-remove multiplatform dependency, library upgrade WIP

14 files changed, 897 insertions, 9 deletions

diff --git a/taler-kotlin-android/build.gradle b/taler-kotlin-android/build.gradle
index e47efe9..b4590c4 100644
--- a/taler-kotlin-android/build.gradle
+++ b/taler-kotlin-android/build.gradle
@@ -58,8 +58,6 @@ android {
 }
 
 dependencies {
-    api project(":multiplatform:common")
-
     implementation 'androidx.appcompat:appcompat:1.4.1'
     implementation 'androidx.core:core-ktx:1.7.0'
     implementation "androidx.constraintlayout:constraintlayout:$constraintlayout_version"
diff --git a/taler-kotlin-android/src/main/AndroidManifest.xml b/taler-kotlin-android/src/main/AndroidManifest.xml
index c1f6146..f475748 100644
--- a/taler-kotlin-android/src/main/AndroidManifest.xml
+++ b/taler-kotlin-android/src/main/AndroidManifest.xml
@@ -18,9 +18,6 @@
     xmlns:tools="http://schemas.android.com/tools">
 
     <uses-sdk tools:overrideLibrary="com.google.zxing.client.android" />
-
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
-    <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.NFC" />
 
 </manifest>
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt b/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt
new file mode 100644
index 0000000..a36c0ab
--- /dev/null
+++ b/taler-kotlin-android/src/main/java/net/taler/common/Amount.kt
@@ -0,0 +1,199 @@
+/*
+ * 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.common
+
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Serializer
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlin.math.floor
+import kotlin.math.pow
+import kotlin.math.roundToInt
+
+public class AmountParserException(msg: String? = null, cause: Throwable? = null) : Exception(msg, cause)
+public class AmountOverflowException(msg: String? = null, cause: Throwable? = null) : Exception(msg, cause)
+
+@Serializable(with = KotlinXAmountSerializer::class)
+public data class Amount(
+    /**
+     * name of the currency using either a three-character ISO 4217 currency code,
+     * or a regional currency identifier starting with a "*" followed by at most 10 characters.
+     * ISO 4217 exponents in the name are not supported,
+     * although the "fraction" is corresponds to an ISO 4217 exponent of 6.
+     */
+    val currency: String,
+
+    /**
+     * The integer part may be at most 2^52.
+     * Note that "1" here would correspond to 1 EUR or 1 USD, depending on currency, not 1 cent.
+     */
+    val value: Long,
+
+    /**
+     * Unsigned 32 bit fractional value to be added to value representing
+     * an additional currency fraction, in units of one hundred millionth (1e-8)
+     * of the base currency value.  For example, a fraction
+     * of 50_000_000 would correspond to 50 cents.
+     */
+    val fraction: Int
+) : Comparable<Amount> {
+
+    public companion object {
+
+        private const val FRACTIONAL_BASE: Int = 100000000 // 1e8
+
+        private val REGEX_CURRENCY = Regex("""^[-_*A-Za-z0-9]{1,12}$""")
+        public val MAX_VALUE: Long = 2.0.pow(52).toLong()
+        private const val MAX_FRACTION_LENGTH = 8
+        public const val MAX_FRACTION: Int = 99_999_999
+
+        public fun zero(currency: String): Amount {
+            return Amount(checkCurrency(currency), 0, 0)
+        }
+
+        public fun fromJSONString(str: String): Amount {
+            val split = str.split(":")
+            if (split.size != 2) throw AmountParserException("Invalid Amount Format")
+            return fromString(split[0], split[1])
+        }
+
+        public fun fromString(currency: String, str: String): Amount {
+            // value
+            val valueSplit = str.split(".")
+            val value = checkValue(valueSplit[0].toLongOrNull())
+            // fraction
+            val fraction: Int = if (valueSplit.size > 1) {
+                val fractionStr = valueSplit[1]
+                if (fractionStr.length > MAX_FRACTION_LENGTH)
+                    throw AmountParserException("Fraction $fractionStr too long")
+                val fraction = "0.$fractionStr".toDoubleOrNull()
+                    ?.times(FRACTIONAL_BASE)
+                    ?.roundToInt()
+                checkFraction(fraction)
+            } else 0
+            return Amount(checkCurrency(currency), value, fraction)
+        }
+
+        public fun min(currency: String): Amount = Amount(currency, 0, 1)
+        public fun max(currency: String): Amount = Amount(currency, MAX_VALUE, MAX_FRACTION)
+
+
+        internal fun checkCurrency(currency: String): String {
+            if (!REGEX_CURRENCY.matches(currency))
+                throw AmountParserException("Invalid currency: $currency")
+            return currency
+        }
+
+        internal fun checkValue(value: Long?): Long {
+            if (value == null || value > MAX_VALUE)
+                throw AmountParserException("Value $value greater than $MAX_VALUE")
+            return value
+        }
+
+        internal fun checkFraction(fraction: Int?): Int {
+            if (fraction == null || fraction > MAX_FRACTION)
+                throw AmountParserException("Fraction $fraction greater than $MAX_FRACTION")
+            return fraction
+        }
+
+    }
+
+    public val amountStr: String
+        get() = if (fraction == 0) "$value" else {
+            var f = fraction
+            var fractionStr = ""
+            while (f > 0) {
+                fractionStr += f / (FRACTIONAL_BASE / 10)
+                f = (f * 10) % FRACTIONAL_BASE
+            }
+            "$value.$fractionStr"
+        }
+
+    public operator fun plus(other: Amount): Amount {
+        check(currency == other.currency) { "Can only subtract from same currency" }
+        val resultValue = value + other.value + floor((fraction + other.fraction).toDouble() / FRACTIONAL_BASE).toLong()
+        if (resultValue > MAX_VALUE)
+            throw AmountOverflowException()
+        val resultFraction = (fraction + other.fraction) % FRACTIONAL_BASE
+        return Amount(currency, resultValue, resultFraction)
+    }
+
+    public operator fun times(factor: Int): Amount {
+        // TODO consider replacing with a faster implementation
+        if (factor == 0) return zero(currency)
+        var result = this
+        for (i in 1 until factor) result += this
+        return result
+    }
+
+    public operator fun minus(other: Amount): Amount {
+        check(currency == other.currency) { "Can only subtract from same currency" }
+        var resultValue = value
+        var resultFraction = fraction
+        if (resultFraction < other.fraction) {
+            if (resultValue < 1L)
+                throw AmountOverflowException()
+            resultValue--
+            resultFraction += FRACTIONAL_BASE
+        }
+        check(resultFraction >= other.fraction)
+        resultFraction -= other.fraction
+        if (resultValue < other.value)
+            throw AmountOverflowException()
+        resultValue -= other.value
+        return Amount(currency, resultValue, resultFraction)
+    }
+
+    public fun isZero(): Boolean {
+        return value == 0L && fraction == 0
+    }
+
+    public fun toJSONString(): String {
+        return "$currency:$amountStr"
+    }
+
+    override fun toString(): String {
+        return "$amountStr $currency"
+    }
+
+    override fun compareTo(other: Amount): Int {
+        check(currency == other.currency) { "Can only compare amounts with the same currency" }
+        when {
+            value == other.value -> {
+                if (fraction < other.fraction) return -1
+                if (fraction > other.fraction) return 1
+                return 0
+            }
+            value < other.value -> return -1
+            else -> return 1
+        }
+    }
+
+}
+
+@Suppress("EXPERIMENTAL_API_USAGE")
+@Serializer(forClass = Amount::class)
+internal object KotlinXAmountSerializer : KSerializer<Amount> {
+    override fun serialize(encoder: Encoder, value: Amount) {
+        encoder.encodeString(value.toJSONString())
+    }
+
+    override fun deserialize(decoder: Decoder): Amount {
+        return Amount.fromJSONString(decoder.decodeString())
+    }
+}
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/AndroidUtils.kt b/taler-kotlin-android/src/main/java/net/taler/common/AndroidUtils.kt
index 4ac2e73..d86e744 100644
--- a/taler-kotlin-android/src/main/java/net/taler/common/AndroidUtils.kt
+++ b/taler-kotlin-android/src/main/java/net/taler/common/AndroidUtils.kt
@@ -49,7 +49,6 @@ import androidx.navigation.fragment.findNavController
 import com.github.pedrovgs.lynx.LynxActivity
 import com.github.pedrovgs.lynx.LynxConfig
 import net.taler.lib.android.ErrorBottomSheet
-import net.taler.lib.common.Version
 
 fun View.fadeIn(endAction: () -> Unit = {}) {
     if (visibility == VISIBLE && alpha == 1f) return
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/ContractTerms.kt b/taler-kotlin-android/src/main/java/net/taler/common/ContractTerms.kt
index fb30692..910cc36 100644
--- a/taler-kotlin-android/src/main/java/net/taler/common/ContractTerms.kt
+++ b/taler-kotlin-android/src/main/java/net/taler/common/ContractTerms.kt
@@ -20,8 +20,6 @@ import android.os.Build
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 import net.taler.common.TalerUtils.getLocalizedString
-import net.taler.lib.common.Amount
-import net.taler.lib.common.Timestamp
 
 @Serializable
 data class ContractTerms(
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/TalerUri.kt b/taler-kotlin-android/src/main/java/net/taler/common/TalerUri.kt
new file mode 100644
index 0000000..a1b7225
--- /dev/null
+++ b/taler-kotlin-android/src/main/java/net/taler/common/TalerUri.kt
@@ -0,0 +1,62 @@
+/*
+ * 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.common
+
+import java.util.Locale
+
+public object TalerUri {
+
+    private const val SCHEME = "taler://"
+    private const val SCHEME_INSECURE = "taler+http://"
+    private const val AUTHORITY_PAY = "pay"
+    private const val AUTHORITY_WITHDRAW = "withdraw"
+    private const val AUTHORITY_REFUND = "refund"
+    private const val AUTHORITY_TIP = "tip"
+
+    public data class WithdrawUriResult(
+        val bankIntegrationApiBaseUrl: String,
+        val withdrawalOperationId: String
+    )
+
+    /**
+     * Parses a withdraw URI and returns a bank status URL or null if the URI was invalid.
+     */
+    public fun parseWithdrawUri(uri: String): WithdrawUriResult? {
+        val (resultScheme, prefix) = when {
+            uri.startsWith(SCHEME, ignoreCase = true) -> {
+                Pair("https://", "${SCHEME}${AUTHORITY_WITHDRAW}/")
+            }
+            uri.startsWith(SCHEME_INSECURE, ignoreCase = true) -> {
+                Pair("http://", "${SCHEME_INSECURE}${AUTHORITY_WITHDRAW}/")
+            }
+            else -> return null
+        }
+        if (!uri.startsWith(prefix)) return null
+        val parts = uri.let {
+            (if (it.endsWith("/")) it.dropLast(1) else it).substring(prefix.length).split('/')
+        }
+        if (parts.size < 2) return null
+        val host = parts[0].lowercase(Locale.ROOT)
+        val pathSegments = parts.slice(1 until parts.size - 1).joinToString("/")
+        val withdrawId = parts.last()
+        if (withdrawId.isBlank()) return null
+        val url = "${resultScheme}${host}/${pathSegments}"
+
+        return WithdrawUriResult(url, withdrawId)
+    }
+
+}
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/Time.kt b/taler-kotlin-android/src/main/java/net/taler/common/Time.kt
new file mode 100644
index 0000000..61bbce8
--- /dev/null
+++ b/taler-kotlin-android/src/main/java/net/taler/common/Time.kt
@@ -0,0 +1,129 @@
+/*
+ * 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.common
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.JsonTransformingSerializer
+import kotlinx.serialization.json.contentOrNull
+import kotlinx.serialization.json.jsonPrimitive
+import kotlinx.serialization.json.longOrNull
+import kotlin.math.max
+
+@Serializable
+data class Timestamp(
+    @SerialName("t_ms")
+    @Serializable(NeverSerializer::class)
+    val old_ms: Long? = null,
+    @SerialName("t_s")
+    @Serializable(NeverSerializer::class)
+    private val s: Long? = null,
+) : Comparable<Timestamp> {
+
+    constructor(ms: Long) : this(ms, null)
+
+    companion object {
+        private const val NEVER: Long = -1
+        fun now(): Timestamp = Timestamp(System.currentTimeMillis())
+        fun never(): Timestamp = Timestamp(NEVER)
+    }
+
+    val ms: Long = if (s != null) {
+        s * 1000L
+    } else if (old_ms !== null) {
+        old_ms
+    } else  {
+        throw Exception("timestamp didn't have t_s or t_ms")
+    }
+
+
+    /**
+     * Returns a copy of this [Timestamp] rounded to seconds.
+     */
+    fun truncateSeconds(): Timestamp {
+        if (ms == NEVER) return Timestamp(ms)
+        return Timestamp((ms / 1000L) * 1000L)
+    }
+
+    operator fun minus(other: Timestamp): Duration = when {
+        ms == NEVER -> Duration(Duration.FOREVER)
+        other.ms == NEVER -> throw Error("Invalid argument for timestamp comparision")
+        ms < other.ms -> Duration(0)
+        else -> Duration(ms - other.ms)
+    }
+
+    operator fun minus(other: Duration): Timestamp = when {
+        ms == NEVER -> this
+        other.ms == Duration.FOREVER -> Timestamp(0)
+        else -> Timestamp(max(0, ms - other.ms))
+    }
+
+    override fun compareTo(other: Timestamp): Int {
+        return if (ms == NEVER) {
+            if (other.ms == NEVER) 0
+            else 1
+        } else {
+            if (other.ms == NEVER) -1
+            else ms.compareTo(other.ms)
+        }
+    }
+
+}
+
+@Serializable
+data class Duration(
+    @SerialName("d_ms")
+    @Serializable(ForeverSerializer::class) val old_ms: Long? = null,
+    @SerialName("d_s")
+    @Serializable(ForeverSerializer::class)
+    private val s: Long? = null,
+) {
+    val ms: Long = if (s != null) {
+        s * 1000L
+    } else if (old_ms !== null) {
+        old_ms
+    } else  {
+        throw Exception("duration didn't have d_s or d_ms")
+    }
+
+    constructor(ms: Long) : this(ms, null)
+
+    companion object {
+        internal const val FOREVER: Long = -1
+        fun forever(): Duration = Duration(FOREVER)
+    }
+}
+
+internal abstract class MinusOneSerializer(private val keyword: String) :
+    JsonTransformingSerializer<Long>(Long.serializer()) {
+
+    override fun transformDeserialize(element: JsonElement): JsonElement {
+        return if (element.jsonPrimitive.contentOrNull == keyword) return JsonPrimitive(-1)
+        else super.transformDeserialize(element)
+    }
+
+    override fun transformSerialize(element: JsonElement): JsonElement {
+        return if (element.jsonPrimitive.longOrNull == -1L) return JsonPrimitive(keyword)
+        else element
+    }
+}
+
+internal object NeverSerializer : MinusOneSerializer("never")
+internal object ForeverSerializer : MinusOneSerializer("forever")
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/Version.kt b/taler-kotlin-android/src/main/java/net/taler/common/Version.kt
new file mode 100644
index 0000000..f46913e
--- /dev/null
+++ b/taler-kotlin-android/src/main/java/net/taler/common/Version.kt
@@ -0,0 +1,70 @@
+/*
+ * 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.common
+
+import kotlin.math.sign
+
+/**
+ * Semantic versioning, but libtool-style.
+ * See https://www.gnu.org/software/libtool/manual/html_node/Libtool-versioning.html
+ */
+public data class Version(
+    val current: Int,
+    val revision: Int,
+    val age: Int
+) {
+    public companion object {
+        public fun parse(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)
+        }
+    }
+
+    /**
+     * Compare two libtool-style versions.
+     *
+     * Returns a [VersionMatchResult] or null if the given version was null.
+     */
+    public fun compare(other: Version?): VersionMatchResult? {
+        if (other == null) return null
+        val compatible = current - age <= other.current &&
+                current >= other.current - other.age
+        val currentCmp = sign((current - other.current).toDouble()).toInt()
+        return VersionMatchResult(compatible, currentCmp)
+    }
+
+    /**
+     * Result of comparing two libtool versions.
+     */
+    public 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
+    )
+
+}
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt
new file mode 100644
index 0000000..3343b52
--- /dev/null
+++ b/taler-kotlin-android/src/test/java/net/taler/common/AmountTest.kt
@@ -0,0 +1,221 @@
+/*
+ * 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.common
+
+import kotlin.random.Random
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Assert.assertFalse
+import org.junit.Test
+
+class AmountTest {
+
+    companion object {
+        fun getRandomAmount() = getRandomAmount(getRandomString(1, Random.nextInt(1, 12)))
+        fun getRandomAmount(currency: String): Amount {
+            val value = Random.nextLong(0, Amount.MAX_VALUE)
+            val fraction = Random.nextInt(0, Amount.MAX_FRACTION)
+            return Amount(currency, value, fraction)
+        }
+    }
+
+    @Test
+    fun testFromJSONString() {
+        var str = "TESTKUDOS:23.42"
+        var amount = Amount.fromJSONString(str)
+        assertEquals(str, amount.toJSONString())
+        assertEquals("TESTKUDOS", amount.currency)
+        assertEquals(23, amount.value)
+        assertEquals((0.42 * 1e8).toInt(), amount.fraction)
+        assertEquals("23.42 TESTKUDOS", amount.toString())
+
+        str = "EUR:500000000.00000001"
+        amount = Amount.fromJSONString(str)
+        assertEquals(str, amount.toJSONString())
+        assertEquals("EUR", amount.currency)
+        assertEquals(500000000, amount.value)
+        assertEquals(1, amount.fraction)
+        assertEquals("500000000.00000001 EUR", amount.toString())
+
+        str = "EUR:1500000000.00000003"
+        amount = Amount.fromJSONString(str)
+        assertEquals(str, amount.toJSONString())
+        assertEquals("EUR", amount.currency)
+        assertEquals(1500000000, amount.value)
+        assertEquals(3, amount.fraction)
+        assertEquals("1500000000.00000003 EUR", amount.toString())
+    }
+
+    @Test
+    fun testFromJSONStringAcceptsMaxValuesRejectsAbove() {
+        val maxValue = 4503599627370496
+        val str = "TESTKUDOS123:$maxValue.99999999"
+        val amount = Amount.fromJSONString(str)
+        assertEquals(str, amount.toJSONString())
+        assertEquals("TESTKUDOS123", amount.currency)
+        assertEquals(maxValue, amount.value)
+        assertEquals("$maxValue.99999999 TESTKUDOS123", amount.toString())
+
+        // longer currency not accepted
+        assertThrows<AmountParserException>("longer currency was accepted") {
+            Amount.fromJSONString("TESTKUDOS1234:$maxValue.99999999")
+        }
+
+        // max value + 1 not accepted
+        assertThrows<AmountParserException>("max value + 1 was accepted") {
+            Amount.fromJSONString("TESTKUDOS123:${maxValue + 1}.99999999")
+        }
+
+        // max fraction + 1 not accepted
+        assertThrows<AmountParserException>("max fraction + 1 was accepted") {
+            Amount.fromJSONString("TESTKUDOS123:$maxValue.999999990")
+        }
+    }
+
+    @Test
+    fun testFromJSONStringRejections() {
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString("TESTKUDOS:0,5")
+        }
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString("+TESTKUDOS:0.5")
+        }
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString("0.5")
+        }
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString(":0.5")
+        }
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString("EUR::0.5")
+        }
+        assertThrows<AmountParserException> {
+            Amount.fromJSONString("EUR:.5")
+        }
+    }
+
+    @Test
+    fun testAddition() {
+        assertEquals(
+            Amount.fromJSONString("EUR:2"),
+            Amount.fromJSONString("EUR:1") + Amount.fromJSONString("EUR:1")
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:3"),
+            Amount.fromJSONString("EUR:1.5") + Amount.fromJSONString("EUR:1.5")
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:500000000.00000002"),
+            Amount.fromJSONString("EUR:500000000.00000001") + Amount.fromJSONString("EUR:0.00000001")
+        )
+        assertThrows<AmountOverflowException>("addition didn't overflow") {
+            Amount.fromJSONString("EUR:4503599627370496.99999999") + Amount.fromJSONString("EUR:0.00000001")
+        }
+        assertThrows<AmountOverflowException>("addition didn't overflow") {
+            Amount.fromJSONString("EUR:4000000000000000") + Amount.fromJSONString("EUR:4000000000000000")
+        }
+    }
+
+    @Test
+    fun testTimes() {
+        assertEquals(
+            Amount.fromJSONString("EUR:2"),
+            Amount.fromJSONString("EUR:2") * 1
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:2"),
+            Amount.fromJSONString("EUR:1") * 2
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:4.5"),
+            Amount.fromJSONString("EUR:1.5") * 3
+        )
+        assertEquals(Amount.fromJSONString("EUR:0"), Amount.fromJSONString("EUR:1.11") * 0)
+        assertEquals(Amount.fromJSONString("EUR:1.11"), Amount.fromJSONString("EUR:1.11") * 1)
+        assertEquals(Amount.fromJSONString("EUR:2.22"), Amount.fromJSONString("EUR:1.11") * 2)
+        assertEquals(Amount.fromJSONString("EUR:3.33"), Amount.fromJSONString("EUR:1.11") * 3)
+        assertEquals(Amount.fromJSONString("EUR:4.44"), Amount.fromJSONString("EUR:1.11") * 4)
+        assertEquals(Amount.fromJSONString("EUR:5.55"), Amount.fromJSONString("EUR:1.11") * 5)
+        assertEquals(
+            Amount.fromJSONString("EUR:1500000000.00000003"),
+            Amount.fromJSONString("EUR:500000000.00000001") * 3
+        )
+        assertThrows<AmountOverflowException>("times didn't overflow") {
+            Amount.fromJSONString("EUR:4000000000000000") * 2
+        }
+    }
+
+    @Test
+    fun testSubtraction() {
+        assertEquals(
+            Amount.fromJSONString("EUR:0"),
+            Amount.fromJSONString("EUR:1") - Amount.fromJSONString("EUR:1")
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:1.5"),
+            Amount.fromJSONString("EUR:3") - Amount.fromJSONString("EUR:1.5")
+        )
+        assertEquals(
+            Amount.fromJSONString("EUR:500000000.00000001"),
+            Amount.fromJSONString("EUR:500000000.00000002") - Amount.fromJSONString("EUR:0.00000001")
+        )
+        assertThrows<AmountOverflowException>("subtraction didn't underflow") {
+            Amount.fromJSONString("EUR:23.42") - Amount.fromJSONString("EUR:42.23")
+        }
+        assertThrows<AmountOverflowException>("subtraction didn't underflow") {
+            Amount.fromJSONString("EUR:0.5") - Amount.fromJSONString("EUR:0.50000001")
+        }
+    }
+
+    @Test
+    fun testIsZero() {
+        assertTrue(Amount.zero("EUR").isZero())
+        assertTrue(Amount.fromJSONString("EUR:0").isZero())
+        assertTrue(Amount.fromJSONString("EUR:0.0").isZero())
+        assertTrue(Amount.fromJSONString("EUR:0.00000").isZero())
+        assertTrue((Amount.fromJSONString("EUR:1.001") - Amount.fromJSONString("EUR:1.001")).isZero())
+
+        assertFalse(Amount.fromJSONString("EUR:0.00000001").isZero())
+        assertFalse(Amount.fromJSONString("EUR:1.0").isZero())
+        assertFalse(Amount.fromJSONString("EUR:0001.0").isZero())
+    }
+
+    @Test
+    fun testComparision() {
+        assertTrue(Amount.fromJSONString("EUR:0") <= Amount.fromJSONString("EUR:0"))
+        assertTrue(Amount.fromJSONString("EUR:0") <= Amount.fromJSONString("EUR:0.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:0") < Amount.fromJSONString("EUR:0.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:0") < Amount.fromJSONString("EUR:1"))
+        assertEquals(Amount.fromJSONString("EUR:0"), Amount.fromJSONString("EUR:0"))
+        assertEquals(Amount.fromJSONString("EUR:42"), Amount.fromJSONString("EUR:42"))
+        assertEquals(
+            Amount.fromJSONString("EUR:42.00000001"),
+            Amount.fromJSONString("EUR:42.00000001")
+        )
+        assertTrue(Amount.fromJSONString("EUR:42.00000001") >= Amount.fromJSONString("EUR:42.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:42.00000002") >= Amount.fromJSONString("EUR:42.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:42.00000002") > Amount.fromJSONString("EUR:42.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:0.00000002") > Amount.fromJSONString("EUR:0.00000001"))
+        assertTrue(Amount.fromJSONString("EUR:0.00000001") > Amount.fromJSONString("EUR:0"))
+        assertTrue(Amount.fromJSONString("EUR:2") > Amount.fromJSONString("EUR:1"))
+
+        assertThrows<IllegalStateException>("could compare amounts with different currencies") {
+            Amount.fromJSONString("EUR:0.5") < Amount.fromJSONString("USD:0.50000001")
+        }
+    }
+
+}
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/ContractTermsTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/ContractTermsTest.kt
index 3a2cdb4..f7b83a9 100644
--- a/taler-kotlin-android/src/test/java/net/taler/common/ContractTermsTest.kt
+++ b/taler-kotlin-android/src/test/java/net/taler/common/ContractTermsTest.kt
@@ -18,7 +18,6 @@ package net.taler.common
 
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
-import net.taler.lib.common.Timestamp
 import org.junit.Assert.assertEquals
 import org.junit.Test
 
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/TalerUriTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/TalerUriTest.kt
new file mode 100644
index 0000000..128f707
--- /dev/null
+++ b/taler-kotlin-android/src/test/java/net/taler/common/TalerUriTest.kt
@@ -0,0 +1,65 @@
+/*
+ * 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.common
+
+import net.taler.common.TalerUri.parseWithdrawUri
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class TalerUriTest {
+
+    @Test
+    fun testParseWithdrawUri() {
+        // correct parsing
+        var uri = "taler://withdraw/bank.example.com/12345"
+        var expected = TalerUri.WithdrawUriResult("https://bank.example.com/", "12345")
+        assertEquals(expected, parseWithdrawUri(uri))
+
+        // correct parsing with insecure http
+        uri = "taler+http://withdraw/bank.example.org/foo"
+        expected = TalerUri.WithdrawUriResult("http://bank.example.org/", "foo")
+        assertEquals(expected, parseWithdrawUri(uri))
+
+        // correct parsing with long path
+        uri = "taler://withdraw/bank.example.com/foo/bar/23/42/1337/1234567890"
+        expected =
+            TalerUri.WithdrawUriResult("https://bank.example.com/foo/bar/23/42/1337", "1234567890")
+        assertEquals(expected, parseWithdrawUri(uri))
+
+        // rejects incorrect scheme
+        uri = "talerx://withdraw/bank.example.com/12345"
+        assertNull(parseWithdrawUri(uri))
+
+        // rejects incorrect authority
+        uri = "taler://withdrawx/bank.example.com/12345"
+        assertNull(parseWithdrawUri(uri))
+
+        // rejects incorrect authority with insecure http
+        uri = "taler+http://withdrawx/bank.example.com/12345"
+        assertNull(parseWithdrawUri(uri))
+
+        // rejects empty withdrawalId
+        uri = "taler://withdraw/bank.example.com//"
+        assertNull(parseWithdrawUri(uri))
+
+        // rejects empty path and withdrawalId
+        uri = "taler://withdraw/bank.example.com////"
+        assertNull(parseWithdrawUri(uri))
+    }
+
+}
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/TestUtils.kt b/taler-kotlin-android/src/test/java/net/taler/common/TestUtils.kt
new file mode 100644
index 0000000..b0f191d
--- /dev/null
+++ b/taler-kotlin-android/src/test/java/net/taler/common/TestUtils.kt
@@ -0,0 +1,40 @@
+/*
+ * 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.common
+
+import kotlin.random.Random
+import org.junit.Assert.assertTrue
+import org.junit.Assert.fail
+
+private val charPool: List<Char> = ('a'..'z') + ('A'..'Z') + ('0'..'9')
+fun getRandomString(minLength: Int = 1, maxLength: Int = Random.nextInt(0, 1337)) =
+    (minLength..maxLength)
+        .map { Random.nextInt(0, charPool.size) }
+        .map(charPool::get)
+        .joinToString("")
+
+inline fun <reified T : Throwable> assertThrows(
+    msg: String? = null,
+    function: () -> Any
+) {
+    try {
+        function.invoke()
+        fail(msg)
+    } catch (e: Exception) {
+        assertTrue(e is T)
+    }
+}
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/TimeTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/TimeTest.kt
new file mode 100644
index 0000000..beda621
--- /dev/null
+++ b/taler-kotlin-android/src/test/java/net/taler/common/TimeTest.kt
@@ -0,0 +1,46 @@
+/*
+ * 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.common
+
+import kotlinx.serialization.json.Json.Default.decodeFromString
+import kotlinx.serialization.json.Json.Default.encodeToString
+import kotlin.random.Random
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+// TODO test other functionality of Timestamp and Duration
+class TimeTest {
+
+    @Test
+    fun testSerialize() {
+        for (i in 0 until 42) {
+            val t = Random.nextLong()
+            assertEquals("""{"t_ms":$t}""", encodeToString(Timestamp.serializer(), Timestamp(t)))
+        }
+        assertEquals("""{"t_ms":"never"}""", encodeToString(Timestamp.serializer(), Timestamp.never()))
+    }
+
+    @Test
+    fun testDeserialize() {
+        for (i in 0 until 42) {
+            val t = Random.nextLong()
+            assertEquals(Timestamp(t), decodeFromString(Timestamp.serializer(), """{ "t_ms": $t }"""))
+        }
+        assertEquals(Timestamp.never(), decodeFromString(Timestamp.serializer(), """{ "t_ms": "never" }"""))
+    }
+
+}
diff --git a/taler-kotlin-android/src/test/java/net/taler/common/VersionTest.kt b/taler-kotlin-android/src/test/java/net/taler/common/VersionTest.kt
new file mode 100644
index 0000000..d8d7149
--- /dev/null
+++ b/taler-kotlin-android/src/test/java/net/taler/common/VersionTest.kt
@@ -0,0 +1,65 @@
+/*
+ * 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.common
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+
+class VersionTest {
+
+    @Test
+    fun testParse() {
+        assertNull(Version.parse(""))
+        assertNull(Version.parse("foo"))
+        assertNull(Version.parse("foo:bar:foo"))
+        assertNull(Version.parse("0:0:0:"))
+        assertNull(Version.parse("0:0:"))
+        assertEquals(Version(0, 0, 0), Version.parse("0:0:0"))
+        assertEquals(Version(1, 2, 3), Version.parse("1:2:3"))
+        assertEquals(Version(1337, 42, 23), Version.parse("1337:42:23"))
+    }
+
+    @Test
+    fun testComparision() {
+        assertEquals(
+            Version.VersionMatchResult(true, 0),
+            Version.parse("0:0:0")!!.compare(Version.parse("0:0:0"))
+        )
+        assertEquals(
+            Version.VersionMatchResult(true, -1),
+            Version.parse("0:0:0")!!.compare(Version.parse("1:0:1"))
+        )
+        assertEquals(
+            Version.VersionMatchResult(true, -1),
+            Version.parse("0:0:0")!!.compare(Version.parse("1:5:1"))
+        )
+        assertEquals(
+            Version.VersionMatchResult(false, -1),
+            Version.parse("0:0:0")!!.compare(Version.parse("1:5:0"))
+        )
+        assertEquals(
+            Version.VersionMatchResult(false, 1),
+            Version.parse("1:0:0")!!.compare(Version.parse("0:5:0"))
+        )
+        assertEquals(
+            Version.VersionMatchResult(true, 0),
+            Version.parse("1:0:1")!!.compare(Version.parse("1:5:1"))
+        )
+    }
+
+}