Update Protocols, Services, Utilities and docs

Summary:
- Sources: update Protocols, Services, Utilities
- Docs: update docs for README

Stats:
- 4 files changed, 108 insertions(+), 36 deletions(-)

README.md

@@ -131,7 +131,36 @@ let token = try await StorageRouter.shared.get(key)
 try await StorageRouter.shared.remove(key)
 ```
 
-## Storage Domains
+### Complex Codable Support
+LocalData handles complex `Codable` types automatically. You are not limited to simple strings or integers.
+
+```swift
+struct UserProfile: Codable {
+    let id: UUID
+    let name: String
+    let settings: [String: String]
+}
+
+extension StorageKeys {
+    struct ProfileKey: StorageKey {
+        typealias Value = UserProfile // Library handles serialization
+        let name = "user_profile"
+        let domain: StorageDomain = .fileSystem(directory: .documents)
+        // ... other properties
+    }
+}
+
+## Storage Design Philosophy
+
+This app intentionally uses a **Type-Safe Storage Design**. Unlike standard iOS development which uses string keys (e.g., `UserDefaults.standard.string(forKey: "user_name")`), this library requires you to define a `StorageKey` type.
+
+### Why types instead of strings?
+1.  **Safety**: The compiler prevents typos. You can't accidentally load from `"user_name"` and save to `"username"`.
+2.  **Codable Support**: Keys define their own value types. You can store complex `Codable` structs or classes just as easily as strings, and the library handles the JSON/Plist serialization automatically.
+3.  **Visibility**: All data your app stores is discoverable in the `StorageKeys/` folder. It serves as a manifest of your app's persistence layer.
+4.  **Migration**: You can move a piece of data from `UserDefaults` to `EncryptedFileSystem` just by changing the `domain` in the Key definition. No UI code needs to change.
+
+## Storage Key Examples
 
 | Domain | Use Case |
 |--------|----------|

Sources/LocalData/Protocols/StorageKey.swift

@@ -11,4 +11,11 @@ public protocol StorageKey: Sendable, CustomStringConvertible {
 
     var availability: PlatformAvailability { get }
     var syncPolicy: SyncPolicy { get }
+
+    /// Optional list of legacy keys to migrate data from if this key is empty.
+    var migrationSources: [AnyStorageKey] { get }
+}
+
+extension StorageKey {
+    public var migrationSources: [AnyStorageKey] { [] }
 }

Sources/LocalData/Services/StorageRouter.swift

@@ -72,7 +72,7 @@ public actor StorageRouter: StorageProviding {
         try validatePlatformAvailability(for: key)
         
         let data = try serialize(value, with: key.serializer)
-        let securedData = try await applySecurity(data, for: key, isEncrypt: true)
+        let securedData = try await applySecurity(data, for: .from(key), isEncrypt: true)
         
         try await store(securedData, for: key)
         try await handleSync(key, data: securedData)
@@ -88,15 +88,42 @@ public actor StorageRouter: StorageProviding {
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
         
-        guard let securedData = try await retrieve(for: key) else {
-            Logger.debug("<<< [STORAGE] GET NOT FOUND: \(key.name)")
-            throw StorageError.notFound
+        // 1. Try primary location
+        if let securedData = try await retrieve(for: .from(key)) {
+            let data = try await applySecurity(securedData, for: .from(key), isEncrypt: false)
+            let result = try deserialize(data, with: key.serializer)
+            Logger.debug("<<< [STORAGE] GET SUCCESS: \(key.name)")
+            return result
         }
         
-        let data = try await applySecurity(securedData, for: key, isEncrypt: false)
-        let result = try deserialize(data, with: key.serializer)
-        Logger.debug("<<< [STORAGE] GET SUCCESS: \(key.name)")
-        return result
+        // 2. Try migration sources
+        for source in key.migrationSources {
+            let descriptor = source.descriptor
+            Logger.debug("!!! [STORAGE] MIGRATION: Checking source '\(descriptor.name)' for key '\(key.name)'")
+            
+            if let securedOldData = try await retrieve(for: descriptor) {
+                Logger.info("!!! [STORAGE] MIGRATION: Found data for '\(key.name)' at legacy source '\(descriptor.name)'. Migrating...")
+                
+                // Unsecure using OLD key's policy
+                let oldData = try await applySecurity(securedOldData, for: descriptor, isEncrypt: false)
+                
+                // Decode using NEW key's serializer (assuming types are compatible)
+                let value = try deserialize(oldData, with: key.serializer)
+                
+                // Store in NEW location with NEW security
+                // This will also handle sync and catalog validation via recursive call to public set
+                try await self.set(value, for: key)
+                
+                // Delete OLD data
+                try await delete(for: descriptor)
+                
+                Logger.info("!!! [STORAGE] MIGRATION: Successfully migrated '\(key.name)' from '\(descriptor.name)'")
+                return value
+            }
+        }
+        
+        Logger.debug("<<< [STORAGE] GET NOT FOUND: \(key.name)")
+        throw StorageError.notFound
     }
     
     /// Removes the value for the given key.
@@ -105,7 +132,7 @@ public actor StorageRouter: StorageProviding {
     public func remove<Key: StorageKey>(_ key: Key) async throws {
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
-        try await delete(for: key)
+        try await delete(for: .from(key))
     }
     
     /// Checks if a value exists for the given key.
@@ -216,10 +243,10 @@ public actor StorageRouter: StorageProviding {
     
     private func applySecurity(
         _ data: Data,
-        for key: any StorageKey,
+        for descriptor: StorageKeyDescriptor,
         isEncrypt: Bool
     ) async throws -> Data {
-        switch key.security {
+        switch descriptor.security {
         case .none:
             return data
             
@@ -227,13 +254,13 @@ public actor StorageRouter: StorageProviding {
             if isEncrypt {
                 return try await EncryptionHelper.shared.encrypt(
                     data,
-                    keyName: key.name,
+                    keyName: descriptor.name,
                     policy: encryptionPolicy
                 )
             } else {
                 return try await EncryptionHelper.shared.decrypt(
                     data,
-                    keyName: key.name,
+                    keyName: descriptor.name,
                     policy: encryptionPolicy
                 )
             }
@@ -247,23 +274,24 @@ public actor StorageRouter: StorageProviding {
     // MARK: - Storage Operations
     
     private func store(_ data: Data, for key: any StorageKey) async throws {
-        switch key.domain {
+        let descriptor = StorageKeyDescriptor.from(key)
+        switch descriptor.domain {
         case .userDefaults(let suite):
-            try await UserDefaultsHelper.shared.set(data, forKey: key.name, suite: suite)
+            try await UserDefaultsHelper.shared.set(data, forKey: descriptor.name, suite: suite)
             
         case .appGroupUserDefaults(let identifier):
             let resolvedId = try resolveIdentifier(identifier)
-            try await UserDefaultsHelper.shared.set(data, forKey: key.name, appGroupIdentifier: resolvedId)
+            try await UserDefaultsHelper.shared.set(data, forKey: descriptor.name, appGroupIdentifier: resolvedId)
             
         case .keychain(let service):
-            guard case let .keychain(accessibility, accessControl) = key.security else {
+            guard case let .keychain(accessibility, accessControl) = descriptor.security else {
                 throw StorageError.securityApplicationFailed
             }
             let resolvedService = try resolveService(service)
             try await KeychainHelper.shared.set(
                 data,
                 service: resolvedService,
-                key: key.name,
+                key: descriptor.name,
                 accessibility: accessibility,
                 accessControl: accessControl
             )
@@ -272,7 +300,7 @@ public actor StorageRouter: StorageProviding {
             try await FileStorageHelper.shared.write(
                 data,
                 to: directory,
-                fileName: key.name,
+                fileName: descriptor.name,
                 useCompleteFileProtection: false
             )
             
@@ -280,7 +308,7 @@ public actor StorageRouter: StorageProviding {
             try await FileStorageHelper.shared.write(
                 data,
                 to: directory,
-                fileName: key.name,
+                fileName: descriptor.name,
                 useCompleteFileProtection: true
             )
             
@@ -289,56 +317,56 @@ public actor StorageRouter: StorageProviding {
             try await FileStorageHelper.shared.write(
                 data,
                 to: directory,
-                fileName: key.name,
+                fileName: descriptor.name,
                 appGroupIdentifier: resolvedId,
                 useCompleteFileProtection: false
             )
         }
     }
     
-    private func retrieve(for key: any StorageKey) async throws -> Data? {
-        switch key.domain {
+    private func retrieve(for descriptor: StorageKeyDescriptor) async throws -> Data? {
+        switch descriptor.domain {
         case .userDefaults(let suite):
-            return try await UserDefaultsHelper.shared.get(forKey: key.name, suite: suite)
+            return try await UserDefaultsHelper.shared.get(forKey: descriptor.name, suite: suite)
         case .appGroupUserDefaults(let identifier):
             let resolvedId = try resolveIdentifier(identifier)
-            return try await UserDefaultsHelper.shared.get(forKey: key.name, appGroupIdentifier: resolvedId)
+            return try await UserDefaultsHelper.shared.get(forKey: descriptor.name, appGroupIdentifier: resolvedId)
             
         case .keychain(let service):
             let resolvedService = try resolveService(service)
-            return try await KeychainHelper.shared.get(service: resolvedService, key: key.name)
+            return try await KeychainHelper.shared.get(service: resolvedService, key: descriptor.name)
             
         case .fileSystem(let directory), .encryptedFileSystem(let directory):
-            return try await FileStorageHelper.shared.read(from: directory, fileName: key.name)
+            return try await FileStorageHelper.shared.read(from: directory, fileName: descriptor.name)
         case .appGroupFileSystem(let identifier, let directory):
             let resolvedId = try resolveIdentifier(identifier)
             return try await FileStorageHelper.shared.read(
                 from: directory,
-                fileName: key.name,
+                fileName: descriptor.name,
                 appGroupIdentifier: resolvedId
             )
         }
     }
     
-    private func delete(for key: any StorageKey) async throws {
-        switch key.domain {
+    private func delete(for descriptor: StorageKeyDescriptor) async throws {
+        switch descriptor.domain {
         case .userDefaults(let suite):
-            try await UserDefaultsHelper.shared.remove(forKey: key.name, suite: suite)
+            try await UserDefaultsHelper.shared.remove(forKey: descriptor.name, suite: suite)
         case .appGroupUserDefaults(let identifier):
             let resolvedId = try resolveIdentifier(identifier)
-            try await UserDefaultsHelper.shared.remove(forKey: key.name, appGroupIdentifier: resolvedId)
+            try await UserDefaultsHelper.shared.remove(forKey: descriptor.name, appGroupIdentifier: resolvedId)
             
         case .keychain(let service):
             let resolvedService = try resolveService(service)
-            try await KeychainHelper.shared.delete(service: resolvedService, key: key.name)
+            try await KeychainHelper.shared.delete(service: resolvedService, key: descriptor.name)
             
         case .fileSystem(let directory), .encryptedFileSystem(let directory):
-            try await FileStorageHelper.shared.delete(from: directory, fileName: key.name)
+            try await FileStorageHelper.shared.delete(from: directory, fileName: descriptor.name)
         case .appGroupFileSystem(let identifier, let directory):
             let resolvedId = try resolveIdentifier(identifier)
             try await FileStorageHelper.shared.delete(
                 from: directory,
-                fileName: key.name,
+                fileName: descriptor.name,
                 appGroupIdentifier: resolvedId
             )
         }

Sources/LocalData/Utilities/Logger.swift

@@ -12,6 +12,14 @@ enum Logger {
         #endif
     }
     
+    static func info(_ message: String) {
+        #if DEBUG
+        if isLoggingEnabled {
+            print(" {LOCAL_DATA} 📢 \(message)")
+        }
+        #endif
+    }
+    
     static func error(_ message: String, error: Error? = nil) {
         #if DEBUG
         var logMessage = " {LOCAL_DATA} ❌ \(message)"