로또 생성 로직 리팩토링

Author: gunkim

lotto/src/main/kotlin/io/github/gunkim/lotto/application/LottoSystem.kt

@@ -4,7 +4,7 @@ import io.github.gunkim.lotto.application.io.Input
 import io.github.gunkim.lotto.application.io.Output
 import io.github.gunkim.lotto.application.io.console.ConsoleInput
 import io.github.gunkim.lotto.application.io.console.ConsoleOutput
-import io.github.gunkim.lotto.domain.CreateRandomNumberPolicy
+import io.github.gunkim.lotto.domain.CreateRandomLottoPolicy
 import io.github.gunkim.lotto.domain.Lotto
 import io.github.gunkim.lotto.domain.LottoMachine
 import io.github.gunkim.lotto.domain.LottoNumber
@@ -43,7 +43,7 @@ class LottoSystem(
         fun default(): LottoSystem = LottoSystem(
             ConsoleInput(),
             ConsoleOutput(),
-            LottoMachine(CreateRandomNumberPolicy())
+            LottoMachine(CreateRandomLottoPolicy())
         )
     }
 }

lotto/src/main/kotlin/io/github/gunkim/lotto/application/io/console/ConsoleOutput.kt

@@ -31,12 +31,19 @@ class ConsoleOutput : Output {
     override fun showStatistics(results: Map<Rank, Int>) {
         println("당첨 통계")
         println("---------")
-        Rank.entries.reversed().forEach { showRank(it, results) }
+        Rank.entries.forEach { showRank(it, results) }
     }
 
     private fun showRank(rank: Rank, results: Map<Rank, Int>) {
         val resultCnt = results[rank] ?: return
-        val (reward, matchCnt) = rank
-        println("${matchCnt}개 일치 ($reward)-${resultCnt}개")
+        val reward = rank.reward
+
+        println("${rank.number}등 (${formatMoney(reward)}) - ${resultCnt}개")
+    }
+
+    private fun formatMoney(money: Int) = money.toString().replace(MONEY_PATTERN, "$1,")
+
+    companion object {
+        private val MONEY_PATTERN = Regex("(\\d)(?=(?:\\d{3})+(?!\\d))")
     }
 }

lotto/src/main/kotlin/io/github/gunkim/lotto/domain/CreateLottoPolicy.kt

@@ -0,0 +1,5 @@
+package io.github.gunkim.lotto.domain
+
+fun interface CreateLottoPolicy {
+    fun createLotto(): Lotto
+}

lotto/src/main/kotlin/io/github/gunkim/lotto/domain/CreateNumberPolicy.kt

@@ -0,0 +1,20 @@
+package io.github.gunkim.lotto.domain
+
+import java.util.random.RandomGenerator
+
+class CreateRandomLottoPolicy : CreateLottoPolicy {
+    override fun createLotto() = Lotto(
+        generateSequence(::createLottoNumber)
+            .distinct()
+            .take(Lotto.NUMBER_SIZE)
+            .toList()
+    )
+
+    private fun createLottoNumber() = LottoNumber(
+        randomGenerator.nextInt(LottoNumber.MAX_NUMBER) + 1
+    )
+
+    companion object {
+        private val randomGenerator = RandomGenerator.getDefault()
+    }
+}

lotto/src/main/kotlin/io/github/gunkim/lotto/domain/CreateRandomLottoPolicy.kt

@@ -1,25 +1,16 @@
 package io.github.gunkim.lotto.domain
 
-import io.github.gunkim.lotto.domain.Lotto.Companion.NUMBER_SIZE
-
 data class LottoMachine(
-    private val factory: CreateNumberPolicy
+    private val factory: CreateLottoPolicy,
 ) {
     fun buy(money: Int): List<Lotto> {
         require(money >= PRICE) { "한장도 살 수 없는 금액입니다." }
 
-        return generateSequence { createLottoNumbers() }
+        return generateSequence(factory::createLotto)
             .take(money / PRICE)
-            .map(::Lotto)
             .toList()
     }
 
-    private fun createLottoNumbers() = generateSequence(factory::create)
-        .distinct()
-        .take(NUMBER_SIZE)
-        .map(::LottoNumber)
-        .toList()
-
     companion object {
         private const val PRICE = 1_000
     }

lotto/src/main/kotlin/io/github/gunkim/lotto/domain/CreateRandomNumberPolicy.kt

@@ -2,14 +2,15 @@ package io.github.gunkim.lotto.domain
 
 enum class Rank(
     val reward: Int,
-    val matchCnt: Int
+    val matchCnt: Int,
+    val number: Int,
 ) {
-    FIRST(2_000_000_000, 6),
-    SECOND(30_000_000, 5),
-    THIRD(1_500_000, 5),
-    FOURTH(50_000, 4),
-    FIFTH(5_000, 3),
-    MISS(0, 0)
+    FIRST(2_000_000_000, 6, 1),
+    SECOND(30_000_000, 5, 2),
+    THIRD(1_500_000, 5, 3),
+    FOURTH(50_000, 4, 4),
+    FIFTH(5_000, 3, 5),
+    MISS(0, 0, 6)
     ;
 
     operator fun component1(): Int = reward

lotto/src/main/kotlin/io/github/gunkim/lotto/domain/LottoMachine.kt

@@ -8,12 +8,12 @@ import io.kotest.matchers.collections.shouldHaveSize
 @DisplayName("로또 발권기는")
 class LottoMachineTests : StringSpec({
     "받은 돈 만큼 로또 티켓을 발행한다" {
-        var i = 1
-        val lottos = LottoMachine { i++ }.buy(2_500)
+        val buyMoney = 2_500
+        val lottos = LottoMachine { Lotto.from("1,2,3,4,5,6") }.buy(buyMoney)
 
         lottos shouldHaveSize 2
     }
     "티켓 한장 가격보다 적은 돈을 받을 경우 예외가 발생한다" {
-        shouldThrow<IllegalArgumentException> { LottoMachine { 1 }.buy(500) }
+        shouldThrow<IllegalArgumentException> { LottoMachine { Lotto.from("1,2,3,4,5,6") }.buy(500) }
     }
 })