Server which responds to get requests

src/main/scala/server/Server.scala

@@ -1,5 +1,51 @@
 package server
 
-class Server {
-  // TODO proly BlazeServerBuilder which accepts requests from client and serves parsed data
+import cats.effect._
+import org.http4s._
+import org.http4s.dsl.io._
+import org.http4s.implicits._
+import org.http4s.server.Router
+import org.http4s.server.blaze.BlazeServerBuilder
+
+import java.time.LocalDateTime
+import java.time.format.DateTimeFormatter
+import scala.util.Try
+
+object Server extends IOApp {
+  private val formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmm")
+  private val appRoutes = HttpRoutes.of[IO] {
+    // http://localhost:3000/202304131030-202304132030/riga,liepaja/tempAvg
+    case GET -> Root / timestampRange / cities / weatherParam =>
+      // TODO proly better to Validated with chained errors
+      val res = for {
+        (from, to) <- timestampRange.split("-").toList
+          .map(str => Try(LocalDateTime.parse(str, formatter)).toOption) match {
+          case List(Some(from), Some(to)) => Some(from, to)
+          case _ => None
+        }
+        cityList <- cities.split(",").toList match {
+          case list => Some(list)
+          case Nil => None
+        }
+        param <- if (weatherParam.isEmpty) None else Some(weatherParam)
+      }
+        // TODO yield to parser method which accepts those args
+      yield s"Timestamp From: $from, Timestamp To: $to, Cities: ${cityList.mkString(", ")}, Weather Param: $param"
+
+      res match {
+        case Some(responseTxt) => Ok(responseTxt)
+        case _ => BadRequest(s"Invalid request format")
+      }
+  }
+
+  private val httpApp = Router("/" -> appRoutes).orNotFound
+
+  override def run(args: List[String]): IO[ExitCode] =
+    BlazeServerBuilder[IO]
+      .bindHttp(3000, "localhost")
+      .withHttpApp(httpApp)
+      .serve
+      .compile
+      .drain
+      .as(ExitCode.Success)
 }