this.unmount();
        const { viewport = {} } = this.node.getProps();
        const { root, margin: rootMargin, amount = "some", once } = viewport;
        const options = {
            root: root ? root.current : undefined,
            rootMargin,
            threshold: typeof amount === "number" ? amount : thresholdNames[amount],
        };
        const onIntersectionUpdate = (entry) => {
            const { isIntersecting } = entry;
            /**
             * If there's been no change in the viewport state, early return.
             */
            if (this.isInView === isIntersecting)
                return;
            this.isInView = isIntersecting;
            /**
             * Handle hasEnteredView. If this is only meant to run once, and
             * element isn't visible, early return. Otherwise set hasEnteredView to true.
             */
            if (once && !isIntersecting && this.hasEnteredView) {
                return;
            }
            else if (isIntersecting) {
                this.hasEnteredView = true;
            }
            if (this.node.animationState) {
                this.node.animationState.setActive("whileInView", isIntersecting);
            }
            /**
             * Use the latest committed props rather than the ones in scope
             * when this observer is created
             */
            const { onViewportEnter, onViewportLeave } = this.node.getProps();
            const callback = isIntersecting ? onViewportEnter : onViewportLeave;
            callback && callback(entry);
        };
        return observeIntersection(this.node.current, options, onIntersectionUpdate);
    }
    mount() {
        this.startObserver();
    }
    update() {
        if (typeof IntersectionObserver === "undefined")
            return;
        const { props, prevProps } = this.node;
        const hasOptionsChanged = ["amount", "margin", "root"].some(hasViewportOptionChanged(props, prevProps));
        if (hasOptionsChanged) {
            this.startObserver();
        }
    }
    unmount() { }
}
function hasViewportOptionChanged({ viewport = {} }, { viewport: prevViewport = {} } = {}) {
    return (name) => viewport[name] !== prevViewport[name];
}

export { InViewFeature };