import { prop, computed, id } from '../node_modules/frptools/src/index.js';

import { Watcher } from './watcher.js';
import { pouchDocArrayHash } from './utils.js';

// LiveArray is a subscribable property function that always returns the db results that match
// the provided selector and calls subscribers when the results change.
export function LiveArray(db, selector, opts = {}) {
	const mapper = opts.mapper || id;
	opts.mapper && delete opts.mapper;
	opts.include_docs = true;
	const _watcher = Watcher(db, selector, opts);
	let changeSub = null;

	const ready = prop(false);
	const data = prop({ docs: [] });
	const docs = computed(r => r.docs.map(mapper), [data], pouchDocArrayHash);

	const cleanup = () => {
		docs.unsubscribeAll();
		ready.unsubscribeAll();
		if (changeSub) {
			changeSub();
			changeSub = null;
		}
		data({ docs: [] });
	};

	const refresh = async function refresh(...args) {
		data(await db.find({ selector }));
	};

	docs.ready = ready;
	docs.cleanup = cleanup;
	docs.selector = selector;
	docs.db = db;

	refresh()
		.then(() => {
			changeSub = _watcher(refresh);
			ready(true);
		})
		.then(() => {
			ready.unsubscribeAll();
		});
	return docs;
}