import * as _ from './utils'

export class Storage {
	clear(): void {
		_.internalsOf<StorageInternals>(this, 'Storage', 'clear').storage.clear()
	}

	getItem(key: string): string | null {
		return getStringOrNull(
			_.internalsOf<StorageInternals>(this, 'Storage', 'getItem').storage.get(
				String(key)
			)
		)
	}

	key(index: number): string | null {
		return getStringOrNull(
			[
				..._.internalsOf<StorageInternals>(
					this,
					'Storage',
					'key'
				).storage.keys(),
			][Number(index) || 0]
		)
	}

	removeItem(key: string): void {
		_.internalsOf<StorageInternals>(this, 'Storage', 'getItem').storage.delete(
			String(key)
		)
	}

	setItem(key: string, value: any): void {
		_.internalsOf<StorageInternals>(this, 'Storage', 'getItem').storage.set(
			String(key),
			String(value)
		)
	}

	get length() {
		return _.internalsOf<StorageInternals>(this, 'Storage', 'size').storage.size
	}
}

const getStringOrNull = (value: string | void) =>
	typeof value === 'string' ? value : null

export const initStorage = (target: Target, exclude: Set<string>) => {
	if (exclude.has('Storage') || exclude.has('localStorage')) return

	target.localStorage = Object.create(Storage.prototype)

	const storageInternals = new Map<string, string>()

	_.INTERNALS.set(target.localStorage, {
		storage: storageInternals,
	} as StorageInternals)
}

interface StorageInternals {
	storage: Map<string, string>
}

interface Target {
	localStorage: Storage
}