// Package connector implements the Telegram gRPC service (pkg/proto/telegram/v1):
// the gateway calls ValidateInitData (Mini App auth) and Notify (out-of-app push);
// the admin surface (Stage 10) will call SendToUser and SendToGameChannel. The
// generic methods address a recipient by the identity external_id, so a future
// platform connector can implement the same service.
package connector

import (
	"context"
	"fmt"
	"strconv"

	"go.uber.org/zap"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	telegramv1 "scrabble/pkg/proto/telegram/v1"
	"scrabble/platform/telegram/internal/initdata"
	"scrabble/platform/telegram/internal/render"
)

// Sender delivers Telegram messages to a chat. *bot.Bot implements it.
type Sender interface {
	// Notify sends a notification with a Mini App launch button to chatID.
	Notify(ctx context.Context, chatID int64, text, buttonText, startParam string) error
	// SendText sends a plain text message to chatID.
	SendText(ctx context.Context, chatID int64, text string) error
}

// Server implements telegramv1.TelegramServer.
type Server struct {
	telegramv1.UnimplementedTelegramServer
	validator initdata.Validator
	sender    Sender
	channelID int64
	log       *zap.Logger
}

// NewServer builds the gRPC service from a validator (for ValidateInitData), a
// sender (the bot), and the configured game channel id (0 disables channel posts).
func NewServer(validator initdata.Validator, sender Sender, channelID int64, log *zap.Logger) *Server {
	if log == nil {
		log = zap.NewNop()
	}
	return &Server{validator: validator, sender: sender, channelID: channelID, log: log}
}

// ValidateInitData verifies Mini App launch data and returns the user identity.
func (s *Server) ValidateInitData(ctx context.Context, req *telegramv1.ValidateInitDataRequest) (*telegramv1.ValidateInitDataResponse, error) {
	u, err := s.validator.Validate(req.GetInitData())
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}
	return &telegramv1.ValidateInitDataResponse{
		ExternalId:   u.ExternalID,
		Username:     u.Username,
		FirstName:    u.FirstName,
		LanguageCode: u.LanguageCode,
	}, nil
}

// Notify renders and delivers an out-of-app notification. It reports
// delivered=false (without an error) for a kind that is not pushed out-of-app or a
// delivery the bot could not complete (e.g. the user never started the bot), so the
// gateway treats a fallback miss as best-effort.
func (s *Server) Notify(ctx context.Context, req *telegramv1.NotifyRequest) (*telegramv1.NotifyResponse, error) {
	msg, ok := render.Render(req.GetKind(), req.GetPayload(), req.GetLanguage())
	if !ok {
		return &telegramv1.NotifyResponse{Delivered: false}, nil
	}
	chat, err := parseChatID(req.GetExternalId())
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}
	if err := s.sender.Notify(ctx, chat, msg.Text, msg.ButtonText, msg.StartParam); err != nil {
		s.log.Warn("notify delivery failed", zap.String("kind", req.GetKind()), zap.Error(err))
		return &telegramv1.NotifyResponse{Delivered: false}, nil
	}
	return &telegramv1.NotifyResponse{Delivered: true}, nil
}

// SendToUser sends an arbitrary admin message to one user.
func (s *Server) SendToUser(ctx context.Context, req *telegramv1.SendToUserRequest) (*telegramv1.SendResponse, error) {
	chat, err := parseChatID(req.GetExternalId())
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}
	if err := s.sender.SendText(ctx, chat, req.GetText()); err != nil {
		s.log.Warn("send to user failed", zap.Error(err))
		return &telegramv1.SendResponse{Delivered: false}, nil
	}
	return &telegramv1.SendResponse{Delivered: true}, nil
}

// SendToGameChannel posts an admin message to the configured game channel.
func (s *Server) SendToGameChannel(ctx context.Context, req *telegramv1.SendToGameChannelRequest) (*telegramv1.SendResponse, error) {
	if s.channelID == 0 {
		return nil, status.Error(codes.FailedPrecondition, "game channel is not configured")
	}
	if err := s.sender.SendText(ctx, s.channelID, req.GetText()); err != nil {
		s.log.Warn("send to channel failed", zap.Error(err))
		return &telegramv1.SendResponse{Delivered: false}, nil
	}
	return &telegramv1.SendResponse{Delivered: true}, nil
}

// parseChatID converts a Telegram identity external_id into a numeric chat id.
func parseChatID(externalID string) (int64, error) {
	id, err := strconv.ParseInt(externalID, 10, 64)
	if err != nil {
		return 0, fmt.Errorf("invalid external_id %q", externalID)
	}
	return id, nil
}