// AddConnection adds a new peer connection to the model. An initial index will
// be sent to the connected peer, thereafter index updates whenever the local
// folder changes.
func (m *Model) AddConnection(rawConn io.Closer, protoConn protocol.Connection) {
	deviceID := protoConn.ID()

	m.pmut.Lock()
	if _, ok := m.protoConn[deviceID]; ok {
		panic("add existing device")
	}
	m.protoConn[deviceID] = protoConn
	if _, ok := m.rawConn[deviceID]; ok {
		panic("add existing device")
	}
	m.rawConn[deviceID] = rawConn

	cm := m.clusterConfig(deviceID)
	protoConn.ClusterConfig(cm)

	m.fmut.RLock()
	for _, folder := range m.deviceFolders[deviceID] {
		fs := m.folderFiles[folder]
		go sendIndexes(protoConn, folder, fs, m.folderIgnores[folder])
	}
	m.fmut.RUnlock()
	m.pmut.Unlock()

	m.deviceWasSeen(deviceID)
}

func sendIndexes(conn protocol.Connection, folder string, fs *db.FileSet, ignores *ignore.Matcher) {
	deviceID := conn.ID()
	name := conn.Name()
	var err error

	if debug {
		l.Debugf("sendIndexes for %s-%s/%q starting", deviceID, name, folder)
	}

	minLocalVer, err := sendIndexTo(true, 0, conn, folder, fs, ignores)

	for err == nil {
		time.Sleep(5 * time.Second)
		if fs.LocalVersion(protocol.LocalDeviceID) <= minLocalVer {
			continue
		}

		minLocalVer, err = sendIndexTo(false, minLocalVer, conn, folder, fs, ignores)
	}

	if debug {
		l.Debugf("sendIndexes for %s-%s/%q exiting: %v", deviceID, name, folder, err)
	}
}

func sendIndexTo(initial bool, minLocalVer int64, conn protocol.Connection, folder string, fs *db.FileSet, ignores *ignore.Matcher) (int64, error) {
	deviceID := conn.ID()
	name := conn.Name()
	batch := make([]protocol.FileInfo, 0, indexBatchSize)
	currentBatchSize := 0
	maxLocalVer := int64(0)
	var err error

	fs.WithHave(protocol.LocalDeviceID, func(fi db.FileIntf) bool {
		f := fi.(protocol.FileInfo)
		if f.LocalVersion <= minLocalVer {
			return true
		}

		if f.LocalVersion > maxLocalVer {
			maxLocalVer = f.LocalVersion
		}

		if ignores.Match(f.Name) || symlinkInvalid(folder, f) {
			if debug {
				l.Debugln("not sending update for ignored/unsupported symlink", f)
			}
			return true
		}

		if len(batch) == indexBatchSize || currentBatchSize > indexTargetSize {
			if initial {
				if err = conn.Index(folder, batch, 0, nil); err != nil {
					return false
				}
				if debug {
					l.Debugf("sendIndexes for %s-%s/%q: %d files (<%d bytes) (initial index)", deviceID, name, folder, len(batch), currentBatchSize)
				}
				initial = false
			} else {
				if err = conn.IndexUpdate(folder, batch, 0, nil); err != nil {
					return false
				}
				if debug {
					l.Debugf("sendIndexes for %s-%s/%q: %d files (<%d bytes) (batched update)", deviceID, name, folder, len(batch), currentBatchSize)
				}
			}

			batch = make([]protocol.FileInfo, 0, indexBatchSize)
			currentBatchSize = 0
		}

		batch = append(batch, f)
		currentBatchSize += indexPerFileSize + len(f.Blocks)*indexPerBlockSize
		return true
	})

	if initial && err == nil {
		err = conn.Index(folder, batch, 0, nil)
		if debug && err == nil {
			l.Debugf("sendIndexes for %s-%s/%q: %d files (small initial index)", deviceID, name, folder, len(batch))
		}
	} else if len(batch) > 0 && err == nil {
		err = conn.IndexUpdate(folder, batch, 0, nil)
		if debug && err == nil {
			l.Debugf("sendIndexes for %s-%s/%q: %d files (last batch)", deviceID, name, folder, len(batch))
		}
	}

	return maxLocalVer, err
}