syntax = "proto3";

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

// This is the Service Interface Version: change these numbers according to semver rules
// anytime the service-level protocol changes (e.g. string or bytes format). Such version
// cannot change at runtime during service execution.
//
// Examples of how to change version (M.m.p) for the KV protocol are:
// 1. bump M obtaining (M+1.m.p) when
// - changing table name i.e. bucketName field in Cursor
// - changing key/value format i.e. k, v fields in Pair
// 2. bump m obtaining (M.m+1.p) when
// - adding new table name i.e. bucketName field in Cursor
// 3. bump p obtaining (M.m.p+1) when
// - correcting wrong data in value i.e. v field in Pair
option (types.service_major_version) = 1;
option (types.service_minor_version) = 0;
option (types.service_patch_version) = 0;

package remote;

option go_package = "./remote;remote";

// Provides methods to access key-value data
service KV {
  // Version returns the service version number
  rpc Version(google.protobuf.Empty) returns (types.VersionReply);

  // Tx exposes read-only transactions for the key-value store
  rpc Tx(stream Cursor) returns (stream Pair);
}

enum Op {
  FIRST = 0;
  FIRST_DUP = 1;
  SEEK = 2;
  SEEK_BOTH = 3;
  CURRENT = 4;
  LAST = 6;
  LAST_DUP = 7;
  NEXT = 8;
  NEXT_DUP = 9;
  NEXT_NO_DUP = 11;
  PREV = 12;
  PREV_DUP = 13;
  PREV_NO_DUP = 14;
  SEEK_EXACT = 15;
  SEEK_BOTH_EXACT = 16;

  OPEN = 30;
  CLOSE = 31;
}

message Cursor {
  Op op = 1;
  string bucketName = 2;
  uint32 cursor = 3;
  bytes k = 4;
  bytes v = 5;
}

message Pair {
  bytes k = 1;
  bytes v = 2;
  uint32 cursorID = 3;
}