import { readFile, writeFile } from "node:fs/promises";
import { Schedule } from "~/shared/types/schedule";
import { generateDemoSchedule } from "./generate-demo-schedule";
import { Subscription } from "~/shared/types/account";

// For this demo I'm just storing the runtime data in JSON files. When making
// this into proper application this should be replaced with an actual database.

const schedulePath = "data/schedule.json";
const subscriptionsPath = "data/subscriptions.json";

async function readJson<T>(filePath: string, fallback: T) {
	let data: T extends () => infer R ? R : T;
	try {
		data = JSON.parse(await readFile(filePath, "utf-8"));
	} catch (err: any) {
		if (err.code !== "ENOENT")
			throw err;
		data = typeof fallback === "function" ? fallback() : fallback;
	}
	return data;
}

export async function readSchedule() {
	return readJson(schedulePath, generateDemoSchedule);
}

export async function writeSchedule(schedule: Schedule) {
	await writeFile(schedulePath, JSON.stringify(schedule, undefined, "\t") + "\n", "utf-8");
}

export async function readSubscriptions() {
	let subscriptions = await readJson<Subscription[]>(subscriptionsPath, []);
	if (subscriptions.length && "keys" in subscriptions[0]) {
		// Discard old format
		subscriptions = [];
	}
	return subscriptions;
}

export async function writeSubscriptions(subscriptions: Subscription[]) {
	await writeFile(subscriptionsPath, JSON.stringify(subscriptions, undefined, "\t") + "\n", "utf-8");
}