// Lazy content observer - renders content only when visible in viewport
window.lazyContentObserver = {
    _observers: new Map(),

    observe: function (element, dotNetRef, rootMargin, threshold) {
        if (!element) {
            console.error('[MgLazyLoadContent] Element not found');
            return false;
        }

        // Clean up existing observer for this element
        this.unobserve(element);

        const options = {
            root: null, // viewport
            rootMargin: rootMargin || '50px',
            threshold: threshold || 0.01
        };

        // Check immediate visibility before setting up observer
        const rect = element.getBoundingClientRect();
        const isCurrentlyVisible = (
            rect.top < window.innerHeight &&
            rect.bottom > 0 &&
            rect.left < window.innerWidth &&
            rect.right > 0
        );

        const observer = new IntersectionObserver((entries) => {
            entries.forEach(entry => {
                // Invoke .NET callback
                dotNetRef.invokeMethodAsync('OnVisibilityChanged', entry.isIntersecting)
                    .catch(err => console.error('[MgLazyLoadContent] Callback error:', err));
            });
        }, options);

        observer.observe(element);
        this._observers.set(element, { observer, dotNetRef });

        console.log('[MgLazyLoadContent] Observer initialized. Currently visible:', isCurrentlyVisible);

        // Return immediate visibility status
        return isCurrentlyVisible;
    },

    unobserve: function (element) {
        if (!element) return;

        const data = this._observers.get(element);
        if (data) {
            data.observer.disconnect();
            this._observers.delete(element);
            console.log('[MgLazyLoadContent] Observer removed');
        }
    },

    dispose: function () {
        this._observers.forEach((data, element) => {
            data.observer.disconnect();
        });
        this._observers.clear();
        console.log('[MgLazyLoadContent] All observers disposed');
    }
};