/*
Copyright 2014 The Kubernetes 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 net

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/spf13/cobra"

	"k8s.io/kubernetes/test/images/agnhost/net/common"
	"k8s.io/kubernetes/test/images/agnhost/net/nat"
)

type runnerMap map[string]common.Runner

var (
	// flags for the command line. See usage args below for
	// descriptions.
	flags struct {
		Serve         string
		Runner        string
		Options       string
		DelayShutdown int
	}
	// runners is a map from runner name to runner instance.
	runners = makeRunnerMap()
)

type logOutput struct {
	b bytes.Buffer
}

// CmdNet is used by agnhost Cobra.
var CmdNet = &cobra.Command{
	Use:   "net",
	Short: "Creates webserver or runner for various networking tests",
	Long: `The subcommand will run the network tester in server mode if the "--serve" flag is given, and the runners are triggered through HTTP requests.

Alternatively, if the "--runner" flag is given, it will execute the given runner directly. Note that "--runner" and "--serve" flags cannot be given at the same time.

Examples:

    agnhost net --runner nat-closewait-client --options '{"RemoteAddr":"127.0.0.1:9999"}'

    agnhost net --serve :8889 && curl -v -X POST localhost:8889/run/nat-closewait-server -d '{"LocalAddr":"127.0.0.1:9999"}'
`,
	Args: cobra.MaximumNArgs(0),
	Run:  main,
}

func init() {
	legalRunners := ""
	for k := range runners {
		legalRunners += " " + k
	}
	CmdNet.Flags().StringVar(&flags.Serve, "serve", "",
		"Address and port to bind to (e.g. 127.0.0.1:8080). Setting this will "+
			"run the network tester in server mode runner are triggered through "+
			"HTTP requests.")
	CmdNet.Flags().StringVar(&flags.Runner, "runner", "", "Runner to execute (available:"+legalRunners+")")
	CmdNet.Flags().StringVar(&flags.Options, "options", "", "JSON options to the Runner")
	CmdNet.Flags().IntVar(&flags.DelayShutdown, "delay-shutdown", 0, "Number of seconds to delay shutdown when receiving SIGTERM.")
}

func main(cmd *cobra.Command, args []string) {
	if flags.Runner == "" && flags.Serve == "" {
		log.Fatalf("Must set either --runner or --serve, see --help")
	}

	if flags.DelayShutdown > 0 {
		termCh := make(chan os.Signal, 1)
		signal.Notify(termCh, syscall.SIGTERM)
		go func() {
			<-termCh
			log.Printf("Sleeping %d seconds before terminating...", flags.DelayShutdown)
			time.Sleep(time.Duration(flags.DelayShutdown) * time.Second)
			os.Exit(0)
		}()
	}

	log.SetFlags(log.Flags() | log.Lshortfile)

	if flags.Serve == "" {
		output, err := executeRunner(flags.Runner, flags.Options)
		if err == nil {
			fmt.Print("output:\n\n" + output.b.String())
			os.Exit(0)
		} else {
			log.Printf("Error: %v", err)
			fmt.Print("output:\n\n" + output.b.String())
			os.Exit(1)
		}
	} else {
		http.HandleFunc("/run/", handleRunRequest)
		log.Printf("Running server on %v", flags.Serve)
		log.Fatal(http.ListenAndServe(flags.Serve, nil))
	}
}

func makeRunnerMap() runnerMap {
	// runner name is <pkg>-<file>-<specific>.
	return runnerMap{
		"nat-closewait-client": nat.NewCloseWaitClient(),
		"nat-closewait-server": nat.NewCloseWaitServer(),
	}
}

func executeRunner(name string, rawOptions string) (logOutput, error) {
	runner, ok := runners[name]
	if ok {
		options := runner.NewOptions()
		if err := json.Unmarshal([]byte(rawOptions), options); err != nil {
			return logOutput{}, fmt.Errorf("Invalid options JSON: %v", err)
		}

		log.Printf("Options: %+v", options)

		output := logOutput{}
		logger := log.New(&output.b, "# ", log.Lshortfile)

		return output, runner.Run(logger, options)
	}

	return logOutput{}, fmt.Errorf("Invalid runner: '%v', see --help", runner)
}

// handleRunRequest handles a request JSON to the network tester.
func handleRunRequest(w http.ResponseWriter, r *http.Request) {
	log.Printf("handleRunRequest %v", *r)

	urlParts := strings.Split(r.URL.Path, "/")
	if len(urlParts) != 3 {
		http.Error(w, fmt.Sprintf("invalid request to run: %v", urlParts), 400)
		return
	}

	runner := urlParts[2]
	if r.Body == nil || r.Body == http.NoBody {
		http.Error(w, "Missing request body", 400)
		return
	}

	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, fmt.Sprintf("error reading body: %v", err), 400)
		return
	}

	var output logOutput
	if output, err = executeRunner(runner, string(body)); err != nil {
		contents := fmt.Sprintf("Error from runner: %v\noutput:\n\n%s",
			err, output.b.String())
		http.Error(w, contents, 500)
		return
	}

	fmt.Fprintf(w, "ok\noutput:\n\n"+output.b.String())
}