import { Injectable, Logger } from "@nestjs/common";
import { ConfigService } from "@nestjs/config";
import * as jose from "jose";

@Injectable()
export class JwtService {
	private readonly logger = new Logger(JwtService.name);
	private readonly jwtSecret: Uint8Array;

	constructor(private configService: ConfigService) {
		const secret = this.configService.get<string>("JWT_SECRET");
		if (!secret) {
			this.logger.warn(
				"JWT_SECRET is not defined, using a default insecure secret for development",
			);
		}
		this.jwtSecret = new TextEncoder().encode(
			secret || "default-secret-change-me-in-production",
		);
	}

	async generateJwt(
		payload: jose.JWTPayload,
		expiresIn = "2h",
	): Promise<string> {
		return new jose.SignJWT(payload)
			.setProtectedHeader({ alg: "HS256" })
			.setIssuedAt()
			.setExpirationTime(expiresIn)
			.sign(this.jwtSecret);
	}

	async verifyJwt<T extends jose.JWTPayload>(token: string): Promise<T> {
		const { payload } = await jose.jwtVerify(token, this.jwtSecret);
		return payload as T;
	}
}