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

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

	constructor(private configService: ConfigService) {
		const secret = this.configService.get<string>("JWT_SECRET");
		this.jwtSecret = new TextEncoder().encode(
			secret || "default-secret-change-me-in-production",
		);

		const encKey = this.configService.get<string>("ENCRYPTION_KEY");
		if (!encKey) {
			this.logger.warn(
				"ENCRYPTION_KEY is not defined, using a default insecure key for development",
			);
		}
		const rawKey = encKey || "default-encryption-key-32-chars-";
		this.encryptionKey = new TextEncoder().encode(
			rawKey.padEnd(32, "0").substring(0, 32),
		);
	}

	async encryptContent(content: string): Promise<string> {
		const data = new TextEncoder().encode(content);
		return new jose.CompactEncrypt(data)
			.setProtectedHeader({ alg: "dir", enc: "A256GCM" })
			.encrypt(this.encryptionKey);
	}

	async decryptContent(jwe: string): Promise<string> {
		const { plaintext } = await jose.compactDecrypt(jwe, this.encryptionKey);
		return new TextDecoder().decode(plaintext);
	}

	async signContent(content: string): Promise<string> {
		const data = new TextEncoder().encode(content);
		return new jose.CompactSign(data)
			.setProtectedHeader({ alg: "HS256" })
			.sign(this.jwtSecret);
	}

	async verifyContentSignature(jws: string): Promise<string> {
		const { payload } = await jose.compactVerify(jws, this.jwtSecret);
		return new TextDecoder().decode(payload);
	}

	getPgpEncryptionKey(): string {
		return (
			this.configService.get<string>("PGP_ENCRYPTION_KEY") || "default-pgp-key"
		);
	}
}