import { ZodError } from "dbtype";
import type { Context, Next } from "koa";

export interface ErrorFormat {
	code: number;
	message: string;
	detail?: string;
}

class ClientRequestError implements Error {
	name: string;
	message: string;
	stack?: string | undefined;
	code: number;

	constructor(code: number, message: string) {
		this.name = "client request error";
		this.message = message;
		this.code = code;
	}
}

const code_to_message_table: { [key: number]: string | undefined } = {
	400: "BadRequest",
	404: "NotFound",
};

export const error_handler = async (ctx: Context, next: Next) => {
	try {
		await next();
	} catch (err) {
		if (err instanceof ClientRequestError) {
			const body: ErrorFormat = {
				code: err.code,
				message: code_to_message_table[err.code] ?? "",
				detail: err.message,
			};
			ctx.status = err.code;
			ctx.body = body;
		} 
		else if (err instanceof ZodError) {
			const body: ErrorFormat = {
				code: 400,
				message: "BadRequest",
				detail: err.errors.map((x) => x.message).join(", "),
			};
			ctx.status = 400;
			ctx.body = body;
		}
		else {
			throw err;
		}
	}
};

export const sendError = (code: number, message?: string) => {
	throw new ClientRequestError(code, message ?? "");
};

export default error_handler;