Add methods to Endpoint to apply any kind of in/out codec

- add some convenience methods for creating header codecs
- make text codecs implicit for easy usage in header and query codec

zio-http/src/main/scala/zio/http/codec/HeaderCodecs.scala

@@ -16,6 +16,8 @@
 
 package zio.http.codec
 
+import scala.util.Try
+
 import zio.http.Header
 import zio.http.Header.HeaderType
 
@@ -27,6 +29,29 @@ private[codec] trait HeaderCodecs {
     headerCodec(headerType.name, TextCodec.string)
       .transformOrFailLeft(headerType.parse(_), headerType.render(_))
 
+  def name[A](name: String)(implicit codec: TextCodec[A]): HeaderCodec[A] =
+    headerCodec(name, codec)
+
+  def nameTransform[A, B](name: String, parse: B => Either[String, A], render: A => B)(implicit
+    codec: TextCodec[B],
+  ): HeaderCodec[A] =
+    headerCodec(name, codec).transformOrFailLeft(parse, render)
+
+  def nameTransformOpt[A, B](name: String, parse: B => Option[A], render: A => B)(implicit
+    codec: TextCodec[B],
+  ): HeaderCodec[A] =
+    headerCodec(name, codec).transformOrFailLeft(parse(_).toRight(s"Failed to parse header $name"), render)
+
+  def nameTransformOrFail[A, B](
+    name: String,
+    parse: B => A,
+    render: A => B,
+  )(implicit codec: TextCodec[B]): HeaderCodec[A] =
+    headerCodec(name, codec).transformOrFailLeft(
+      s => Try(parse(s)).toEither.left.map(e => s"Failed to parse header $name: ${e.getMessage}"),
+      render,
+    )
+
   final val accept: HeaderCodec[Header.Accept]                 = header(Header.Accept)
   final val acceptEncoding: HeaderCodec[Header.AcceptEncoding] = header(Header.AcceptEncoding)
   final val acceptLanguage: HeaderCodec[Header.AcceptLanguage] = header(Header.AcceptLanguage)

zio-http/src/main/scala/zio/http/codec/QueryCodecs.scala

@@ -28,4 +28,5 @@ private[codec] trait QueryCodecs {
 
   def queryAs[A](name: String)(implicit codec: TextCodec[A]): QueryCodec[A] =
     HttpCodec.Query(name, codec)
+
 }

zio-http/src/main/scala/zio/http/codec/TextCodec.scala

@@ -45,15 +45,15 @@ sealed trait TextCodec[A] extends PartialFunction[String, A] { self =>
 }
 
 object TextCodec {
-  val boolean: TextCodec[Boolean] = BooleanCodec
+  implicit val boolean: TextCodec[Boolean] = BooleanCodec
 
   def constant(string: String): TextCodec[Unit] = Constant(string)
 
-  val int: TextCodec[Int] = IntCodec
+  implicit val int: TextCodec[Int] = IntCodec
 
-  val string: TextCodec[String] = StringCodec
+  implicit val string: TextCodec[String] = StringCodec
 
-  val uuid: TextCodec[UUID] = UUIDCodec
+  implicit val uuid: TextCodec[UUID] = UUIDCodec
 
   final case class Constant(string: String) extends TextCodec[Unit] {
 

zio-http/src/main/scala/zio/http/endpoint/Endpoint.scala

@@ -25,7 +25,6 @@ import zio.stream.ZStream
 import zio.schema._
 
 import zio.http.Status
-import zio.http.codec.HttpCodecType.ResponseType
 import zio.http.codec._
 import zio.http.endpoint.Endpoint.OutErrors
 
@@ -145,6 +144,15 @@ final case class Endpoint[Input, Err, Output, Middleware <: EndpointMiddleware](
   ): Endpoint[combiner.Out, Err, Output, Middleware] =
     copy(input = input ++ HttpCodec.Content(schema))
 
+  /**
+   * Returns a new endpoint derived from this one, whose request must satisfy
+   * the specified codec.
+   */
+  def inCodec[Input2](codec: HttpCodec[HttpCodecType.RequestType, Input2])(implicit
+    combiner: Combiner[Input, Input2],
+  ): Endpoint[combiner.Out, Err, Output, Middleware] =
+    copy(input = input ++ codec)
+
   /**
    * Returns a new endpoint derived from this one whose middleware is composed
    * from the existing middleware of this endpoint, and the specified
@@ -193,6 +201,15 @@ final case class Endpoint[Input, Err, Output, Middleware <: EndpointMiddleware](
 
   def outErrors[Err2]: OutErrors[Input, Err, Output, Middleware, Err2] = OutErrors(self)
 
+  /**
+   * Returns a new endpoint derived from this one, whose response must satisfy
+   * the specified codec.
+   */
+  def outCodec[Output2](codec: HttpCodec[HttpCodecType.ResponseType, Output2])(implicit
+    alt: Alternator[Output, Output2],
+  ): Endpoint[Input, Err, alt.Out, Middleware] =
+    copy(output = self.output | codec)
+
   /**
    * Returns a new endpoint derived from this one, whose output type is a stream
    * of the specified type for the ok status code.

zio-http/src/test/scala/zio/http/endpoint/EndpointSpec.scala

@@ -234,6 +234,77 @@ object EndpointSpec extends ZIOSpecDefault {
           "path(users, 123, posts, 555, comments, 777, replies, 999)",
         )
 
+      },
+      test("composite in codecs") {
+        val headerOrQuery = HeaderCodec.name[String]("X-Header") | QueryCodec.query("header")
+
+        val endpoint = Endpoint.get(literal("test")).out[String].inCodec(headerOrQuery)
+
+        val routes = endpoint.implement(header => ZIO.succeed(header))
+
+        val request = Request.get(
+          URL
+            .decode("/test?header=query-value")
+            .toOption
+            .get,
+        )
+
+        val requestWithHeaderAndQuery = request.addHeader("X-Header", "header-value")
+
+        val requestWithHeader = Request
+          .get(
+            URL
+              .decode("/test")
+              .toOption
+              .get,
+          )
+          .addHeader("X-Header", "header-value")
+
+        for {
+          response       <- routes.toApp.runZIO(request)
+          onlyQuery      <- response.body.asString.orDie
+          response       <- routes.toApp.runZIO(requestWithHeader)
+          onlyHeader     <- response.body.asString.orDie
+          response       <- routes.toApp.runZIO(requestWithHeaderAndQuery)
+          headerAndQuery <- response.body.asString.orDie
+        } yield assertTrue(
+          onlyQuery == """"query-value"""",
+          onlyHeader == """"header-value"""",
+          headerAndQuery == """"header-value"""",
+        )
+      },
+      test("composite out codecs") {
+        val headerOrQuery = HeaderCodec.name[String]("X-Header") | StatusCodec.status(Status.Created)
+
+        val endpoint = Endpoint.get(literal("test")).query(QueryCodec.queryBool("Created")).outCodec(headerOrQuery)
+
+        val routes =
+          endpoint.implement(created => if (created) ZIO.succeed(Right(())) else ZIO.succeed(Left("not created")))
+
+        val requestCreated = Request.get(
+          URL
+            .decode("/test?Created=true")
+            .toOption
+            .get,
+        )
+
+        val requestNotCreated = Request.get(
+          URL
+            .decode("/test?Created=false")
+            .toOption
+            .get,
+        )
+
+        for {
+          notCreated <- routes.toApp.runZIO(requestNotCreated)
+          header = notCreated.rawHeader("X-Header").get
+          response <- routes.toApp.runZIO(requestCreated)
+        } yield assertTrue(
+          header == "not created",
+          notCreated.status == Status.Ok,
+          response.status == Status.Created,
+        )
+
       },
       suite("request bodies")(
         test("simple input") {