(dsl): Support GetById request (#5)

build.sbt

@@ -28,6 +28,13 @@ lazy val library =
   project
     .in(file("modules/library"))
     .settings(stdSettings("zio-elasticsearch"))
+    .settings(
+      libraryDependencies ++= List(
+        "dev.zio" %% "zio-json"        % "0.3.0",
+        "dev.zio" %% "zio-schema"      % "0.3.1",
+        "dev.zio" %% "zio-schema-json" % "0.3.1"
+      )
+    )
 
 lazy val example =
   project

modules/library/src/main/scala/zio/elasticsearch/DocumentId.scala

@@ -0,0 +1,3 @@
+package zio.elasticsearch
+
+final case class DocumentId(value: String) extends AnyVal

modules/library/src/main/scala/zio/elasticsearch/ElasticError.scala

@@ -0,0 +1,16 @@
+package zio.elasticsearch
+
+sealed trait ElasticError
+
+object ElasticError {
+
+  sealed abstract class DocumentRetrievingError
+
+  object DocumentRetrievingError {
+
+    final case object DocumentNotFound extends DocumentRetrievingError
+
+    final case class DecoderError(reason: String) extends DocumentRetrievingError
+
+  }
+}

modules/library/src/main/scala/zio/elasticsearch/ElasticRequest.scala

@@ -0,0 +1,33 @@
+package zio.elasticsearch
+
+import zio.elasticsearch.ElasticError.DocumentRetrievingError._
+import zio.elasticsearch.ElasticError._
+import zio.schema.Schema
+
+sealed trait ElasticRequest[+A] { self =>
+  final def map[B](f: A => B): ElasticRequest[B] = ElasticRequest.Map(self, f)
+
+}
+
+object ElasticRequest {
+
+  private[elasticsearch] final case class Map[A, B](request: ElasticRequest[A], mapper: A => B)
+      extends ElasticRequest[B]
+
+  def getById[A: Schema](
+    index: IndexName,
+    id: DocumentId,
+    routing: Option[Routing] = None
+  ): ElasticRequest[Either[DocumentRetrievingError, A]] =
+    GetById(index, id, routing).map {
+      case Some(document) => document.decode.left.map(err => DecoderError(err.message))
+      case None           => Left(DocumentNotFound)
+    }
+
+  private[elasticsearch] final case class GetById(
+    index: IndexName,
+    id: DocumentId,
+    routing: Option[Routing] = None
+  ) extends ElasticRequest[Option[Document]]
+
+}

modules/library/src/main/scala/zio/elasticsearch/IndexName.scala

@@ -0,0 +1,3 @@
+package zio.elasticsearch
+
+final case class IndexName(name: String) extends AnyVal

modules/library/src/main/scala/zio/elasticsearch/Routing.scala

@@ -0,0 +1,3 @@
+package zio.elasticsearch
+
+final case class Routing(value: String) extends AnyVal

modules/library/src/main/scala/zio/elasticsearch/package.scala

@@ -0,0 +1,11 @@
+package zio
+
+import zio.schema.Schema
+import zio.schema.codec.DecodeError
+import zio.schema.codec.JsonCodec.JsonDecoder
+
+package object elasticsearch {
+  private[elasticsearch] final case class Document(json: String) {
+    def decode[A](implicit schema: Schema[A]): Either[DecodeError, A] = JsonDecoder.decode(schema, json)
+  }
+}