// lib/storage.js
import fs from "fs/promises";
import path from "path";

const ROOT = process.env.NAS_ROOT_PATH;

if (!ROOT) {
	console.warn(
		"[storage] NAS_ROOT_PATH ist nicht gesetzt – Dateizugriff wird fehlschlagen"
	);
}

function fullPath(...segments) {
	if (!ROOT) {
		throw new Error("NAS_ROOT_PATH ist nicht gesetzt");
	}

	return path.join(ROOT, ...segments.map(String));
}

// Hilfsfunktion: sortiert numerische Strings wie "1","2","10" korrekt
function sortNumericStrings(a, b) {
	const na = parseInt(a, 10);
	const nb = parseInt(b, 10);
	if (!Number.isNaN(na) && !Number.isNaN(nb)) {
		return na - nb;
	}
	return a.localeCompare(b, "de");
}

export async function listBranches() {
	const entries = await fs.readdir(fullPath(), { withFileTypes: true });

	return entries
		.filter(
			(e) =>
				e.isDirectory() &&
				e.name !== "@Recently-Snapshot" &&
				/^NL\d+$/i.test(e.name)
		)
		.map((e) => e.name)
		.sort((a, b) =>
			sortNumericStrings(a.replace("NL", ""), b.replace("NL", ""))
		);
}

export async function listYears(branch) {
	const dir = fullPath(branch);
	const entries = await fs.readdir(dir, { withFileTypes: true });

	return entries
		.filter((e) => e.isDirectory() && /^\d{4}$/.test(e.name))
		.map((e) => e.name)
		.sort(sortNumericStrings);
}

export async function listMonths(branch, year) {
	const dir = fullPath(branch, year);
	const entries = await fs.readdir(dir, { withFileTypes: true });

	return entries
		.filter((e) => e.isDirectory() && /^\d{1,2}$/.test(e.name))
		.map((e) => e.name.padStart(2, "0"))
		.sort(sortNumericStrings);
}

export async function listDays(branch, year, month) {
	const dir = fullPath(branch, month.length === 1 ? year : year, month);
	const entries = await fs.readdir(dir, { withFileTypes: true });

	return entries
		.filter((e) => e.isDirectory() && /^\d{1,2}$/.test(e.name))
		.map((e) => e.name.padStart(2, "0"))
		.sort(sortNumericStrings);
}

export async function listFiles(branch, year, month, day) {
	const dir = fullPath(branch, year, month, day);
	const entries = await fs.readdir(dir, { withFileTypes: true });

	return entries
		.filter((name) => name.toLowerCase().endsWith(".pdf"))
		.sort((a, b) => a.localeCompare(b, "de"))
		.map((name) => ({
			name,
			// relativer Pfad, den du später für Downloads nutzen kannst
			relativePath: `${branch}/${year}/${month}/${day}/${name}`,
		}));
}