package modules

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"

	"github.com/heroiclabs/nakama-common/runtime"

	// adjust these imports to match your actual module path / packages
	"localrepo/plugins/structs"
	"localrepo/plugins/games"
)

const (
	OpMove  int64 = 1
	OpState int64 = 2
)

// GenericMatch is a match implementation that delegates game-specific logic
// to a game.GameRules implementation chosen by the match params ("game").
type GenericMatch struct {
	// registry maps game name -> GameRules implementation
	Registry map[string]game.GameRules
}

// NewGenericMatch returns a factory function suitable for RegisterMatch.
// Provide a registry mapping game names (strings) to implementations.
func NewGenericMatch(registry map[string]game.GameRules) func(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
) (runtime.Match, error) {

	return func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule) (runtime.Match, error) {
		return &GenericMatch{Registry: registry}, nil
	}
}

// -------------------------
// Helpers
// -------------------------

func indexOfPlayerByID(players []*structs.Player, userID string) int {
	for i, p := range players {
		if p.UserID == userID {
			return i
		}
	}
	return -1
}

func newEmptyBoard(rows, cols int) *structs.Board {
	b := &structs.Board{
		Rows: rows,
		Cols: cols,
		Grid: make([][]string, rows),
	}
	for r := 0; r < rows; r++ {
		b.Grid[r] = make([]string, cols)
	}
	return b
}

// -------------------------
// Match interface methods
// -------------------------

// MatchInit: create initial state. Expects params to include "game" (string) and optionally "mode" and board size.
func (m *GenericMatch) MatchInit(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	params map[string]interface{},
) (interface{}, int, string) {

	// Determine requested game
	gameName := ""
	if g, ok := params["game"].(string); ok {
		gameName = g
	}
	mode := ""
	if md, ok := params["mode"].(string); ok {
		mode = md
	}

	// Pick rules if registered
	rules, found := m.Registry[gameName]
	if !found {
		logger.Warn("GenericMatch MatchInit: unknown game '%s' — match will start but no rules attached", gameName)
	}

	// board size fallback defaults (3x3). Games can re-initialize in Setup if required.
	rows := 3
	cols := 3
	if r, ok := params["rows"].(float64); ok { // JSON numbers come as float64
		rows = int(r)
	}
	if c, ok := params["cols"].(float64); ok {
		cols = int(c)
	}

	// Build base state
	state := &structs.MatchState{
		Players:  []*structs.Player{},
		Board:    newEmptyBoard(rows, cols),
		Turn:     0,
		Winner:   -1,
		GameOver: false,
	}

	label := "generic"
	if gameName != "" {
		label = fmt.Sprintf("%s:%s", gameName, mode)
	}

	// store selected game in metadata so MatchLoop knows which rules to call
	// We'll attach it to the state's "Players" metadata of a synthetic player at index - not ideal,
	// so include in logger and rely on match params available in MatchInit -> MatchLoop via the match object instance.
	// Note: Nakama doesn't pass params to MatchLoop directly; we keep chosen rules in the GenericMatch instance by mapping match label -> rules could be implemented,
	// but to keep this simple, we'll rely on the convention that the match label contains the game name (above).
	// Most importantly, store the chosen game in state via Player Metadata by creating a pseudo player entry (not visible to clients).
	// However to keep MatchState pure, we instead keep the mapping in memory using the label. That requires matches to be one-per-factory instance,
	// which is the case: each match instance is independent.

	logger.Info("MatchInit: game=%s mode=%s rows=%d cols=%d label=%s", gameName, mode, rows, cols, label)
	// Store the gameName in the match's Registry via a reserved key? Simpler: keep label informative and rely on Registry lookup by gameName later.

	// Tick rate 5 (200ms) is a sensible default; can be tuned per game.
	return state, 5, label
}

// MatchJoinAttempt: basic capacity check using rules.MaxPlayers()
func (m *GenericMatch) MatchJoinAttempt(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	presence runtime.Presence,
	metadata map[string]string,
) (interface{}, bool, string) {

	s := state.(*structs.MatchState)

	// We can't know the game name safely here (params not passed). We use MaxPlayers based on the first player's "game" property if provided in metadata.
	// metadata may contain "game" from client at join time; fallback to 2 players if unknown.
	maxPlayers := 2
	if gameName, ok := metadata["game"]; ok {
		if rules, found := m.Registry[gameName]; found {
			maxPlayers = rules.MaxPlayers()
		}
	}

	if len(s.Players) >= maxPlayers {
		return s, false, "match full"
	}

	return s, true, ""
}

// MatchJoin: add players, fetch usernames, assign indices; when full, call rules.AssignPlayerSymbols
func (m *GenericMatch) MatchJoin(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	presences []runtime.Presence,
) interface{} {

	s := state.(*structs.MatchState)

	for _, p := range presences {
		userID := p.GetUserId()
		// avoid duplicates
		if indexOfPlayerByID(s.Players, userID) != -1 {
			continue
		}

		username := ""
		if acc, err := nk.AccountGetId(ctx, userID); err == nil && acc != nil && acc.GetUser() != nil {
			username = acc.GetUser().GetUsername()
		}
		player := &structs.Player{
			UserID:   userID,
			Username: username,
			Index:    len(s.Players),
		}
		// ensure metadata map exists
		player.Metadata = make(map[string]string)

		s.Players = append(s.Players, player)
	}

	logger.Info("MatchJoin: now %d players", len(s.Players))

	// determine game name from dispatcher match label if possible
	// Nakama does not expose match params to MatchJoin; to keep things simple we infer from the match label which was set in MatchInit (format "game:mode")
	// The runtime Match object cannot directly access that label; in practice you should pass the chosen game into the match via factory closure.
	// For maximum compatibility, attempt to read a "game" key from the first player's metadata (clients should send it on join)
	if len(s.Players) == 0 {
    logger.Error("MatchLoop: no players in match")
    return s
  }

  gameName, ok := s.Players[0].Metadata["game"]
  if !ok || gameName == "" {
    logger.Error("MatchLoop: missing required metadata 'game'")
    s.GameOver = true
    s.Winner = -1
    return s
  }

	rules, found := m.Registry[gameName]
	if !found {
		logger.Warn("MatchJoin: no rules registered for game '%s'", gameName)
	} else {
		if len(s.Players) == rules.MaxPlayers() {
			// call AssignPlayerSymbols to allow games to annotate players (symbols, colors, etc.)
			// convert []*structs.Player to []*game.Player if your Player type differs — here we assume same
			// However earlier your Player resides in structs package; we call the game.AssignPlayerSymbols with structs players if compatible.
			rules.AssignPlayerSymbols(convertToGamePlayers(s.Players))
			// Broadcast initial state
			if data, err := json.Marshal(s); err == nil {
				if err := dispatcher.BroadcastMessage(OpState, data, nil, nil, true); err != nil {
					logger.Error("BroadcastMessage (initial state) failed: %v", err)
				}
			}
		}
	}

	return s
}

// convertToGamePlayers converts structs.Player -> game.Player if necessary.
// If your game package expects the same Player struct, this is a no-op conversion.
// We perform a shallow conversion assuming the fields are compatible.
func convertToGamePlayers(players []*structs.Player) []*game.Player {
	out := make([]*game.Player, 0, len(players))
	for i, p := range players {
		// create a game.Player with compatible fields. If game.Player has NewPlayer helper, consider using it.
		out = append(out, &game.Player{
			UserID:   p.UserID,
			Username: p.Username,
			Index:    i,
			Metadata: p.Metadata,
		})
	}
	return out
}

// MatchLeave: mark forfeit and call game.ForfeitWinner
func (m *GenericMatch) MatchLeave(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	presences []runtime.Presence,
) interface{} {

	s := state.(*structs.MatchState)

	if s.GameOver {
		return s
	}

	// determine leaving player index from presence list
	leaverIdx := -1
	if len(presences) > 0 {
		leaverID := presences[0].GetUserId()
		leaverIdx = indexOfPlayerByID(s.Players, leaverID)
	}

	// determine game name & rules as in Join (best-effort)
	gameName := "tictactoe"
	if len(s.Players) > 0 {
		if gm, ok := s.Players[0].Metadata["game"]; ok && gm != "" {
			gameName = gm
		}
	}
	rules, found := m.Registry[gameName]
	if found {
		w := rules.ForfeitWinner(s, leaverIdx)
		if w >= 0 {
			s.Winner = w
			s.GameOver = true
		} else if w == -1 {
			// draw
			s.Winner = -1
			s.GameOver = true
		}
	} else {
		// fallback: end match as forfeit
		s.GameOver = true
		s.Winner = -1
	}

	// broadcast final state
	if data, err := json.Marshal(s); err == nil {
		if err := dispatcher.BroadcastMessage(OpState, data, nil, nil, true); err != nil {
			logger.Error("BroadcastMessage (forfeit) failed: %v", err)
		}
	}

	return s
}

// MatchLoop: handle incoming move messages, delegate to the GameRules implementation
func (m *GenericMatch) MatchLoop(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	messages []runtime.MatchData,
) interface{} {

	s := state.(*structs.MatchState)

	if s.GameOver {
		return s
	}

	changed := false

	// determine game/rules (best-effort same as other methods)
	gameName := "tictactoe"
	if len(s.Players) > 0 {
		if gm, ok := s.Players[0].Metadata["game"]; ok && gm != "" {
			gameName = gm
		}
	}
	rules, found := m.Registry[gameName]
	if !found {
		// without rules we cannot apply moves
		logger.Warn("MatchLoop: no rules registered for game '%s' -- ignoring messages", gameName)
		return s
	}

	for _, msg := range messages {
		if msg.GetOpCode() != OpMove {
			continue
		}

		// decode generic payload into MovePayload (map[string]interface{})
		var payload game.MovePayload
		if err := json.Unmarshal(msg.GetData(), &payload); err != nil {
			logger.Warn("Invalid move payload from %s: %v", msg.GetUserId(), err)
			continue
		}

		playerID := msg.GetUserId()
		playerIdx := indexOfPlayerByID(s.Players, playerID)
		if playerIdx == -1 {
			logger.Warn("Move rejected: unknown player %s", playerID)
			continue
		}

		if playerIdx != s.Turn {
			logger.Warn("Move rejected: not player's turn (idx=%d turn=%d)", playerIdx, s.Turn)
			continue
		}

		// Delegate to rules.ApplyMove which returns (changed, gameOver, winnerIndex)
		stateChanged, gameOver, winnerIdx := rules.ApplyMove(s, playerIdx, payload)

		if stateChanged {
			changed = true
		}

		if gameOver {
			s.GameOver = true
			s.Winner = winnerIdx
		} else {
			// rotate to next player if game not over
			if len(s.Players) > 0 {
				s.Turn = (s.Turn + 1) % len(s.Players)
			}
		}

		// optional: if gameOver and winnerIdx >= 0, write leaderboard here if desired
		// This code left intentionally out — you can add leaderboard writes by asking for that feature.
	}

	if changed {
		if data, err := json.Marshal(s); err == nil {
			if err := dispatcher.BroadcastMessage(OpState, data, nil, nil, true); err != nil {
				logger.Error("BroadcastMessage failed: %v", err)
			}
		} else {
			logger.Error("Failed to marshal state: %v", err)
		}
	}

	return s
}

// MatchTerminate
func (m *GenericMatch) MatchTerminate(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	graceSeconds int,
) interface{} {
	logger.Info("MatchTerminate: grace=%d", graceSeconds)
	return state
}

// MatchSignal
func (m *GenericMatch) MatchSignal(
	ctx context.Context,
	logger runtime.Logger,
	db *sql.DB,
	nk runtime.NakamaModule,
	dispatcher runtime.MatchDispatcher,
	tick int64,
	state interface{},
	data string,
) (interface{}, string) {
	logger.Debug("MatchSignal: %s", data)
	return state, ""
}