// Copyright 2021 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
//
//      http://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 main

import (
	"errors"
	"fmt"
	"io"

	"github.com/ahmetb/kubectx/internal/kubeconfig"
	"github.com/ahmetb/kubectx/internal/printer"
)

// UnsetOp indicates intention to remove current namespace preference.
type UnsetOp struct{}

func (_ UnsetOp) Run(_, stderr io.Writer) error {
	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
	defer kc.Close()
	if err := kc.Parse(); err != nil {
		return fmt.Errorf("kubeconfig error: %w", err)
	}

	ns, err := clearNamespace(kc)
	if err != nil {
		return err
	}
	err = printer.Success(stderr, "Active namespace is \"%s\".", printer.SuccessColor.Sprint(ns))
	return err
}

func clearNamespace(kc *kubeconfig.Kubeconfig) (string, error) {
	ctx, err := kc.GetCurrentContext()
	if err != nil {
		return "", fmt.Errorf("failed to get current context: %w", err)
	}
	ns := "default"
	if ctx == "" {
		return "", errors.New("current-context is not set")
	}

	if err := kc.SetNamespace(ctx, ns); err != nil {
		return "", fmt.Errorf("failed to clear namespace: %w", err)
	}
	if err := kc.Save(); err != nil {
		return "", fmt.Errorf("failed to save kubeconfig file: %w", err)
	}
	return ns, nil
}