Allow specifying direction to get next search query

We're trying to support LightBox functionality that was introduced here: guardian/frontend#20462

Co-authored-by: Roberto Tyley <[email protected]>

client/src/main/scala/com.gu.contentapi.client/model/Queries.scala

@@ -86,7 +86,7 @@ case class SearchQuery(parameterHolder: Map[String, Parameter] = Map.empty)
 
   protected override def nextQueryGivenFull(response: SearchResponse) = for {
     nextId <- PaginatedApiResponse.searchResponse.getNextId(response)
-  } yield NextSearchQuery(this, nextId)
+  } yield NextSearchQuery(this, nextId, Next)
 
 }
 
@@ -214,16 +214,27 @@ case class FilmReviewsQuery(parameterHolder: Map[String, Parameter] = Map.empty)
   override def pathSegment: String = "atoms/reviews/film"
 }
 
-case class NextSearchQuery[Q <: PaginatedApiQuery[SearchResponse, Content]](originalQuery: Q, contentId: String)
-  extends PaginatedApiQuery[SearchResponse, Content] {
+sealed trait Direction {
+  val pathSegment: String
+}
+object Next extends Direction {
+  override val pathSegment: String = "next"
+}
+object Previous extends Direction {
+  override val pathSegment: String = "prev"
+}
+
+case class NextSearchQuery[Q <: PaginatedApiQuery[SearchResponse, Content]](
+  originalQuery: Q, contentId: String, direction: Direction
+) extends PaginatedApiQuery[SearchResponse, Content] {
 
   def parameters: Map[String, String] = originalQuery.parameters.filterKeys(not(isPaginationParameter)).toMap
 
-  override def pathSegment: String = s"""content/${contentId}/next"""
+  override def pathSegment: String = s"content/$contentId/${direction.pathSegment}"
 
   protected override def nextQueryGivenFull(response: SearchResponse): Option[PaginatedApiQuery[SearchResponse, Content]] = for {
     nextId <- PaginatedApiResponse.searchResponse.getNextId(response)
-  } yield NextSearchQuery(originalQuery, nextId)
+  } yield copy(contentId = nextId)
 
   override def normalised: PaginatedApiQuery[SearchResponse, Content] = originalQuery.normalised
 }