draft

.gitignore

@@ -0,0 +1,32 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

src/main/kotlin/dev/darktale/AccrualCalculator.kt

@@ -0,0 +1,60 @@
+package dev.darktale
+
+import dev.darktale.model.Asset
+import dev.darktale.model.CompoundInterestDeposit
+import dev.darktale.model.Deposit
+import java.math.BigDecimal
+import java.time.LocalDate
+
+interface AccrualCalculator {
+    fun calculateAccrual(
+        asset: Asset,
+        dateFrom: LocalDate? = null,
+        dateTo: LocalDate
+    ): BigDecimal
+}
+
+class DepositAccrualCalculator : AccrualCalculator {
+    override fun calculateAccrual(
+        asset: Asset,
+        dateFrom: LocalDate?,
+        dateTo: LocalDate,
+    ): BigDecimal {
+        val deposit = asset as Deposit
+        val startDate = asset.dateFrom
+        var curDateFrom = startDate
+        var curDateTo: LocalDate? = deposit.nextAccrualDate(curDateFrom)
+        var calculatedAccrual = BigDecimal.ZERO
+        while (curDateTo != null && curDateTo <= dateTo) {
+            if (curDateFrom.year == curDateTo.year)
+                calculatedAccrual += accrualBetween(
+                    curDateFrom, curDateTo,
+                    asset.quantity + calculatedAccrual,
+                    deposit.percent
+                    )
+            else
+                calculatedAccrual +=  (accrualBetween(
+                    curDateFrom, LocalDate.of(curDateFrom.year, 12, 31),
+                    asset.quantity + calculatedAccrual,
+                    deposit.percent
+                ) + accrualBetween(
+                    LocalDate.of(curDateTo.year, 1, 1), curDateTo,
+                    asset.quantity + calculatedAccrual,
+                    deposit.percent
+                ))
+            curDateFrom = curDateTo
+            curDateTo = deposit.nextAccrualDate(curDateFrom)
+        }
+        return calculatedAccrual - if (dateFrom != null && dateFrom > asset.dateFrom)
+            calculateAccrual(asset, asset.dateFrom, startDate) else BigDecimal.ZERO
+    }
+
+    private fun accrualBetween(
+        dateFrom: LocalDate,
+        dateTo: LocalDate,
+        baseAmount: BigDecimal,
+        percent: BigDecimal,
+    ) = baseAmount * percent *
+            BigDecimal.valueOf((dateTo.dayOfYear - dateFrom.dayOfYear + 1).toLong()) /
+            BigDecimal.valueOf(dateFrom.lengthOfYear().toLong())
+}

src/main/kotlin/dev/darktale/Main.kt

@@ -1,5 +1,4 @@
-package org.example
+package dev.darktale
-
 fun main() {
     println("Hello World!")
 }

src/main/kotlin/dev/darktale/model/Asset.kt

@@ -0,0 +1,58 @@
+package dev.darktale.model
+
+import java.math.BigDecimal
+import java.time.LocalDate
+import java.time.LocalTime
+
+interface Asset {
+    val assetType: AssetType
+    var quantity: BigDecimal
+    var storagePlace: StoragePlace
+    val dateFrom: LocalDate
+    var dateTo: LocalDate?
+}
+
+enum class AssetType {
+    TRADING_INSTRUMENT,
+    DEPOSIT;
+}
+
+interface Deposit : Asset {
+    override val assetType: AssetType
+        get() = AssetType.DEPOSIT
+    var percent: BigDecimal
+
+    fun nextAccrualDate(onDate: LocalDate): LocalDate?
+}
+
+class CompoundInterestDeposit(
+    override var quantity: BigDecimal,
+    override var storagePlace: StoragePlace,
+    override var dateFrom: LocalDate,
+    override var dateTo: LocalDate?,
+    override var percent: BigDecimal,
+    var accrualDay: Int,
+) : Deposit {
+    override fun nextAccrualDate(onDate: LocalDate): LocalDate? {
+        val currentMonthAccrualDate = LocalDate.of(
+            onDate.year,
+            onDate.month,
+            accrualDay.coerceAtMost(onDate.lengthOfMonth())
+        )
+        val calculatedDate = if (currentMonthAccrualDate > onDate) currentMonthAccrualDate
+        else currentMonthAccrualDate.plusMonths(1)
+        return calculatedDate.takeIf { it < dateTo }
+    }
+}
+
+class SimpleInterestDeposit(
+    override var quantity: BigDecimal,
+    override var storagePlace: StoragePlace,
+    override var dateFrom: LocalDate,
+    override var dateTo: LocalDate?,
+    override var percent: BigDecimal,
+) : Deposit {
+    override fun nextAccrualDate(onDate: LocalDate) = dateTo.takeIf { it != null && it > onDate }
+
+    override fun toString() = "$quantity since $dateFrom till $dateTo with ${percent*BigDecimal.valueOf(100L)}%"
+}

src/main/kotlin/dev/darktale/model/StoragePlace.kt

@@ -1,4 +1,4 @@
-package org.example.model
+package dev.darktale.model
 
 interface StoragePlace {
     var name: String

src/main/kotlin/model/Asset.kt

@@ -1,14 +0,0 @@
-package org.example.model
-
-import java.math.BigDecimal
-
-interface Asset {
-    var quantity: BigDecimal
-    var assetType: AssetType
-    var storagePlace: StoragePlace
-}
-
-enum class AssetType {
-    TRADING_INSTRUMENT,
-    DEPOSIT;
-}

src/test/java/dev/darktale/DepositAccrualCalculatorTest.kt

@@ -0,0 +1,53 @@
+package dev.darktale
+
+import dev.darktale.model.Deposit
+import dev.darktale.model.SimpleInterestDeposit
+import dev.darktale.model.StoragePlace
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.ArgumentsProvider
+import org.junit.jupiter.params.provider.ArgumentsSource
+import java.math.BigDecimal
+import java.time.LocalDate
+import java.time.LocalTime
+import java.util.stream.Stream
+
+class DepositAccrualCalculatorTest {
+    @ParameterizedTest
+    @ArgumentsSource(DepositProvider::class)
+    fun testAccrual(deposit: Deposit, dateFrom: LocalDate, dateTo:LocalDate, expected: BigDecimal) {
+        val accrued = DepositAccrualCalculator().calculateAccrual(deposit, dateFrom, dateTo).stripTrailingZeros()
+
+        assertEquals(
+            0, expected.compareTo(accrued),
+            "expected $expected, actual $accrued"
+        )
+    }
+}
+
+class DepositProvider : ArgumentsProvider {
+    private val testStoragePlace = object : StoragePlace {
+        override var name: String = "Qwe"
+    }
+
+    override fun provideArguments(context: ExtensionContext): Stream<Arguments> {
+        val yearStart = LocalDate.of(2024, 1, 1)
+        val yearEnd = LocalDate.of(2024, 12, 31)
+
+        val deposit = SimpleInterestDeposit(
+            BigDecimal.valueOf(1000L),
+            testStoragePlace,
+            yearStart,
+            yearEnd,
+            BigDecimal.valueOf(0.1),
+        )
+
+        return Stream.of(
+            Arguments.of(deposit, yearStart, yearEnd, BigDecimal.valueOf(100L)),
+            Arguments.of(deposit, yearStart, yearEnd.minusDays(1), BigDecimal.ZERO),
+            Arguments.of(deposit, yearEnd.minusDays(1), yearEnd, BigDecimal.valueOf(100L)),
+        )
+    }
+}