/*
Copyright 2021 The KubeVela Authors.

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 cli

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/spf13/cobra"
	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/cli-runtime/pkg/genericclioptions"
	"k8s.io/client-go/kubernetes"
	cmdexec "k8s.io/kubectl/pkg/cmd/exec"
	k8scmdutil "k8s.io/kubectl/pkg/cmd/util"

	"github.com/oam-dev/kubevela/apis/core.oam.dev/v1beta1"
	"github.com/oam-dev/kubevela/apis/types"
	"github.com/oam-dev/kubevela/pkg/oam"
	"github.com/oam-dev/kubevela/pkg/utils/common"
	"github.com/oam-dev/kubevela/pkg/utils/util"
	"github.com/oam-dev/kubevela/references/appfile"
)

const (
	podRunningTimeoutFlag = "pod-running-timeout"
	defaultPodExecTimeout = 60 * time.Second
	defaultStdin          = true
	defaultTTY            = true
)

// VelaExecOptions creates options for `exec` command
type VelaExecOptions struct {
	Cmd         *cobra.Command
	Args        []string
	Stdin       bool
	TTY         bool
	ServiceName string

	context.Context
	VelaC common.Args
	Env   *types.EnvMeta
	App   *v1beta1.Application

	f             k8scmdutil.Factory
	kcExecOptions *cmdexec.ExecOptions
	ClientSet     kubernetes.Interface
}

// NewExecCommand creates `exec` command
func NewExecCommand(c common.Args, ioStreams util.IOStreams) *cobra.Command {
	o := &VelaExecOptions{
		kcExecOptions: &cmdexec.ExecOptions{
			StreamOptions: cmdexec.StreamOptions{
				IOStreams: genericclioptions.IOStreams{
					In:     ioStreams.In,
					Out:    ioStreams.Out,
					ErrOut: ioStreams.ErrOut,
				},
			},
			Executor: &cmdexec.DefaultRemoteExecutor{},
		},
	}
	cmd := &cobra.Command{
		Use:   "exec [flags] APP_NAME -- COMMAND [args...]",
		Short: "Execute command in a container",
		Long:  "Execute command in a container",
		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
			if err := c.SetConfig(); err != nil {
				return err
			}
			o.VelaC = c
			return nil
		},
		RunE: func(cmd *cobra.Command, args []string) error {
			if len(args) < 1 {
				ioStreams.Error("Please specify an application name.")
				return nil
			}
			if len(args) == 1 {
				ioStreams.Error("Please specify at least one command for the container.")
				return nil
			}
			argsLenAtDash := cmd.ArgsLenAtDash()
			if argsLenAtDash != 1 {
				ioStreams.Error("vela exec APP_NAME COMMAND is not supported. Use vela exec APP_NAME -- COMMAND instead.")
				return nil
			}

			if err := o.Init(context.Background(), cmd, args); err != nil {
				return err
			}
			if err := o.Complete(); err != nil {
				return err
			}
			if err := o.Run(); err != nil {
				return err
			}
			return nil
		},
		Annotations: map[string]string{
			types.TagCommandType: types.TypeApp,
		},
	}
	cmd.Flags().BoolVarP(&o.Stdin, "stdin", "i", defaultStdin, "Pass stdin to the container")
	cmd.Flags().BoolVarP(&o.TTY, "tty", "t", defaultTTY, "Stdin is a TTY")
	cmd.Flags().Duration(podRunningTimeoutFlag, defaultPodExecTimeout,
		"The length of time (like 5s, 2m, or 3h, higher than zero) to wait until at least one pod is running",
	)
	cmd.Flags().StringVarP(&o.ServiceName, "svc", "s", "", "service name")
	return cmd
}

// Init prepares the arguments accepted by the Exec command
func (o *VelaExecOptions) Init(ctx context.Context, c *cobra.Command, argsIn []string) error {
	o.Context = ctx
	o.Cmd = c
	o.Args = argsIn

	env, err := GetEnv(o.Cmd)
	if err != nil {
		return err
	}
	o.Env = env
	app, err := appfile.LoadApplication(env.Namespace, o.Args[0], o.VelaC)
	if err != nil {
		return err
	}
	o.App = app

	cf := genericclioptions.NewConfigFlags(true)
	cf.Namespace = &o.Env.Namespace
	o.f = k8scmdutil.NewFactory(k8scmdutil.NewMatchVersionFlags(cf))

	if o.ClientSet == nil {
		c, err := kubernetes.NewForConfig(o.VelaC.Config)
		if err != nil {
			return err
		}
		o.ClientSet = c
	}
	return nil
}

// Complete loads data from the command environment
func (o *VelaExecOptions) Complete() error {
	compName, err := o.getComponentName()
	if err != nil {
		return err
	}
	podName, err := o.getPodName(compName)
	if err != nil {
		return err
	}
	o.kcExecOptions.StreamOptions.Stdin = o.Stdin
	o.kcExecOptions.StreamOptions.TTY = o.TTY

	args := make([]string, len(o.Args))
	copy(args, o.Args)
	// args for kcExecOptions MUST be in such formart:
	// [podName, COMMAND...]
	args[0] = podName
	return o.kcExecOptions.Complete(o.f, o.Cmd, args, 1)
}

func (o *VelaExecOptions) getComponentName() (string, error) {
	svcName := o.ServiceName

	if svcName != "" {
		for _, cc := range o.App.Spec.Components {
			if cc.Name == svcName {
				return svcName, nil
			}
		}
		o.Cmd.Printf("The service name '%s' is not valid\n", svcName)
	}

	compName, err := common.AskToChooseOneService(appfile.GetComponents(o.App))
	if err != nil {
		return "", err
	}
	return compName, nil
}

func (o *VelaExecOptions) getPodName(compName string) (string, error) {
	podList, err := o.ClientSet.CoreV1().Pods(o.Env.Namespace).List(o.Context, v1.ListOptions{
		LabelSelector: labels.Set(map[string]string{
			// TODO(roywang) except core workloads, not any workloads will pass these label to pod
			// find a rigorous way to get pod by compname
			oam.LabelAppComponent: compName,
		}).String(),
	})
	if err != nil {
		return "", err
	}
	if podList != nil && len(podList.Items) == 0 {
		return "", fmt.Errorf("cannot get pods")
	}
	for _, p := range podList.Items {
		if strings.HasPrefix(p.Name, compName+"-") {
			return p.Name, nil
		}
	}
	// if no pod with name matched prefix as component name
	// just return the first one
	return podList.Items[0].Name, nil
}

// Run executes a validated remote execution against a pod
func (o *VelaExecOptions) Run() error {
	return o.kcExecOptions.Run()
}