fga-eps-mds/2019.1-unbrake

package main

import (
    "encoding/json"
    "io/ioutil"
    "log"
    "os"
    "path"
)

var (
    configFile ConfigFile
)

// Serial constants
const (
    bufferSize       = 48
    serialPortEnv    = "SERIAL_PORT"
    baudRate         = 115200
    frequencyReading = 100
    numSerialAttrs   = 11 // number of attributes read simultaneously from serial device

)

// MQTT constants
const (
    mqttHostEnv              = "MQTT_HOST"
    mqttDefaultHost          = "unbrake.ml"
    mqttDefaultPort          = "8080"
    mqttPortEnv              = "MQTT_PORT"
    mqttChannelPrefixDefault = "unbrake/galpao"
    mqttChannelPrefixEnv     = "MQTT_CHANNEL_PREFIX"
    mqttKeyEnv               = "MQTT_KEY"
)

// ConfigFile used to set global parameters
type ConfigFile struct {
    SerialPort        string
    MqttHost          string
    MqttPort          string
    MqttKey           string
    MqttChannelPrefix string
}

// General application constants
const (
    logFilePath           = "unbrake.log"
    applicationFolderName = "UnBrake"
    configFileName        = "config.json"
)

// Based on current OS will create application folder
// and log file (if not exists). Returns the log file
// as a File object
func getLogFile() *os.File {
    logPath := getLogPath()

    os.MkdirAll(logPath, os.ModePerm)
    logPath = path.Join(logPath, logFilePath)

    logFile, err := os.OpenFile(logPath, os.O_SYNC|os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
    if err != nil {
        log.Fatalf("error opening file: %v", err)
    }
    log.SetFlags(log.Ldate | log.Ltime | log.Lmicroseconds)
    log.SetOutput(logFile)

    return logFile
}

func loadConfigFile() {
    data, err := ioutil.ReadFile(path.Join(aplicationFolderPath, configFileName))
    if err != nil {
        log.Println("Not possible to read configuration file, default will be used, or from environment variables")
    }
    err = json.Unmarshal(data, &configFile)
    if err != nil {
        log.Printf("Invalid Config file: %v\n", err)
    }
}

func getMqttKey() string {
    key, doesExists := os.LookupEnv(mqttKeyEnv)
    if !doesExists {
        if configFile.MqttKey != "" {
            key = configFile.MqttKey
        } else {
            key = ""
        }
    }
    return key
}

func getMqttChannelPrefix() string {
    channelPrefix, doesExists := os.LookupEnv(mqttChannelPrefixEnv)
    if !doesExists {
        if configFile.MqttChannelPrefix != "" {
            channelPrefix = configFile.MqttChannelPrefix
        } else {
            channelPrefix = mqttChannelPrefixDefault
        }
    }
    return channelPrefix
}

func getSerialPort() string {
    port, doesExists := os.LookupEnv(serialPortEnv)
    if !doesExists {
        if configFile.SerialPort != "" {
            port = configFile.SerialPort
        } else {
            port = ""
        }
    }
    return port
}

// Get complete host name with port of the MQTT broker
func getMqttHost() string {
    host, doesExists := os.LookupEnv(mqttHostEnv)
    if !doesExists {
        if configFile.MqttHost != "" {
            host = configFile.MqttHost
        } else {
            host = mqttDefaultHost
        }
    }

    port, doesExists := os.LookupEnv(mqttPortEnv)
    if !doesExists {
        if configFile.MqttPort != "" {
            port = configFile.MqttPort
        } else {
            port = mqttDefaultPort
        }
    }

    return "tcp://" + host + ":" + port
}