/**
 * Public event presentation config: the colour theme and the comments feature flag,
 * served unauthenticated from `GET /api/v1/event`. Loaded once on boot (and refreshed
 * on the `event-updated` SSE) so the theme applies before the user has even joined and
 * the comment UI reflects the instance setting.
 *
 * The resolved theme CSS is cached in localStorage so the boot script in app.html can
 * paint the right colours before the JS bundle loads (no flash of the default palette).
 */
import { writable } from 'svelte/store';
import { buildPaletteCss, applyPaletteCss, type ThemeConfig } from './theme/palette';

export const PALETTE_CACHE_KEY = 'eventsnap_palette_css';

export type EventConfig = {
	name: string;
	slug: string;
	commentsEnabled: boolean;
	theme: ThemeConfig;
};

export const eventConfig = writable<EventConfig | null>(null);
/** Convenience flag for the comment UI. Optimistic `true` until /event resolves. */
export const commentsEnabled = writable<boolean>(true);

/** Fetch /event, apply the theme, and cache the resolved CSS for the next boot. */
export async function loadEventConfig(): Promise<void> {
	try {
		const res = await fetch('/api/v1/event');
		if (!res.ok) return;
		const b = await res.json();
		const theme: ThemeConfig = {
			preset: b.theme_preset ?? 'champagne-gold',
			primary: b.theme_primary ?? '#8a6a2b',
			accent: b.theme_accent ?? '#8a6a2b'
		};
		eventConfig.set({
			name: b.name,
			slug: b.slug,
			commentsEnabled: b.comments_enabled ?? true,
			theme
		});
		commentsEnabled.set(b.comments_enabled ?? true);

		const css = buildPaletteCss(theme);
		applyPaletteCss(css);
		try {
			localStorage.setItem(PALETTE_CACHE_KEY, css);
		} catch {
			/* private mode / quota — the theme still applied for this session */
		}
	} catch {
		/* offline / server down — keep whatever the boot script already painted */
	}
}

/** Apply a theme immediately without persisting — used by the admin live preview. */
export function previewTheme(theme: ThemeConfig): void {
	applyPaletteCss(buildPaletteCss(theme));
}