package game

import (
	"doudizhu-server/internal/models"
	"math/rand"
	"sort"
	"sync"
	"time"
)

type CardLogic struct{}

func NewCardLogic() *CardLogic {
	return &CardLogic{}
}

func (cl *CardLogic) CreateDeck() []models.Card {
	deck := make([]models.Card, 0, 55)
	suits := []models.Suit{models.SuitHeart, models.SuitDiamond, models.SuitClub, models.SuitSpade}
	for _, suit := range suits {
		for value := 3; value <= 15; value++ {
			deck = append(deck, models.Card{Suit: suit, Value: value})
		}
	}
	deck = append(deck, models.Card{Suit: models.SuitJoker, Value: 16})
	deck = append(deck, models.Card{Suit: models.SuitJoker, Value: 17})
	deck = append(deck, models.Card{Suit: models.SuitSuper, Value: 18})
	return deck
}

func (cl *CardLogic) Shuffle(deck []models.Card) {
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	r.Shuffle(len(deck), func(i, j int) { deck[i], deck[j] = deck[j], deck[i] })
}

func (cl *CardLogic) SortCards(cards []models.Card) {
	sort.Slice(cards, func(i, j int) bool {
		if cards[i].Value != cards[j].Value {
			return cards[i].Value > cards[j].Value
		}
		return cards[i].Suit < cards[j].Suit
	})
}

func (cl *CardLogic) GetCardType(cards []models.Card) models.CardType {
	n := len(cards)
	if n == 0 {
		return models.CardTypeInvalid
	}

	if cl.isRocket(cards) {
		return models.CardTypeRocket
	}

	sorted := make([]models.Card, n)
	copy(sorted, cards)
	cl.SortCards(sorted)
	counts := cl.getValueCounts(sorted)

	switch n {
	case 1:
		return models.CardTypeSingle
	case 2:
		if len(counts) == 1 {
			return models.CardTypePair
		}
		return models.CardTypeInvalid
	case 3:
		if len(counts) == 1 {
			return models.CardTypeBomb
		}
		if cl.isStraight(sorted) {
			return models.CardTypeStraight
		}
		return models.CardTypeInvalid
	case 4:
		if len(counts) == 1 {
			return models.CardTypeBomb
		}
		if len(counts) == 2 {
			for _, c := range counts {
				if c == 3 {
					return models.CardTypeTripleOne
				}
			}
		}
		if cl.isStraight(sorted) {
			return models.CardTypeStraight
		}
		if cl.isDoubleStraight(sorted, counts) {
			return models.CardTypeDoubleStraight
		}
		return models.CardTypeInvalid
	default:
		if cl.isStraight(sorted) {
			return models.CardTypeStraight
		}
		if cl.isDoubleStraight(sorted, counts) {
			return models.CardTypeDoubleStraight
		}
		hasTriple := false
		for _, c := range counts {
			if c >= 3 {
				hasTriple = true
				break
			}
		}
		if hasTriple && (n == 4 || n == 5) {
			return models.CardTypeTripleOne
		}
		return models.CardTypeInvalid
	}
}

func (cl *CardLogic) isRocket(cards []models.Card) bool {
	if len(cards) != 2 {
		return false
	}
	hasSmall, hasBig := false, false
	for _, c := range cards {
		if c.Suit == models.SuitJoker {
			if c.Value == 16 {
				hasSmall = true
			} else if c.Value == 17 {
				hasBig = true
			}
		}
	}
	return hasSmall && hasBig
}

func (cl *CardLogic) isStraight(cards []models.Card) bool {
	if len(cards) < 3 {
		return false
	}
	for _, c := range cards {
		if c.Value >= 15 || c.Suit == models.SuitJoker || c.Suit == models.SuitSuper {
			return false
		}
	}
	values := make([]int, len(cards))
	for i, c := range cards {
		values[i] = c.Value
	}
	sort.Ints(values)
	for i := 1; i < len(values); i++ {
		if values[i] != values[i-1]+1 {
			return false
		}
	}
	return true
}

func (cl *CardLogic) isDoubleStraight(cards []models.Card, counts map[int]int) bool {
	if len(cards) < 4 || len(cards)%2 != 0 {
		return false
	}
	pairs := make([]int, 0)
	for v, c := range counts {
		if c != 2 {
			return false
		}
		if v >= 15 {
			return false
		}
		pairs = append(pairs, v)
	}
	sort.Ints(pairs)
	for i := 1; i < len(pairs); i++ {
		if pairs[i] != pairs[i-1]+1 {
			return false
		}
	}
	return true
}

func (cl *CardLogic) getValueCounts(cards []models.Card) map[int]int {
	counts := make(map[int]int)
	for _, c := range cards {
		counts[c.Value]++
	}
	return counts
}

func (cl *CardLogic) CanPlay(cards []models.Card, lastPlay *models.PlayRecord) bool {
	cardType := cl.GetCardType(cards)
	if cardType == models.CardTypeInvalid {
		return false
	}
	if lastPlay == nil {
		return true
	}

	if cardType == models.CardTypeRocket {
		return true
	}

	if cardType == models.CardTypeBomb {
		if lastPlay.CardType == models.CardTypeBomb {
			return cl.getMainValue(cards) > cl.getMainValue(lastPlay.Cards)
		}
		if lastPlay.CardType == models.CardTypeRocket {
			return false
		}
		return true
	}

	if lastPlay.CardType == models.CardTypeBomb || lastPlay.CardType == models.CardTypeRocket {
		return false
	}

	if cardType != lastPlay.CardType || len(cards) != len(lastPlay.Cards) {
		return false
	}
	return cl.getMainValue(cards) > cl.getMainValue(lastPlay.Cards)
}

func (cl *CardLogic) getMainValue(cards []models.Card) int {
	counts := cl.getValueCounts(cards)
	maxValue, maxCount := 0, 0
	for v, c := range counts {
		if c > maxCount || (c == maxCount && v > maxValue) {
			maxCount, maxValue = c, v
		}
	}
	return maxValue
}

type GameManager struct {
	rooms   map[string]*models.Room
	players map[string]*models.Player
	deck    map[string][]models.Card
	discard map[string][]models.Card
	mu      sync.RWMutex
	cl      *CardLogic
}

func NewGameManager() *GameManager {
	return &GameManager{
		rooms:   make(map[string]*models.Room),
		players: make(map[string]*models.Player),
		deck:    make(map[string][]models.Card),
		discard: make(map[string][]models.Card),
		cl:      NewCardLogic(),
	}
}

func (gm *GameManager) CreateRoom(playerName string, maxPlayers int) (*models.Room, *models.Player) {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	roomID := generateID()
	playerID := generateID()
	player := &models.Player{ID: playerID, Name: playerName, IsOnline: true}
	room := &models.Room{
		ID:         roomID,
		Players:    []*models.Player{player},
		MaxPlayers: maxPlayers,
		State:      models.RoomStateWaiting,
	}

	deck := gm.cl.CreateDeck()
	gm.cl.Shuffle(deck)

	gm.rooms[roomID] = room
	gm.players[playerID] = player
	gm.deck[roomID] = deck
	gm.discard[roomID] = make([]models.Card, 0)

	return room, player
}

func (gm *GameManager) JoinRoom(roomID, playerName string) (*models.Room, *models.Player, error) {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return nil, nil, ErrRoomNotFound
	}
	if len(room.Players) >= room.MaxPlayers {
		return nil, nil, ErrRoomFull
	}
	if room.State == models.RoomStatePlaying {
		return nil, nil, ErrGameStarted
	}

	playerID := generateID()
	player := &models.Player{ID: playerID, Name: playerName, IsOnline: true}
	room.Players = append(room.Players, player)
	gm.players[playerID] = player

	return room, player, nil
}

func (gm *GameManager) LeaveRoom(roomID, playerID string) error {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return ErrRoomNotFound
	}

	for i, p := range room.Players {
		if p.ID == playerID {
			room.Players = append(room.Players[:i], room.Players[i+1:]...)
			delete(gm.players, playerID)
			if len(room.Players) == 0 {
				delete(gm.rooms, roomID)
				delete(gm.deck, roomID)
				delete(gm.discard, roomID)
			}
			return nil
		}
	}
	return ErrPlayerNotFound
}

func (gm *GameManager) SetReady(roomID, playerID string, ready bool) error {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return ErrRoomNotFound
	}
	
	if room.State == models.RoomStatePlaying {
		return ErrGameStarted
	}
	
	for _, p := range room.Players {
		if p.ID == playerID {
			p.IsReady = ready
			if room.State == models.RoomStateFinished {
				room.State = models.RoomStateWaiting
			}
			return nil
		}
	}
	return ErrPlayerNotFound
}

func (gm *GameManager) StartGame(roomID string) error {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return ErrRoomNotFound
	}
	if len(room.Players) < 2 {
		return ErrNotEnoughPlayers
	}
	if room.State == models.RoomStatePlaying {
		return ErrGameStarted
	}

	for _, p := range room.Players {
		p.Cards = make([]models.Card, 0)
		p.CardCount = 0
		p.IsReady = false
	}

	deck := gm.cl.CreateDeck()
	gm.cl.Shuffle(deck)
	gm.deck[roomID] = deck
	gm.discard[roomID] = make([]models.Card, 0)

	room.State = models.RoomStatePlaying
	room.RoundCount = 1
	room.CurrentTurn = 0
	room.LastPlay = nil
	room.LastWinner = ""

	gm.dealCards(roomID, 5)
	return nil
}

func (gm *GameManager) dealCards(roomID string, count int) {
	room := gm.rooms[roomID]
	deck := gm.deck[roomID]

	for i := 0; i < count; i++ {
		for _, p := range room.Players {
			if len(deck) == 0 {
				deck = gm.discard[roomID]
				gm.cl.Shuffle(deck)
				gm.discard[roomID] = make([]models.Card, 0)
			}
			if len(deck) > 0 {
				p.Cards = append(p.Cards, deck[0])
				deck = deck[1:]
			}
		}
	}
	gm.deck[roomID] = deck

	for _, p := range room.Players {
		gm.cl.SortCards(p.Cards)
		p.CardCount = len(p.Cards)
	}
}

func (gm *GameManager) PlayCards(roomID, playerID string, cards []models.Card) error {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return ErrRoomNotFound
	}
	if room.State != models.RoomStatePlaying {
		return ErrGameNotStarted
	}
	if room.Players[room.CurrentTurn].ID != playerID {
		return ErrNotYourTurn
	}

	player := room.Players[room.CurrentTurn]
	if !gm.hasCards(player, cards) {
		return ErrCardsNotInHand
	}

	cardType := gm.cl.GetCardType(cards)
	if cardType == models.CardTypeInvalid {
		return ErrInvalidCardType
	}
	if !gm.cl.CanPlay(cards, room.LastPlay) {
		return ErrCannotBeat
	}

	gm.removeCards(player, cards)
	player.CardCount = len(player.Cards)

	room.LastPlay = &models.PlayRecord{
		PlayerID: playerID,
		Cards:    cards,
		CardType: cardType,
	}
	gm.discard[roomID] = append(gm.discard[roomID], cards...)

	if len(player.Cards) == 0 {
		room.LastWinner = playerID
		room.State = models.RoomStateFinished
		return nil
	}

	gm.nextTurn(room)
	return nil
}

func (gm *GameManager) Pass(roomID, playerID string) error {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return ErrRoomNotFound
	}
	if room.State != models.RoomStatePlaying {
		return ErrGameNotStarted
	}
	if room.Players[room.CurrentTurn].ID != playerID {
		return ErrNotYourTurn
	}
	if room.LastPlay == nil || room.LastPlay.PlayerID == playerID {
		return ErrCannotPass
	}

	gm.nextTurn(room)

	if room.Players[room.CurrentTurn].ID == room.LastPlay.PlayerID {
		room.LastPlay = nil
		gm.dealCards(roomID, 1)
		room.RoundCount++
	}
	return nil
}

func (gm *GameManager) nextTurn(room *models.Room) {
	room.CurrentTurn = (room.CurrentTurn + 1) % len(room.Players)
}

func (gm *GameManager) hasCards(player *models.Player, cards []models.Card) bool {
	hand := make(map[string]int)
	for _, c := range player.Cards {
		hand[cardKey(c)]++
	}
	for _, c := range cards {
		k := cardKey(c)
		if hand[k] == 0 {
			return false
		}
		hand[k]--
	}
	return true
}

func (gm *GameManager) removeCards(player *models.Player, cards []models.Card) {
	toRemove := make(map[string]int)
	for _, c := range cards {
		toRemove[cardKey(c)]++
	}
	newCards := make([]models.Card, 0)
	removed := make(map[string]int)
	for _, c := range player.Cards {
		k := cardKey(c)
		if removed[k] < toRemove[k] {
			removed[k]++
		} else {
			newCards = append(newCards, c)
		}
	}
	player.Cards = newCards
}

func (gm *GameManager) GetRoom(roomID string) (*models.Room, error) {
	gm.mu.RLock()
	defer gm.mu.RUnlock()
	room, ok := gm.rooms[roomID]
	if !ok {
		return nil, ErrRoomNotFound
	}
	return room, nil
}

func (gm *GameManager) GetRoomState(roomID, playerID string) *models.Room {
	gm.mu.RLock()
	defer gm.mu.RUnlock()

	room, ok := gm.rooms[roomID]
	if !ok {
		return nil
	}

	players := make([]*models.Player, len(room.Players))
	for i, p := range room.Players {
		pp := &models.Player{
			ID:        p.ID,
			Name:      p.Name,
			IsReady:   p.IsReady,
			IsOnline:  p.IsOnline,
			CardCount: p.CardCount,
		}
		if p.ID == playerID {
			pp.Cards = p.Cards
		}
		players[i] = pp
	}

	return &models.Room{
		ID:          room.ID,
		Players:     players,
		CurrentTurn: room.CurrentTurn,
		State:       room.State,
		LastPlay:    room.LastPlay,
		LastWinner:  room.LastWinner,
		RoundCount:  room.RoundCount,
		MaxPlayers:  room.MaxPlayers,
	}
}