import { existsSync, readFileSync, writeFileSync, mkdirpSync } from "fs-extra";
import { dirname } from "path";

export default class FileBasedMap<T> extends Map<string, T> {
	constructor(private filePath: string) {
		super()

		this.load()
	}

	private load() {
		super.clear() // clear in-memory map

		if (existsSync(this.filePath) === false) {
			mkdirpSync(dirname(this.filePath))
			writeFileSync(this.filePath, "{}")
		}
		const content = readFileSync(this.filePath)
		const data: { [key: string]: T } = JSON.parse(content.toString())
		// load into the map
		Object.keys(data).forEach((key) => super.set(key, data[key]))
	}

	private dump() {
		const data = Array.from(super.keys()).reduce((data, key) => {
			data[key] = super.get(key)
			return data
		}, {} as any);

		writeFileSync(this.filePath, JSON.stringify(data, null, 4))
	}

	set(key: string, value: T) {
		super.set(key, value)
		this.dump()
		return this
	}
	clear() {
		super.clear()
		this.dump()
	}

	delete(key: string): boolean {
		const deleted = super.delete(key)
		if (deleted) this.dump()
		return deleted
	}
}