'use strict';

var x509 = module.exports;
var ASN1 = require('./asn1/packer.js');
var Asn1 = ASN1.Any;
var UInt = ASN1.UInt;
var BitStr = ASN1.BitStr;
var Enc = require('omnibuffer');

// 1.2.840.10045.3.1.7
// prime256v1 (ANSI X9.62 named elliptic curve)
var OBJ_ID_EC = '06 08 2A8648CE3D030107'.replace(/\s+/g, '').toLowerCase();
// 1.3.132.0.34
// secp384r1 (SECG (Certicom) named elliptic curve)
var OBJ_ID_EC_384 = '06 05 2B81040022'.replace(/\s+/g, '').toLowerCase();
// 1.2.840.10045.2.1
// ecPublicKey (ANSI X9.62 public key type)
var OBJ_ID_EC_PUB = '06 07 2A8648CE3D0201'.replace(/\s+/g, '').toLowerCase();

x509.parseSec1 = function parseEcOnlyPrivkey(u8, jwk) {
	var index = 7;
	var len = 32;
	var olen = OBJ_ID_EC.length / 2;

	if ('P-384' === jwk.crv) {
		olen = OBJ_ID_EC_384.length / 2;
		index = 8;
		len = 48;
	}
	if (len !== u8[index - 1]) {
		throw new Error('Unexpected bitlength ' + len);
	}

	// private part is d
	var d = u8.slice(index, index + len);
	// compression bit index
	var ci = index + len + 2 + olen + 2 + 3;
	var c = u8[ci];
	var x, y;

	if (0x04 === c) {
		y = u8.slice(ci + 1 + len, ci + 1 + len + len);
	} else if (0x02 !== c) {
		throw new Error('not a supported EC private key');
	}
	x = u8.slice(ci + 1, ci + 1 + len);

	return {
		kty: jwk.kty,
		crv: jwk.crv,
		d: Enc.bufToUrlBase64(d),
		//, dh: Enc.bufToHex(d)
		x: Enc.bufToUrlBase64(x),
		//, xh: Enc.bufToHex(x)
		y: Enc.bufToUrlBase64(y)
		//, yh: Enc.bufToHex(y)
	};
};

x509.packPkcs1 = function(jwk) {
	var n = UInt(Enc.base64ToHex(jwk.n));
	var e = UInt(Enc.base64ToHex(jwk.e));

	if (!jwk.d) {
		return Enc.hexToBuf(Asn1('30', n, e));
	}

	return Enc.hexToBuf(
		Asn1(
			'30',
			UInt('00'),
			n,
			e,
			UInt(Enc.base64ToHex(jwk.d)),
			UInt(Enc.base64ToHex(jwk.p)),
			UInt(Enc.base64ToHex(jwk.q)),
			UInt(Enc.base64ToHex(jwk.dp)),
			UInt(Enc.base64ToHex(jwk.dq)),
			UInt(Enc.base64ToHex(jwk.qi))
		)
	);
};

x509.parsePkcs8 = function parseEcPkcs8(u8, jwk) {
	var index = 24 + OBJ_ID_EC.length / 2;
	var len = 32;
	if ('P-384' === jwk.crv) {
		index = 24 + OBJ_ID_EC_384.length / 2 + 2;
		len = 48;
	}

	//console.log(index, u8.slice(index));
	if (0x04 !== u8[index]) {
		//console.log(jwk);
		throw new Error('privkey not found');
	}
	var d = u8.slice(index + 2, index + 2 + len);
	var ci = index + 2 + len + 5;
	var xi = ci + 1;
	var x = u8.slice(xi, xi + len);
	var yi = xi + len;
	var y;
	if (0x04 === u8[ci]) {
		y = u8.slice(yi, yi + len);
	} else if (0x02 !== u8[ci]) {
		throw new Error('invalid compression bit (expected 0x04 or 0x02)');
	}

	return {
		kty: jwk.kty,
		crv: jwk.crv,
		d: Enc.bufToUrlBase64(d),
		//, dh: Enc.bufToHex(d)
		x: Enc.bufToUrlBase64(x),
		//, xh: Enc.bufToHex(x)
		y: Enc.bufToUrlBase64(y)
		//, yh: Enc.bufToHex(y)
	};
};

x509.parseSpki = function parsePem(u8, jwk) {
	var ci = 16 + OBJ_ID_EC.length / 2;
	var len = 32;

	if ('P-384' === jwk.crv) {
		ci = 16 + OBJ_ID_EC_384.length / 2;
		len = 48;
	}

	var c = u8[ci];
	var xi = ci + 1;
	var x = u8.slice(xi, xi + len);
	var yi = xi + len;
	var y;
	if (0x04 === c) {
		y = u8.slice(yi, yi + len);
	} else if (0x02 !== c) {
		throw new Error('not a supported EC private key');
	}

	return {
		kty: jwk.kty,
		crv: jwk.crv,
		x: Enc.bufToUrlBase64(x),
		//, xh: Enc.bufToHex(x)
		y: Enc.bufToUrlBase64(y)
		//, yh: Enc.bufToHex(y)
	};
};
x509.parsePkix = x509.parseSpki;

x509.packSec1 = function(jwk) {
	var d = Enc.base64ToHex(jwk.d);
	var x = Enc.base64ToHex(jwk.x);
	var y = Enc.base64ToHex(jwk.y);
	var objId = 'P-256' === jwk.crv ? OBJ_ID_EC : OBJ_ID_EC_384;
	return Enc.hexToBuf(
		Asn1(
			'30',
			UInt('01'),
			Asn1('04', d),
			Asn1('A0', objId),
			Asn1('A1', BitStr('04' + x + y))
		)
	);
};
/**
 * take a private jwk and creates a der from it
 * @param {*} jwk
 */
x509.packPkcs8 = function(jwk) {
	if ('RSA' === jwk.kty) {
		if (!jwk.d) {
			// Public RSA
			return Enc.hexToBuf(
				Asn1(
					'30',
					Asn1('30', Asn1('06', '2a864886f70d010101'), Asn1('05')),
					BitStr(
						Asn1(
							'30',
							UInt(Enc.base64ToHex(jwk.n)),
							UInt(Enc.base64ToHex(jwk.e))
						)
					)
				)
			);
		}

		// Private RSA
		return Enc.hexToBuf(
			Asn1(
				'30',
				UInt('00'),
				Asn1('30', Asn1('06', '2a864886f70d010101'), Asn1('05')),
				Asn1(
					'04',
					Asn1(
						'30',
						UInt('00'),
						UInt(Enc.base64ToHex(jwk.n)),
						UInt(Enc.base64ToHex(jwk.e)),
						UInt(Enc.base64ToHex(jwk.d)),
						UInt(Enc.base64ToHex(jwk.p)),
						UInt(Enc.base64ToHex(jwk.q)),
						UInt(Enc.base64ToHex(jwk.dp)),
						UInt(Enc.base64ToHex(jwk.dq)),
						UInt(Enc.base64ToHex(jwk.qi))
					)
				)
			)
		);
	}

	var d = Enc.base64ToHex(jwk.d);
	var x = Enc.base64ToHex(jwk.x);
	var y = Enc.base64ToHex(jwk.y);
	var objId = 'P-256' === jwk.crv ? OBJ_ID_EC : OBJ_ID_EC_384;
	return Enc.hexToBuf(
		Asn1(
			'30',
			UInt('00'),
			Asn1('30', OBJ_ID_EC_PUB, objId),
			Asn1(
				'04',
				Asn1(
					'30',
					UInt('01'),
					Asn1('04', d),
					Asn1('A1', BitStr('04' + x + y))
				)
			)
		)
	);
};
x509.packSpki = function(jwk) {
	if (/EC/i.test(jwk.kty)) {
		return x509.packSpkiEc(jwk);
	}
	return x509.packSpkiRsa(jwk);
};
x509.packSpkiRsa = function(jwk) {
	if (!jwk.d) {
		// Public RSA
		return Enc.hexToBuf(
			Asn1(
				'30',
				Asn1('30', Asn1('06', '2a864886f70d010101'), Asn1('05')),
				BitStr(
					Asn1(
						'30',
						UInt(Enc.base64ToHex(jwk.n)),
						UInt(Enc.base64ToHex(jwk.e))
					)
				)
			)
		);
	}

	// Private RSA
	return Enc.hexToBuf(
		Asn1(
			'30',
			UInt('00'),
			Asn1('30', Asn1('06', '2a864886f70d010101'), Asn1('05')),
			Asn1(
				'04',
				Asn1(
					'30',
					UInt('00'),
					UInt(Enc.base64ToHex(jwk.n)),
					UInt(Enc.base64ToHex(jwk.e)),
					UInt(Enc.base64ToHex(jwk.d)),
					UInt(Enc.base64ToHex(jwk.p)),
					UInt(Enc.base64ToHex(jwk.q)),
					UInt(Enc.base64ToHex(jwk.dp)),
					UInt(Enc.base64ToHex(jwk.dq)),
					UInt(Enc.base64ToHex(jwk.qi))
				)
			)
		)
	);
};
x509.packSpkiEc = function(jwk) {
	var x = Enc.base64ToHex(jwk.x);
	var y = Enc.base64ToHex(jwk.y);
	var objId = 'P-256' === jwk.crv ? OBJ_ID_EC : OBJ_ID_EC_384;
	return Enc.hexToBuf(
		Asn1('30', Asn1('30', OBJ_ID_EC_PUB, objId), BitStr('04' + x + y))
	);
};
x509.packPkix = x509.packSpki;

x509.packCsrRsaPublicKey = function(jwk) {
	// Sequence the key
	var n = UInt(Enc.base64ToHex(jwk.n));
	var e = UInt(Enc.base64ToHex(jwk.e));
	var asn1pub = Asn1('30', n, e);

	// Add the CSR pub key header
	return Asn1(
		'30',
		Asn1('30', Asn1('06', '2a864886f70d010101'), Asn1('05')),
		BitStr(asn1pub)
	);
};

x509.packCsrEcPublicKey = function(jwk) {
	var ecOid = x509._oids[jwk.crv];
	if (!ecOid) {
		throw new Error(
			"Unsupported namedCurve '" +
				jwk.crv +
				"'. Supported types are " +
				Object.keys(x509._oids)
		);
	}
	var cmp = '04'; // 04 == x+y, 02 == x-only
	var hxy = '';
	// Placeholder. I'm not even sure if compression should be supported.
	if (!jwk.y) {
		cmp = '02';
	}
	hxy += Enc.base64ToHex(jwk.x);
	if (jwk.y) {
		hxy += Enc.base64ToHex(jwk.y);
	}

	// 1.2.840.10045.2.1 ecPublicKey
	return Asn1(
		'30',
		Asn1('30', Asn1('06', '2a8648ce3d0201'), Asn1('06', ecOid)),
		BitStr(cmp + hxy)
	);
};
x509._oids = {
	// 1.2.840.10045.3.1.7 prime256v1
	// (ANSI X9.62 named elliptic curve) (06 08 - 2A 86 48 CE 3D 03 01 07)
	'P-256': '2a8648ce3d030107',
	// 1.3.132.0.34 P-384 (06 05 - 2B 81 04 00 22)
	// (SEC 2 recommended EC domain secp256r1)
	'P-384': '2b81040022'
	// requires more logic and isn't a recommended standard
	// 1.3.132.0.35 P-521 (06 05 - 2B 81 04 00 23)
	// (SEC 2 alternate P-521)
	//, 'P-521': '2B 81 04 00 23'
};