

// Heavily inspired by https://github.com/kubernetes/kubernetes/blob/master/test/e2e/framework/exec_util.go

package exec

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"github.com/pkg/errors"
	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/remotecommand"
)

// ExecOptions passed to ExecWithOptions
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
}

// RemotePodCommandExecutor is an exec.Executor that execs every command in a remote container
// This is especially useful when the CephCluster networking type is Multus and when the Operator pod
// does not have the right network annotations.
type RemotePodCommandExecutor struct {
	ClientSet  kubernetes.Interface
	RestClient *rest.Config
}

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

	logger.Debugf("ExecWithOptions %+v", options)

	req := e.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(http.MethodPost, req.URL(), e.RestClient, options.Stdin, &stdout, &stderr, tty)

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

// ExecCommandInContainerWithFullOutput executes a command in the
// specified container and return stdout, stderr and error
func (e *RemotePodCommandExecutor) ExecCommandInContainerWithFullOutput(appLabel, containerName, namespace string, cmd ...string) (string, string, error) {
	options := metav1.ListOptions{LabelSelector: fmt.Sprintf("app=%s", appLabel)}
	pods, err := e.ClientSet.CoreV1().Pods(namespace).List(context.TODO(), options)
	if err != nil {
		return "", "", err
	}

	if len(pods.Items) == 0 {
		return "", "", errors.Errorf("no pods found with selector %q", appLabel)
	}

	return e.ExecWithOptions(ExecOptions{
		Command:   cmd,
		Namespace: namespace,
		// Always pick the first pod, it's always 1 unless stretched cluster is enabled
		// TODO: if we have 2 pods we could try each result if the command fails to run due to a network partition-related error.
		PodName:            pods.Items[0].Name,
		ContainerName:      containerName,
		Stdin:              nil,
		CaptureStdout:      true,
		CaptureStderr:      true,
		PreserveWhitespace: false,
	})
}

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

func (e *RemotePodCommandExecutor) ExecCommandInContainerWithFullOutputWithTimeout(appLabel, containerName, namespace string, cmd ...string) (string, string, error) {
	return e.ExecCommandInContainerWithFullOutput(appLabel, containerName, namespace, append([]string{"timeout", strconv.Itoa(int(CephCommandsTimeout.Seconds()))}, cmd...)...)
}
