/**
 * Blog single: TOC from H2 headings + share links + lightweight scroll spy.
 */
(function () {
	'use strict';

	function slugify(text) {
		return text
			.toString()
			.trim()
			.toLowerCase()
			.replace(/\s+/g, '-')
			.replace(/[^\w-]+/g, '')
			.replace(/--+/g, '-')
			.replace(/^-+/, '')
			.replace(/-+$/, '');
	}

	function shareUrl() {
		var wrap = document.querySelector('.viitorx-blog-single-page');
		return wrap && wrap.getAttribute('data-share-url')
			? wrap.getAttribute('data-share-url')
			: window.location.href;
	}

	function buildToc() {
		var root = document.getElementById('blog-article-body');
		var tocNav = document.getElementById('blog-single-toc');
		var empty = document.getElementById('blog-toc-empty');
		if (!root || !tocNav) {
			return;
		}

		var headings = root.querySelectorAll('h2, .blog-prose__heading');
		if (!headings.length) {
			if (empty) {
				empty.hidden = false;
			}
			tocNav.hidden = true;
			return;
		}

		if (empty) {
			empty.hidden = true;
		}
		tocNav.hidden = false;
		tocNav.innerHTML = '';

		var list = document.createElement('ul');
		list.className = 'toc__list';

		headings.forEach(function (h, i) {
			var id = h.id || slugify(h.textContent) || 'section-' + (i + 1);
			if (!h.id) {
				h.id = id;
			}

			var li = document.createElement('li');
			li.className = 'toc__item';

			var a = document.createElement('a');
			a.className = 'toc__link';
			a.href = '#' + id;
			a.textContent = h.textContent.trim();

			li.appendChild(a);
			list.appendChild(li);
		});

		tocNav.appendChild(list);
		tocSpy(headings, tocNav.querySelectorAll('.toc__link'));
	}

	function navOffset() {
		var nav = document.getElementById('sticky-nav');
		var base = nav ? nav.getBoundingClientRect().height : 88;
		return base + 32;
	}

	function tocSpy(headings, links) {
		if (!headings.length || !links.length) {
			return;
		}

		function update() {
			var offset = window.scrollY + navOffset();
			var current = headings[0].id;
			for (var i = headings.length - 1; i >= 0; i--) {
				var top = headings[i].getBoundingClientRect().top + window.scrollY;
				if (top <= offset) {
					current = headings[i].id;
					break;
				}
			}
			links.forEach(function (link) {
				link.classList.toggle('is-active', link.getAttribute('href') === '#' + current);
			});
		}

		/* Smooth-scroll TOC clicks with nav offset */
		links.forEach(function (link) {
			link.addEventListener('click', function (e) {
				var id = link.getAttribute('href').slice(1);
				var target = document.getElementById(id);
				if (!target) return;
				e.preventDefault();
				var top = target.getBoundingClientRect().top + window.scrollY - navOffset();
				window.scrollTo({ top: top, behavior: 'smooth' });
				history.pushState(null, '', '#' + id);
			});
		});

		window.addEventListener('scroll', update, { passive: true });
		update();
	}

	function wireShare() {
		var wrap = document.querySelector('.viitorx-blog-single-page');
		if (!wrap) {
			return;
		}

		function copyTextFallback(text, onDone) {
			var ta = document.createElement('textarea');
			ta.value = text;
			ta.setAttribute('readonly', '');
			ta.style.position = 'fixed';
			ta.style.left = '-9999px';
			ta.style.top = '0';
			document.body.appendChild(ta);
			ta.focus();
			ta.select();
			try {
				var ok = document.execCommand('copy');
				document.body.removeChild(ta);
				if (ok) {
					onDone();
				} else {
					window.prompt('Copy link:', text);
					onDone();
				}
			} catch (err) {
				document.body.removeChild(ta);
				window.prompt('Copy link:', text);
				onDone();
			}
		}

		function copyTextToClipboard(text, onDone) {
			if (navigator.clipboard && window.isSecureContext && navigator.clipboard.writeText) {
				navigator.clipboard.writeText(text).then(onDone).catch(function () {
					copyTextFallback(text, onDone);
				});
				return;
			}
			copyTextFallback(text, onDone);
		}

		wrap.querySelectorAll('[data-share="copy"]').forEach(function (el) {
			el.addEventListener('click', function (e) {
				e.preventDefault();
				var plain = shareUrl();
				function notify() {
					var prev = el.getAttribute('aria-label');
					el.setAttribute('data-label-original', prev || '');
					el.setAttribute('aria-label', 'Link copied');
					window.setTimeout(function () {
						el.setAttribute('aria-label', el.getAttribute('data-label-original') || prev || '');
					}, 2000);
				}
				copyTextToClipboard(plain, notify);
			});
		});
	}

	function init() {
		buildToc();
		wireShare();
	}

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