import { by_character, by_lurid } from '@andyburke/fsdb/organizers';
import { FSDB_COLLECTION } from '@andyburke/fsdb';
import { FSDB_INDEXER_SYMLINKS } from '@andyburke/fsdb/indexers';
import { EMOJIS } from '../public/js/emojis/en.ts';

/**
 * @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;
};

// TODO: separate out these different validators somewhere?
export function VALIDATE_EVENT(event: EVENT) {
	const errors: any[] = [];

	const [type, id] = (event.id ?? '').split(':', 2);

	if (typeof type !== 'string' || type.length === 0) {
		errors.push({
			cause: 'missing_event_type_in_id',
			message: 'An event must have a type that is also encoded into its id, eg: chat:able-fish-wife...'
		});
	}

	if (typeof id !== 'string' || id.length !== 49) {
		errors.push({
			cause: 'invalid_event_id',
			message: 'An event must have a type and a lurid id, eg: chat:able-fish-gold-wing-trip-form-seed-cost-rope-wife'
		});
	}

	switch (event.type) {
		case 'chat':
			if (event.data?.message?.length <= 0) {
				errors.push({
					cause: 'chat_message_missing',
					message: 'A chat message event cannot be empty.'
				});
			}
			break;
		case 'post':
			if (event.data?.subject?.length <= 0) {
				errors.push({
					cause: 'post_missing_subject',
					message: 'A post cannot have an empty subject.'
				});
			}
			break;
		case 'blurb':
			if (event.data?.blurb?.length <= 0) {
				errors.push({
					cause: 'blurb_missing',
					message: 'A blurb cannot be empty.'
				});
			} else if (event.data?.blurb?.length > 2 ** 8) {
				errors.push({
					cause: 'blurb_length_limit_exceeded',
					message: 'A blurb cannot be longer than 256 characters.'
				});
			}
			break;
		case 'essay':
			if (event.data?.title?.length <= 0) {
				errors.push({
					cause: 'essay_title_missing',
					message: 'An essay must have a title.'
				});
			} else if (event.data?.title?.length > 2 ** 7) {
				errors.push({
					cause: 'essay_title_length_limit_exceeded',
					message: 'An essay title cannot be longer than 128 characters.'
				});
			} else if (event.data?.essay?.length <= 0) {
				errors.push({
					cause: 'essay_missing',
					message: 'An essay cannot be empty.'
				});
			} else if (event.data?.essay?.length > 2 ** 16) {
				errors.push({
					cause: 'essay_length_limit_exceeded',
					message: 'An essay cannot be longer than 65536 characters - that would be a screed, which we do not yet support.'
				});
			}
			break;
		case 'reaction':
			if (typeof event.parent_id !== 'string') {
				errors.push({
					cause: 'reaction_missing_parent_id',
					message: 'A reaction must have a parent_id that refers to another event.'
				});
			} else if (typeof event.data?.reaction !== 'string') {
				errors.push({
					cause: 'reaction_must_be_an_emoji',
					message: 'A reaction event must have a `data.reaction` that is an emoji.'
				});
			} else if (typeof EMOJIS.MAP[event.data?.reaction] === 'undefined') {
				errors.push({
					cause: 'reaction_must_be_an_emoji',
					message: 'A reaction event must have a `data.reaction` that is an emoji.'
				});
			}
			break;
		case 'test':
			if (Deno.env.get('DENO_ENV') !== 'test') {
				errors.push({
					cause: 'unknown_event_type',
					message: 'Event types allowed: ' + ['chat', 'post', 'blurb', 'essay', 'reaction'].join(', ')
				});
			}
			break;
		default:
			errors.push({
				cause: 'unknown_event_type',
				message: 'Event types allowed: ' + ['chat', 'post', 'blurb', 'essay', 'reaction'].join(', ')
			});
			break;
	}

	return errors.length ? errors : undefined;
}

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: Record<string, string> | undefined = TOPIC_EVENT_ID_MATCHER.exec(id ?? '')?.groups;

				if (!groups) {
					throw new Error('Could not parse event id: ' + id);
				}

				const event_type = groups.event_type;
				const event_id = groups.event_id;

				return [
					event_type,
					event_id.slice(0, 14),
					event_id.slice(0, 34),
					event_id,
					`${event_id}.json` /* TODO: this should be ${id}.json - need to write a converter */
				];
			},
			indexers: {
				creator_id: new FSDB_INDEXER_SYMLINKS<EVENT>({
					name: 'creator_id',
					field: 'creator_id',
					to_many: true,
					organize: by_lurid
				}),

				parent_id: new FSDB_INDEXER_SYMLINKS<EVENT>({
					name: 'parent_id',
					field: 'parent_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];
	}
}