refactor(navigation): 전역 경로 기반 단일 내비게이션 흐름으로 전환한다

SodaLive/Sources/App/AppState.swift

@@ -7,13 +7,23 @@
 
 import Foundation
 
+struct AppRoute: Hashable {
+    let id = UUID()
+}
+
 class AppState: ObservableObject {
     static let shared = AppState()
     
-    private var appStepBackStack = [AppStep]()
+    private var routeStepMap: [AppRoute: AppStep] = [:]
     
     @Published var alreadyUpdatedMarketingInfo = false
     @Published private(set) var appStep: AppStep = .splash
+    @Published private(set) var rootStep: AppStep = .splash
+    @Published var navigationPath: [AppRoute] = [] {
+        didSet {
+            syncStepWithNavigationPath()
+        }
+    }
     
     @Published var isShowPlayer = false {
         didSet {
@@ -53,28 +63,52 @@ class AppState: ObservableObject {
     @Published var isShowErrorPopup = false
     @Published var errorMessage = ""
     
-    func setAppStep(step: AppStep) {
-        switch step {
-        case .splash, .main:
-            appStepBackStack.removeAll()
-            
-        default:
-            appStepBackStack.append(appStep)
-        }
+    private func syncStepWithNavigationPath() {
+        let validRoutes = Set(navigationPath)
+        routeStepMap = routeStepMap.filter { validRoutes.contains($0.key) }
         
+        if let route = navigationPath.last,
+           let step = routeStepMap[route] {
+            appStep = step
+        } else {
+            appStep = rootStep
+        }
+    }
+    
+    func appStep(for route: AppRoute) -> AppStep? {
+        routeStepMap[route]
+    }
+    
+    func setAppStep(step: AppStep) {
         DispatchQueue.main.async {
-            self.appStep = step
+            switch step {
+            case .splash, .main:
+                self.rootStep = step
+                self.routeStepMap.removeAll()
+                self.navigationPath.removeAll()
+                self.appStep = step
+                
+            default:
+                let route = AppRoute()
+                self.routeStepMap[route] = step
+                self.navigationPath.append(route)
+                self.appStep = step
+            }
         }
     }
     
     func back() {
-        if let step = appStepBackStack.popLast() {
-            self.appStep = step
-        } else {
-            self.appStep = .main
+        DispatchQueue.main.async {
+            if self.navigationPath.isEmpty {
+                self.rootStep = .main
+                self.appStep = .main
+                return
+            }
+            
+            _ = self.navigationPath.popLast()
         }
     }
-
+    
     // 언어 적용 직후 앱을 소프트 재시작(스플래시 -> 메인)하여 전역 UI를 새로고침
     func softRestart() {
         isRestartApp = true