syntax = "proto3";

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

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);

  rpc ReceiveStateChanges(google.protobuf.Empty) returns (stream StateChange);
}

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;
}

enum Action {
  STORAGE = 0;     // Change only in the storage
  UPSERT = 1;      // Change of balance or nonce (and optionally storage)
  CODE = 2;        // Change of code (and optionally storage)
  UPSERT_CODE = 3; // Change in (balance or nonce) and code (and optinally storage)
  DELETE = 4;      // Account is deleted
}

message StorageChange {
  types.H256 location = 1;
  bytes data = 2;
}

message AccountChange {
  types.H160 address = 1;
  uint64 incarnation = 2;
  Action action = 3;
  bytes data = 4; // nil if there is no UPSERT in action
  bytes code = 5; // nil if there is no CODE in action
  repeated StorageChange storageChanges = 6;
}

enum Direction {
  FORWARD = 0;
  UNWIND = 1;
}

message StateChange {
  Direction direction = 1;
  uint64 blockHeight = 2;
  types.H256 blockHash = 3;
  repeated AccountChange changes = 4;
}