Create DBService to read and write

src/main/scala/db/DBService.scala

@@ -0,0 +1,74 @@
+package db
+
+import cats.effect.unsafe.implicits.global
+import cats.effect.{IO, Resource}
+import cats.implicits.toTraverseOps
+
+import java.io.File
+import java.nio.file.{Files, Paths}
+import java.time.LocalDateTime
+import java.time.format.DateTimeFormatter
+import scala.io.Source
+import scala.util.Try
+
+object DBService {
+  private val dateFormatter = DateTimeFormatter.ofPattern("yyyyMMdd_HHmm")
+  private val dataPath = "/Users/guntissmaukstelis/sandbox/WeatherTool/data/"
+
+  private def readFile(fileName: String): IO[String] = {
+    val file = new File(dataPath, fileName)
+    val sourceResource = Resource.fromAutoCloseable(IO(Source.fromFile(file)))
+    sourceResource.use(source => IO(source.mkString)).handleErrorWith(_ => IO.pure(""))
+  }
+
+  private def readFileNames(path: String): IO[List[String]] =
+    IO(new File(path).listFiles.toList.map(_.getName))
+      .handleErrorWith(_ => IO.pure(List.empty))
+
+  private def inRange(fileName: String, from: LocalDateTime, to: LocalDateTime): Boolean = {
+    def fileToDateTime(fileName: String): Option[LocalDateTime] = {
+      val dateString = fileName.split("\\.").head
+      Try(LocalDateTime.parse(dateString, dateFormatter)).toOption
+    }
+
+    val fileDateTime = fileToDateTime(fileName.stripSuffix (".csv"))
+    fileDateTime match {
+      case Some (date) => date.plusSeconds (1).isAfter (from) && date.minusSeconds (1).isBefore (to)
+      case None => false
+    }
+  }
+
+  def getInRange(from: LocalDateTime, to: LocalDateTime): IO[List[String]] = {
+    for {
+      fileNames <- readFileNames(dataPath)
+        .map (_.filter (inRange (_, from, to)))
+      fileContent <- fileNames.traverse(readFile)
+    } yield fileContent
+  }
+
+  def save(fileName: String, content: String): IO[Unit] = {
+    val path = Paths.get(s"$dataPath/$fileName")
+    // TODO redeemWith instead of flatMap
+    IO(Files.writeString(path, content)).attempt.flatMap {
+      case Right(_) => IO.println(s"write: $fileName")
+      case Left(error) => IO.println(s"Write file '$fileName' failed with error: ${error.getMessage}")
+    }
+  }
+
+  // TODO remove this. Just testing
+  private def run: IO[Unit] = {
+    println("----------------> db main")
+
+    val from = LocalDateTime.parse("20230414_2200", dateFormatter)
+    val to = LocalDateTime.parse("20230501_1230", dateFormatter)
+
+    for {
+      lines <- getInRange(from, to)
+      _ <- lines.traverse(IO.println)
+    } yield ()
+  }
+
+  def main(args: Array[String]): Unit = {
+    run.unsafeRunSync()
+  }
+}