move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/updates/access_hash_feeder.go

@@ -0,0 +1,134 @@
+package updates
+
+import (
+	"fmt"
+
+	"go.uber.org/zap"
+	"golang.org/x/net/context"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func (s *internalState) saveChannelHashes(ctx context.Context, chats []tg.ChatClass) {
+	ctx, span := s.tracer.Start(ctx, "updates.saveChannelHashes")
+	defer span.End()
+
+	for _, c := range chats {
+		switch c := c.(type) {
+		case *tg.Channel:
+			if c.Min {
+				continue
+			}
+
+			if hash, ok := c.GetAccessHash(); ok {
+				if _, ok = s.channels[c.ID]; ok {
+					continue
+				}
+				s.log.Debug("New channel access hash",
+					zap.Int64("channel_id", c.ID),
+					zap.String("title", c.Title),
+				)
+				if err := s.hasher.SetChannelAccessHash(ctx, s.selfID, c.ID, hash); err != nil {
+					s.log.Error("SetChannelAccessHash error", zap.Error(err))
+				}
+			}
+		case *tg.ChannelForbidden:
+			if _, ok := s.channels[c.ID]; ok {
+				continue
+			}
+			s.log.Debug("New channel access hash",
+				zap.Int64("channel_id", c.ID),
+				zap.String("title", c.Title),
+			)
+			if err := s.hasher.SetChannelAccessHash(ctx, s.selfID, c.ID, c.AccessHash); err != nil {
+				s.log.Error("SetChannelAccessHash error", zap.Error(err))
+			}
+		}
+	}
+}
+
+func (s *internalState) saveUserHashes(ctx context.Context, chats []tg.UserClass) {
+	ctx, span := s.tracer.Start(ctx, "updates.saveChannelHashes")
+	defer span.End()
+
+	for _, u := range chats {
+		if user, ok := u.(*tg.User); !ok {
+			continue
+		} else if hash, ok := user.GetAccessHash(); !ok {
+			continue
+		} else if user.Min {
+			s.log.Debug("User is min, not saving access hash")
+			continue
+		} else {
+			s.log.Debug("New user access hash", zap.Int64("user_id", user.ID))
+			if err := s.hasher.SetUserAccessHash(ctx, s.selfID, user.ID, hash); err != nil {
+				s.log.Error("SetUserAccessHash error", zap.Error(err))
+			}
+		}
+	}
+}
+
+func (s *internalState) handleDifference(ctx context.Context, date int) (chats []tg.ChatClass, users []tg.UserClass, err error) {
+	ctx, span := s.tracer.Start(ctx, "updates.handleDifference")
+	defer span.End()
+
+	diff, err := s.client.UpdatesGetDifference(ctx, &tg.UpdatesGetDifferenceRequest{
+		Pts:  s.pts.State(),
+		Qts:  s.qts.State(),
+		Date: date,
+	})
+	if err != nil {
+		s.log.Error("UpdatesGetDifference error", zap.Error(err))
+		return nil, nil, fmt.Errorf("get difference: %w", err)
+	}
+
+	switch diff := diff.(type) {
+	case *tg.UpdatesDifference:
+		chats = diff.Chats
+		users = diff.Users
+	case *tg.UpdatesDifferenceSlice:
+		chats = diff.Chats
+		users = diff.Users
+	}
+
+	s.saveChannelHashes(ctx, chats)
+	s.saveUserHashes(ctx, users)
+	return chats, users, nil
+}
+
+func (s *internalState) restoreChannelAccessHash(ctx context.Context, channelID int64, date int) (accessHash int64, ok bool) {
+	ctx, span := s.tracer.Start(ctx, "updates.restoreAccessHash")
+	defer span.End()
+
+	chats, _, err := s.handleDifference(ctx, date)
+	if err != nil {
+		s.log.Error("getDifference error", zap.Error(err))
+		return 0, false
+	}
+
+	for _, c := range chats {
+		switch c := c.(type) {
+		case *tg.Channel:
+			if c.Min {
+				continue
+			}
+
+			if c.ID != channelID {
+				continue
+			}
+
+			if hash, ok := c.GetAccessHash(); ok {
+				return hash, true
+			}
+
+		case *tg.ChannelForbidden:
+			if c.ID != channelID {
+				continue
+			}
+
+			return c.AccessHash, true
+		}
+	}
+
+	return 0, false
+}