package BingoManager

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"errors"
	"log"
	mathrand "math/rand"
	"strings"
	"sync"
	"time"

	"github.com/golang/protobuf/proto"
	"github.com/segmentio/kafka-go"

	glbingopb "git.alfi.li/gamelang/protobuf/gamelang-bingo"
)

// BingoManager manages holds
type BingoManager struct {
	Games     map[string]*glbingopb.Bingo
	GamesLock sync.Mutex

	kafkaBroker []string
	kafkaR      *kafka.Reader
	kafkaW      *kafka.Writer

	notichan chan glbingopb.Event
}

// NewBingoManager returns an initialized BingoManager
func NewBingoManager(kafkaBroker []string, notichan chan glbingopb.Event) *BingoManager {
	// default broker: []string{"localhost:9092"}
	bs := BingoManager{notichan: notichan}
	bs.Games = map[string]*glbingopb.Bingo{}
	if len(kafkaBroker) > 0 {
		bs.kafkaBroker = kafkaBroker
		bs.InitKafka()
	}
	go bs.CheckWin()
	return &bs
}

func (bs *BingoManager) CheckWin() {
	for {
		bs.GamesLock.Lock()
		games := bs.Games
		for _, game := range games {
			//log.Println("CheckWin: checking game", game)
			if strings.Split(game.Name, "\uffff")[1] == "lobby" {
				continue
			}
			win, winner := bs.CheckHorizontal(game)
			if !win {
				win, winner = bs.CheckVertical(game)
			}

			if win {
				game.Winner = winner
				game.Finished = true
				bs.notify(glbingopb.Event{Type: "Win", Gamename: game.Name, Username: winner})
			}
		}
		bs.GamesLock.Unlock()
		time.Sleep(time.Second)
	}
}

func (bs *BingoManager) CheckHorizontal(game *glbingopb.Bingo) (bool, string) {
	log.Println("CheckHorizontal: checking game", game.Name)
	fields := game.GetFields()
	for _, row := range fields.GetRows() {
		//log.Println("CheckHorizontal: checking row", i)
		hits := uint32(0)
		winner := ""
		for _, field := range row.GetFields() {
			//log.Println("CheckHorizontal: checking field", y)
			if field.Checked {
				if winner == "" {
					winner = field.Checker[0]
					//log.Println("CheckHorizontal: new winner", winner)
					hits++
					continue
				}
				if winner == field.Checker[0] {
					//log.Println("CheckHorizontal: same winner", winner)
					hits++
					continue
				}
				//log.Println("CheckHorizontal: other winner", winner)
				break
			} //else {
			//log.Println("CheckHorizontal: not checked")
			//}
		}
		if hits == game.Numcols {
			//log.Println("got a winner", winner)
			return true, winner
		}
	}
	return false, ""
}

func (bs *BingoManager) CheckVertical(game *glbingopb.Bingo) (bool, string) {
	log.Println("CheckHorizontal: checking game", game.Name)
	fields := game.GetFields()
	hits := uint32(0)
	winner := ""
	for col := uint32(0); col < game.GetNumcols(); col++ {
		for _, row := range fields.GetRows() {
			field := row.Fields[col]
			if field.Checked {
				//log.Println("CheckHorizontal: checking field", y)
				if field.Checked {
					if winner == "" {
						winner = field.Checker[0]
						//log.Println("CheckHorizontal: new winner", winner)
						hits++
						continue
					}
					if winner == field.Checker[0] {
						//log.Println("CheckHorizontal: same winner", winner)
						hits++
						continue
					}
					//log.Println("CheckHorizontal: other winner", winner)
					break
				}
			}
		}
	}
	if hits == game.Numrows {
		//log.Println("got a winner", winner)
		return true, winner
	}
	return false, ""
}

// CraftGame crafts a new Game
func (bs *BingoManager) CraftGame(id uint32, name string, wordlist []string, numrows, numcols uint32, options ...*glbingopb.Option) glbingopb.Bingo {
	log.Println("crafting game", name)
	newGame := glbingopb.Bingo{Id: id, Name: name, Textlist: wordlist, Options: options, Numrows: numrows, Numcols: numcols}
	log.Println("new game:\n", newGame)
	matrix := glbingopb.FieldMatrix{Rows: []*glbingopb.FieldMatrix_MatrixRow{}}
	for row := uint32(0); row < numrows; row += 1 {
		matrix.Rows = append(matrix.Rows, &glbingopb.FieldMatrix_MatrixRow{})
		matrix.Rows[row].Fields = []*glbingopb.Field{}
		for col := uint32(0); col < numrows; col += 1 {
			if getOption(options, "unique fields").Value == "true" {
				var word string
				word, wordlist = pickRandomEntryAndDelete(wordlist)
				matrix.Rows[row].Fields = append(matrix.Rows[row].Fields, &glbingopb.Field{Text: word})
			} else {
				word, _ := pickRandomEntry(wordlist)
				matrix.Rows[row].Fields = append(matrix.Rows[row].Fields, &glbingopb.Field{Text: word})
			}
		}
	}
	newGame.Fields = &matrix
	return newGame
}

func getOption(options []*glbingopb.Option, search string) *glbingopb.Option {
	for _, option := range options {
		if option.Key == search {
			return option
		}
	}
	return &glbingopb.Option{}
}

func pickRandomEntry(list []string) (string, int) {
	index := mathrand.Int() % len(list)
	return list[index], index
}

func pickRandomEntryAndDelete(list []string) (string, []string) {
	entry, index := pickRandomEntry(list)

	list[index] = list[len(list)-1]
	return entry, list[:len(list)-1]

}

// Create adds an entry into the Game database
func (bs *BingoManager) Create(newGame glbingopb.Bingo) error {
	log.Println("BingoManager: create game", newGame.Name)
	if bs.kafkaW != nil {
		newGameBin, _ := proto.Marshal(&newGame)
		if err := bs.kafkaW.WriteMessages(context.Background(), kafka.Message{Key: []byte("Game:create"), Value: newGameBin}); err != nil {
			log.Println("ERROR: cannot write to kafka\n", err.Error())
			return err
		}
		return nil

	} else {
		log.Println("creating Game:\n", newGame)
		bs._create(newGame)
		return nil
	}
}

func (bs *BingoManager) _create(newGame glbingopb.Bingo) {
	bs.GamesLock.Lock()
	bs.Games[newGame.Name] = &newGame
	bs.GamesLock.Unlock()
	log.Println("BingoManager: Game has been created", newGame)
}

// Remove removes an entry from the Game database
func (bs *BingoManager) Remove(name string) error {
	if bs.kafkaW != nil {
		bs.GamesLock.Lock()
		delGame := bs.Games[name]
		bs.GamesLock.Unlock()
		delGameBin, _ := proto.Marshal(delGame)
		if err := bs.kafkaW.WriteMessages(context.Background(), kafka.Message{Key: []byte("Game:delete"), Value: delGameBin}); err != nil {
			log.Fatal(err)
		} else {
			// print common key info
			log.Print("Delete is done")
		}
	} else {
		bs.GamesLock.Lock()
		delete(bs.Games, name)
		bs.GamesLock.Unlock()
	}
	return nil
}

// Get returns an Instance of a Game
func (bs *BingoManager) Get(searchGame glbingopb.Bingo) glbingopb.Bingo {
	bs.GamesLock.Lock()
	Game, ok := bs.Games[searchGame.Name]
	bs.GamesLock.Unlock()
	if !ok {
		log.Println("BingoManager: cannot find Game", searchGame.Name)
		return glbingopb.Bingo{}
	}
	return *Game
}

// List returns a list of all Games
func (bs *BingoManager) List() []glbingopb.Bingo {
	list := []glbingopb.Bingo{}
	bs.GamesLock.Lock()
	games := bs.Games
	for _, Game := range games {
		list = append(list, *Game)
	}
	bs.GamesLock.Unlock()
	return list
}

// Modify adapts the changeset in modifyGame
func (bs *BingoManager) Modify(modGame glbingopb.Bingo) error {
	if bs.kafkaW != nil {
		modGameBin, _ := proto.Marshal(&modGame)
		if err := bs.kafkaW.WriteMessages(context.Background(), kafka.Message{Key: []byte("Game:modify"), Value: modGameBin}); err != nil {
			log.Fatal(err)
			return err
		} else {
			log.Print("modify sent")
			return nil
		}
	} else {
		return bs._modifyGame(modGame)
	}
}

// modifyGame _actually_ applies the diff to the live game
func (bs *BingoManager) _modifyGame(modGame glbingopb.Bingo) error {
	bs.GamesLock.Lock()
	Game, ok := bs.Games[modGame.Name]
	bs.GamesLock.Unlock()
	if !ok {
		log.Printf("BingoManager: Game \"%v\" not found", modGame.Name)
		return errors.New("Game not found")
	}

	// do nothing if game is won by someone
	if Game.Finished {
		return errors.New("game is already finished")
	}

	bs.GamesLock.Lock()
	bs.Games[modGame.Name] = &modGame
	bs.GamesLock.Unlock()
	return nil
}

// HandleEvent handles incoming game events
func (bs *BingoManager) HandleEvent(event glbingopb.Event) error {
	bs.GamesLock.Lock()
	game, ok := bs.Games[event.Gamename]
	if game.Finished {
		return errors.New("game finished")
	}
	if !ok {
		return errors.New("game not found")
	}
	bs.GamesLock.Unlock()
	if bs.kafkaW != nil {
		eventBin, _ := proto.Marshal(&event)
		if err := bs.kafkaW.WriteMessages(context.Background(), kafka.Message{Key: []byte("Game:event"), Value: eventBin}); err != nil {
			log.Fatal(err)
			return err
		} else {
			log.Print("event sent")
			return nil
		}
	} else {
		return bs._handleEvent(event)
	}
}

// HandleEvent _actually_ handles incoming game events
func (bs *BingoManager) _handleEvent(event glbingopb.Event) error {
	log.Println("BingoManager: handling event", event)

	// if this is not a common game, all other games from the world should also receive the event
	neighbors := event.GetNeighborgames()
	if len(neighbors) > 0 {
		for _, game := range neighbors {
			event.Gamename = game
			event.Neighborgames = []string{}
			log.Println("BingoManager: trigger event for", game, "with", event)
			go bs._handleEvent(event)
		}
	}

	if event.Type == "checkField" {
		bs.GamesLock.Lock()
		game, ok := bs.Games[event.Gamename]
		bs.GamesLock.Unlock()
		if !ok {
			log.Println("BingoManager: cannot find Game to check", event.Gamename)
			return errors.New("cannot find Game")
		}
		checkedgame := bs.checkField(event.Value, *game, event.Username)
		bs.GamesLock.Lock()
		bs.Games[event.Gamename] = &checkedgame
		bs.GamesLock.Unlock()

		// send the event out to wss clients
		go bs.notify(event)

		return nil
	}
	return errors.New("unknown event type")
}

func (bs *BingoManager) checkField(text string, game glbingopb.Bingo, checker string) glbingopb.Bingo {
	matrix := game.GetFields()
	for _, row := range matrix.GetRows() {
		for _, field := range row.Fields {
			if field.Text == text {
				field.Checked = true
				field.Checker = append(field.Checker, checker)
			}
		}
	}
	//game.Fields = matrix
	return game
}

func (bs *BingoManager) notify(event glbingopb.Event) {
	log.Println("BingoManager: notify", event)
	bs.notichan <- event
	log.Print("BingoManager: notify sent")
}

// ReceiveMessages handles kafka messages
func (bs *BingoManager) ReceiveMessages(msg kafka.Message) {
	log.Println("bs receive: new msg", msg.Offset, string(msg.Key))

	switch string(msg.Key) {
	// uc - Game create event
	case "Game:create":
		newGame := &glbingopb.Bingo{}
		proto.Unmarshal(msg.Value, newGame)
		bs._create(*newGame)
		log.Println("bs receive: Game \"", newGame.Name, "\" has been created")
	// ur - Game remove event
	case "Game:remove":
		delGame := &glbingopb.Bingo{}
		proto.Unmarshal(msg.Value, delGame)
		name := delGame.Name
		bs.GamesLock.Lock()
		delete(bs.Games, name)
		bs.GamesLock.Unlock()
		log.Println("bs receive: Game \"", delGame.Name, "\" has been deleted")
	case "Game:modify":
		modGame := &glbingopb.Bingo{}
		proto.Unmarshal(msg.Value, modGame)
		bs._modifyGame(*modGame)
	case "Game:event":
		event := &glbingopb.Event{}
		proto.Unmarshal(msg.Value, event)
		bs._handleEvent(*event)
	default:
		log.Println("unknown type ", string(msg.Key))
	}

}

// InitKafka initializes the kafka reader and writer and starts the watch thread
func (bs *BingoManager) InitKafka() error {
	bs.kafkaR = kafka.NewReader(kafka.ReaderConfig{
		Brokers:   bs.kafkaBroker,
		Topic:     "BingoManager",
		Partition: 0,
		MinBytes:  10e3, // 10KB
		MaxBytes:  10e6, // 10MB
	})

	bs.kafkaW = kafka.NewWriter(kafka.WriterConfig{
		Brokers:  bs.kafkaBroker,
		Topic:    "BingoManager",
		Balancer: &kafka.LeastBytes{},
	})

	go bs.pollKafka()
	return nil
}

func (bs *BingoManager) pollKafka() error {
	for {
		m, err := bs.kafkaR.ReadMessage(context.Background())
		if err != nil {
			log.Print(err)
			time.Sleep(time.Second)
			continue
		}
		bs.ReceiveMessages(m)
	}
}

func randomHex(n int) (string, error) {
	bytes := make([]byte, n)
	if _, err := rand.Read(bytes); err != nil {
		return "", err
	}
	return hex.EncodeToString(bytes), nil
}