import { ArrayBuffers } from '../../io/ArrayBuffers';
import type { Bytes } from '../../io/types';

export interface Block {
	/**
	 * @see https://github.com/openssl/openssl/blob/master/include/openssl/pem.h#L35-L60 openssl/pem.h
	 */
	type:
		| string
		| `${'RSA' | 'DSA'} ${'PRIVATE' | 'PUBLIC'} KEY`
		| `${'X509' | 'TRUSTED'} CERTIFICATE`
		| 'CERTIFICATE'
		| 'X509 CRL'
		| 'CERTIFICATE REQUEST'
		| 'NEW CERTIFICATE REQUEST'
		| 'ANY PRIVATE KEY'
		| 'PUBLIC KEY'
		| 'PKCS7'
		| 'PKCS #7 SIGNED DATA'
		| 'ENCRYPTED PRIVATE KEY'
		| 'PRIVATE KEY'
		| 'DH PARAMETERS'
		| 'X9.42 DH PARAMETERS'
		| 'SSL SESSION PARAMETERS'
		| 'DSA PARAMETERS'
		| 'ECDSA PUBLIC KEY'
		| 'EC PARAMETERS'
		| 'EC PRIVATE KEY'
		| 'PARAMETERS'
		| 'CMS'
		| 'SM2 PARAMETERS';

	header: Record<string, string>;
	bytes: Bytes;
}

export class PEM {
	static decode(data: string): { block: Block; tail: string; head: string } {
		const match = data.match(
			/^-----BEGIN (?<type>[^\r\n-]+)-----$\r?\n(?<headers>(^[^:\r\n]+:[^\n\r]+\r?\n)+\r?\n)?(?<data>[a-zA-Z0-9/_=\n\r+]+?)^-----END \1-----$\r?\n?/ms,
		);
		if (!match?.groups) throw new Error('Invalid PEM data');
		const { type, headers = '', data: b64 } = match.groups;
		const header = headers
			.split('\n')
			.filter((v) => v.trim())
			.map((h) => {
				const [k, ...v] = h.split(':');
				return [k.trim(), v.join(':').trim()];
			})
			.reduce((a, [k, v]) => ({ ...a, [k]: v }), {});
		return {
			block: {
				type,
				header,
				//  avoid replaceAll
				bytes: ArrayBuffers.from(b64.replace(/[\r\n]/g, ''), 'base64', Uint8Array),
			},
			head: data.slice(0, match.index || 0),
			tail: data.slice((match.index || 0) + match[0].length),
		};
	}

	static encode(block: { type: string; bytes: string | BufferSource; header?: Record<string, string> }): string {
		const { type, header, bytes } = block;
		const headers = Object.entries(header || {})
			.map(([k, v]) => `${k}: ${v}`)
			.join('\n');
		return `-----BEGIN ${type}-----\n${headers}${headers.length ? '\n\n' : ''}${
			ArrayBuffers.toString(bytes, 'base64')
				.match(/.{1,64}/g)
				?.join('\n') || ''
		}\n-----END ${type}-----\n`;
	}
}