portfolio/packages/gallery/src/services/db.js

import core from 'pouchdb-core';
import idb from 'pouchdb-adapter-idb';
import http from 'pouchdb-adapter-http';
import replication from 'pouchdb-replication';
import find from 'pouchdb-find';

import { log, warn } from './console.js';
import { isObject } from '../utils/comparators.js';
import { LiveArray } from '../utils/livearray.js';
import { Watcher } from '../utils/watcher.js';
import { deepAssign, pouchDocHash } from '../utils/conversion.js';

export const PouchDB = core
	.plugin(idb)
	.plugin(http)
	.plugin(replication)
	.plugin(find)
	.plugin(PouchORM);

export class TypeSpec {
	constructor(props) {
		this._populateId(props);
		Object.assign(this, { $links: {} }, props, { type: this._prefix });
	}

	static getUniqueID(doc) {
		throw 'NotImplemented';
	}

	static validate(doc) {}

	instantiate(doc) {
		return new this._cls(docs);
	}

	_populateId(doc) {
		if (!doc._id) {
			doc._id = `${this._prefix}_${this._cls.getUniqueID(doc)}`;
		}
		return doc;
	}

	_hash() {
		return pouchDocHash(this);
	}

	async delete() {
		return await this.update({ _deleted: true });
	}

	async save() {
		this._cls.validate(this);
		const { rev } = await this._db.put(this);
		this._rev = rev;
		return this;
	}

	async addAttachment(attName, dataBlob) {
		const { rev } = await this._db.putAttachment(
			this._id,
			attName,
			this._rev,
			dataBlob,
			dataBlob.type
		);

		this._rev = rev;
		return this;
	}

	async getAttachment(attName) {
		return await this._db.getAttachment(this._id, attName);
	}

	async removeAttachment(attName) {
		return await this._db.removeAttachment(this._id, attName, this._rev);
	}

	async update(props, save = true) {
		deepAssign(this, props);
		if (save) {
			await this.save();
		}
		return this;
	}
}

export function PouchORM(PouchDB) {
	PouchDB.registerType = (name, cls, db) => {
		const prefix = name.toLowerCase();
		const _db = db || PouchDB(prefix);
		_db.setMaxListeners(1000);
		const _baseSelector = Object.freeze({
			_id: { $gt: `${prefix}_0`, $lt: `${prefix}_\ufff0` }
		});
		const watch = Watcher(_db, _baseSelector, { include_docs: true });

		if (!cls.hasOwnProperty('validate')) {
			warn(`${cls.name} has no validation.`);
		}

		const instantiate = doc => new cls(doc);

		async function find(idOrSelector, opts = {}) {
			if (typeof idOrSelector === 'string') {
				return instantiate(await _db.get(idOrSelector));
			}

			const isSelector = isObject(idOrSelector);

			const selector = Object.assign(
				isSelector && idOrSelector._deleted ? { _deleted: true } : { _deleted: { exists: false } },
				isSelector ? idOrSelector : _baseSelector
			);
			if (opts.index) {
				opts.use_index = [prefix, opts.index];
				delete opts.index;
			}
			if (opts.live) {
				opts.mapper = instantiate;
				return LiveArray(_db, idOrSelector, opts);
			}
			return (await _db.find(Object.assign({ selector: idOrSelector }, opts))).docs.map(instantiate);
		}

		async function getOrCreate(props) {
			let doc = await new cls(props);
			try {
				await doc.save();
			} catch (e) {
				if (e.status !== 409) {
					throw e;
				}
				doc = await find(doc._id);
			}
			return doc;
		}

		async function _delete(id) {
			try {
				const doc = await find(id);
				doc._deleted = true;
				await _db.put(doc);
			} catch (e) {
				if (e.status !== 404) {
					throw e;
				}
			}
		}

		async function _index(name, fields) {
			return _db.createIndex({
				index: {
					ddoc: prefix,
					fields,
					name
				}
			});
		}

		Object.defineProperties(cls.prototype, {
			_name: { value: name },
			_prefix: { value: prefix },
			_db: { value: _db },
			_cls: { value: cls },
			_baseSelector: { value: _baseSelector }
		});

		Object.defineProperties(cls, {
			getOrCreate: { value: getOrCreate },
			find: { value: find },
			index: { value: _index },
			delete: { value: _delete },
			subscribe: { value: watch },
			db: { value: _db },
			name: { value: name },
			prefix: { value: prefix },
			selector: { value: _baseSelector }
		});

		return cls;
	};
}