import { AsyncStorage } from 'react-native'
// https://aws-amplify.github.io/docs/js/authentication#using-components-in-react--react-native

const MEMORY_KEY_PREFIX = '@MyStorage:'
let dataMemory = {}

/** @class */
class MyStorage {
	static syncPromise = null
	/**
	 * This is used to set a specific item in storage
	 */
	static setItem(key, value) {
		AsyncStorage.setItem(MEMORY_KEY_PREFIX + key, value)
		dataMemory[key] = value
		return dataMemory[key]
	}

	/**
	 * This is used to get a specific key from storage
	 */
	static getItem(key) {
		return Object.prototype.hasOwnProperty.call(dataMemory, key) ? dataMemory[key] : undefined
	}

	/**
	 * This is used to remove an item from storage
	 */
	static removeItem(key) {
		AsyncStorage.removeItem(MEMORY_KEY_PREFIX + key)
		return delete dataMemory[key]
	}

	/**
	 * This is used to clear the storage
	 */
	static clear() {
		dataMemory = {}
		return dataMemory
	}

	/**
	 * Will sync the MemoryStorage data from AsyncStorage to storageWindow MemoryStorage
	 */
	static sync() {
		if (!MemoryStorage.syncPromise) {
			MemoryStorage.syncPromise = new Promise((res, rej) => {
				AsyncStorage.getAllKeys((errKeys, keys) => {
					if (errKeys) rej(errKeys)
					const memoryKeys = keys.filter(key => key.startsWith(MEMORY_KEY_PREFIX))
					AsyncStorage.multiGet(memoryKeys, (err, stores) => {
						if (err) rej(err)
						stores.map((result, index, store) => {
							const key = store[index][0]
							const value = store[index][1]
							const memoryKey = key.replace(MEMORY_KEY_PREFIX, '')
							dataMemory[memoryKey] = value
						})
						res()
					})
				})
			})
		}
		return MemoryStorage.syncPromise
	}
}