memes-telegram-integration/memogram.go

package memogram

import (
	"context"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"path/filepath"
	"strings"
	"sync"

	"github.com/go-telegram/bot"
	"github.com/go-telegram/bot/models"
	"github.com/pkg/errors"
	v1pb "github.com/usememos/memos/proto/gen/api/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/metadata"
)

// userAccessTokenCache is a cache for user access token.
// Key is the user id from telegram.
// Value is the access token from memos.
// TODO: save it to a persistent storage.
var userAccessTokenCache sync.Map // map[int64]string

type Service struct {
	config *Config
	client *MemosClient
	bot    *bot.Bot
}

func NewService() (*Service, error) {
	config, err := getConfigFromEnv()
	if err != nil {
		return nil, errors.Wrap(err, "failed to get config from env")
	}

	conn, err := grpc.Dial(config.ServerAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		slog.Error("failed to connect to server", slog.Any("err", err))
		return nil, errors.Wrap(err, "failed to connect to server")
	}
	client := NewMemosClient(conn)

	s := &Service{
		config: config,
		client: client,
	}

	opts := []bot.Option{
		bot.WithDefaultHandler(s.handler),
	}

	b, err := bot.New(config.BotToken, opts...)
	if err != nil {
		return nil, errors.Wrap(err, "failed to create bot")
	}
	s.bot = b

	return s, nil
}

func (s *Service) Start(ctx context.Context) {
	slog.Info("Memogram started")
	s.bot.Start(ctx)
}

func (s *Service) handler(ctx context.Context, b *bot.Bot, m *models.Update) {
	if strings.HasPrefix(m.Message.Text, "/start ") {
		s.startHandler(ctx, b, m)
		return
	}

	userID := m.Message.From.ID
	if _, ok := userAccessTokenCache.Load(userID); !ok {
		b.SendMessage(ctx, &bot.SendMessageParams{
			ChatID: m.Message.Chat.ID,
			Text:   "Please start the bot with /start <access_token>",
		})
		return
	}

	message := m.Message
	// TODO: handle message.Entities to get markdown text.
	text := message.Text
	hasResource := message.Document != nil || len(message.Photo) > 0
	if text == "" && !hasResource {
		b.SendMessage(ctx, &bot.SendMessageParams{
			ChatID: m.Message.Chat.ID,
			Text:   "Please input memo content",
		})
		return
	}

	accessToken, _ := userAccessTokenCache.Load(userID)
	ctx = metadata.NewOutgoingContext(ctx, metadata.Pairs("Authorization", fmt.Sprintf("Bearer %s", accessToken.(string))))
	memo, err := s.client.MemoService.CreateMemo(ctx, &v1pb.CreateMemoRequest{
		Content: text,
	})
	if err != nil {
		slog.Error("failed to create memo", slog.Any("err", err))
		b.SendMessage(ctx, &bot.SendMessageParams{
			ChatID: m.Message.Chat.ID,
			Text:   "Failed to create memo",
		})
		return
	}

	if message.Document != nil {
		file, err := b.GetFile(ctx, &bot.GetFileParams{FileID: message.Document.FileID})
		if err != nil {
			s.sendError(b, m.Message.Chat.ID, errors.Wrap(err, "failed to get file"))
			return
		}

		_, err = s.saveResourceFromFile(ctx, file, memo)
		if err != nil {
			s.sendError(b, m.Message.Chat.ID, errors.Wrap(err, "failed to save resource"))
			return
		}
	}
	if len(message.Photo) > 0 {
		photo := message.Photo[len(message.Photo)-1]
		file, err := b.GetFile(ctx, &bot.GetFileParams{FileID: photo.FileID})
		if err != nil {
			s.sendError(b, m.Message.Chat.ID, errors.Wrap(err, "failed to get file"))
			return
		}

		_, err = s.saveResourceFromFile(ctx, file, memo)
		if err != nil {
			s.sendError(b, m.Message.Chat.ID, errors.Wrap(err, "failed to save resource"))
			return
		}
	}

	b.SendMessage(ctx, &bot.SendMessageParams{
		ChatID: m.Message.Chat.ID,
		Text:   fmt.Sprintf("Memo created with %s", memo.Name),
	})
}

func (s *Service) startHandler(ctx context.Context, b *bot.Bot, m *models.Update) {
	userID := m.Message.From.ID
	accessToken := strings.TrimPrefix(m.Message.Text, "/start ")

	ctx = metadata.NewOutgoingContext(ctx, metadata.Pairs("Authorization", fmt.Sprintf("Bearer %s", accessToken)))
	user, err := s.client.AuthService.GetAuthStatus(ctx, &v1pb.GetAuthStatusRequest{})
	if err != nil {
		b.SendMessage(ctx, &bot.SendMessageParams{
			ChatID: m.Message.Chat.ID,
			Text:   "Invalid access token",
		})
		return
	}

	userAccessTokenCache.Store(userID, accessToken)
	b.SendMessage(ctx, &bot.SendMessageParams{
		ChatID: m.Message.Chat.ID,
		Text:   fmt.Sprintf("Hello %s!", user.Nickname),
	})
}

func (s *Service) saveResourceFromFile(ctx context.Context, file *models.File, memo *v1pb.Memo) (*v1pb.Resource, error) {
	fileLink := s.bot.FileDownloadLink(file)
	response, err := http.Get(fileLink)
	if err != nil {
		return nil, errors.Wrap(err, "failed to download file")
	}
	defer response.Body.Close()

	bytes, err := io.ReadAll(response.Body)
	if err != nil {
		return nil, errors.Wrap(err, "failed to read file")
	}
	contentType, err := getContentType(fileLink)
	if err != nil {
		return nil, errors.Wrap(err, "failed to get content type")
	}

	resource, err := s.client.ResourceService.CreateResource(ctx, &v1pb.CreateResourceRequest{
		Resource: &v1pb.Resource{
			Filename: filepath.Base(file.FilePath),
			Type:     contentType,
			Size:     file.FileSize,
			Content:  bytes,
			Memo:     &memo.Name,
		},
	})
	if err != nil {
		return nil, errors.Wrap(err, "failed to create resource")
	}

	return resource, nil
}

func (s *Service) sendError(b *bot.Bot, chatID int64, err error) {
	slog.Error("error", slog.Any("err", err))
	b.SendMessage(context.Background(), &bot.SendMessageParams{
		ChatID: chatID,
		Text:   fmt.Sprintf("Error: %s", err.Error()),
	})
}