package poker

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"sync"
	"time"
)

// Phase represents the current state of a poker hand.
type Phase string

const (
	PhaseWaiting  Phase = "waiting"   // waiting for enough players
	PhaseDealing  Phase = "dealing"   // cards being dealt (brief transition)
	PhasePreflop  Phase = "preflop"
	PhaseFlop     Phase = "flop"
	PhaseTurn     Phase = "turn"
	PhaseRiver    Phase = "river"
	PhaseShowdown Phase = "showdown"
)

// Config holds immutable table configuration.
type Config struct {
	ID          string `json:"id"`
	Name        string `json:"name"`
	SeatCount   int    `json:"seatCount"`
	SmallBlind  int64  `json:"smallBlind"`
	BigBlind    int64  `json:"bigBlind"`
	MinBuyin    int64  `json:"minBuyin"`
	MaxBuyin    int64  `json:"maxBuyin"`
	TurnTimer   int    `json:"turnTimer"` // seconds
}

// Seat holds per-seat state.
type Seat struct {
	Username string `json:"username,omitempty"`
	Stack    int64  `json:"stack"`
	Bet      int64  `json:"bet"`      // current street bet
	Folded   bool   `json:"folded"`
	SitOut   bool   `json:"sitOut"`
	Revealed bool   `json:"revealed"` // hole cards shown to all
}

// HandState holds the mutable state for a single hand.
type HandState struct {
	Phase         Phase    `json:"phase"`
	Community     []string `json:"community"`
	Pot           int64    `json:"pot"`
	ActionOn      int      `json:"actionOn"`      // seat index
	ActionDeadline int64   `json:"actionDeadline"` // unix timestamp
	DealerSeat    int      `json:"dealerSeat"`
	LastRaise     int64    `json:"lastRaise"`
	MinRaise      int64    `json:"minRaise"`
}

// Table is the central struct — holds config, seats, and hand state.
type Table struct {
	mu     sync.RWMutex
	Config Config
	Seats  []*Seat
	Hand   HandState

	deck     []string
	hands    map[string][]string // username -> hole cards, never sent to other players
	folded   map[string]bool
	acted    map[string]bool

	cancelTurn context.CancelFunc // cancels the current turn timer

	// Broadcast is set by the manager — called whenever state changes
	// that all connected clients should know about.
	Broadcast func(msg interface{})

	// SendPrivate sends a message to a single username only.
	SendPrivate func(username string, msg interface{})
}

// NewTable creates a Table from a Config.
func NewTable(cfg Config) *Table {
	seats := make([]*Seat, cfg.SeatCount)
	for i := range seats {
		seats[i] = &Seat{}
	}
	return &Table{
		Config:   cfg,
		Seats:    seats,
		Hand:     HandState{Phase: PhaseWaiting, Community: []string{}},
		hands:    make(map[string][]string),
		folded:   make(map[string]bool),
		acted:    make(map[string]bool),
	}
}

// ── Seat management ──────────────────────────────────────────────

// Sit places a player in a seat and deducts the buy-in from their stack.
// The caller is responsible for deducting from the player's wallet first.
func (t *Table) Sit(username string, seatIndex int, buyin int64) error {
	t.mu.Lock()

	if seatIndex < 0 || seatIndex >= len(t.Seats) {
		t.mu.Unlock()
		return errors.New("invalid seat index")
	}
	if t.Seats[seatIndex].Username != "" {
		t.mu.Unlock()
		return errors.New("seat taken")
	}
	for _, s := range t.Seats {
		if s.Username == username {
			t.mu.Unlock()
			return errors.New("already seated")
		}
	}
	if buyin < t.Config.MinBuyin || buyin > t.Config.MaxBuyin {
		t.mu.Unlock()
		return fmt.Errorf("buy-in must be between %d and %d", t.Config.MinBuyin, t.Config.MaxBuyin)
	}

	t.Seats[seatIndex].Username = username
	t.Seats[seatIndex].Stack = buyin
	t.Seats[seatIndex].Folded = false
	t.Seats[seatIndex].SitOut = false
	t.mu.Unlock()

	t.broadcastState()
	t.maybeStartHand()
	return nil
}

// Stand removes a player from their seat and returns their remaining stack.
// Cannot stand mid-hand unless folded.
func (t *Table) Stand(username string) (int64, error) {
	t.mu.Lock()

	seat := t.findSeat(username)
	if seat == nil {
		t.mu.Unlock()
		return 0, errors.New("not seated")
	}
	// Allow standing if folded OR if marked as disconnected (SitOut mid-hand)
	if t.Hand.Phase != PhaseWaiting && !seat.Folded && !seat.SitOut {
		t.mu.Unlock()
		return 0, errors.New("cannot stand mid-hand while active")
	}

	stack := seat.Stack
	*seat = Seat{}
	t.mu.Unlock()

	t.broadcastState()
	return stack, nil
}

func (t *Table) Disconnect(username string) (int64, bool) {
	t.mu.Lock()
	seat := t.findSeat(username)
	if seat == nil {
		t.mu.Unlock()
		return 0, false
	}

	if t.Hand.Phase == PhaseWaiting {
		stack := seat.Stack
		*seat = Seat{}
		t.mu.Unlock()
		t.broadcastState()
		return stack, true // safe to refund immediately
	}

	// Mid-hand — mark sitout and let the hand clean up
	seat.SitOut = true
	if t.Seats[t.Hand.ActionOn].Username == username {
		if t.cancelTurn != nil {
			t.cancelTurn()
		}
	}
	t.mu.Unlock()
	t.broadcastState()
	return 0, false // refund will happen via player:disconnect:stand after hand ends
}

// TopUp adds chips to a seated player's stack (between hands only).
func (t *Table) TopUp(username string, amount int64) error {
	t.mu.Lock()

	if t.Hand.Phase != PhaseWaiting {
		t.mu.Unlock()
		return errors.New("can only top up between hands")
	}
	seat := t.findSeat(username)
	if seat == nil {
		t.mu.Unlock()
		return errors.New("not seated")
	}
	if seat.Stack+amount > t.Config.MaxBuyin {
		t.mu.Unlock()
		return fmt.Errorf("would exceed max buy-in of %d", t.Config.MaxBuyin)
	}
	seat.Stack += amount
	t.mu.Unlock()

	t.broadcastState()
	return nil
}

// ── Hand flow ────────────────────────────────────────────────────

func (t *Table) activeSeatCount() int {
	n := 0
	for _, s := range t.Seats {
		if s.Username != "" && !s.SitOut && s.Stack > 0 {
			n++
		}
	}
	return n
}

func (t *Table) maybeStartHand() {
	if t.Hand.Phase == PhaseWaiting && t.activeSeatCount() >= 2 {
		go t.startHand()
	}
}

func (t *Table) startHand() {
	t.mu.Lock()

	// Reset per-hand state
	t.deck = NewDeck()
	t.hands = make(map[string][]string)
	t.folded = make(map[string]bool)
	t.acted = make(map[string]bool)

	for _, s := range t.Seats {
		s.Bet = 0
		s.Folded = false
		s.Revealed = false
	}

	// Advance dealer button
	t.Hand.DealerSeat = t.nextActiveSeat(t.Hand.DealerSeat)
	t.Hand.Community = []string{}
	t.Hand.Pot = 0
	t.Hand.Phase = PhaseDealing

	// Deal hole cards
	active := t.activeSeats()
	for _, idx := range active {
		var cards []string
		cards, t.deck = Deal(t.deck, 2)
		t.hands[t.Seats[idx].Username] = cards
	}

	t.mu.Unlock()

	// Send private hole cards
	for username, cards := range t.hands {
		if t.SendPrivate != nil {
			t.SendPrivate(username, map[string]interface{}{
				"type":  "hand:dealt",
				"cards": cards,
			})
		}
	}

	t.mu.Lock()

	// Post blinds
	sbSeat := t.nextActiveSeat(t.Hand.DealerSeat)
	bbSeat := t.nextActiveSeat(sbSeat)
	t.postBlind(sbSeat, t.Config.SmallBlind)
	t.postBlind(bbSeat, t.Config.BigBlind)

	t.Hand.LastRaise = t.Config.BigBlind
	t.Hand.MinRaise = t.Config.BigBlind * 2
	t.Hand.Phase = PhasePreflop

	// Action starts left of big blind
	t.Hand.ActionOn = t.nextActiveSeat(bbSeat)
	t.mu.Unlock()

	t.broadcastState()
	t.startTurnTimer()
}

func (t *Table) postBlind(seatIdx int, amount int64) {
	seat := t.Seats[seatIdx]
	if seat.Stack < amount {
		amount = seat.Stack // all-in blind
	}
	seat.Stack -= amount
	seat.Bet += amount
	t.Hand.Pot += amount
}

// ── Player actions ───────────────────────────────────────────────

type ActionType string

const (
	ActionFold  ActionType = "fold"
	ActionCheck ActionType = "check"
	ActionCall  ActionType = "call"
	ActionRaise ActionType = "raise"
)

// Action processes a player's action. Returns an error if invalid.
func (t *Table) Action(username string, action ActionType, amount int64) error {
	t.mu.Lock()

	if t.Hand.Phase == PhaseWaiting || t.Hand.Phase == PhaseDealing || t.Hand.Phase == PhaseShowdown {
		t.mu.Unlock()
		return errors.New("no action in current phase")
	}

	seatIdx := t.findSeatIndex(username)
	if seatIdx < 0 {
		t.mu.Unlock()
		return errors.New("not seated")
	}
	if seatIdx != t.Hand.ActionOn {
		t.mu.Unlock()
		return errors.New("not your turn")
	}

	seat := t.Seats[seatIdx]
	currentBet := t.maxBet()

	switch action {
	case ActionFold:
		seat.Folded = true
		t.folded[username] = true

	case ActionCheck:
		if seat.Bet < currentBet {
			t.mu.Unlock()
			return errors.New("cannot check — must call or raise")
		}

	case ActionCall:
		toCall := currentBet - seat.Bet
		if toCall <= 0 {
			t.mu.Unlock()
			return errors.New("nothing to call — check instead")
		}
		if toCall > seat.Stack {
			toCall = seat.Stack // all-in
		}
		seat.Stack -= toCall
		seat.Bet += toCall
		t.Hand.Pot += toCall

	case ActionRaise:
		if amount < t.Hand.MinRaise {
			t.mu.Unlock()
			return fmt.Errorf("minimum raise is %d", t.Hand.MinRaise)
		}
		toCall := currentBet - seat.Bet
		total := toCall + amount
		if total > seat.Stack {
			total = seat.Stack // all-in
		}
		seat.Stack -= total
		seat.Bet += total
		t.Hand.Pot += total
		t.Hand.LastRaise = amount
		t.Hand.MinRaise = currentBet + amount
		t.acted = make(map[string]bool) // raise reopens action

	default:
		t.mu.Unlock()
		return fmt.Errorf("unknown action: %s", action)
	}

	t.acted[username] = true

	// Cancel the current turn timer
	if t.cancelTurn != nil {
		t.cancelTurn()
		t.cancelTurn = nil
	}

	t.mu.Unlock()
	t.broadcastAction(username, action, amount)
	t.advance()
	return nil
}

// Reveal marks a player's hole cards as public.
func (t *Table) Reveal(username string) {
	t.mu.Lock()
	seat := t.findSeat(username)
	if seat == nil {
		t.mu.Unlock()
		return
	}
	seat.Revealed = true
	cards := t.hands[username]
	t.mu.Unlock()

	if t.Broadcast != nil {
		t.Broadcast(map[string]interface{}{
			"type":     "hand:reveal",
			"username": username,
			"cards":    cards,
		})
	}
}

// ── Street advancement ───────────────────────────────────────────

func (t *Table) advance() {
	t.mu.Lock()
	defer t.mu.Unlock()

	// Check if only one player remains
	if t.countActivePlayers() == 1 {
		t.awardPot()
		return
	}

	// Check if betting is complete for this street
	if !t.bettingComplete() {
		t.Hand.ActionOn = t.nextActiveSeat(t.Hand.ActionOn)
		t.mu.Unlock()
		t.broadcastState()
		t.startTurnTimer()
		t.mu.Lock()
		return
	}

	// Advance to next street
	switch t.Hand.Phase {
	case PhasePreflop:
		var cards []string
		cards, t.deck = Deal(t.deck, 3)
		t.Hand.Community = cards
		t.Hand.Phase = PhaseFlop
	case PhaseFlop:
		var cards []string
		cards, t.deck = Deal(t.deck, 1)
		t.Hand.Community = append(t.Hand.Community, cards...)
		t.Hand.Phase = PhaseTurn
	case PhaseTurn:
		var cards []string
		cards, t.deck = Deal(t.deck, 1)
		t.Hand.Community = append(t.Hand.Community, cards...)
		t.Hand.Phase = PhaseRiver
	case PhaseRiver:
		t.Hand.Phase = PhaseShowdown
		t.mu.Unlock()
		t.doShowdown()
		t.mu.Lock()
		return
	}

	// Reset bets for new street
	for _, s := range t.Seats {
		s.Bet = 0
	}
	t.acted = make(map[string]bool)
	t.Hand.LastRaise = 0
	t.Hand.MinRaise = t.Config.BigBlind

	// Action starts left of dealer post-flop
	t.Hand.ActionOn = t.nextActiveSeat(t.Hand.DealerSeat)
	t.mu.Unlock()
	t.broadcastState()
	t.startTurnTimer()
	t.mu.Lock()
}

func (t *Table) doShowdown() {
	remaining := make(map[string][]string)
	for username, cards := range t.hands {
		if !t.folded[username] {
			remaining[username] = cards
		}
	}

	winners := Winners(remaining, t.Hand.Community)

	revealedHands := make(map[string][]string)
	for _, w := range winners {
		revealedHands[w.Username] = remaining[w.Username]
	}
	t.mu.RLock()
	for _, seat := range t.Seats {
		if seat.Revealed && seat.Username != "" {
			revealedHands[seat.Username] = t.hands[seat.Username]
		}
	}
	t.mu.RUnlock()

	winnerNames := make([]string, len(winners))
	winnerDescs := make(map[string]string)
	for i, w := range winners {
		winnerNames[i] = w.Username
		winnerDescs[w.Username] = w.Desc
	}

	share := t.Hand.Pot / int64(len(winners))
	remainder := t.Hand.Pot % int64(len(winners))
	t.mu.Lock()
	for i, w := range winners {
		seat := t.findSeat(w.Username)
		if seat != nil {
			extra := int64(0)
			if i == 0 {
				extra = remainder
			}
			seat.Stack += share + extra
		}
	}
	t.Hand.Pot = 0
	t.mu.Unlock()

	if t.Broadcast != nil {
		t.Broadcast(map[string]interface{}{
			"type":    "hand:end",
			"winners": winnerNames,
			"descs":   winnerDescs,
			"hands":   revealedHands,
		})
	}

	time.Sleep(5 * time.Second)
	t.mu.Lock()
	t.Hand.Phase = PhaseWaiting
	t.cleanupSeats()
	t.mu.Unlock()
	t.broadcastState()
	t.mu.Lock()
	t.maybeStartHand()
	t.mu.Unlock()
}

func (t *Table) awardPot() {
	for _, s := range t.Seats {
		if s.Username != "" && !s.Folded {
			s.Stack += t.Hand.Pot
			if t.Broadcast != nil {
				t.Broadcast(map[string]interface{}{
					"type":    "hand:end",
					"winners": []string{s.Username},
					"descs":   map[string]string{},
					"hands":   map[string][]string{},
				})
			}
			break
		}
	}
	t.Hand.Pot = 0
	time.Sleep(2 * time.Second)
	t.mu.Lock()
	t.Hand.Phase = PhaseWaiting
	t.cleanupSeats()
	t.mu.Unlock()
	t.broadcastState()
	t.maybeStartHand()
}

// ── Turn timer ───────────────────────────────────────────────────

func (t *Table) startTurnTimer() {
	t.mu.Lock()
	if t.cancelTurn != nil {
		t.cancelTurn()
	}
	ctx, cancel := context.WithTimeout(context.Background(),
		time.Duration(t.Config.TurnTimer)*time.Second)
	t.cancelTurn = cancel
	username := t.Seats[t.Hand.ActionOn].Username
	t.Hand.ActionDeadline = time.Now().Add(
		time.Duration(t.Config.TurnTimer) * time.Second).Unix()
	t.mu.Unlock()

	go func() {
		<-ctx.Done()
		if ctx.Err() == context.DeadlineExceeded {
			log.Printf("[poker] turn timer expired for %s at table %s", username, t.Config.ID)
			t.Action(username, ActionFold, 0)
		}
	}()
}

// ── Helpers ──────────────────────────────────────────────────────

func (t *Table) findSeat(username string) *Seat {
	for _, s := range t.Seats {
		if s.Username == username {
			return s
		}
	}
	return nil
}

func (t *Table) findSeatIndex(username string) int {
	for i, s := range t.Seats {
		if s.Username == username {
			return i
		}
	}
	return -1
}

func (t *Table) activeSeats() []int {
	var idxs []int
	for i, s := range t.Seats {
		if s.Username != "" && !s.SitOut && s.Stack > 0 {
			idxs = append(idxs, i)
		}
	}
	return idxs
}

func (t *Table) nextActiveSeat(from int) int {
	n := len(t.Seats)
	for i := 1; i <= n; i++ {
		idx := (from + i) % n
		s := t.Seats[idx]
		if s.Username != "" && !s.SitOut && !s.Folded && s.Stack > 0 {
			return idx
		}
	}
	return from
}

func (t *Table) countActivePlayers() int {
	n := 0
	for _, s := range t.Seats {
		if s.Username != "" && !s.Folded {
			n++
		}
	}
	return n
}

func (t *Table) maxBet() int64 {
	var max int64
	for _, s := range t.Seats {
		if s.Bet > max {
			max = s.Bet
		}
	}
	return max
}

func (t *Table) bettingComplete() bool {
	currentBet := t.maxBet()
	for _, s := range t.Seats {
		if s.Username == "" || s.Folded || s.SitOut {
			continue
		}
		if s.Stack == 0 {
			continue // all-in
		}
		if !t.acted[s.Username] {
			return false
		}
		if s.Bet < currentBet {
			return false
		}
	}
	return true
}

func (t *Table) cleanupSeats() {
    for _, s := range t.Seats {
        if s.Username == "" {
            continue
        }
        if s.Stack == 0 {
            log.Printf("[poker] %s busted", s.Username)
            if t.Broadcast != nil {
                t.Broadcast(map[string]interface{}{
                    "type":     "player:bust",
                    "username": s.Username,
                    "tableId":  t.Config.ID,
                })
            }
            *s = Seat{}
        } else if s.SitOut {
            log.Printf("[poker] standing disconnected player %s with %d chips", s.Username, s.Stack)
            if t.Broadcast != nil {
                t.Broadcast(map[string]interface{}{
                    "type":     "player:disconnect:stand",
                    "username": s.Username,
                    "stack":    s.Stack,
                    "tableId":  t.Config.ID,
                })
            }
            *s = Seat{}
        }
    }
}

// ── State broadcast ──────────────────────────────────────────────

// PublicState returns the table state safe to send to all clients.
// Hole cards are never included.
func (t *Table) PublicState() map[string]interface{} {
	t.mu.RLock()
	defer t.mu.RUnlock()

	seats := make([]map[string]interface{}, len(t.Seats))
	for i, s := range t.Seats {
		seats[i] = map[string]interface{}{
			"username": s.Username,
			"stack":    s.Stack,
			"bet":      s.Bet,
			"folded":   s.Folded,
			"sitOut":   s.SitOut,
			"revealed": s.Revealed,
		}
	}

	return map[string]interface{}{
		"type":           "table:state",
		"tableId":        t.Config.ID,
		"phase":          t.Hand.Phase,
		"community":      t.Hand.Community,
		"pot":            t.Hand.Pot,
		"actionOn":       t.Hand.ActionOn,
		"actionDeadline": t.Hand.ActionDeadline,
		"dealerSeat":     t.Hand.DealerSeat,
		"seats":          seats,
		"config":         t.Config,
	}
}

func (t *Table) broadcastState() {
	if t.Broadcast != nil {
		t.Broadcast(t.PublicState())
	}
}

func (t *Table) broadcastAction(username string, action ActionType, amount int64) {
	if t.Broadcast != nil {
		t.Broadcast(map[string]interface{}{
			"type":     "player:action",
			"tableId":  t.Config.ID,
			"username": username,
			"action":   action,
			"amount":   amount,
		})
	}
}

// MarshalConfig serialises the table config to JSON for Redis storage.
func (c Config) Marshal() ([]byte, error) {
	return json.Marshal(c)
}