Kotlin conversion: SignatureCreationDateComparator, SignatureValidityComparator

pgpainless-core/src/main/kotlin/org/pgpainless/signature/consumer/SignatureCreationDateComparator.kt

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.signature.consumer
+
+import org.bouncycastle.openpgp.PGPSignature
+
+/**
+ * Create a new comparator which sorts signatures according to the passed ordering.
+ * @param order ordering
+ */
+class SignatureCreationDateComparator(
+        private val order: Order = Order.OLD_TO_NEW
+) : Comparator<PGPSignature> {
+
+    enum class Order {
+        /**
+         * Oldest signatures first.
+         */
+        OLD_TO_NEW,
+        /**
+         * Newest signatures first.
+         */
+        NEW_TO_OLD
+    }
+
+    override fun compare(one: PGPSignature, two: PGPSignature): Int {
+        return when(order) {
+            Order.OLD_TO_NEW -> one.creationTime.compareTo(two.creationTime)
+            Order.NEW_TO_OLD -> two.creationTime.compareTo(one.creationTime)
+        }
+    }
+}

pgpainless-core/src/main/kotlin/org/pgpainless/signature/consumer/SignatureValidityComparator.kt

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.signature.consumer
+
+import org.bouncycastle.extensions.isHardRevocation
+import org.bouncycastle.openpgp.PGPSignature
+
+/**
+ * Comparator which sorts signatures based on an ordering and on revocation hardness.
+ *
+ * If a list of signatures gets ordered using this comparator, hard revocations will always
+ * come first.
+ * Further, signatures are ordered by date according to the [SignatureCreationDateComparator.Order].
+ */
+class SignatureValidityComparator(
+        order: SignatureCreationDateComparator.Order = SignatureCreationDateComparator.Order.OLD_TO_NEW
+) : Comparator<PGPSignature> {
+
+    private val creationDateComparator: SignatureCreationDateComparator = SignatureCreationDateComparator(order)
+    override fun compare(one: PGPSignature, two: PGPSignature): Int {
+        return if (one.isHardRevocation == two.isHardRevocation) {
+            // Both have the same hardness, so compare creation time
+            creationDateComparator.compare(one, two)
+        }
+        // else favor the "harder" signature
+        else if (one.isHardRevocation) -1 else 1
+    }
+
+}