pgpainless/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/SignatureSubpacketsHelper.kt

// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0

package org.pgpainless.signature.subpackets

import org.bouncycastle.bcpg.sig.*
import org.bouncycastle.openpgp.PGPSignatureSubpacketGenerator
import org.bouncycastle.openpgp.PGPSignatureSubpacketVector
import org.pgpainless.algorithm.*
import org.pgpainless.key.util.RevocationAttributes

class SignatureSubpacketsHelper {

    companion object {
        @JvmStatic
        fun applyFrom(vector: PGPSignatureSubpacketVector, subpackets: SignatureSubpackets) = subpackets.apply {
            for (subpacket in vector.toArray()) {
                val type = SignatureSubpacket.requireFromCode(subpacket.type)
                when (type) {
                    SignatureSubpacket.signatureCreationTime,
                    SignatureSubpacket.issuerKeyId,
                    SignatureSubpacket.issuerFingerprint -> { /* ignore, we override this anyway */ }
                    SignatureSubpacket.signatureExpirationTime -> (subpacket as SignatureExpirationTime).let {
                        subpackets.setSignatureExpirationTime(it.isCritical, it.time)
                    }
                    SignatureSubpacket.exportableCertification -> (subpacket as Exportable).let {
                        subpackets.setExportable(it.isCritical, it.isExportable)
                    }
                    SignatureSubpacket.trustSignature -> (subpacket as TrustSignature).let {
                        subpackets.setTrust(it.isCritical, it.depth, it.trustAmount)
                    }
                    SignatureSubpacket.revocable -> (subpacket as Revocable).let {
                        subpackets.setRevocable(it.isCritical, it.isRevocable)
                    }
                    SignatureSubpacket.keyExpirationTime -> (subpacket as KeyExpirationTime).let {
                        subpackets.setKeyExpirationTime(it.isCritical, it.time)
                    }
                    SignatureSubpacket.preferredSymmetricAlgorithms -> (subpacket as PreferredAlgorithms).let {
                        subpackets.setPreferredSymmetricKeyAlgorithms(PreferredAlgorithms(it.type, it.isCritical, it.isLongLength, it.data))
                    }
                    SignatureSubpacket.preferredHashAlgorithms -> (subpacket as PreferredAlgorithms).let {
                        subpackets.setPreferredHashAlgorithms(PreferredAlgorithms(it.type, it.isCritical, it.isLongLength, it.data))
                    }
                    SignatureSubpacket.preferredCompressionAlgorithms -> (subpacket as PreferredAlgorithms).let {
                        subpackets.setPreferredCompressionAlgorithms(PreferredAlgorithms(it.type, it.isCritical, it.isLongLength, it.data))
                    }
                    SignatureSubpacket.revocationKey -> (subpacket as RevocationKey).let {
                        subpackets.addRevocationKey(RevocationKey(it.isCritical, it.signatureClass, it.algorithm, it.fingerprint))
                    }
                    SignatureSubpacket.notationData -> (subpacket as NotationData).let {
                        subpackets.addNotationData(it.isCritical, it.isHumanReadable, it.notationName, it.notationValue)
                    }
                    SignatureSubpacket.primaryUserId -> (subpacket as PrimaryUserID).let {
                        subpackets.setPrimaryUserId(PrimaryUserID(it.isCritical, it.isPrimaryUserID))
                    }
                    SignatureSubpacket.keyFlags -> (subpacket as KeyFlags).let {
                        subpackets.setKeyFlags(it.isCritical, *(KeyFlag.fromBitmask(it.flags).toTypedArray()))
                    }
                    SignatureSubpacket.signerUserId -> (subpacket as SignerUserID).let {
                        subpackets.setSignerUserId(it.isCritical, it.id)
                    }
                    SignatureSubpacket.revocationReason -> (subpacket as RevocationReason).let {
                        subpackets.setRevocationReason(it.isCritical, RevocationAttributes.Reason.fromCode(it.revocationReason), it.revocationDescription)
                    }
                    SignatureSubpacket.features -> (subpacket as Features).let {
                        subpackets.setFeatures(it.isCritical, *(Feature.fromBitmask(it.features.toInt()).toTypedArray()))
                    }
                    SignatureSubpacket.signatureTarget -> (subpacket as SignatureTarget).let {
                        subpackets.setSignatureTarget(it.isCritical,
                                PublicKeyAlgorithm.requireFromId(it.publicKeyAlgorithm),
                                HashAlgorithm.requireFromId(it.hashAlgorithm),
                                it.hashData)
                    }
                    SignatureSubpacket.embeddedSignature -> (subpacket as EmbeddedSignature).let {
                        subpackets.addEmbeddedSignature(it)
                    }
                    SignatureSubpacket.intendedRecipientFingerprint -> (subpacket as IntendedRecipientFingerprint).let {
                        subpackets.addIntendedRecipientFingerprint(it)
                    }
                    SignatureSubpacket.policyUrl -> (subpacket as PolicyURI).let {
                        subpackets.setPolicyUrl(it)
                    }
                    SignatureSubpacket.regularExpression -> (subpacket as RegularExpression).let {
                        subpackets.setRegularExpression(it)
                    }
                    SignatureSubpacket.keyServerPreferences,
                        SignatureSubpacket.preferredKeyServers,
                        SignatureSubpacket.placeholder,
                        SignatureSubpacket.preferredAEADAlgorithms,
                        SignatureSubpacket.attestedCertification -> subpackets.addResidualSubpacket(subpacket)
                }
            }
        }

        @JvmStatic
        fun applyTo(subpackets: SignatureSubpackets, generator: PGPSignatureSubpacketGenerator): PGPSignatureSubpacketGenerator {
            return generator.apply {
                addSubpacket(subpackets.issuerKeyIdSubpacket)
                addSubpacket(subpackets.issuerFingerprintSubpacket)
                addSubpacket(subpackets.signatureCreationTimeSubpacket)
                addSubpacket(subpackets.signatureExpirationTimeSubpacket)
                addSubpacket(subpackets.exportableSubpacket)
                addSubpacket(subpackets.policyURISubpacket)
                addSubpacket(subpackets.regularExpressionSubpacket)
                for (notation in subpackets.notationDataSubpackets) {
                    addSubpacket(notation)
                }
                for (recipient in subpackets.intendedRecipientFingerprintSubpackets) {
                    addSubpacket(recipient)
                }
                for (revocationKey in subpackets.revocationKeySubpackets) {
                    addSubpacket(revocationKey)
                }
                addSubpacket(subpackets.signatureTargetSubpacket)
                addSubpacket(subpackets.featuresSubpacket)
                addSubpacket(subpackets.keyFlagsSubpacket)
                addSubpacket(subpackets.trustSubpacket)
                addSubpacket(subpackets.preferredCompressionAlgorithmsSubpacket)
                addSubpacket(subpackets.preferredSymmetricKeyAlgorithmsSubpacket)
                addSubpacket(subpackets.preferredHashAlgorithmsSubpacket)
                for (embedded in subpackets.embeddedSignatureSubpackets) {
                    addSubpacket(embedded)
                }
                addSubpacket(subpackets.signerUserIdSubpacket)
                addSubpacket(subpackets.keyExpirationTimeSubpacket)
                addSubpacket(subpackets.primaryUserIdSubpacket)
                addSubpacket(subpackets.revocableSubpacket)
                addSubpacket(subpackets.revocationReasonSubpacket)
                for (residual in subpackets.residualSubpackets) {
                    addSubpacket(residual)
                }
            }
        }

        @JvmStatic
        private fun PGPSignatureSubpacketGenerator.addSubpacket(subpacket: org.bouncycastle.bcpg.SignatureSubpacket?) {
            if (subpacket != null) {
                this.addCustomSubpacket(subpacket)
            }
        }

        @JvmStatic
        fun toVector(subpackets: SignatureSubpackets): PGPSignatureSubpacketVector {
            return PGPSignatureSubpacketGenerator().let {
                applyTo(subpackets, it)
                it.generate()
            }
        }

        @JvmStatic
        fun toVector(subpackets: RevocationSignatureSubpackets): PGPSignatureSubpacketVector {
            return PGPSignatureSubpacketGenerator().let {
                applyTo(subpackets as SignatureSubpackets, it)
                it.generate()
            }
        }
    }
}