/**
 * Preview access guards.
 *
 * Browser preview handlers all read `projectId` from the connection and grab a
 * project-scoped `BrowserPreviewService` from the manager. Without an explicit
 * project-membership check, a connection that managed to land in another
 * project's room could drive that project's browser. These helpers compose the
 * membership guard with the service lookup so handlers cannot forget either.
 */

import type { WSConnection } from '$shared/utils/ws-server';
import { ws } from '$backend/utils/ws';
import { requireCurrentProjectAccess, requireProjectAccess } from '../access';
import { browserPreviewServiceManager } from '../../preview/index';
import { makeScopeKey, scopeProjectId } from '$shared/utils/workspace-scope';

type PreviewService = ReturnType<typeof browserPreviewServiceManager.getService>;
type Tab = NonNullable<ReturnType<PreviewService['getActiveTab']>>;

export interface BrowserPreviewContext {
	userId: string;
	projectId: string;
	previewService: PreviewService;
}

export function requireBrowserPreviewAccess(conn: WSConnection): BrowserPreviewContext {
	const { userId, projectId } = requireCurrentProjectAccess(conn);
	// Tabs are scoped to the tree being viewed, so a worktree's preview never
	// shows the main project's pages.
	const previewService = browserPreviewServiceManager.getService(
		makeScopeKey(projectId, ws.getWorktreeId(conn))
	);
	return { userId, projectId, previewService };
}

/**
 * Resolve preview access for an explicitly-supplied project, after verifying
 * the caller is a member. Used by session-recovery reads (tab list / switch)
 * that fire during a project switch: the connection's room context may not have
 * caught up yet (the context-sync round-trip can resolve via timeout), so
 * trusting it would recover the *previous* project's tabs. Passing the target
 * projectId explicitly makes recovery deterministic.
 */
export function requireBrowserPreviewAccessFor(
	conn: WSConnection,
	scopeKey: string
): BrowserPreviewContext {
	// The caller passes a workspace scope key; membership is always decided on
	// the project it belongs to.
	const projectId = scopeProjectId(scopeKey);
	requireProjectAccess(conn, projectId); // throws if the caller isn't a member
	const userId = ws.getUserId(conn);
	const previewService = browserPreviewServiceManager.getService(scopeKey);
	return { userId, projectId, previewService };
}

/**
 * Resolve a tab in the caller's project. If `tabId` is omitted the active tab
 * is returned. Throws if the caller can't access the project, or if no tab
 * matches.
 */
export function requireBrowserTabAccess(
	conn: WSConnection,
	tabId?: string
): BrowserPreviewContext & { tab: Tab } {
	const ctx = requireBrowserPreviewAccess(conn);
	const tab = tabId ? ctx.previewService.getTab(tabId) : ctx.previewService.getActiveTab();
	if (!tab) {
		throw new Error(tabId ? `Tab not found: ${tabId}` : 'No active tab');
	}
	return { ...ctx, tab };
}