src.dualinventive.com/go/redis-proxy/internal/redis/process_msg.go

package redis

import (
	"encoding/json"
	"errors"
	"fmt"
	"strconv"
	"strings"

	"github.com/gomodule/redigo/redis"
	"src.dualinventive.com/go/dinet/ditime"
	"src.dualinventive.com/go/dinet/rpc"
	"src.dualinventive.com/go/lib/dilog"
)

type redisResultValueItem struct {
	rpc.ResultValueItem
	LastUpdate ditime.Time `json:"last_update"`
}

// marshalResult converts the result object to JSON for redis. It adds last_update to the JSON string
func marshalResult(result interface{}) ([]byte, error) {
	var values interface{}

	switch res := result.(type) {
	case map[string]interface{}:
		res["last_update"] = ditime.Now()
		values = res

	case rpc.ResultValueItem:
		nRes := redisResultValueItem{res, ditime.Now()}
		values = nRes
	default:
		return nil, errors.New("unknown marshal result type")
	}
	return json.Marshal(values)
}

// processMsgResult converts the result to JSON and writes it to redis. Id is used for key calculation
//  the caller can use e.g sensor item uid: sensor:10:data.
func (r *Redis) processMsgResult(logger dilog.Logger, key, field string, result interface{}) error {
	value, err := marshalResult(result)
	if err != nil {
		return fmt.Errorf("json marshal failed: %v", err)
	}

	err = r.write(logger, key, field, value)
	if err != nil {
		return fmt.Errorf("redis write failed: %v", err)
	}
	return nil
}

// processGeneralClassMethod process all messages that don't have a specific result object
func (r *Redis) processGeneralClassMethod(logger dilog.Logger, m *rpc.Msg, valueItems []map[string]interface{}) error {
	newUIDFields := make([]string, len(valueItems))
	key := keyName(m)
	if key == "" {
		logger.Warning("processGeneralClassMethod keyName is empty")
		return nil
	}

	logger = logger.WithField("key", key)

	for i, result := range valueItems {
		var time ditime.Time
		if _, ok := result["time"].(ditime.Time); !ok {
			// Add server time when not existing in the message
			time = m.Time
			result["time"] = time
		}
		var id uint16
		// Add id if exist
		if uid, ok := result["uid"]; ok {
			if fuid, ok := uid.(float64); ok {
				id = uint16(fuid)
			}
		}
		if rid, ok := result["id"]; ok {
			if fid, ok := rid.(float64); ok {
				id = uint16(fid)
			}
		}
		newUIDFields[i] = strconv.Itoa(int(id))

		field := fieldName(m, id)
		if !r.IsNew(logger, key, field, time) {
			logger.WithFields(dilog.Fields{
				"field": field,
				"time":  time,
			}).Debug("not new")
			continue
		}
		err := r.processMsgResult(logger, key, field, result)
		if err != nil {
			return err
		}
		r.UpdateCache(key, field, time)
	}
	if err := r.removeOldInfoFields(m, newUIDFields); err != nil {
		logger.WithError(err).Error("error removing info fields")
	}
	return nil
}

// processSensorData process all sensor data messages
func (r *Redis) processSensorData(logger dilog.Logger, m *rpc.Msg, result []rpc.ResultValueItem) error {
	key := keyName(m)
	if key == "" {
		logger.Warning("processSensorData keyName is empty")
		return nil
	}

	logger = logger.WithField("key", key)

	for _, sensorItem := range result {
		field := fieldName(m, sensorItem.UID)

		// Should not happen, but just in case
		if sensorItem.Time == 0 {
			sensorItem.Time = m.Time
		}

		if !r.IsNew(logger, key, field, sensorItem.Time) {
			logger.WithFields(dilog.Fields{
				"field": field,
				"time":  sensorItem.Time,
			}).Debug("not new")
			continue
		}

		if sensorItem.UID == rpc.SensorGPS.UID() {
			r.processGPSData(logger, m, sensorItem)
		}

		err := r.processMsgResult(logger, key, field, sensorItem)
		if err != nil {
			return err
		}
		r.UpdateCache(key, field, sensorItem.Time)
	}
	return nil
}

// processGPSData grabs the GPS data and send it to redis
func (r *Redis) processGPSData(logger dilog.Logger, m *rpc.Msg, sensorItem rpc.ResultValueItem) {
	// Grab GPS
	rawValue, ok := sensorItem.Value.(*json.RawMessage)
	if ok {
		gpsData := rpc.GPSSensorData{}
		if err := json.Unmarshal(*rawValue, &gpsData); err != nil {
			logger.WithField("data", *rawValue).Error("Invalid GPS data")
		} else if err := r.writeSensorGPS(m, gpsData); err != nil {
			logger.WithError(err).Error("cannot writeGPS data")
		}
	}
}

func (r *Redis) removeOldInfoFields(m *rpc.Msg, uids []string) error {
	// Skip non reply messages
	if m.Type != rpc.MsgTypeReply {
		return nil
	}
	// Skip non info messages
	if m.Method() != "info" {
		return nil
	}
	class := m.Class()

	hKey := keyName(m)
	if hKey == "" {
		return fmt.Errorf("keyName is empty")
	}

	c, err := r.getConn()
	if err != nil {
		return err
	}

	defer func() {
		closeerr := c.Close()
		// we are closing the connection so it is too late for errors.
		_ = closeerr
	}()

	keys, err := redis.Strings(c.Do("HKEYS", hKey))
	if err != nil {
		return err
	}

	rKeys := make([]interface{}, 0, len(uids)+1)
	rKeys = append(rKeys, hKey)
	for _, k := range keys {
		if removeInfoField(uids, class, k) {
			// Append missing key
			rKeys = append(rKeys, k)
		}
	}
	if len(rKeys) > 1 {
		// Remove missing keys
		_, err = c.Do("HDEL", rKeys...)
	}
	return err
}

// removeInfoField returns true when the given key is an info field of class 'class' and contains none of the given ids
func removeInfoField(uids []string, class rpc.Class, key string) bool {
	p := strings.SplitN(key, ":", 3)
	// Skip keys that don't contains id's
	if len(p) != 3 {
		return false
	}
	// Skip non info keys
	if p[0] != string(class) || p[2] != "info" {
		return false
	}

	for _, i := range uids {
		if i == p[1] {
			return false
		}
	}
	return true
}