import { by_character, by_lurid } from '@andyburke/fsdb/organizers';
import { FSDB_COLLECTION } from '@andyburke/fsdb';
import { FSDB_INDEXER_SYMLINKS } from '@andyburke/fsdb/indexers';

/**
 * @typedef {object} TIMESTAMPS
 * @property {string} created		when the event was created
 * @property {string} updated		when the event was last updated
 */

/**
 * Event
 *
 * @property {string} id					- lurid
 * @property {string} creator_id			- id of the source user
 * @property {string} type					- event type
 * @property {string} [parent_id]			- optional parent event id
 * @property {string[]} [tags]				- optional event tags
 * @property {Record<string,any>} [data]	- optional data payload of the event
 * @property {TIMESTAMPS} timestamps		- timestamps that will be set by the server
 */
export type EVENT = {
	id: string;
	creator_id: string;
	type: string;
	parent_id?: string;
	tags?: string[];
	data?: Record<string, any>;
	timestamps: {
		created: string;
		updated: string;
	};
};

type TOPIC_EVENT_CACHE_ENTRY = {
	collection: FSDB_COLLECTION<EVENT>;
	eviction_timeout: number;
};

const TOPIC_EVENT_ID_MATCHER = /^(?<event_type>.*):(?<event_id>.*)$/;

const TOPIC_EVENTS: Record<string, TOPIC_EVENT_CACHE_ENTRY> = {};
export function get_events_collection_for_topic(topic_id: string): FSDB_COLLECTION<EVENT> {
	TOPIC_EVENTS[topic_id] = TOPIC_EVENTS[topic_id] ?? {
		collection: new FSDB_COLLECTION<EVENT>({
			name: `topics/${topic_id.slice(0, 14)}/${topic_id.slice(0, 34)}/${topic_id}/events`,
			id_field: 'id',
			organize: (id) => {
				TOPIC_EVENT_ID_MATCHER.lastIndex = 0;

				const {
					groups: {
						event_type,
						event_id
					}
				} = TOPIC_EVENT_ID_MATCHER.exec(id ?? '') ?? {
					groups: {}
				};

				return [
					event_type,
					event_id.slice(0, 14),
					event_id.slice(0, 34),
					event_id,
					`${event_id}.json`
				];
			},
			indexers: {
				creator_id: new FSDB_INDEXER_SYMLINKS<EVENT>({
					name: 'creator_id',
					field: 'creator_id',
					to_many: true,
					organize: by_lurid
				}),

				tags: new FSDB_INDEXER_SYMLINKS<EVENT>({
					name: 'tags',
					get_values_to_index: (event: EVENT): string[] => {
						return (event.tags ?? []).map((tag: string) => tag.toLowerCase());
					},
					to_many: true,
					organize: by_character
				})
			}
		}),
		eviction_timeout: 0
	};

	if (TOPIC_EVENTS[topic_id].eviction_timeout) {
		clearTimeout(TOPIC_EVENTS[topic_id].eviction_timeout);
	}

	TOPIC_EVENTS[topic_id].eviction_timeout = setTimeout(() => {
		delete TOPIC_EVENTS[topic_id];
	}, 60_000 * 5);

	return TOPIC_EVENTS[topic_id].collection;
}

export function clear_topic_events_cache() {
	for (const [topic_id, cached] of Object.entries(TOPIC_EVENTS)) {
		if (cached.eviction_timeout) {
			clearTimeout(cached.eviction_timeout);
		}
		delete TOPIC_EVENTS[topic_id];
	}
}