/**
 * Calendar-link helpers — port of schedule-jeffemmett/src/lib/calendar-links.ts.
 *
 * Used in confirmation emails so guests can add the booking to their calendar
 * with one click, and in `.ics` attachments for Apple Calendar / Outlook.
 */

function formatUtcDate(iso: string): string {
	return new Date(iso).toISOString().replace(/[-:]/g, "").replace(/\.\d{3}/, "");
}

export interface CalLinkParams {
	startUtc: string;
	endUtc: string;
	title: string;
	meetingLink?: string | null;
	guestNote?: string | null;
	locationOverride?: string | null;
}

export function getGoogleCalendarUrl(p: CalLinkParams): string {
	const start = formatUtcDate(p.startUtc);
	const end = formatUtcDate(p.endUtc);
	const details = [p.guestNote ? `Note: ${p.guestNote}` : "", p.meetingLink ? `Join: ${p.meetingLink}` : ""].filter(Boolean).join("\n");
	const q = new URLSearchParams({
		action: "TEMPLATE",
		text: p.title,
		dates: `${start}/${end}`,
		...(details && { details }),
		...(p.meetingLink ? { location: p.meetingLink } : p.locationOverride ? { location: p.locationOverride } : {}),
	});
	return `https://calendar.google.com/calendar/render?${q.toString()}`;
}

export function getOutlookCalendarUrl(p: CalLinkParams): string {
	const body = [p.guestNote ? `Note: ${p.guestNote}` : "", p.meetingLink ? `Join: ${p.meetingLink}` : ""].filter(Boolean).join("\n");
	const q = new URLSearchParams({
		path: "/calendar/action/compose",
		rru: "addevent",
		subject: p.title,
		startdt: new Date(p.startUtc).toISOString(),
		enddt: new Date(p.endUtc).toISOString(),
		...(body && { body }),
		...(p.meetingLink ? { location: p.meetingLink } : {}),
	});
	return `https://outlook.live.com/calendar/0/action/compose?${q.toString()}`;
}

export function getYahooCalendarUrl(p: CalLinkParams): string {
	const start = formatUtcDate(p.startUtc);
	const end = formatUtcDate(p.endUtc);
	const desc = [p.guestNote ? `Note: ${p.guestNote}` : "", p.meetingLink ? `Join: ${p.meetingLink}` : ""].filter(Boolean).join("\n");
	const q = new URLSearchParams({
		v: "60",
		title: p.title,
		st: start,
		et: end,
		...(desc && { desc }),
		...(p.meetingLink ? { in_loc: p.meetingLink } : {}),
	});
	return `https://calendar.yahoo.com/?${q.toString()}`;
}

export interface IcsParams extends CalLinkParams {
	attendees?: string[];
	organizerEmail: string;
	organizerName: string;
	uidDomain?: string;
	method?: "REQUEST" | "PUBLISH" | "CANCEL";
}

export function generateIcsContent(p: IcsParams): string {
	const start = formatUtcDate(p.startUtc);
	const end = formatUtcDate(p.endUtc);
	const uid = `${Date.now()}-${Math.random().toString(36).slice(2)}@${p.uidDomain || "rschedule.rspace.online"}`;
	const stamp = formatUtcDate(new Date().toISOString());

	const description = [p.guestNote ? `Note: ${p.guestNote}` : "", p.meetingLink ? `Join: ${p.meetingLink}` : ""].filter(Boolean).join("\\n");
	const method = p.method ?? (p.attendees?.length ? "REQUEST" : "PUBLISH");

	const lines = [
		"BEGIN:VCALENDAR",
		"VERSION:2.0",
		"PRODID:-//rSchedule//Booking//EN",
		"CALSCALE:GREGORIAN",
		`METHOD:${method}`,
		"BEGIN:VEVENT",
		`UID:${uid}`,
		`DTSTAMP:${stamp}`,
		`DTSTART:${start}`,
		`DTEND:${end}`,
		`SUMMARY:${p.title.replace(/([;,\\\n])/g, "\\$1")}`,
		...(description ? [`DESCRIPTION:${description}`] : []),
		...(p.meetingLink ? [`LOCATION:${p.meetingLink}`, `URL:${p.meetingLink}`] : []),
		`ORGANIZER;CN=${p.organizerName}:mailto:${p.organizerEmail}`,
		`ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=${p.organizerName}:mailto:${p.organizerEmail}`,
		...(p.attendees || []).map((e) => `ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE:mailto:${e}`),
		"END:VEVENT",
		"END:VCALENDAR",
	];
	return lines.join("\r\n");
}