/*
SPDX-License-Identifier: Apache-2.0

Copyright Contributors to the Submariner project.

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 resource

import (
	"bytes"
	"io"
	"net/url"
	"strings"

	v1 "k8s.io/api/core/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/remotecommand"
)

func ExecOptionsFromPod(pod *v1.Pod) ExecOptions {
	return ExecOptions{
		Namespace:          pod.Namespace,
		PodName:            pod.Name,
		ContainerName:      pod.Spec.Containers[0].Name,
		Stdin:              nil,
		CaptureStdout:      true,
		CaptureStderr:      true,
		PreserveWhitespace: false,
	}
}

type ExecConfig struct {
	RestConfig *rest.Config
	ClientSet  kubernetes.Interface
}

/* Following are sourced from:
   https://github.com/kubernetes/kubernetes/blob/master/test/e2e/framework/exec_util.go
*/
type ExecOptions struct {
	Command       []string
	Namespace     string
	PodName       string
	ContainerName string
	Stdin         io.Reader
	CaptureStdout bool
	CaptureStderr bool
	// If false, whitespace in std{err,out} will be removed.
	PreserveWhitespace bool
	Quiet              bool
}

// ExecWithOptions executes a command in the specified container,
// returning stdout, stderr and error. `options` allowed for
// additional parameters to be passed.
func ExecWithOptions(config ExecConfig, options ExecOptions) (string, string, error) {
	const tty = false

	req := config.ClientSet.CoreV1().RESTClient().Post().
		Resource("pods").
		Name(options.PodName).
		Namespace(options.Namespace).
		SubResource("exec").
		Param("container", options.ContainerName)
	req.VersionedParams(&v1.PodExecOptions{
		Container: options.ContainerName,
		Command:   options.Command,
		Stdin:     options.Stdin != nil,
		Stdout:    options.CaptureStdout,
		Stderr:    options.CaptureStderr,
		TTY:       tty,
	}, scheme.ParameterCodec)

	var stdout, stderr bytes.Buffer
	err := execute("POST", req.URL(), config.RestConfig, options.Stdin, &stdout, &stderr, tty)

	if options.PreserveWhitespace {
		return stdout.String(), stderr.String(), err
	}
	return strings.TrimSpace(stdout.String()), strings.TrimSpace(stderr.String()), err
}

func execute(method string, link *url.URL, config *rest.Config, stdin io.Reader, stdout, stderr io.Writer, tty bool) error {
	exec, err := remotecommand.NewSPDYExecutor(config, method, link)
	if err != nil {
		return err
	}
	return exec.Stream(remotecommand.StreamOptions{
		Stdin:  stdin,
		Stdout: stdout,
		Stderr: stderr,
		Tty:    tty,
	})
}
