package main

import (
	"encoding/binary"
	"encoding/json"
	"fmt"
	"net/http"
	_ "net/http/pprof"
	"os"
	"os/signal"
	"path/filepath"
	"time"

	"github.com/Sirupsen/logrus"
	"github.com/dgraph-io/badger"
	"github.com/dgraph-io/badger/options"
	"github.com/dgraph-io/badger/y"
)

type writable struct {
	key   []byte
	value []byte
}

var (
	// store the first key we've seen so we can try and query it to see when it's expired from view
	firstKey       []byte
	firstKeyStored bool //
	stopWriting    = false
)

func main() {

	go func() {
		// you can hit:
		// go tool pprof http://localhost:8001/debug/pprof/heap
		// go tool pprof http://localhost:8001/debug/pprof/profile
		logrus.Infof("starting debug web server....")
		logrus.Info(http.ListenAndServe("localhost:8001", nil))
	}()

	done := make(chan struct{})
	bt := NewBadgerTest()
	bt.Start()

	<-done // wait
}

type BadgerTest struct {
	db *badger.DB
}

func NewBadgerTest() *BadgerTest {

	dir := "/home/mrjn/badgertest"
	opts := badger.DefaultOptions
	opts.Dir = dir
	opts.ValueDir = dir
	opts.ValueLogLoadingMode = options.FileIO
	opts.TableLoadingMode = options.FileIO
	// opts.NumCompactors = 20
	// opts.MaxTableSize = .25 * 1073741824 // .25GB
	opts.NumMemtables = 2
	opts.ValueLogFileSize = 1 * 1073741824 // 2GB
	opts.SyncWrites = false

	bytes, _ := json.Marshal(&opts)
	logrus.Infof("BADGER OPTIONS=%s", string(bytes))

	db, err := badger.Open(opts)
	if err != nil {
		panic(fmt.Sprintf("unable to open badger db; %s", err))
	}
	bt := &BadgerTest{
		db: db,
	}

	go bt.filecounts(dir)
	return bt

}

func (b *BadgerTest) Start() {
	a := y.NewCloser(3)

	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	go func() {
		for range c {
			fmt.Println("Signaling...")
			a.SignalAndWait()
			fmt.Printf("Closing, error: %v\n", b.db.Close())
			os.Exit(0)
		}
	}()

	workers := 1
	for i := 0; i < workers; i++ {
		go b.write(a)
	}
	//go b.write()
	go b.badgerGC(a)

	go func() {
		defer a.Done()
		tick := time.NewTicker(1 * time.Minute)
		for {
			select {
			case <-tick.C:
				b.readKey()
			case <-a.HasBeenClosed():
				fmt.Println("Returning from readKey")
				return
			}
		}
	}()

	//go func() {
	//	tick := time.NewTicker(15 * time.Minute)
	//	for _ = range tick.C {
	//		stopWriting = true
	//		return
	//	}
	//}()
}

func (b *BadgerTest) Stop() {
	b.db.Close()
	logrus.Infof("%s shut down badger test", time.Now())
	time.Sleep(1 * time.Second)
}

func (b *BadgerTest) filecounts(dir string) {

	ticker := time.NewTicker(60 * time.Second)
	for _ = range ticker.C {

		logFiles := int64(0)
		sstFiles := int64(0)
		_ = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {

			if filepath.Ext(path) == ".sst" {
				sstFiles++
			}
			if filepath.Ext(path) == ".vlog" {
				logFiles++
			}
			return nil
		})

		logrus.Infof("%s updated gauges vlog=%d sst=%d", time.Now(), logFiles, sstFiles)

	}

}

func (b *BadgerTest) write(a *y.Closer) {
	defer a.Done()

	data := `{"randomstring":"6446D58D6DFAFD58586D3EA85A53F4A6B3CC057F933A22BB58E188A74AC8F663","refID":12495494,"testfield1234":"foo bar baz","date":"2018-01-01 12:00:00"}`
	batchSize := 1
	rows := []writable{}
	var cnt uint64
	for {
		select {
		case <-a.HasBeenClosed():
			logrus.Infof("%s stopping writing, let it catch up", time.Now())
			return
		default:
		}

		// cnt = (cnt + 1) % 5
		cnt++
		// ts := time.Now().UnixNano()
		buf := make([]byte, 8)
		// binary.BigEndian.PutUint64(buf[0:], uint64(ts))
		binary.BigEndian.PutUint64(buf, cnt)
		// fmt.Printf("Key: %x\n", buf)

		if !firstKeyStored {
			firstKey = buf
			firstKeyStored = true
			logrus.Infof("%s firstkey stored %x", time.Now(), firstKey)
		}
		w := writable{key: buf, value: []byte(data)}
		rows = append(rows, w)
		if len(rows) > batchSize {
			b.saveRows(rows)
			rows = []writable{}
		}
	}

}

func (b *BadgerTest) saveRows(rows []writable) {
	// ttl := 30 * time.Minute
	ttl := 90 * time.Second

	txn := b.db.NewTransaction(true)

	for _, row := range rows {
		if err := txn.SetWithTTL(row.key, row.value, ttl); err == badger.ErrTxnTooBig {
			logrus.Infof("%s TX too big, committing...", time.Now())
			_ = txn.Commit(nil)
			txn = b.db.NewTransaction(true)
			err = txn.SetWithTTL(row.key, row.value, ttl)
		} else if err != nil && err != badger.ErrTxnTooBig {
			logrus.Errorf("unable to set key-val in transaction; %s", err)
		}
	}
	err := txn.Commit(nil)
	if err != nil {
		logrus.Errorf("unable to commit transaction; %s", err)
	}
}

func (b *BadgerTest) readKey() {
	// at some point our first key should be expired
	err := b.db.View(func(txn *badger.Txn) error {
		item, err := txn.Get([]byte(firstKey))
		if err != nil {
			return err
		}
		val, err := item.Value()
		if err != nil {
			return err
		}
		logrus.Infof("%s FIRSTKEY VALUE=%s", time.Now(), val)
		return nil
	})
	if err != nil {
		logrus.Errorf("%s FIRSTKEY unable to read first key from badger; %s", time.Now(), err)
	}
}

func (b *BadgerTest) badgerGC(a *y.Closer) {
	defer a.Done()

	_, lastVlogSize := b.db.Size()
	logrus.Infof("lastVLOGSize=%v", lastVlogSize)
	ticker := time.NewTicker(2 * time.Minute)
	const GB = int64(1 << 30)
	for {
		select {
		case <-a.HasBeenClosed():
			fmt.Println("Returning from GC")
			return
		case <-ticker.C:
			_, currentVlogSize := b.db.Size()
			if currentVlogSize < lastVlogSize+GB {
				continue
			}

			logrus.Infof("%s CLEANUP starting to purge keys", time.Now())
			err := b.db.PurgeOlderVersions()
			if err != nil {
				logrus.Errorf("%s badgerOps unable to purge older versions; %s", time.Now(), err)
			}
			logrus.Infof("%s CLEANUP PurgeOlderVersions completed", time.Now())

			// If size increased by 3.5 GB, then we run this 3 times.
			numTimes := (currentVlogSize - lastVlogSize) / GB
			for i := 0; i < int(numTimes); i++ {
				err := b.db.RunValueLogGC(0.5)
				if err != nil {
					logrus.Errorf("%s badgerOps unable to RunValueLogGC; %s", time.Now(), err)
				}
				logrus.Infof("%s CLEANUP RunValueLogGC completed iteration=%d", time.Now(), i)
			}
			_, lastVlogSize = b.db.Size()
		}
	}
}