/*
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/oam-dev/kubevela/pkg/multicluster"

	"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, order string, ioStreams util.IOStreams) *cobra.Command {
	largs := &Args{Args: c}
	cmd := &cobra.Command{
		Use:   "logs APP_NAME",
		Short: "Tail logs for application.",
		Long:  "Tail logs for vela application.",
		Args:  cobra.ExactArgs(1),
		PreRunE: func(cmd *cobra.Command, args []string) error {
			config, err := c.GetConfig()
			if err != nil {
				return err
			}
			largs.Args = c
			config.Wrap(multicluster.NewSecretModeMultiClusterRoundTripper)
			return nil
		},
		RunE: func(cmd *cobra.Command, args []string) error {
			var err error
			largs.Namespace, err = GetFlagNamespaceOrEnv(cmd, c)
			if err != nil {
				return err
			}
			app, err := appfile.LoadApplication(largs.Namespace, args[0], c)
			if err != nil {
				return err
			}
			largs.Namespace, err = GetFlagNamespaceOrEnv(cmd, c)
			if err != nil {
				return err
			}
			largs.App = app
			ctx := context.Background()
			if err := largs.Run(ctx, ioStreams); err != nil {
				return err
			}
			return nil
		},
		Annotations: map[string]string{
			types.TagCommandOrder: order,
			types.TagCommandType:  types.TypeApp,
		},
	}

	cmd.Flags().StringVarP(&largs.Output, "output", "o", "default", "output format for logs, support: [default, raw, json]")
	cmd.Flags().StringVarP(&largs.Container, "container", "c", "", "specify container name for output")
	cmd.Flags().StringVar(&largs.Name, "name", "", "specify resource name for output")
	addNamespaceAndEnvArg(cmd)
	return cmd
}

// Args creates arguments for `logs` command
type Args struct {
	Output    string
	Args      common.Args
	Namespace string
	Container string
	Name      string
	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 {
	// TODO(wonderflow): we could get labels from service to narrow the pods scope selected
	labelSelector := labels.Everything()
	config, err := l.Args.GetConfig()
	if err != nil {
		return err
	}
	clientSet, err := kubernetes.NewForConfig(config)
	if err != nil {
		return err
	}
	selectedRes, err := common.AskToChooseOneEnvResource(l.App, l.Name)
	if err != nil {
		return err
	}
	if selectedRes.Kind == "Configuration" {
		selectedRes.Cluster = "local"
		if l.App.DeletionTimestamp == nil {
			selectedRes.Name += "-apply"
			labelSelector = labels.SelectorFromSet(map[string]string{
				"job-name": selectedRes.Name,
			})
		}
		// TODO(zzxwill) : We should also support showing logs when the terraform is destroying resources.
		// But currently, when deleting an application, it won't hold on its deletion. So `vela logs` miss application
		// parameter and is unable to display any logs.
	}

	if selectedRes.Cluster != "" && selectedRes.Cluster != "local" {
		ctx = multicluster.ContextWithClusterName(ctx, selectedRes.Cluster)
	}
	pod, err := regexp.Compile(selectedRes.Name + "-.*")
	if err != nil {
		return fmt.Errorf("fail to compile '%s' for logs query", selectedRes.Name+".*")
	}
	container := regexp.MustCompile(".*")
	if l.Container != "" {
		container = regexp.MustCompile(l.Container + ".*")
	}
	namespace := selectedRes.Namespace
	added, removed, err := stern.Watch(ctx, clientSet.CoreV1().Pods(namespace), pod, container, nil, []stern.ContainerState{stern.RUNNING, stern.TERMINATED}, 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
}