Limit all dates asking to 3 months range

src/main/scala/server/Server.scala

@@ -6,7 +6,7 @@ import com.comcast.ip4s.IpLiteralSyntax
 import db.DataService
 import fetch.FetchService
 import parse.{Aggregate, Parser, WeatherData}
-import server.ValidateRoutes.{AggKey, CityList, DateTimeRange, Granularity, ValidDate}
+import server.ValidateRoutes.{AggKey, CityList, DateTimeRange, Granularity, ValidDate, ValidateMonths}
 import io.circe.{Json, Printer}
 import org.http4s._
 import org.http4s.dsl.io._
@@ -89,6 +89,12 @@ class Server(dataService: DataService, fetch: FetchService, log: Logger[IO]) {
         Ok(dates.asJson.pretty)
       )
 
+    // http://0.0.0.0:8080/api/show/months/202304,202305,202306
+    case GET -> Root / "show" / "months" / ValidateMonths(monthList) =>
+      dataService.getDatesByMonths(monthList).flatMap(dates =>
+        Ok(dates.asJson.pretty)
+      )
+
     // http://0.0.0.0:8080/api/show/date/20230423
     case GET -> Root / "show" / "date" / ValidDate(date) =>
       dataService.getDateFileNames(date).flatMap(fileNames =>

src/main/scala/server/ValidateRoutes.scala

@@ -27,6 +27,21 @@ object ValidateRoutes {
     }
   }
 
+  object ValidateMonths {
+    def unapply(str: String): Option[List[LocalDate]] = {
+      val formatter = DateTimeFormatter.ofPattern("yyyyMMdd")
+      val monthList = str
+        .split(",")
+        .toList
+        .flatMap(str => Try(LocalDate.parse(str + "01", formatter)).toOption)
+
+      monthList match {
+        case Nil => None
+        case list => Some(list)
+      }
+    }
+  }
+
   object CityList {
     def unapply(str: String): Option[List[String]] = {
       str.split(",").toList match {