feat(home): implement sorting functionality for coin list

home/presentation/src/main/java/io/soma/cryptobook/home/presentation/HomeContract.kt

@@ -4,12 +4,15 @@ import io.soma.cryptobook.core.domain.model.CoinPriceVO
 import io.soma.cryptobook.core.presentation.Event
 import io.soma.cryptobook.core.presentation.SideEffect
 import io.soma.cryptobook.core.presentation.UiState
+import io.soma.cryptobook.home.presentation.component.sortheader.SortDirection
 import java.math.BigDecimal
 
 data class HomeUiState(
     val coins: List<CoinItem> = emptyList(),
     val isLoading: Boolean = false,
     val errorMsg: String? = null,
+    val sortField: SortField = SortField.Price,
+    val sortDirection: SortDirection = SortDirection.Desc,
 ) : UiState
 
 data class CoinItem(
@@ -19,10 +22,17 @@ data class CoinItem(
     val priceChangePercentage24h: Double,
 )
 
+enum class SortField {
+    Symbol,
+    Price,
+    Change,
+}
+
 sealed interface HomeEvent : Event {
     data object OnRefresh : HomeEvent
     data object OnBackClicked : HomeEvent
     data class OnCoinClicked(val symbol: String) : HomeEvent
+    data class OnSortClicked(val field: SortField) : HomeEvent
 }
 
 sealed interface HomeSideEffect : SideEffect

home/presentation/src/main/java/io/soma/cryptobook/home/presentation/HomeScreen.kt

@@ -64,14 +64,21 @@ internal fun HomeScreen(state: HomeUiState, onEvent: (HomeEvent) -> Unit, modifi
             }
         }
 
-        // Sort Header (TODO: 정렬 기능 구현)
+        // Sort Header
+        val symbolSort =
+            if (state.sortField == SortField.Symbol) state.sortDirection else SortDirection.None
+        val priceSort =
+            if (state.sortField == SortField.Price) state.sortDirection else SortDirection.None
+        val changeSort =
+            if (state.sortField == SortField.Change) state.sortDirection else SortDirection.None
+
         SortHeader(
-            symbolSort = SortDirection.None,
-            priceSort = SortDirection.Desc,
-            changeSort = SortDirection.None,
-            onSymbolClick = { /* TODO: 정렬 기능 구현 */ },
-            onPriceClick = { /* TODO: 정렬 기능 구현 */ },
-            onChangeClick = { /* TODO: 정렬 기능 구현 */ },
+            symbolSort = symbolSort,
+            priceSort = priceSort,
+            changeSort = changeSort,
+            onSymbolClick = { onEvent(HomeEvent.OnSortClicked(SortField.Symbol)) },
+            onPriceClick = { onEvent(HomeEvent.OnSortClicked(SortField.Price)) },
+            onChangeClick = { onEvent(HomeEvent.OnSortClicked(SortField.Change)) },
         )
 
         // Coin List

home/presentation/src/main/java/io/soma/cryptobook/home/presentation/HomeViewModel.kt

@@ -7,6 +7,7 @@ import io.soma.cryptobook.core.domain.navigation.AppPage
 import io.soma.cryptobook.core.domain.navigation.NavigationHelper
 import io.soma.cryptobook.core.presentation.MviViewModel
 import io.soma.cryptobook.home.domain.usecase.ObserveCoinListUseCase
+import io.soma.cryptobook.home.presentation.component.sortheader.SortDirection
 import javax.inject.Inject
 
 @HiltViewModel
@@ -31,6 +32,7 @@ class HomeViewModel @Inject constructor(
             is HomeEvent.OnCoinClicked -> navigationHelper.navigate(
                 AppPage.CoinDetail(event.symbol),
             )
+            is HomeEvent.OnSortClicked -> updateSort(event.field)
         }
     }
 
@@ -39,11 +41,16 @@ class HomeViewModel @Inject constructor(
             observeCoinListUseCase().collect { result ->
                 when (result) {
                     is ObserveCoinListUseCase.Result.Success -> {
+                        val sortedCoins = sortCoins(
+                            coins = result.coinList.map { it.toCoinItem() },
+                            sortField = currentState.sortField,
+                            sortDirection = currentState.sortDirection,
+                        )
                         reduce {
                             copy(
                                 isLoading = false,
                                 errorMsg = null,
-                                coins = result.coinList.map {
+                                coins = sortedCoins.coinList.map {
                                     it.toCoinItem(coinImageResolver.getImageUrl(it.symbol))
                                 },
                             )
@@ -63,4 +70,49 @@ class HomeViewModel @Inject constructor(
             }
         }
     }
+
+    private fun updateSort(field: SortField) {
+        val newDirection = if (field == currentState.sortField) {
+            toggleDirection(currentState.sortDirection)
+        } else {
+            defaultSortDirection(field)
+        }
+
+        reduce {
+            copy(
+                sortField = field,
+                sortDirection = newDirection,
+                coins = sortCoins(coins, field, newDirection),
+            )
+        }
+    }
+
+    private fun sortCoins(
+        coins: List<CoinItem>,
+        sortField: SortField,
+        sortDirection: SortDirection,
+    ): List<CoinItem> {
+        val comparator = when (sortField) {
+            SortField.Symbol -> compareBy<CoinItem> { it.symbol }
+            SortField.Price -> compareBy<CoinItem> { it.price }
+            SortField.Change -> compareBy<CoinItem> { it.priceChangePercentage24h }
+        }
+
+        return if (sortDirection == SortDirection.Desc) {
+            coins.sortedWith(comparator).asReversed()
+        }else{
+            coins.sortedWith(comparator)
+        }
+    }
+
+    private fun toggleDirection(current: SortDirection): SortDirection {
+        return if (current == SortDirection.Asc) SortDirection.Desc else SortDirection.Asc
+    }
+
+    private fun defaultSortDirection(field: SortField): SortDirection {
+        return when (field) {
+            SortField.Symbol -> SortDirection.Asc
+            SortField.Price, SortField.Change -> SortDirection.Desc
+        }
+    }
 }

home/presentation/src/main/java/io/soma/cryptobook/home/presentation/component/sortheader/SortHeaderItem.kt

@@ -80,7 +80,7 @@ fun SortHeaderItem(
             text = label,
             fontFamily = fontFamily,
             fontWeight = FontWeight.Bold,
-            fontSize = 14.sp,
+            fontSize = 12.sp,
             lineHeight = 20.sp,
             color = textColor,
         )