SolarPower web server - copies Derby database, reads solar power status and publishes to local web server every minute. Compatible with SolarPower 1.14

build.gradle

apply plugin: 'kotlin'
apply plugin: 'application'

mainClassName = 'MainKt'

buildscript {
    ext.kotlin_version = '1.3.71'
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}
repositories {
    mavenCentral()
}
dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'org.apache.derby:derby:10.14.1.0'
    compile 'com.github.seratch:kotliquery:1.3.0'
    compile "com.sparkjava:spark-kotlin:1.0.0-alpha"
}

main.kt

import kotliquery.queryOf
import kotliquery.sessionOf
import kotliquery.using
import spark.kotlin.Http
import spark.kotlin.ignite
import java.io.File
import java.sql.DriverManager
import java.util.*
import kotlin.concurrent.schedule
import kotlin.system.exitProcess

data class Status(
    val workmode: String,
    val batteryVoltage: String, val chargingCurrent: String, val inputPower: String,
    val timestamp: String
)

fun main(args: Array<String>) {
    if (args.isEmpty() || !File(args[0]).exists()) {
        println("Derby dir does no exists ${Arrays.toString(args)}")
        exitProcess(1)
    }

    var status: Status? = null

    Timer().schedule(delay = 1000, period = 60000) {// every minute
        status = getStatus(args[0])
    }

    val http: Http = ignite()
    http.port(80)

    http.get("/") {
        when (status) {
            null -> "Starting"
            else -> {
                "${status?.workmode}<br>" +
                        "Solar power: ${status?.inputPower}W<br>" +
                        "Battery voltage: ${status?.batteryVoltage}V<br>" +
                        "Battery charging: ${status?.chargingCurrent}A<br>" +
                        "At: ${status?.timestamp}"
            }
        }
    }
    println("started at port ${http.port()}")
}


fun getStatus(dir: String): Status {

    val tmpDir: File = createTempDir("sp-")
    val srcFile = File(dir)

    srcFile.copyRecursively(tmpDir, overwrite = true)

    val connString = "jdbc:derby:${tmpDir}"
    val select =
        "select workmode, PBATTERYVOLTAGE,CURRENTTIME, CHARGINGCURRENT, PVINPUTPOWER1 " +
                "from WORK_DATA order by WORKID desc fetch " +
                "first 1 rows only"

    return using(sessionOf(connString, "", "")) { session ->
        val stateQuery = queryOf(select).map { row ->
            Status(
                row.string("workmode"),
                row.string("PBATTERYVOLTAGE"),
                row.string("CHARGINGCURRENT"),
                row.string("PVINPUTPOWER1"),
                row.string("CURRENTTIME")
            )
        }.asList
        val status: List<Status> = session.run(stateQuery)

        try {       // hack to work on Windows
            DriverManager.getConnection("${connString};shutdown=true");
        } catch (e:Exception) {}
        
        status[0]
    }
}