// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package regional_parametermanager

// [START parametermanager_update_regional_param_kms_key]
import (
	"context"
	"fmt"
	"io"

	parametermanager "cloud.google.com/go/parametermanager/apiv1"
	parametermanagerpb "cloud.google.com/go/parametermanager/apiv1/parametermanagerpb"
	"google.golang.org/api/option"
	"google.golang.org/genproto/protobuf/field_mask"
)

// updateRegionalParamKmsKey updates a regional parameter kms_key using the Parameter Manager SDK for GCP.
//
// w: The io.Writer object used to write the output.
// projectID: The ID of the project where the parameter is located.
// locationID: The ID of the location where the parameter is located.
// parameterID: The ID of the parameter to be updated.
// kmsKey: The ID of the KMS key to be used for encryption.
// (e.g. "projects/my-project/locations/us-central1/keyRings/my-key-ring/cryptoKeys/my-encryption-key")
// (For more information, see: https://cloud.google.com/secret-manager/parameter-manager/docs/cmek)
//
// The function returns an error if the parameter creation fails.
func updateRegionalParamKmsKey(w io.Writer, projectID, locationID, parameterID, kmsKey string) error {
	// Create a context and a Parameter Manager client.
	ctx := context.Background()

	// Create a Parameter Manager client.
	endpoint := fmt.Sprintf("parametermanager.%s.rep.googleapis.com:443", locationID)
	client, err := parametermanager.NewClient(ctx, option.WithEndpoint(endpoint))
	if err != nil {
		return fmt.Errorf("failed to create Parameter Manager client: %w", err)
	}
	defer client.Close()

	// Construct the name of the create parameter.
	name := fmt.Sprintf("projects/%s/locations/%s/parameters/%s", projectID, locationID, parameterID)

	// Create a parameter with unformatted format.
	req := &parametermanagerpb.UpdateParameterRequest{
		Parameter: &parametermanagerpb.Parameter{
			Name:   name,
			Format: parametermanagerpb.ParameterFormat_UNFORMATTED,
			KmsKey: &kmsKey,
		},
		UpdateMask: &field_mask.FieldMask{
			Paths: []string{"kms_key"},
		},
	}
	parameter, err := client.UpdateParameter(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to update parameter: %w", err)
	}

	fmt.Fprintf(w, "Updated regional parameter %s with kms_key %s\n", parameter.Name, *parameter.KmsKey)
	return nil
}

// [END parametermanager_update_regional_param_kms_key]
