diff options
Diffstat (limited to 'taler-kotlin-common/src/main/java/net/taler/common/Amount.kt')
| -rw-r--r-- | taler-kotlin-common/src/main/java/net/taler/common/Amount.kt | 192 |
1 files changed, 165 insertions, 27 deletions
diff --git a/taler-kotlin-common/src/main/java/net/taler/common/Amount.kt b/taler-kotlin-common/src/main/java/net/taler/common/Amount.kt index 0389db1..48bd643 100644 --- a/taler-kotlin-common/src/main/java/net/taler/common/Amount.kt +++ b/taler-kotlin-common/src/main/java/net/taler/common/Amount.kt @@ -16,47 +16,185 @@ package net.taler.common +import android.annotation.SuppressLint +import com.fasterxml.jackson.core.JsonParser +import com.fasterxml.jackson.databind.DeserializationContext +import com.fasterxml.jackson.databind.JsonMappingException +import com.fasterxml.jackson.databind.annotation.JsonDeserialize +import com.fasterxml.jackson.databind.deser.std.StdDeserializer import org.json.JSONObject +import java.lang.Math.floorDiv +import kotlin.math.pow +import kotlin.math.roundToInt -data class Amount(val currency: String, val amount: String) { +class AmountDeserializer : StdDeserializer<Amount>(Amount::class.java) { + override fun deserialize(p: JsonParser, ctxt: DeserializationContext): Amount { + val node = p.codec.readValue(p, String::class.java) + try { + return Amount.fromJSONString(node) + } catch (e: AmountParserException) { + throw JsonMappingException(p, "Error parsing Amount", e) + } + } +} + +class AmountParserException(msg: String? = null, cause: Throwable? = null) : Exception(msg, cause) +class AmountOverflowException(msg: String? = null, cause: Throwable? = null) : Exception(msg, cause) + +@JsonDeserialize(using = AmountDeserializer::class) +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 +) { companion object { - private const val FRACTIONAL_BASE = 1e8 - private val SIGNED_REGEX = Regex("""([+\-])(\w+):([0-9.]+)""") - fun fromString(strAmount: String): Amount { - val components = strAmount.split(":") - return Amount(components[0], components[1]) + private const val FRACTIONAL_BASE: Int = 100000000 // 1e8 + + @Suppress("unused") + private val REGEX = Regex("""^[-_*A-Za-z0-9]{1,12}:([0-9]+)\.?([0-9]+)?$""") + private val REGEX_CURRENCY = Regex("""^[-_*A-Za-z0-9]{1,12}$""") + private val MAX_VALUE = 2.0.pow(52) + private const val MAX_FRACTION_LENGTH = 8 + private const val MAX_FRACTION = 99_999_999 + + @Throws(AmountParserException::class) + @SuppressLint("CheckedExceptions") + fun zero(currency: String): Amount { + return Amount(checkCurrency(currency), 0, 0) + } + + @Throws(AmountParserException::class) + @SuppressLint("CheckedExceptions") + fun fromJSONString(str: String): Amount { + val split = str.split(":") + if (split.size != 2) throw AmountParserException("Invalid Amount Format") + // currency + val currency = checkCurrency(split[0]) + // value + val valueSplit = split[1].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(currency, value, fraction) + } + + @Throws(AmountParserException::class) + @SuppressLint("CheckedExceptions") + fun fromJsonObject(json: JSONObject): Amount { + val currency = checkCurrency(json.optString("currency")) + val value = checkValue(json.optString("value").toLongOrNull()) + val fraction = checkFraction(json.optString("fraction").toIntOrNull()) + return Amount(currency, value, fraction) + } + + @Throws(AmountParserException::class) + private fun checkCurrency(currency: String): String { + if (!REGEX_CURRENCY.matches(currency)) + throw AmountParserException("Invalid currency: $currency") + return currency + } + + @Throws(AmountParserException::class) + private fun checkValue(value: Long?): Long { + if (value == null || value > MAX_VALUE) + throw AmountParserException("Value $value greater than $MAX_VALUE") + return value } - fun fromStringSigned(strAmount: String): Amount? { - val groups = SIGNED_REGEX.matchEntire(strAmount)?.groupValues ?: emptyList() - if (groups.size < 4) return null - var amount = groups[3].toDoubleOrNull() ?: return null - if (groups[1] == "-") amount *= -1 - val currency = groups[2] - val amountStr = amount.toString() - // only display as many digits as required to precisely render the balance - return Amount(currency, amountStr.removeSuffix(".0")) + @Throws(AmountParserException::class) + private fun checkFraction(fraction: Int?): Int { + if (fraction == null || fraction > MAX_FRACTION) + throw AmountParserException("Fraction $fraction greater than $MAX_FRACTION") + return fraction + } + + } + + val amountStr: String + get() = if (fraction == 0) "$value" else { + var f = fraction + var fractionStr = "" + while (f > 0) { + fractionStr += f / (FRACTIONAL_BASE / 10) + f = (f * 10) % FRACTIONAL_BASE + } + "$value.$fractionStr" } - fun fromJson(jsonAmount: JSONObject): Amount { - val amountCurrency = jsonAmount.getString("currency") - val amountValue = jsonAmount.getString("value") - val amountFraction = jsonAmount.getString("fraction") - val amountIntValue = Integer.parseInt(amountValue) - val amountIntFraction = Integer.parseInt(amountFraction) - return Amount( - amountCurrency, - (amountIntValue + amountIntFraction / FRACTIONAL_BASE).toString() - ) + @Throws(AmountOverflowException::class) + operator fun plus(other: Amount): Amount { + check(currency == other.currency) { "Can only subtract from same currency" } + val resultValue = value + other.value + floorDiv(fraction + other.fraction, FRACTIONAL_BASE) + if (resultValue > MAX_VALUE) + throw AmountOverflowException() + val resultFraction = (fraction + other.fraction) % FRACTIONAL_BASE + return Amount(currency, resultValue, resultFraction) + } + + @Throws(AmountOverflowException::class) + operator fun times(factor: Int): Amount { + var result = this + for (i in 1 until factor) result += this + return result + } + + @Throws(AmountOverflowException::class) + 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) } fun isZero(): Boolean { - return amount.toDouble() == 0.0 + return value == 0L && fraction == 0 } - override fun toString() = "$amount $currency" + fun toJSONString(): String { + return "$currency:$amountStr" + } + + override fun toString(): String { + return "$amountStr $currency" + } } |