package c4game

import (
	"encoding/json"
	"net/http"
	"strconv"
	"sync"
	"time"

	"github.com/alexedwards/scs/v2"
	"github.com/go-chi/chi/v5"
	"github.com/nats-io/nats.go"
	"github.com/ryanhamamura/c4/db"
	"github.com/ryanhamamura/c4/features/c4game/components"
	"github.com/ryanhamamura/c4/features/c4game/pages"
	"github.com/ryanhamamura/c4/game"
	"github.com/starfederation/datastar-go/datastar"
)

func HandleGamePage(store *game.GameStore, sessions *scs.SessionManager, chatPersister *db.ChatPersister) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			http.Redirect(w, r, "/", http.StatusFound)
			return
		}

		playerID := game.PlayerID(sessions.GetString(r.Context(), "player_id"))
		if playerID == "" {
			playerID = game.PlayerID(game.GenerateID(8))
			sessions.Put(r.Context(), "player_id", string(playerID))
		}

		userID := sessions.GetString(r.Context(), "user_id")
		if userID != "" {
			playerID = game.PlayerID(userID)
		}

		nickname := sessions.GetString(r.Context(), "nickname")

		// Auto-join if player has a nickname but isn't in the game yet
		if nickname != "" && gi.GetPlayerColor(playerID) == 0 {
			player := &game.Player{
				ID:       playerID,
				Nickname: nickname,
			}
			if userID != "" {
				player.UserID = &userID
			}
			gi.Join(&game.PlayerSession{Player: player})
		}

		myColor := gi.GetPlayerColor(playerID)

		if myColor == 0 {
			// Player not in game
			isGuest := r.URL.Query().Get("guest") == "1"
			if userID == "" && !isGuest {
				// Show join prompt (login vs guest)
				if err := pages.JoinPage(gameID).Render(r.Context(), w); err != nil {
					http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
				}
				return
			}
			// Show nickname prompt
			if err := pages.NicknamePage(gameID).Render(r.Context(), w); err != nil {
				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
			}
			return
		}

		// Player is in the game — render full game page
		g := gi.GetGame()
		uiMsgs, _ := chatPersister.LoadChatMessages(gameID)
		msgs := uiChatToComponents(uiMsgs)

		if err := pages.GamePage(g, myColor, msgs).Render(r.Context(), w); err != nil {
			http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
		}
	}
}

func HandleGameEvents(store *game.GameStore, nc *nats.Conn, sessions *scs.SessionManager, chatPersister *db.ChatPersister) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			http.Error(w, "game not found", http.StatusNotFound)
			return
		}

		playerID := game.PlayerID(sessions.GetString(r.Context(), "player_id"))
		userID := sessions.GetString(r.Context(), "user_id")
		if userID != "" {
			playerID = game.PlayerID(userID)
		}

		myColor := gi.GetPlayerColor(playerID)

		sse := datastar.NewSSE(w, r)

		// Load initial chat messages
		uiMsgs, _ := chatPersister.LoadChatMessages(gameID)
		var chatMu sync.Mutex
		chatMessages := uiChatToComponents(uiMsgs)

		// Send initial render of all components
		sendGameComponents(sse, gi, myColor, chatMessages, &chatMu, gameID)

		// Subscribe to game state updates
		gameCh := make(chan *nats.Msg, 64)
		gameSub, err := nc.ChanSubscribe("game."+gameID, gameCh)
		if err != nil {
			return
		}
		defer gameSub.Unsubscribe()

		// Subscribe to chat messages
		chatCh := make(chan *nats.Msg, 64)
		chatSub, err := nc.ChanSubscribe("game.chat."+gameID, chatCh)
		if err != nil {
			return
		}
		defer chatSub.Unsubscribe()

		ctx := r.Context()
		for {
			select {
			case <-ctx.Done():
				return
			case <-gameCh:
				// Re-read player color in case we just joined
				myColor = gi.GetPlayerColor(playerID)
				sendGameComponents(sse, gi, myColor, chatMessages, &chatMu, gameID)
			case msg := <-chatCh:
				var uiMsg game.ChatMessage
				if err := json.Unmarshal(msg.Data, &uiMsg); err != nil {
					continue
				}
				cm := components.ChatMessage{
					Nickname: uiMsg.Nickname,
					Color:    uiMsg.Color,
					Message:  uiMsg.Message,
					Time:     uiMsg.Time,
				}
				chatMu.Lock()
				chatMessages = append(chatMessages, cm)
				if len(chatMessages) > 50 {
					chatMessages = chatMessages[len(chatMessages)-50:]
				}
				chatMu.Unlock()

				chatMu.Lock()
				msgs := make([]components.ChatMessage, len(chatMessages))
				copy(msgs, chatMessages)
				chatMu.Unlock()

				if err := sse.PatchElementTempl(components.Chat(msgs, gameID), datastar.WithSelectorID("c4-chat")); err != nil {
					return
				}
			}
		}
	}
}

func HandleDropPiece(store *game.GameStore, sessions *scs.SessionManager) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			http.Error(w, "game not found", http.StatusNotFound)
			return
		}

		colStr := r.URL.Query().Get("col")
		col, err := strconv.Atoi(colStr)
		if err != nil {
			http.Error(w, "invalid column", http.StatusBadRequest)
			return
		}

		playerID := game.PlayerID(sessions.GetString(r.Context(), "player_id"))
		userID := sessions.GetString(r.Context(), "user_id")
		if userID != "" {
			playerID = game.PlayerID(userID)
		}

		myColor := gi.GetPlayerColor(playerID)
		if myColor == 0 {
			http.Error(w, "not in game", http.StatusForbidden)
			return
		}

		gi.DropPiece(col, myColor)

		// The store's notifyFunc publishes to NATS, which triggers SSE updates.
		// Return empty SSE response.
		datastar.NewSSE(w, r)
	}
}

func HandleSendChat(store *game.GameStore, nc *nats.Conn, sessions *scs.SessionManager, chatPersister *db.ChatPersister) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			http.Error(w, "game not found", http.StatusNotFound)
			return
		}

		type ChatSignals struct {
			ChatMsg string `json:"chatMsg"`
		}
		var signals ChatSignals
		if err := datastar.ReadSignals(r, &signals); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		if signals.ChatMsg == "" {
			datastar.NewSSE(w, r)
			return
		}

		playerID := game.PlayerID(sessions.GetString(r.Context(), "player_id"))
		userID := sessions.GetString(r.Context(), "user_id")
		if userID != "" {
			playerID = game.PlayerID(userID)
		}

		myColor := gi.GetPlayerColor(playerID)
		if myColor == 0 {
			datastar.NewSSE(w, r)
			return
		}

		g := gi.GetGame()
		nick := ""
		for _, p := range g.Players {
			if p != nil && p.ID == playerID {
				nick = p.Nickname
				break
			}
		}

		cm := game.ChatMessage{
			Nickname: nick,
			Color:    myColor,
			Message:  signals.ChatMsg,
			Time:     time.Now().UnixMilli(),
		}
		chatPersister.SaveChatMessage(gameID, cm)

		data, err := json.Marshal(cm)
		if err != nil {
			datastar.NewSSE(w, r)
			return
		}
		nc.Publish("game.chat."+gameID, data)

		// Clear the chat input
		sse := datastar.NewSSE(w, r)
		sse.MarshalAndPatchSignals(map[string]any{"chatMsg": ""}) //nolint:errcheck
	}
}

func HandleSetNickname(store *game.GameStore, sessions *scs.SessionManager) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			sse := datastar.NewSSE(w, r)
			sse.Redirect("/") //nolint:errcheck
			return
		}

		type NicknameSignals struct {
			Nickname string `json:"nickname"`
		}
		var signals NicknameSignals
		if err := datastar.ReadSignals(r, &signals); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		if signals.Nickname == "" {
			datastar.NewSSE(w, r)
			return
		}

		sessions.Put(r.Context(), "nickname", signals.Nickname)

		playerID := game.PlayerID(sessions.GetString(r.Context(), "player_id"))
		userID := sessions.GetString(r.Context(), "user_id")
		if userID != "" {
			playerID = game.PlayerID(userID)
		}

		if gi.GetPlayerColor(playerID) == 0 {
			player := &game.Player{
				ID:       playerID,
				Nickname: signals.Nickname,
			}
			if userID != "" {
				player.UserID = &userID
			}
			gi.Join(&game.PlayerSession{Player: player})
		}

		sse := datastar.NewSSE(w, r)
		sse.Redirect("/game/" + gameID) //nolint:errcheck
	}
}

func HandleRematch(store *game.GameStore, sessions *scs.SessionManager) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gameID := chi.URLParam(r, "game_id")

		gi, exists := store.Get(gameID)
		if !exists {
			sse := datastar.NewSSE(w, r)
			sse.Redirect("/") //nolint:errcheck
			return
		}

		newGI := gi.CreateRematch(store)
		sse := datastar.NewSSE(w, r)
		if newGI != nil {
			sse.Redirectf("/game/%s", newGI.ID()) //nolint:errcheck
		}
	}
}

// sendGameComponents patches all game-related SSE components.
func sendGameComponents(sse *datastar.ServerSentEventGenerator, gi *game.GameInstance, myColor int, chatMessages []components.ChatMessage, chatMu *sync.Mutex, gameID string) {
	g := gi.GetGame()

	sse.PatchElementTempl(components.Board(g, myColor), datastar.WithSelectorID("c4-board"))         //nolint:errcheck
	sse.PatchElementTempl(components.StatusBanner(g, myColor), datastar.WithSelectorID("c4-status")) //nolint:errcheck
	sse.PatchElementTempl(components.PlayerInfo(g, myColor), datastar.WithSelectorID("c4-players"))  //nolint:errcheck

	chatMu.Lock()
	msgs := make([]components.ChatMessage, len(chatMessages))
	copy(msgs, chatMessages)
	chatMu.Unlock()

	sse.PatchElementTempl(components.Chat(msgs, gameID), datastar.WithSelectorID("c4-chat")) //nolint:errcheck
}

// uiChatToComponents converts ui.C4ChatMessage slice to components.ChatMessage slice.
func uiChatToComponents(uiMsgs []game.ChatMessage) []components.ChatMessage {
	msgs := make([]components.ChatMessage, len(uiMsgs))
	for i, m := range uiMsgs {
		msgs[i] = components.ChatMessage{
			Nickname: m.Nickname,
			Color:    m.Color,
			Message:  m.Message,
			Time:     m.Time,
		}
	}
	return msgs
}