export type LocalAwarenessState = object | null;

export type AwarenessState = Record< string, LocalAwarenessState >;

/**
 * Update types for the sync protocol:
 * - sync_step1: State vector announcement
 * - sync_step2: Acknowledgment, missing updates response
 * - update: Regular document update (persisted until save)
 * - compaction: Merged updates using Y.mergeUpdates replacing all prior updates
 */
export enum SyncUpdateType {
	COMPACTION = 'compaction',
	SYNC_STEP_1 = 'sync_step1',
	SYNC_STEP_2 = 'sync_step2',
	UPDATE = 'update',
}

export interface SyncUpdate {
	data: string; // base64-encoded Yjs update
	type: SyncUpdateType;
}

interface SyncEnvelopeFromClient {
	after: number;
	awareness: LocalAwarenessState;
	client_id: number;
	room: string;
	updates: SyncUpdate[];
}

interface SyncEnvelopeFromServer {
	awareness: AwarenessState;
	compaction_request?: SyncUpdate[]; // deprecated
	end_cursor: number; // use as `after` in next request
	should_compact?: boolean;
	room: string;
	updates: SyncUpdate[];
}

export interface SyncPayload {
	rooms: SyncEnvelopeFromClient[];
}

export interface SyncResponse {
	rooms: SyncEnvelopeFromServer[];
}

export interface UpdateQueue {
	add: ( update: SyncUpdate ) => void;
	addBulk: ( updates: SyncUpdate[] ) => void;
	clear: () => void;
	get: () => SyncUpdate[];
	pause: () => void;
	restore: ( updates: SyncUpdate[] ) => void;
	resume: () => void;
	size: () => number;
}