Feat macos (#2)

---------

Co-authored-by: intelligence <intelligence@debian.local>
Co-authored-by: jourintown <jourintown@proton.me>
Reviewed-on: #2

macos/Sources/Transui/KeychainStore.swift

@@ -0,0 +1,45 @@
+import Foundation
+import Security
+
+enum KeychainAccount: String {
+  case hosted = "remote-api-key"
+  case local = "local-api-key"
+}
+
+enum KeychainStore {
+  private static let service = "io.github.transui.macos"
+
+  static func read(_ account: KeychainAccount) -> String {
+    let query: [String: Any] = [
+      kSecClass as String: kSecClassGenericPassword,
+      kSecAttrService as String: service,
+      kSecAttrAccount as String: account.rawValue,
+      kSecReturnData as String: true,
+      kSecMatchLimit as String: kSecMatchLimitOne,
+    ]
+    var item: CFTypeRef?
+    guard SecItemCopyMatching(query as CFDictionary, &item) == errSecSuccess,
+      let data = item as? Data
+    else { return "" }
+    return String(data: data, encoding: .utf8) ?? ""
+  }
+
+  static func write(_ value: String, account: KeychainAccount) {
+    let identity: [String: Any] = [
+      kSecClass as String: kSecClassGenericPassword,
+      kSecAttrService as String: service,
+      kSecAttrAccount as String: account.rawValue,
+    ]
+    if value.isEmpty {
+      SecItemDelete(identity as CFDictionary)
+      return
+    }
+    let data = Data(value.utf8)
+    let attributes = [kSecValueData as String: data]
+    if SecItemUpdate(identity as CFDictionary, attributes as CFDictionary) == errSecItemNotFound {
+      var item = identity
+      item[kSecValueData as String] = data
+      SecItemAdd(item as CFDictionary, nil)
+    }
+  }
+}