(function () {
	if (window.__externalWarningInitialized) return;
	window.__externalWarningInitialized = true;

	const allowedDomains = [
		'scu.edu',
		'docs.google.com',
		'qualtrics.com'
	];

	function isExternalWarningLink(link) {
		const href = link.getAttribute('href');

		if (!href) return false;
		if (href.startsWith('#')) return false;
		if (href.startsWith('mailto:')) return false;
		if (href.startsWith('tel:')) return false;
		if (href.startsWith('javascript:')) return false;

		const url = new URL(href, window.location.href);
		const hostname = url.hostname.toLowerCase();

		return !allowedDomains.some(function (domain) {
			return hostname === domain || hostname.endsWith('.' + domain);
		});
	}

	function createModal() {
		if (document.getElementById('externalSiteWarningModal')) return;

		const modal = document.createElement('div');
		modal.id = 'externalSiteWarningModal';

		modal.innerHTML = `
			<div class="ext-warning-overlay" role="dialog" aria-modal="true" aria-labelledby="extWarningTitle" aria-hidden="true">
				<div class="ext-warning-modal">
					<div class="ext-warning-header">
						<h2 id="extWarningTitle">Leave Santa Clara University’s Website?</h2>
					</div>
					<div class="ext-warning-body">
						<p>
							You are leaving the Santa Clara University website for a site that is controlled by a third party not affiliated with Santa Clara University. The contents and policies on the third party site you are entering may differ from those of Santa Clara University. We are not responsible for the contents, policies, or the maintenance of the third-party website.
						</p>
					</div>
					<div class="ext-warning-footer">
						<button type="button" class="ext-warning-cancel">Cancel</button>
						<a href="#" class="ext-warning-proceed">Proceed to Site</a>
					</div>
				</div>
			</div>
		`;

		document.body.appendChild(modal);

		if (!document.getElementById('externalSiteWarningStyles')) {
			const style = document.createElement('style');
			style.id = 'externalSiteWarningStyles';
			style.innerHTML = `
				.ext-warning-overlay {
					position: fixed;
					inset: 0;
					background: rgba(0,0,0,0.5);
					display: none;
					align-items: center;
					justify-content: center;
					z-index: 999999;
				}

				.ext-warning-overlay.active {
					display: flex;
				}

				.ext-warning-modal {
					background: #fff;
					max-width: 700px;
					width: 90%;
					border-radius: 6px;
					box-shadow: 0 4px 20px rgba(0,0,0,0.25);
					overflow: hidden;
				}

				.ext-warning-header,
				.ext-warning-body,
				.ext-warning-footer {
					padding: 1rem;
				}

				.ext-warning-header h2 {
					margin: 0;
					font-size: 1.25rem;
				}

				.ext-warning-body p {
					margin: 0;
					padding: 0.75rem 1.25rem;
					border-radius: .25rem;
					background: #fff3cd;
				}

				.ext-warning-footer {
					display: flex;
					justify-content: flex-end;
					gap: 0.5rem;
				}

				.ext-warning-cancel,
				.ext-warning-proceed {
					padding: 0.5rem 1rem;
					border-radius: 4px;
					border: 0;
					cursor: pointer;
					text-decoration: none;
					font: inherit;
				}

				.ext-warning-cancel {
					background: #6c757d;
					color: #fff;
				}

				.ext-warning-proceed {
					background: #b30738;
					color: #fff;
				}
			`;
			document.head.appendChild(style);
		}
	}

	function init() {
		createModal();

		const modal = document.getElementById('externalSiteWarningModal');
		const overlay = modal.querySelector('.ext-warning-overlay');
		const proceedLink = modal.querySelector('.ext-warning-proceed');
		const cancelButton = modal.querySelector('.ext-warning-cancel');

		function openModal(href) {
			proceedLink.setAttribute('href', href);
			overlay.classList.add('active');
			overlay.setAttribute('aria-hidden', 'false');
			cancelButton.focus();
		}

		function closeModal() {
			overlay.classList.remove('active');
			overlay.setAttribute('aria-hidden', 'true');
			proceedLink.setAttribute('href', '#');
		}

		cancelButton.addEventListener('click', closeModal);

		overlay.addEventListener('click', function (event) {
			if (event.target === overlay) closeModal();
		});

		document.addEventListener('keydown', function (event) {
			if (event.key === 'Escape') closeModal();
		});

		document.addEventListener('click', function (event) {
			const link = event.target.closest('a');

			if (!link) return;
			if (link.closest('#externalSiteWarningModal')) return;
			if (!isExternalWarningLink(link)) return;

			event.preventDefault();
			openModal(link.getAttribute('href'));
		});
	}

	if (document.readyState === 'loading') {
		document.addEventListener('DOMContentLoaded', init);
	} else {
		init();
	}
})();