package main

import (
	"bytes"
	"crypto/md5"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/juju/errors"
	"github.com/pingcap/schrodinger/pkg/test_client"
	"github.com/pingcap/schrodinger/util"
	"golang.org/x/net/context"
)

const (
	sleepTime    = 30 * time.Second
	leakCheckURL = "https://schrodinger.pingcap.net/mortem/leak"
)

func main() {
	flag.Parse()
	if *eat == "" {
		flag.PrintDefaults()
		os.Exit(-1)
	}

	if err := template(); err != nil {
		panic(errors.ErrorStack(err))
	}

	client.Info("[leak] start...")

	ctx, cancel := context.WithCancel(context.Background())
	cli := client.New(ctx, client.ModeOnline)

	sc := make(chan os.Signal, 1)
	signal.Notify(sc,
		syscall.SIGHUP,
		syscall.SIGINT,
		syscall.SIGTERM,
		syscall.SIGQUIT)
	go func() {
		sig := <-sc
		client.Infof("[leak] Got signal [%s] to exist.", sig)
		cancel()
		os.Exit(0)
	}()

	for {
		if err := checkTiDBProcess(cli.TiDBs()); err != nil {
			client.Fatalf("[leak] get goroutine fail: %v", client.ErrorStack(err))
			return
		}
		time.Sleep(sleepTime)
	}
}

func checkTiDBProcess(tidbs []string) error {
	for _, tidbAddr := range tidbs {
		// tidbAddr is host:4000, but we need host:10080
		tmp := strings.Split(tidbAddr, ":")
		if len(tmp) != 2 {
			return errors.Errorf("invalid tidb addr format: %s", tidbAddr)
		}
		stacks, body, err := goroutineProfile(tmp[0])
		if err != nil {
			return errors.Trace(err)
		}
		if err := checkLeak(stacks, body, tmp[0]); err != nil {
			return errors.Trace(err)
		}
	}
	return nil
}

var eat = flag.String("eat", "http://pingcap-dev.hk.ufileos.com/schrodinger/eat.txt", "url addr of the eat.txt file")

var leagel map[string]*Stack

func checkLeak(stacks []*Stack, body, tidbIP string) error {
	var leak bool
	var buf bytes.Buffer
	for _, s := range stacks {
		// Consider goroutine lived longer than 20 minutes.
		if s.Up < 20 {
			continue
		}

		sig := s.Signature()
		if _, ok := leagel[string(sig)]; !ok {
			buf.WriteString("goroutine seems to leak:\n")
			buf.Write(s.Raw)
			fmt.Fprintf(&buf, "--------%s %s", tidbIP, time.Now())
			leak = true
		}
	}
	if leak {
		sendCheckBackground(tidbIP)
		client.Info(body)
		client.Fatal(buf.String())
	}
	return nil
}

func template() error {
	stacks, err := parseFile(*eat)
	if err != nil {
		return errors.Trace(err)
	}
	leagel = make(map[string]*Stack)

	for i := 0; i < len(stacks); i++ {
		s := stacks[i]
		if s.Up > 0 {
			sig := s.Signature()
			leagel[string(sig)] = s
		}
	}
	return nil
}

func goroutineProfile(host string) ([]*Stack, string, error) {
	url := fmt.Sprintf("http://%s:10080/debug/pprof/goroutine?debug=2", host)
	resp, err := http.Get(url)
	if err != nil {
		return nil, "", errors.Trace(err)
	}
	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, "", errors.Trace(err)
	}
	stack, err := parseData(body)
	return stack, string(body), err
}

func splitText(input []byte) [][]byte {
	return bytes.Split(input, []byte("\n\n"))
}

// Stack is stack
type Stack struct {
	ID    uint64
	State string
	Up    int
	Func  []string
	Line  []string
	Raw   []byte
}

// Signature signs stack
func (s *Stack) Signature() []byte {
	h := md5.New()
	for _, f := range s.Func {
		pos := strings.LastIndexByte(f, '(')
		if pos > 0 {
			io.WriteString(h, f[:pos])
		} else {
			io.WriteString(h, f)
		}
	}
	return h.Sum(nil)
}

func parseFile(fileURL string) ([]*Stack, error) {
	resp, err := http.Get(fileURL)
	if err != nil {
		return nil, errors.Trace(err)
	}
	defer resp.Body.Close()

	text, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return parseData(text)
}

func parseData(text []byte) ([]*Stack, error) {
	texts := splitText(text)
	ret := make([]*Stack, 0, len(texts))
	for _, text := range texts {
		s, err := parseStack(text)
		if err != nil {
			return nil, errors.Trace(err)
		}
		ret = append(ret, s)
	}
	return ret, nil
}

func parseStack(text []byte) (*Stack, error) {
	var stack Stack
	lines := bytes.Split(text, []byte{'\n'})
	if len(lines) < 3 {
		return nil, errors.Errorf("wrong input:\n%s", text)
	}
	if err := parseGoroutineLine(string(lines[0]), &stack); err != nil {
		return nil, errors.Trace(err)
	}

	lines = lines[1:]
	stack.Func = make([]string, 0, len(lines)/2)
	stack.Line = make([]string, 0, len(lines)/2)
	for len(lines) >= 2 {
		stack.Func = append(stack.Func, string(lines[0]))
		stack.Line = append(stack.Line, string(lines[1]))
		lines = lines[2:]
	}
	stack.Raw = text
	return &stack, nil
}

func parseGoroutineLine(text string, s *Stack) error {
	// text looks like that "goroutine 124 [select, 72 minutes]:"
	fmt.Sscanf(text, "goroutine %d", &s.ID)
	pos := strings.IndexByte(text, '[')
	if pos < 0 {
		return errors.Errorf("wrong input:%s", text)
	}
	text = text[pos+1 : len(text)-2]
	texts := strings.Split(text, ", ")
	s.State = texts[0]
	if len(texts) > 1 && strings.Contains(texts[1], "minutes") {
		fmt.Sscanf(texts[1], "%d minutes", &s.Up)
	}
	return nil
}

// CheckConfig is check config
type CheckConfig struct {
	Host string `json:"host"`
}

func sendCheckBackground(ip string) error {
	config := &CheckConfig{
		Host: ip,
	}
	data, err := json.Marshal(config)
	if err != nil {
		return errors.Trace(err)
	}
	_, err = util.DoPost(http.DefaultClient, leakCheckURL, data)
	if err != nil {
		client.Errorf("sendCheckBackgroundFailed")
		return errors.Trace(err)
	}
	return nil
}