Credential Manager進行google sign

 使用 Android 版 Credential Manager，進行google sign

https://developers.google.com/identity/android-credential-manager

@Composable
fun SignInScreen(viewModel: CredentialSignInViewModel = CredentialSignInViewModel()) {
    val uiState by viewModel.uiState.collectAsState()
    val context = LocalContext.current

    Column(
        modifier = Modifier
            .fillMaxSize()
            .padding(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center
    ) {
        Button(
            onClick = {
                viewModel.signInWithGoogle(
                    context = context,
                    webClientId = "" // 替換為你的 Web 用戶端 ID
                )
            }
        ) {
            Text("Sign in with Google")
        }

        Spacer(modifier = Modifier.height(16.dp))

        when (uiState) {
            is CredentialSignInViewModel.UiState.Loading -> {
                CircularProgressIndicator()
            }

            is CredentialSignInViewModel.UiState.Success -> {
                val successState = uiState as CredentialSignInViewModel.UiState.Success
                Text("Welcome, ${successState.displayName}")
                Text("Email: ${successState.email}")
                Toast.makeText(context, successState.idToken, Toast.LENGTH_LONG).show()
            }

            is CredentialSignInViewModel.UiState.Error -> {
                val errorState = uiState as CredentialSignInViewModel.UiState.Error
                Text("Error: ${errorState.message}")
            }

            else -> {
                Text("Please sign in")
            }
        }
    }
}