1 files changed, 78 insertions, 0 deletions
diff --git a/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/Version.kt b/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/Version.kt
new file mode 100644
index 0000000..45e7840
--- /dev/null
+++ b/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/Version.kt
@@ -0,0 +1,78 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.wallet.kotlin
+
+import kotlin.math.sign
+
+/**
+ * Semantic versioning, but libtool-style.
+ * See https://www.gnu.org/software/libtool/manual/html_node/Libtool-versioning.html
+ */
+
+/**
+ * Result of comparing two libtool versions.
+ */
+data class VersionMatchResult(
+    /**
+     * Is the first version compatible with the second?
+     */
+    val compatible: Boolean,
+    /**
+     * Is the first version older (-1), newer (+1) or identical (0)?
+     */
+    val currentCmp: Int
+)
+
+data class Version(
+    val current: Int,
+    val revision: Int,
+    val age: Int
+)
+
+/**
+ * Compare two libtool-style version strings.
+ */
+fun compareVersions(me: String,other: String): VersionMatchResult? {
+    val meVer = parseVersion (me)
+    val otherVer = parseVersion (other)
+    if (meVer == null || otherVer == null) return null
+
+    val compatible = meVer.current - meVer.age <= otherVer.current &&
+            meVer.current >= otherVer.current - otherVer.age
+
+    val currentCmp = sign((meVer.current - otherVer.current).toDouble()).toInt()
+
+    return VersionMatchResult(compatible, currentCmp)
+}
+
+fun parseVersion(v: String): Version? {
+    val elements = v.split(":")
+    if (elements.size != 3) return null
+    val (currentStr, revisionStr, ageStr) = elements
+    val current = currentStr.toIntOrNull()
+    val revision = revisionStr.toIntOrNull()
+    val age = ageStr.toIntOrNull()
+    if (current == null || revision == null || age == null) return null
+    return Version(current, revision, age)
+}
+
+class SupportedVersions(
+    val walletVersion: Version,
+    val exchangeVersion: Version,
+    val bankVersion: Version,
+    val merchantVersion: Version
+)