// Copyright 2016 Marapongo, Inc. All rights reserved.

syntax = "proto3";

import "google/protobuf/empty.proto";
import "google/protobuf/struct.proto";

package murpc;

// TODO: figure out "transactionality" and possibly "tainting".

// ResourceProvider is a service that understands how to create, read, update, or delete resources for types defined
// within a single MuPackage.  It is driven by the overall Mu toolchain in response to blueprints and graphs.
service ResourceProvider {
    // Create allocates a new instance of the provided resource and returns its unique ID afterwards.  (The input ID
    // must be blank.)  If this call fails, the resource must not have been created (i.e., it is "transacational").
    rpc Create(CreateRequest) returns (CreateResponse) {}
    // Read read the instance state identifier by ID, returning a populated resource object, or an error if not found.
    rpc Read(ReadRequest) returns (ReadResponse) {}
    // Update updates an existing resource with new values.  Only those values in the provided property bag are updated
    // to new values.  The resource ID is returned and may be different if the resource had to be recreated.
    rpc Update(UpdateRequest) returns (UpdateResponse) {}
    // Delete tears down an existing resource with the given ID.  If it fails, the resource is assumed to still exist.
    rpc Delete(DeleteRequest) returns (google.protobuf.Empty) {}
}

message CreateRequest {
    string type = 1;                       // the type token of the resource.
    google.protobuf.Struct properties = 2; // the properties to set during creation.
}

message CreateResponse {
    string id = 1;                         // the ID of the resource created.
}

message ReadRequest {
    string id = 1;                         // the ID of the resource to read.
    string type = 2;                       // the type token of the resource.
    google.protobuf.Struct properties = 3; // an optional list of properties to read (if empty, all).
}

message ReadResponse {
    google.protobuf.Struct properties = 1; // the properties read from the resource.
}

message UpdateRequest {
    string id = 1;                   // the ID of the resource to update.
    string type = 2;                 // the type token of the resource.
    google.protobuf.Struct olds = 3; // the old values of properties to update.
    google.protobuf.Struct news = 4; // the new values of properties to update.
}

message UpdateResponse {
    string id = 1;
}

message DeleteRequest {
    string id = 1;                         // the ID of the resource to delete.
}