/**
 * File system utilities
 */
import { access, readFile } from "node:fs/promises";
import { truncate } from "./format.js";

export async function fileExists(filePath: string): Promise<boolean> {
	try {
		await access(filePath);
		return true;
	} catch {
		return false;
	}
}

export async function readSummary(filePath: string): Promise<string> {
	try {
		const text = await readFile(filePath, "utf8");
		const trimmed = text.trimStart();

		// Look for JSDoc/description patterns
		const descriptionPatterns = [
			/registerCommand\(\s*["'`][^"'`]+["'`]\s*,\s*\{[\s\S]*?description\s*:\s*["'`]([^"'`]+)["'`]/m,
			/registerTool\(\s*\{[\s\S]*?description\s*:\s*["'`]([^"'`]+)["'`]/m,
			/description\s*:\s*["'`]([^"'`]+)["'`]/m,
		];

		for (const pattern of descriptionPatterns) {
			const match = text.match(pattern);
			const value = match?.[1]?.trim();
			if (value) return truncate(value, 80);
		}

		// Look for block comments
		const block = trimmed.match(/^\/\*+[\s\S]*?\*\//);
		if (block?.[0]) {
			const lines = block[0]
				.split("\n")
				.map((line) =>
					line
						.replace(/^\s*\/\*+\s?/, "")
						.replace(/\*\/$/, "")
						.replace(/^\s*\*\s?/, "")
						.trim(),
				)
				.filter((s): s is string => Boolean(s));
			const firstLine = lines[0];
			if (firstLine) return truncate(firstLine, 80);
		}

		// Look for line comments
		const lineComment = trimmed.match(/^(?:\s*\/\/.*\n?)+/);
		if (lineComment?.[0]) {
			const first = lineComment[0]
				.split("\n")
				.map((line) => line.replace(/^\s*\/\/\s?/, "").trim())
				.filter(Boolean)[0];
			if (first) return truncate(first, 80);
		}

		// First non-empty line
		for (const line of text.split("\n")) {
			const clean = line.trim();
			if (clean.length > 0) return truncate(clean, 80);
		}
	} catch {
		// ignore
	}
	return "No description";
}