export interface SanitizeOptions {
	maxChars: number;
}

export interface SanitizedTitle {
	ok: boolean;
	title?: string;
	reason?: string;
}

const ANSI_ESCAPE_PATTERN = /\x1B(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~]|\][^\x07]*(?:\x07|\x1B\\))/g;
const CONTROL_PATTERN = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F\u0080-\u009F]/g;
const MARKDOWN_LINK_PATTERN = /\[([^\]]+)]\(([^)]+)\)/g;

function stripWrapping(value: string): string {
	let output = value.trim();
	const pairs: Array<[string, string]> = [
		["```", "```"],
		["`", "`"],
		['"', '"'],
		["'", "'"],
		["“", "”"],
		["‘", "’"],
		["**", "**"],
		["__", "__"],
		["*", "*"],
		["_", "_"],
		["~~", "~~"],
	];

	let changed = true;
	while (changed) {
		changed = false;
		for (const [start, end] of pairs) {
			if (output.startsWith(start) && output.endsWith(end) && output.length >= start.length + end.length) {
				output = output.slice(start.length, output.length - end.length).trim();
				changed = true;
			}
		}
	}

	return output.replace(/^[`"'“”‘’*_~\s]+|[`"'“”‘’*_~\s]+$/g, "").trim();
}

function cleanCandidate(candidate: string): string {
	let output = candidate.replace(ANSI_ESCAPE_PATTERN, "").replace(CONTROL_PATTERN, "").trim();
	if (!output || /^```[a-zA-Z0-9_-]*$/.test(output)) {
		return "";
	}

	output = output.replace(MARKDOWN_LINK_PATTERN, "$1");
	output = output.replace(/^#{1,6}\s+/, "");
	output = output.replace(/^[-*+]\s+/, "");
	output = output.replace(/^\d+[.)]\s+/, "");
	output = output.replace(/^>\s+/, "");
	output = stripWrapping(output);
	output = output.replace(/[`"'“”‘’]/g, "");
	output = output.replace(/[\r\n]+/g, " ");
	output = output.replace(/\s+/g, " ").trim();
	return stripWrapping(output);
}

function truncateTitle(title: string, maxChars: number): string {
	const chars = Array.from(title);
	if (chars.length <= maxChars) {
		return title;
	}
	return chars.slice(0, maxChars).join("").trim();
}

export function sanitizeTitle(input: unknown, options: SanitizeOptions): SanitizedTitle {
	if (typeof input !== "string") {
		return { ok: false, reason: "Title is not a string." };
	}
	if (!Number.isInteger(options.maxChars) || options.maxChars <= 0) {
		return { ok: false, reason: "maxChars must be a positive integer." };
	}

	const normalized = input.replace(ANSI_ESCAPE_PATTERN, "").replace(CONTROL_PATTERN, "");
	const candidates = normalized.split(/[\r\n]+/);
	for (const candidate of candidates) {
		const cleaned = truncateTitle(cleanCandidate(candidate), options.maxChars);
		if (cleaned) {
			return { ok: true, title: cleaned };
		}
	}

	const cleaned = truncateTitle(cleanCandidate(normalized), options.maxChars);
	if (cleaned) {
		return { ok: true, title: cleaned };
	}

	return { ok: false, reason: "Title is empty after sanitization." };
}