#!/usr/bin/env node
// Automated test runner. Exit 0 = pass, exit 1 = fail.
// Requires root (sudo) for mount and fa2json.

import { createInterface } from 'node:readline';
import { promises as fs } from 'node:fs';
import { join } from 'node:path';
import { setup, spawnFa2json } from './lib/setup.mjs';

// Fanotify mask flags
const FAN_ATTRIB      = 0x4;
const FAN_CLOSE_WRITE = 0x8;
const FAN_CREATE      = 0x100;
const FAN_DELETE      = 0x200;
const FAN_RENAME      = 0x10000000;
const FAN_ONDIR       = 0x40000000;

const { mnt, teardown } = await setup();
const fa2json = spawnFa2json(mnt);

// Event buffer and marker machinery
const events = [];
let markerResolve = null;
let markerName = null;
let markerCounter = 0;

const rl = createInterface({ input: fa2json.stdout });
rl.on('line', line => {
	const event = JSON.parse(line);
	// Strip mount prefix from all path fields
	for (const key of ['name', 'old', 'new']) {
		if (event[key]) event[key] = event[key].slice(mnt.length);
	}
	events.push(event);
	if (markerResolve && event.name === `/.marker_${markerName}` && (event.mask & FAN_CREATE)) {
		markerResolve();
		markerResolve = null;
	}
});

// Perform a FS operation, drop a marker, collect events up to that marker
async function doOp(label, fn) {
	const id = markerCounter++;
	await fn();
	await fs.writeFile(join(mnt, `.marker_${id}`), '');
	await new Promise(resolve => {
		markerName = id;
		markerResolve = resolve;
	});
	// Collect all events since previous marker (excluding marker events themselves)
	const batch = events.splice(0).filter(e => !e.name?.startsWith('/.marker_'));
	return { label, batch };
}

function assert(label, batch, check) {
	if (!check(batch)) {
		console.error(`FAIL: ${label}`);
		console.error('Batch:', JSON.stringify(batch, null, 2));
		throw new Error(`Assertion failed: ${label}`);
	}
}

function hasEvent(batch, flags, path, field = 'name') {
	return batch.some(e => (e.mask & flags) === flags && e[field] === path);
}

try {
	let op;

	op = await doOp('mkdir /dir_a', () => fs.mkdir(join(mnt, 'dir_a')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_CREATE | FAN_ONDIR, '/dir_a'));

	op = await doOp('touch /file_a.txt', () => fs.writeFile(join(mnt, 'file_a.txt'), ''));
	assert(op.label, op.batch, b => hasEvent(b, FAN_CREATE, '/file_a.txt'));

	op = await doOp('write /file_a.txt', () => fs.writeFile(join(mnt, 'file_a.txt'), 'content'));
	assert(op.label, op.batch, b => hasEvent(b, FAN_CLOSE_WRITE, '/file_a.txt'));

	op = await doOp('mkdir /dir_b', () => fs.mkdir(join(mnt, 'dir_b')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_CREATE | FAN_ONDIR, '/dir_b'));

	op = await doOp('touch /dir_b/nested.txt', () => fs.writeFile(join(mnt, 'dir_b', 'nested.txt'), ''));
	assert(op.label, op.batch, b => hasEvent(b, FAN_CREATE, '/dir_b/nested.txt'));

	op = await doOp('mv /file_a.txt /file_b.txt', () => fs.rename(join(mnt, 'file_a.txt'), join(mnt, 'file_b.txt')));
	assert(op.label, op.batch, b => b.some(e => (e.mask & FAN_RENAME) && e.old === '/file_a.txt' && e.new === '/file_b.txt'));

	op = await doOp('mv /dir_b /dir_a/dir_b_moved', () => fs.rename(join(mnt, 'dir_b'), join(mnt, 'dir_a', 'dir_b_moved')));
	assert(op.label, op.batch, b => b.some(e => (e.mask & FAN_RENAME) && (e.mask & FAN_ONDIR) && e.old === '/dir_b' && e.new === '/dir_a/dir_b_moved'));

	op = await doOp('chmod 600 /file_b.txt', () => fs.chmod(join(mnt, 'file_b.txt'), 0o600));
	assert(op.label, op.batch, b => hasEvent(b, FAN_ATTRIB, '/file_b.txt'));

	op = await doOp('touch -m /file_b.txt', () => fs.utimes(join(mnt, 'file_b.txt'), new Date(), new Date()));
	assert(op.label, op.batch, b => hasEvent(b, FAN_ATTRIB, '/file_b.txt'));

	op = await doOp('chmod 755 /dir_a', () => fs.chmod(join(mnt, 'dir_a'), 0o755));
	assert(op.label, op.batch, b => hasEvent(b, FAN_ATTRIB | FAN_ONDIR, '/dir_a'));

	op = await doOp('rm /file_b.txt', () => fs.unlink(join(mnt, 'file_b.txt')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_DELETE, '/file_b.txt'));

	op = await doOp('rm /dir_a/dir_b_moved/nested.txt', () => fs.unlink(join(mnt, 'dir_a', 'dir_b_moved', 'nested.txt')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_DELETE, '/dir_a/dir_b_moved/nested.txt'));

	op = await doOp('rmdir /dir_a/dir_b_moved', () => fs.rmdir(join(mnt, 'dir_a', 'dir_b_moved')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_DELETE | FAN_ONDIR, '/dir_a/dir_b_moved'));

	op = await doOp('rmdir /dir_a', () => fs.rmdir(join(mnt, 'dir_a')));
	assert(op.label, op.batch, b => hasEvent(b, FAN_DELETE | FAN_ONDIR, '/dir_a'));

	console.log('PASS');
} catch (e) {
	console.error(e.message);
	process.exitCode = 1;
} finally {
	fa2json.kill();
	await teardown();
}