#!/usr/bin/env osascript -l JavaScript
/**
 * Exports Apple Notes to one JSON object per line, on stdout.
 *
 * Run this **on the Mac that has the notes**:
 *
 *   osascript -l JavaScript scripts/export-apple-notes.js > notes.ndjson
 *   osascript -l JavaScript scripts/export-apple-notes.js --folder Schule > schule.ndjson
 *
 * then hand the file to `schulcloud note import notes.ndjson`.
 *
 * Why this exists at all: Notes.app has no export. Its database is a Core Data
 * store whose bodies are compressed protobuf, and the iCloud copy is encrypted,
 * so scripting the app is not the clumsy route to the notes — it is the only
 * one. The first run raises a macOS permission dialog ("Terminal wants access
 * to Notes"); without it every note comes back empty.
 *
 * JXA and not AppleScript because it can serialise JSON, and because reading
 * properties one note at a time is what keeps a locked note from aborting the
 * run rather than a language preference.
 *
 * **Nothing here uses `console.log`.** In JXA it writes to standard *error*,
 * not standard output — so `> notes.ndjson` produced an empty file while every
 * note scrolled past on the terminal. Both streams are written through
 * NSFileHandle below, which is the only way to be sure which one you are on.
 */

ObjC.import('stdlib');
ObjC.import('Foundation');

function run(argv) {
	const options = parseArguments(argv);
	const notes = Application('Notes');
	notes.includeStandardAdditions = true;

	let items;
	try {
		items = notes.notes();
	} catch (error) {
		return fail(
			'Could not read Notes. Grant the terminal access under System Settings → Privacy & Security → ' +
				'Automation, then run this again.\n' + error,
		);
	}

	let written = 0;
	let skipped = 0;
	for (let i = 0; i < items.length; i++) {
		const note = items[i];
		// The folder first. The body is the one expensive property — it is
		// decompressed per note and is what makes a big library take minutes —
		// and a note in another folder is not worth reading one for.
		const folder = folderUnder(safe(function () { return folderPath(note.container()); }, ''), options.folder);
		if (folder === null) continue;

		const record = readNote(note, folder);
		if (!record) {
			skipped++;
			continue;
		}
		// One object per line, so a huge export streams and a bad note costs one line.
		emit(JSON.stringify(record));
		written++;
	}

	// stderr, so it never lands in the file being redirected.
	log(
		'Exported ' + written + ' note(s)' +
			(options.folder ? ' from "' + options.folder + '"' : '') +
			(skipped > 0 ? ', skipped ' + skipped + ' unreadable' : '') +
			'.',
	);
	if (written === 0) {
		log(
			options.folder
				? 'No note is in a folder called "' + options.folder + '". Folder names are matched whole, not as a fragment.'
				: 'No notes were readable. Grant the terminal access to Notes and try again.',
		);
	}
	return '';
}

/**
 * A note's folder as seen from the one asked for, or null if it is elsewhere.
 *
 * Matched by path segment, not substring: `--folder Schule` takes `Schule` and
 * everything under it, and leaves `Musikschule` alone.
 *
 * The path is recorded *relative* to that folder, because the import reads the
 * last segment as the subject: `Schule/Deutsch` has to arrive as `Deutsch`, and
 * a note sitting loose in `Schule` has to arrive with no folder at all — a
 * subject of "Schule" is not a subject. Without `--folder` the full path is
 * kept, which is the same thing measured from the top.
 */
function folderUnder(path, wanted) {
	if (!wanted) return path;
	const parts = String(path).split('/');
	const target = wanted.toLowerCase();
	for (let i = 0; i < parts.length; i++) {
		if (parts[i].trim().toLowerCase() === target) return parts.slice(i + 1).join('/');
	}
	return null;
}

function readNote(note, folder) {
	try {
		// Read the body first: it is the property a locked note refuses, and
		// there is no point building a record we cannot fill.
		const body = note.body();
		return {
			id: safe(function () { return note.id(); }, ''),
			name: safe(function () { return note.name(); }, ''),
			body: body || '',
			folder: folder,
			created: safe(function () { return iso(note.creationDate()); }, ''),
			modified: safe(function () { return iso(note.modificationDate()); }, ''),
		};
	} catch (error) {
		// A locked note, or one iCloud has not downloaded. Reported, not dropped
		// silently: a missing lesson is worse than a line in the file.
		return {
			id: safe(function () { return note.id(); }, ''),
			name: safe(function () { return note.name(); }, '(unreadable)'),
			body: '',
			folder: folder,
			error: String(error),
		};
	}
}

/** "Schule/Deutsch" — the import takes the last segment as the subject. */
function folderPath(container) {
	const parts = [];
	let current = container;
	for (let depth = 0; current && depth < 8; depth++) {
		const name = safe(function () { return current.name(); }, '');
		if (!name) break;
		parts.unshift(name);
		current = safe(function () { return current.container(); }, null);
	}
	return parts.join('/');
}

/**
 * A Date as local ISO, not UTC.
 *
 * `toISOString` would shift a note taken at 08:30 in Erfurt back to the
 * previous day for anything written before 01:00 or 02:00, and the date is
 * the whole point of the record.
 */
function iso(date) {
	if (!date) return '';
	const pad = function (value) { return String(value).padStart(2, '0'); };
	return (
		date.getFullYear() + '-' + pad(date.getMonth() + 1) + '-' + pad(date.getDate()) +
		'T' + pad(date.getHours()) + ':' + pad(date.getMinutes()) + ':' + pad(date.getSeconds())
	);
}

function safe(read, fallback) {
	try {
		const value = read();
		return value === undefined || value === null ? fallback : value;
	} catch (error) {
		return fallback;
	}
}

function parseArguments(argv) {
	const options = { folder: '' };
	for (let i = 0; i < argv.length; i++) {
		if (argv[i] === '--folder' && argv[i + 1]) options.folder = argv[++i];
	}
	return options;
}

/** One line of the export, on standard output — the file being redirected. */
function emit(line) {
	write($.NSFileHandle.fileHandleWithStandardOutput, line);
}

/** Progress and problems, on standard error, so they never land in the file. */
function log(message) {
	write($.NSFileHandle.fileHandleWithStandardError, message);
}

function write(handle, text) {
	handle.writeData($.NSString.alloc.initWithUTF8String(text + '\n').dataUsingEncoding($.NSUTF8StringEncoding));
}

function fail(message) {
	log(message);
	$.exit(1);
}