Created
May 24, 2025 08:22
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My solution so far for the inventory kata
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| package io.tripled.backtothefuture | |
| import io.kotest.core.spec.style.FunSpec | |
| import io.kotest.matchers.shouldBe | |
| import java.time.LocalDateTime | |
| import java.time.temporal.ChronoUnit | |
| class InventoryKata : FunSpec( { | |
| val today = LocalDateTime.now() | |
| val yesterday = today.minus(1, ChronoUnit.DAYS) | |
| val tomorrow = today.plus(1, ChronoUnit.DAYS) | |
| test("adding things to the inventory through time") { | |
| val inventory = Inventory() | |
| inventory.add(today, "🍌") | |
| inventory.add(today, "🥝") | |
| inventory.add(tomorrow, "🍊") | |
| inventory.project(yesterday) shouldBe "" | |
| inventory.project(today) shouldBe "🍌🥝" | |
| inventory.project(tomorrow) shouldBe "🍌🥝🍊" | |
| } | |
| test("removing things impacts the inventory"){ | |
| val inventory = Inventory() | |
| inventory.add(today, "🍌"); | |
| inventory.add(today, "🥝"); | |
| inventory.remove(tomorrow, "🍌"); | |
| inventory.project(yesterday) shouldBe "" | |
| inventory.project(today) shouldBe "🍌🥝" | |
| inventory.project(tomorrow) shouldBe "🥝" | |
| } | |
| test("grouping items"){ | |
| val inventory = Inventory() | |
| val future = tomorrow | |
| inventory.add(today, "🍌"); | |
| inventory.add(today, "🥝"); | |
| inventory.add(today, "🍊"); | |
| inventory.add(today, "🍎"); | |
| inventory.project(future) shouldBe "🍌🥝🍊🍎" | |
| inventory.group(tomorrow, listOf("🥝", "🍊")); | |
| inventory.project(future) shouldBe "🍌|🥝🍊|🍎" | |
| } | |
| }) | |
| class Inventory { | |
| private val inventory = mutableListOf<InventoryEvent>() | |
| fun add(momentInTime: LocalDateTime, product: String) { | |
| inventory.add(InventoryEventAdded(momentInTime, SingleItem(product))) | |
| } | |
| fun project(momentInTime: LocalDateTime): String { | |
| val finalState = mutableListOf<Item>() | |
| inventory.sortBy { it.momentInTime } | |
| val eventsSoFar = | |
| inventory.filter { beforeOrAtTheSameTime(it, momentInTime) }.toList() | |
| for (event in eventsSoFar) { | |
| when (event) { | |
| is InventoryEventAdded -> { | |
| finalState.add(event.item) | |
| } | |
| is InventoryEventRemoved -> { | |
| finalState.remove(event.item) | |
| } | |
| is InventoryGroupAdded -> { | |
| finalState.add(event.item) | |
| //finalState.removeAll(event.item.presentation.split("")) | |
| } | |
| } | |
| } | |
| return finalState.joinToString("") { it.presentation } | |
| } | |
| private fun beforeOrAtTheSameTime( | |
| event: InventoryEvent, | |
| momentInTime: LocalDateTime, | |
| ): Boolean = event.momentInTime.isBefore(momentInTime) || momentInTime == event.momentInTime | |
| fun remove(momentInTime: LocalDateTime, product: String) { | |
| inventory.add(InventoryEventRemoved(momentInTime, SingleItem(product))) | |
| } | |
| fun group(momentInTime: LocalDateTime, groupOfProducts: List<String>) { | |
| inventory.add(InventoryGroupAdded(momentInTime, GroupedItem(groupOfProducts))) | |
| } | |
| sealed interface InventoryEvent { | |
| val momentInTime: LocalDateTime | |
| val item: Item | |
| } | |
| class InventoryEventAdded(override val momentInTime: LocalDateTime, override val item: Item) : InventoryEvent | |
| class InventoryEventRemoved(override val momentInTime: LocalDateTime, override val item: Item) : InventoryEvent | |
| class InventoryGroupAdded( | |
| override val momentInTime: LocalDateTime, | |
| override val item: Item, | |
| ) : InventoryEvent | |
| sealed interface Item { | |
| val presentation: String | |
| } | |
| data class SingleItem(val product: String) : Item { | |
| override val presentation: String | |
| get() = product | |
| } | |
| data class GroupedItem(val groupOfProducts: List<String>) : Item { | |
| override val presentation: String | |
| get() = "|${groupOfProducts.joinToString("" ) { it }}|" | |
| } | |
| } |
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