import type { WrappedBuffer } from "@sammo/util";

const crypto = globalThis.crypto;

export function randomBytes(length: number): Buffer {
	const buffer = Buffer.alloc(length);
	crypto.getRandomValues(buffer);
	return buffer;
}

//TODO: 필요할때마다 확장
export type ValidPEMType = 'PUBLIC KEY' | 'EC PRIVATE KEY' | 'CERTIFICATE';

/**
 * PEM string에 내부 타입으로 WrappedBuffer를 보관한 형태
 */
// eslint-disable-next-line @typescript-eslint/ban-types
export type PEMString<T extends Buffer, S extends ValidPEMType> = string & {
	/** 타입구분자. 항상 undefined일 것이다 */
	_pem_b_type?: T;
	_pem_type?: S;
}

export function encodePEM<T extends WrappedBuffer, S extends ValidPEMType>(data: T, pemType: S): PEMString<T, S>;
export function encodePEM(data: Buffer, pemType: ValidPEMType): string;
export function encodePEM(data: Buffer, pemType: ValidPEMType): string {
	const base64text = data.toString('base64');
	const splitText = base64text.match(/.{1,64}/g)?.join('\n') ?? '';

	return `-----BEGIN ${pemType}-----
${splitText}
-----END ${pemType}-----
`;
}


// eslint-disable-next-line @typescript-eslint/no-explicit-any
type InferPEMType<T extends PEMString<any, any>> = Exclude<undefined, T['_pem_type']>;
// eslint-disable-next-line @typescript-eslint/no-explicit-any
type InferPEMBuffer<T extends PEMString<any, any>> = Exclude<undefined, T['_pem_b_type']>;

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export function decodePEM<T extends PEMString<any, any>>(pem: T, pemType: InferPEMType<T>): InferPEMBuffer<T>[];
export function decodePEM(pem: string, pemType?: ValidPEMType): Buffer[];
export function decodePEM(pem: string, pemType?: ValidPEMType): Buffer[] {
	const tag = pemType ?? "[A-Z0-9 ]+";
	const pattern = new RegExp(`-{5}BEGIN ${tag}-{5}([a-zA-Z0-9=+\\/\\n\\r]+)-{5}END ${tag}-{5}`, "g");

	const res: Buffer[] = [];
	let matches: RegExpExecArray | null = null;
	// eslint-disable-next-line no-cond-assign
	while (matches = pattern.exec(pem)) {
		const base64 = matches[1]
			.replace(/\r/g, "")
			.replace(/\n/g, "");
		res.push(Buffer.from(base64, 'base64'));
	}

	return res;
}



// eslint-disable-next-line @typescript-eslint/no-explicit-any
export function decodeSinglePEM<T extends PEMString<any, any>>(pem: T, pemType: InferPEMType<T>): InferPEMBuffer<T>;
export function decodeSinglePEM(pem: string, pemType?: ValidPEMType): Buffer;
export function decodeSinglePEM(pem: string, pemType?: ValidPEMType): Buffer {
	const res = decodePEM(pem, pemType);
	if (res.length != 1) {
		throw new Error("invalid pem");
	}
	return res[0];
}