/*
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"
	"encoding/json"
	"fmt"
	"regexp"
	"text/template"
	"time"

	"github.com/fatih/color"
	"github.com/pkg/errors"
	"github.com/spf13/cobra"
	"github.com/wercker/stern/stern"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/client-go/kubernetes"

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

// NewLogsCommand creates `logs` command to tail logs of application
func NewLogsCommand(c common.Args, ioStreams util.IOStreams) *cobra.Command {
	largs := &Args{C: c}
	cmd := &cobra.Command{}
	cmd.Use = "logs"
	cmd.Short = "Tail logs for application"
	cmd.Long = "Tail logs for application"
	cmd.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
		if err := c.SetConfig(); err != nil {
			return err
		}
		largs.C = c
		return nil
	}
	cmd.RunE = func(cmd *cobra.Command, args []string) error {
		if len(args) < 1 {
			ioStreams.Errorf("please specify app name")
			return nil
		}
		env, err := GetEnv(cmd)
		if err != nil {
			return err
		}
		app, err := appfile.LoadApplication(env.Namespace, args[0], c)
		if err != nil {
			return err
		}
		largs.App = app
		largs.Env = env
		ctx := context.Background()
		if err := largs.Run(ctx, ioStreams); err != nil {
			return err
		}
		return nil
	}
	cmd.Annotations = map[string]string{
		types.TagCommandType: types.TypeApp,
	}
	cmd.Flags().StringVarP(&largs.Output, "output", "o", "default", "output format for logs, support: [default, raw, json]")
	return cmd
}

// Args creates arguments for `logs` command
type Args struct {
	Output string
	Env    *types.EnvMeta
	C      common.Args
	App    *v1beta1.Application
}

// Run refer to the implementation at https://github.com/oam-dev/stern/blob/master/stern/main.go
func (l *Args) Run(ctx context.Context, ioStreams util.IOStreams) error {

	clientSet, err := kubernetes.NewForConfig(l.C.Config)
	if err != nil {
		return err
	}
	compName, err := common.AskToChooseOneService(appfile.GetComponents(l.App))
	if err != nil {
		return err
	}
	// TODO(wonderflow): we could get labels from service to narrow the pods scope selected
	labelSelector := labels.Everything()
	pod, err := regexp.Compile(compName + "-.*")
	if err != nil {
		return fmt.Errorf("fail to compile '%s' for logs query", compName+".*")
	}
	container := regexp.MustCompile(".*")
	namespace := l.Env.Namespace
	added, removed, err := stern.Watch(ctx, clientSet.CoreV1().Pods(namespace), pod, container, nil, stern.RUNNING, labelSelector)
	if err != nil {
		return err
	}
	tails := make(map[string]*stern.Tail)
	logC := make(chan string, 1024)

	go func() {
		for {
			select {
			case str := <-logC:
				ioStreams.Infonln(str)
			case <-ctx.Done():
				return
			}
		}
	}()

	var t string
	switch l.Output {
	case "default":
		if color.NoColor {
			t = "{{.PodName}} {{.ContainerName}} {{.Message}}"
		} else {
			t = "{{color .PodColor .PodName}} {{color .ContainerColor .ContainerName}} {{.Message}}"
		}
	case "raw":
		t = "{{.Message}}"
	case "json":
		t = "{{json .}}\n"
	}
	funs := map[string]interface{}{
		"json": func(in interface{}) (string, error) {
			b, err := json.Marshal(in)
			if err != nil {
				return "", err
			}
			return string(b), nil
		},
		"color": func(color color.Color, text string) string {
			return color.SprintFunc()(text)
		},
	}
	template, err := template.New("log").Funcs(funs).Parse(t)
	if err != nil {
		return errors.Wrap(err, "unable to parse template")
	}

	go func() {
		for p := range added {
			id := p.GetID()
			if tails[id] != nil {
				continue
			}
			// 48h
			dur, _ := time.ParseDuration("48h")
			tail := stern.NewTail(p.Namespace, p.Pod, p.Container, template, &stern.TailOptions{
				Timestamps:   true,
				SinceSeconds: int64(dur.Seconds()),
				Exclude:      nil,
				Include:      nil,
				Namespace:    false,
				TailLines:    nil, // default for all logs
			})
			tails[id] = tail

			tail.Start(ctx, clientSet.CoreV1().Pods(p.Namespace), logC)
		}
	}()

	go func() {
		for p := range removed {
			id := p.GetID()
			if tails[id] == nil {
				continue
			}
			tails[id].Close()
			delete(tails, id)
		}
	}()

	<-ctx.Done()

	return nil
}