package sve

import (
  "log"
  "time"
  "strconv"
  "strings"
  "regexp"
  "fmt"
  "udi/config"
  "udi/handlers/handler"
  "udi/database"
)

var idSeq int = 0

type SingleValueExtractorHandler struct {
  id int
  ready bool
  config localConfig
  payloadRegex *regexp.Regexp
  dbh *database.DatabaseHandle
}

const TOPIC_SEL = "topic"
const PAYLOAD_SEL = "payload"
const PAYLOAD_FULL_SEL = "payload-full"
const CONSTANT_SEL = "constant"

type localConfig struct {
  application string
  deviceFrom string
  devicePart int
  device string
  valueFrom string
  valuePart int
  unitFrom string
  unitPart int
  unit string
}


func NewSveHandler(config config.HandlerConfigT) handler.Handler {
  t := &SingleValueExtractorHandler {
    id: idSeq,
    ready: false,
  }
  idSeq += 1

  var localConfig localConfig
  if config.Attributes["application"] == "" {
    log.Println("Error: application not configured")
    return t
  }
  localConfig.application = config.Attributes["application"]
  
  payloadRegex := config.Attributes["payloadRegex"]
  if payloadRegex != "" {
    t.payloadRegex = regexp.MustCompile(payloadRegex)
  } else {
    t.payloadRegex = nil
  }

  if config.Attributes["deviceFrom"] != TOPIC_SEL && config.Attributes["deviceFrom"] != PAYLOAD_SEL && config.Attributes["deviceFrom"] != CONSTANT_SEL {
    log.Printf("Error: invalid value %s for deviceFrom", config.Attributes["deviceFrom"])
    return t
  }
  localConfig.deviceFrom = config.Attributes["deviceFrom"]

  devicePart, err1 := strconv.Atoi(config.Attributes["devicePart"])
  if err1 != nil {
    log.Printf("Error: unable to convert devicePart to number: %s", err1)
    return t
  }
  localConfig.devicePart = devicePart

  // empty device is valid
  localConfig.device = config.Attributes["device"]

  if config.Attributes["valueFrom"] != TOPIC_SEL && config.Attributes["valueFrom"] != PAYLOAD_SEL && config.Attributes["valueFrom"] != PAYLOAD_FULL_SEL {
    log.Printf("Error: invalid value %s for valueFrom", config.Attributes["valueFrom"])
    return t
  }
  localConfig.valueFrom = config.Attributes["valueFrom"]

  if config.Attributes["valueFrom"] != PAYLOAD_FULL_SEL {
    valuePart, err2 := strconv.Atoi(config.Attributes["valuePart"])
    if err2 != nil {
      log.Printf("Error: unable to convert valuePart to number: %s", err2)
      return t
    }
    localConfig.valuePart = valuePart
  }

  if config.Attributes["unitFrom"] != TOPIC_SEL && config.Attributes["unitFrom"] != PAYLOAD_SEL && config.Attributes["unitFrom"] != CONSTANT_SEL {
    log.Printf("Error: invalid value %s for unitFrom", config.Attributes["unitFrom"])
    return t
  }
  localConfig.unitFrom = config.Attributes["unitFrom"]

  if config.Attributes["unitFrom"] != CONSTANT_SEL {
    unitPart, err3 := strconv.Atoi(config.Attributes["unitPart"])
    if err3 != nil {
      log.Printf("Error: unable to convert unitPart to number: %s", err3)
      return t
    }
    localConfig.unitPart = unitPart
  }

  // empty unit is valid
  localConfig.unit = config.Attributes["unit"]

  t.config = localConfig

  t.ready = true
  t.dbh = database.NewDatabaseHandle(config.DatabaseConnStr)
  return t
}

func (self *SingleValueExtractorHandler) GetId() string {
  return fmt.Sprintf("SVE%d", self.id)
}

func lost(msg string, message handler.MessageT) {
  log.Printf("Error: %s, message %s is lost", msg, message)
}

func (self *SingleValueExtractorHandler) Handle(message handler.MessageT) {
  if ! self.ready {
    log.Println("Handler is not marked as ready, message %s is lost", message)
    return
  }
  //log.Printf("Handler SingleValueExtractor %d processing %s -> %s", self.id, message.Topic, message.Payload)

  var measurement database.Measurement
  measurement.Time = time.Now()
  measurement.Application = self.config.application
  
  subTopics := strings.Split(message.Topic, "/")
  //log.Printf("Subtopics: %s", strings.Join(subTopics, ", "))

  var payloadMatches []string
  if self.payloadRegex != nil {
    payloadMatches = self.payloadRegex.FindStringSubmatch(message.Payload)
    //log.Printf("Matches: %s", strings.Join(payloadMatches, ", "))
  }

  switch self.config.deviceFrom {
  case TOPIC_SEL:
    if self.config.devicePart >= len(subTopics) {
      lost("devicePart out of range", message)
      return
    }
    measurement.Device = subTopics[self.config.devicePart]
  case PAYLOAD_SEL:
    if self.payloadRegex == nil {
      lost("no payloadRegex defined, devicePart can't be used", message)
      return
    }
    if self.config.devicePart >= len(subTopics) {
      lost("devicePart out of range", message)
      return
    }
    measurement.Device = payloadMatches[self.config.devicePart]
  case CONSTANT_SEL:
    measurement.Device = self.config.device
  }

  measurement.Values = make(map[string]database.VariableType)
  var variable database.VariableType
  variable.Label = ""
  variable.Variable = ""

  switch self.config.valueFrom {
  case TOPIC_SEL:
    if self.config.valuePart >= len(subTopics) {
      lost("valuePart out of range", message)
      return
    }
    variable.Value = subTopics[self.config.valuePart]
  case PAYLOAD_SEL:
    if self.payloadRegex == nil {
      lost("no payloadRegex defined, valuePart can't be used", message)
      return
    }
    if self.config.valuePart >= len(subTopics) {
      lost("valuePart out of range", message)
      return
    }
    variable.Value = payloadMatches[self.config.valuePart]
  case PAYLOAD_FULL_SEL:
    variable.Value = message.Payload
  }

  switch self.config.unitFrom {
  case TOPIC_SEL:
    if self.config.unitPart >= len(subTopics) {
      lost("unitPart out of range", message)
      return
    }
    variable.Unit = subTopics[self.config.unitPart]
  case PAYLOAD_SEL:
    if self.payloadRegex == nil {
      lost("no payloadRegex defined, unitPart can't be used", message)
      return
    }
    if self.config.unitPart >= len(subTopics) {
      lost("unitPart out of range", message)
      return
    }
    variable.Unit = payloadMatches[self.config.unitPart]
  case CONSTANT_SEL:
    variable.Unit = self.config.unit
  }

  measurement.Values["Value"] = variable

  //log.Printf("Prepared measurement item: %s", measurement)
  self.dbh.StoreMeasurement(&measurement)
}