import {describe, expect, it} from 'vitest';

import {convertToIcal, escapeText, foldLine} from '../../src/models/calendar/events/icalgenerator.service.js';
import {Event} from '../../src/models/calendar/events/event.interface.js';

/**
 * The iCal export is read by every subscribed calendar app, so a malformed
 * file is an outage nobody on our side sees. These pin RFC 5545's text
 * escaping and line folding, which the generator did not do before: a line
 * break in a description ended the DESCRIPTION property early, and the new
 * calendar frontend's multi-line description field would have produced
 * exactly that.
 */

const event = (overrides: Partial<Event> = {}): Event => ({
	eventId: 1,
	calendarId: 1,
	uuid: 'uuid-1',
	name: 'Konzert',
	description: '',
	startDateTime: new Date('2026-10-03T17:00:00Z'),
	endDateTime: new Date('2026-10-03T19:00:00Z'),
	createdDate: new Date('2026-01-01T12:00:00Z'),
	location: '',
	createdBy: 'Anna',
	url: '',
	wholeDay: false,
	repeatFrequency: '',
	...overrides
});

/** RFC 5545 unfolding: a CRLF followed by one space or tab joins the lines. */
const unfold = (ical: string): string[] => ical.replace(/\r\n[ \t]/g, '').split('\r\n').filter(Boolean);

describe('escapeText', () => {
	it('escapes backslash, semicolon, comma and line breaks', () => {
		expect(escapeText('a\\b;c,d')).toBe('a\\\\b\\;c\\,d');
		expect(escapeText('Zeile 1\nZeile 2\r\nZeile 3\rZeile 4')).toBe('Zeile 1\\nZeile 2\\nZeile 3\\nZeile 4');
	});

	it('escapes the backslash first, so the others are not doubled', () => {
		expect(escapeText(';')).toBe('\\;');
	});
});

describe('foldLine', () => {
	it('leaves a short line alone', () => {
		expect(foldLine('SUMMARY:Konzert')).toBe('SUMMARY:Konzert');
	});

	it('keeps every physical line within 75 octets and unfolds back to the original', () => {
		const line = 'DESCRIPTION:' + 'Probe im Gemeindehaus Süd – bitte Noten mitbringen. '.repeat(6);
		const folded = foldLine(line);
		for (const physical of folded.split('\r\n')) {
			expect(Buffer.byteLength(physical, 'utf8')).toBeLessThanOrEqual(75);
		}
		expect(folded.replace(/\r\n /g, '')).toBe(line);
	});

	it('never splits a multi-byte character', () => {
		const line = 'SUMMARY:' + 'ü'.repeat(80);
		for (const physical of foldLine(line).split('\r\n')) {
			expect(physical.replace(/^ /, '')).toMatch(/^(SUMMARY:)?ü*$/);
			expect(Buffer.byteLength(physical, 'utf8')).toBeLessThanOrEqual(75);
		}
	});
});

describe('convertToIcal', () => {
	it('terminates every line with CRLF', async () => {
		const ical = await convertToIcal([event()]);
		expect(ical.endsWith('END:VCALENDAR\r\n')).toBe(true);
		expect(ical.replace(/\r\n/g, '')).not.toContain('\n');
	});

	it('keeps a multi-line description inside one DESCRIPTION property', async () => {
		const ical = await convertToIcal([event({description: 'Einlass 18:30\nBeginn 19:00; Eintritt frei, Spenden willkommen'})]);
		const lines = unfold(ical);
		expect(lines).toContain('DESCRIPTION:Einlass 18:30\\nBeginn 19:00\\; Eintritt frei\\, Spenden willkommen');
		// Nothing leaked out as a line of its own.
		expect(lines.some((l) => l.startsWith('Beginn'))).toBe(false);
	});

	it('escapes the title and the location too', async () => {
		const lines = unfold(await convertToIcal([event({name: 'Konzert, Teil 2', location: 'Kirche; Karlsruhe'})]));
		expect(lines).toContain('SUMMARY:Konzert\\, Teil 2');
		expect(lines).toContain('LOCATION:Kirche\\; Karlsruhe');
	});

	it('does not escape the URL, but keeps it on one line', async () => {
		const lines = unfold(await convertToIcal([event({url: 'https://nachklang.art/konzert?a=1,2'})]));
		expect(lines).toContain('URL:https://nachklang.art/konzert?a=1,2');
	});

	it('still writes the yearly rule for birthdays', async () => {
		const lines = unfold(await convertToIcal([event({repeatFrequency: 'YEARLY', wholeDay: true})]));
		expect(lines).toContain('RRULE:FREQ=YEARLY');
	});

	it('leaves the event\'s own dates untouched', async () => {
		// formatDate used to add the whole-day end's extra day to the caller's Date in place.
		const whole = event({
			wholeDay: true,
			startDateTime: new Date('2026-10-03T00:00:00'),
			endDateTime: new Date('2026-10-03T23:59:00')
		});
		const endBefore = whole.endDateTime.getTime();
		await convertToIcal([whole]);
		expect(whole.endDateTime.getTime()).toBe(endBefore);
	});
});