namespace aws.polymorph

// Smithy doesn't allow passing resources or services as members of structures, 
// since it doesn't make sense in a client-server world to pass these over the
// wire. However, in our world we do want to be able to pass around references
// to things like Keyrings, so we create a new trait which indicates that 
// a target shape is not actually a structure but instead an opaque reference
// to a service or resource.
@trait(selector: "structure")
structure reference {
  // Can refer to either services or resources
  // @idRef(failWhenMissing: true, selector: "structure")
  service: String,
  // @idRef(failWhenMissing: true, selector: "service")
  resource: String
}

list ServiceList {
  @idRef(failWhenMissing: true, selector: "service")
  member: String
}
// A trait for explicitly modeling the configuration options that should be
// available in the generated methods for creating clients.
@trait(selector: "service")
structure localService {
  @required
  sdkId: String,
  @required
  @idRef(failWhenMissing: true, selector: "structure")
  config: String,
  // Explicitly NOT required
  dependencies: ServiceList
}

// Trait indicates that the member of the given structure MUST be expanded.
// To be used when we want operations to accept
// or return bare values rather than a nested structure.
// Code generation SHOULD throw an error if this is applied to a structure
// that is not used as input or output to an operation.
// At this time,
// Code generation MUST throw an error if this is applied to a structure
// with more than or less than one member.
// i.e: The structure MUST have one and only one member.
// At this time,
// the sole member's requirement status MUST NOT be determined by
// the positional trait.
// TODO: naming
@trait(selector: "structure")
structure positional {}

// Indicates that a string is represented as a sequence of UTF-8 encoded bytes
// in Dafny, rather than the default sequence of UTF-16 chars.
//
// This is a workaround that should be removed when Dafny's string definition
// is improved: <https://github.com/dafny-lang/dafny/issues/413>
@trait(selector: "string")
structure dafnyUtf8Bytes {}

// A trait indicating that the resource may be implemented by native code (instead of Dafny code).
// i.e.: Users may author their own classes that implement and extend this resource.
// Polymorph MUST generate and utilize NativeWrappers for these resources.
// Polymorph MUST generate conversion methods capabale of wrapping & un-wrapping
// these native resources.
// i.e.: The wrapping MUST NOT be a one way door.
@trait(selector: "resource")
structure extendable {}

// A trait to indicate that a resource stores local state
@trait(selector: "resource")
structure mutableLocalState {}

// This is a workaround that should be removed when
// Smithy-Dafny properly supports @documentation
// https://github.com/awslabs/smithy-dafny/issues/247
@trait(selector: "*")
string javadoc