import { childrenIterator } from "./core/childrenIterator.js";

const waited = new Map<any, { resolve(), reject() }>();

const observer = new window.IntersectionObserver((entries) => {
    for (const entry of entries) {
        if (entry.isIntersecting && entry.intersectionRatio > 0.01) {
            const w = waited.get(entry.target);
            if (w) {
                try {
                    w.resolve();
                } catch {}
            }
            observer.unobserve(entry.target);
        }
    }
}, {
    root: document.body
});

export default class ScreenApi {

    static get isMobile() {
        const isMobile = /android|iOS|iPhone/i.test(navigator.userAgent) && !/tablet/i.test(navigator.userAgent);
        Object.defineProperty(ScreenApi, "isMobile", { value: isMobile });
        return isMobile;
    }

    static async waitForVisible(target) {
        return new Promise<void>((resolve, reject) => {
            waited.set(target, { resolve, reject });
            observer.observe(target);
        });
    }

    static getMostVisibleElement(containerDiv: HTMLElement): HTMLElement {
        let mostVisibleElement = null;

        const containerRect = containerDiv.getBoundingClientRect();
        const { left, top , width, height } = containerRect;

        // Iterate through all direct children of the containerDiv
        for (const child of childrenIterator(containerDiv)) {
            const childRect = child.getBoundingClientRect();
            const mpX = (childRect.left + childRect.width) / 2;
            const mpY = (childRect.top + childRect.height) / 2;
            if(
                mpX >= left
                && mpX <= (left + width)
                && mpY >= top
                && mpY <= (top + height)
            ) {
                return child;
            }
        }

        return mostVisibleElement;
    }


}