/**
 * rCal → markwhen projection.
 *
 * Maps `CalendarEvent` records to `MwEvent`. Handles:
 *   - all-day events (normalized to date-only via midnight-UTC)
 *   - per-event timezone (passes through to MwEvent.timezone)
 *   - virtual vs physical events (location shown in description)
 *   - tags: existing event tags + booking status + source name
 *
 * NOT handled yet (future work, flagged in markwhen_integration spec):
 *   - RRULE expansion — only stored master events are emitted.
 *     For recurring, expand the next N instances via rrule.js first.
 */

import type { MarkwhenSourceFactory, MwEvent, MwSource } from '../types';
import type { CalendarDoc, CalendarEvent } from '../../../modules/rcal/schemas';
import { calendarDocId } from '../../../modules/rcal/schemas';
import { loadDoc } from '../doc-loader'; // thin wrapper around local-first storage

const SECTION_LABEL = 'Calendar';
const SECTION_TAG = 'rcal';

function eventToMw(ev: CalendarEvent): MwEvent | null {
	if (!ev.startTime) return null;
	const start = ev.allDay ? Math.floor(ev.startTime / 86_400_000) * 86_400_000 : ev.startTime;
	const end = ev.endTime && ev.endTime > ev.startTime
		? (ev.allDay ? Math.floor(ev.endTime / 86_400_000) * 86_400_000 : ev.endTime)
		: undefined;

	const tags = [...(ev.tags ?? [])];
	if (ev.bookingStatus) tags.push(ev.bookingStatus);
	if (ev.sourceType && ev.sourceType !== 'local') tags.push(ev.sourceType);
	if (ev.isVirtual) tags.push('virtual');

	const descParts: string[] = [];
	if (ev.description) descParts.push(ev.description.slice(0, 500));
	if (ev.locationName) descParts.push(`📍 ${ev.locationName}`);
	else if (ev.locationBreadcrumb) descParts.push(`📍 ${ev.locationBreadcrumb}`);
	if (ev.isVirtual && ev.virtualUrl) descParts.push(`🔗 ${ev.virtualUrl}`);
	if (ev.attendeeCount) descParts.push(`👥 ${ev.attendeeCount} attendee(s)`);

	return {
		start,
		end,
		title: ev.title || '(untitled)',
		description: descParts.length > 0 ? descParts.join('\n') : undefined,
		tags: tags.length > 0 ? tags : undefined,
		timezone: ev.timezone ?? undefined,
		sourceId: `rcal:ev:${ev.id}`,
	};
}

export const rcalMarkwhenSource: MarkwhenSourceFactory = {
	module: 'rcal',
	label: 'Calendar',
	icon: '📅',
	async build({ space, from, to }): Promise<MwSource | null> {
		const doc = await loadDoc<CalendarDoc>(calendarDocId(space));
		if (!doc) return null;

		const events: MwEvent[] = [];
		for (const ev of Object.values(doc.events)) {
			if (from !== undefined && ev.endTime && ev.endTime < from) continue;
			if (to !== undefined && ev.startTime && ev.startTime > to) continue;
			const mw = eventToMw(ev);
			if (mw) events.push(mw);
		}

		return {
			id: 'rcal',
			label: SECTION_LABEL,
			tag: SECTION_TAG,
			color: 'blue',
			events,
		};
	},
};