export interface Section {
	label: string;
	text: string;
}

interface Heading {
	line: number;
	level: number;
	title: string;
}

/** Find markdown ATX sections, ignoring headings inside fenced code blocks. */
export function findSections(markdown: string): Section[] {
	const lines = markdown.split("\n");
	const headings: Heading[] = [];
	let fence: string | undefined;

	for (let line = 0; line < lines.length; line++) {
		const value = lines[line] ?? "";
		const fenceMatch = value.match(/^\s*(`{3,}|~{3,})/);
		if (fenceMatch) {
			const marker = fenceMatch[1]!;
			if (!fence) fence = marker;
			else if (marker[0] === fence[0] && marker.length >= fence.length) fence = undefined;
			continue;
		}
		if (fence) continue;

		const heading = value.match(/^\s{0,3}(#{1,6})\s+(.+?)\s*#*\s*$/);
		if (heading) {
			headings.push({ line, level: heading[1]!.length, title: heading[2]!.trim() });
		}
	}

	return headings.map((heading, index) => {
		let end = lines.length;
		for (let next = index + 1; next < headings.length; next++) {
			if (headings[next]!.level <= heading.level) {
				end = headings[next]!.line;
				break;
			}
		}
		return {
			label: `${"#".repeat(heading.level)} ${heading.title}`,
			text: lines.slice(heading.line, end).join("\n").trimEnd(),
		};
	});
}