import "./MongoBigInt";
import mongoose, { Collection, Connection } from "mongoose";
import { ChangeStream, ChangeEvent, Long } from "mongodb";
import EventEmitter from "events";
const uri = process.env.MONGO_URL || "mongodb://localhost:27017/fosscord?readPreference=secondaryPreferred";

const connection = mongoose.createConnection(uri, { autoIndex: true });

export default <Connection>connection;

export interface MongooseCache {
	on(event: "delete", listener: (id: string) => void): this;
	on(event: "change", listener: (data: any) => void): this;
	on(event: "insert", listener: (data: any) => void): this;
	on(event: "close", listener: () => void): this;
}

export class MongooseCache extends EventEmitter {
	public stream: ChangeStream;
	public data: any;

	constructor(
		public collection: Collection,
		public pipeline: Array<Record<string, unknown>>,
		public opts: {
			onlyEvents: boolean;
		}
	) {
		super();
	}

	async init() {
		this.stream = this.collection.watch(this.pipeline, { fullDocument: "updateLookup" });

		this.stream.on("change", this.change);
		this.stream.on("close", this.destroy);
		this.stream.on("error", console.error);

		if (!this.opts.onlyEvents) {
			const arr = await this.collection.aggregate(this.pipeline).toArray();
			this.data = arr.length ? arr[0] : arr;
		}
	}

	convertResult(obj: any) {
		if (obj instanceof Long) return BigInt(obj.toString());
		if (typeof obj === "object") {
			Object.keys(obj).forEach((key) => {
				obj[key] = this.convertResult(obj[key]);
			});
		}

		return obj;
	}

	change = (doc: ChangeEvent) => {
		// @ts-ignore
		if (doc.fullDocument) {
			// @ts-ignore
			if (!this.opts.onlyEvents) this.data = doc.fullDocument;
		}

		switch (doc.operationType) {
			case "dropDatabase":
				return this.destroy();
			case "drop":
				return this.destroy();
			case "delete":
				return this.emit("delete", doc.documentKey._id.toHexString());
			case "insert":
				return this.emit("insert", doc.fullDocument);
			case "update":
			case "replace":
				return this.emit("change", doc.fullDocument);
			case "invalidate":
				return this.destroy();
			default:
				return;
		}
	};

	destroy() {
		this.stream.off("change", this.change);
		this.emit("close");

		if (this.stream.isClosed()) return;

		return this.stream.close();
	}
}