парсер

tg_parser/internal/adapter/telegram/get_channel_diff.go

@@ -0,0 +1,119 @@
+package telegram
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/TelegramExchange/tgex-parser/internal/domain"
+	"github.com/gotd/td/tg"
+)
+
+func (t *Telegram) GetChannelDiff(ctx context.Context, channel domain.Channel, limit int) (domain.ChannelDiff, error) {
+	req := &tg.UpdatesGetChannelDifferenceRequest{
+		Channel: &tg.InputChannel{
+			ChannelID:  channel.ChannelID(),
+			AccessHash: channel.AccessHash,
+		},
+		Filter: &tg.ChannelMessagesFilterEmpty{},
+		Pts:    channel.Pts,
+		Limit:  limit,
+	}
+
+	rawDiff, err := t.API().UpdatesGetChannelDifference(ctx, req)
+	if err != nil {
+		return domain.ChannelDiff{}, fmt.Errorf("get difference: %w", err)
+	}
+
+	result := domain.ChannelDiff{}
+
+	switch d := rawDiff.(type) {
+	case *tg.UpdatesChannelDifferenceEmpty:
+		result.NewPts = d.Pts
+
+	case *tg.UpdatesChannelDifferenceTooLong:
+		if dialog, ok := d.Dialog.(*tg.Dialog); ok {
+			result.NewPts = dialog.Pts
+		}
+		result.NewPosts = extractPosts(channel, d.Messages)
+		result.UpdatedChannel = extractChannelMeta(channel, d.Chats)
+
+	case *tg.UpdatesChannelDifference:
+		result.NewPts = d.Pts
+		result.NewPosts = extractPosts(channel, d.NewMessages)
+		result.DeletedPosts = extractDeletedPosts(channel, d.OtherUpdates)
+		result.UpdatedChannel = extractChannelMeta(channel, d.Chats)
+
+	default:
+		return domain.ChannelDiff{}, fmt.Errorf("unexpected rawDiff type: %T", rawDiff)
+	}
+
+	return result, nil
+}
+
+func extractPosts(channel domain.Channel, msgs []tg.MessageClass) []domain.Post {
+	posts := make([]domain.Post, 0, len(msgs))
+
+	for _, raw := range msgs {
+		m, ok := raw.(*tg.Message)
+		if !ok {
+			continue
+		}
+
+		p := domain.NewPost(channel, m.ID, m.Message, m.Views)
+		posts = append(posts, p)
+	}
+
+	return posts
+}
+
+func extractDeletedPosts(channel domain.Channel, updates []tg.UpdateClass) []domain.Post {
+	var deleted []domain.Post
+
+	for _, upd := range updates {
+		if u, ok := upd.(*tg.UpdateDeleteChannelMessages); ok {
+			for _, msgID := range u.Messages {
+				p := domain.NewPost(channel, msgID, "", 0)
+				deleted = append(deleted, p)
+			}
+		}
+	}
+
+	return deleted
+}
+
+func extractChannelMeta(currentChannel domain.Channel, chats []tg.ChatClass) *domain.Channel {
+	for _, chat := range chats {
+		ch, ok := chat.(*tg.Channel)
+		if !ok {
+			continue
+		}
+
+		if ch.ID != currentChannel.ChannelID() {
+			continue
+		}
+
+		username := ""
+		if usernameVal, ok := ch.GetUsername(); ok {
+			username = usernameVal
+		}
+
+		// Keep current access hash if new one is not provided or is zero
+		accessHash := currentChannel.AccessHash
+		if accessHashVal, ok := ch.GetAccessHash(); ok && accessHashVal != 0 {
+			accessHash = accessHashVal
+		}
+
+		updated := domain.Channel{
+			ID:         currentChannel.ID,
+			TelegramID: domain.ChatIDFromChannelID(ch.ID),
+			Username:   username,
+			Title:      ch.Title,
+			AccessHash: accessHash,
+			Pts:        currentChannel.Pts,
+		}
+
+		return &updated
+	}
+
+	return nil
+}