// Copyright 2020 The Exonum Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";
import "exonum/crypto/types.proto";
import "google/protobuf/empty.proto";

package exonum.proof;

option java_package = "com.exonum.messages.proof";

// Subset of map elements coupled with a proof. MapProof can assert existence/absence of certain keys
// from the underlying map.
message MapProof {
  // Array with 2 kinds of objects: `{ key, no_value }` for keys missing from
  // the underlying index, and `{ key, value }` for key-value pairs, existence of
  // which is asserted by the proof.
  repeated OptionalEntry entries = 1;
  // Array of { path: ProofPath, hash: Hash } objects.
  repeated MapProofEntry proof = 2;
}

// Key with corresponding value or an empty value if the key is missing
// from the underlying map.
message OptionalEntry {
  // Key serialized as per `BinaryValue` implementation (usually as
  // a Protobuf message, except for primitive types).
  bytes key = 1;
  oneof maybe_value {
    // Value serialized per `BinaryValue` implementation (usually as
    // a Protobuf message, except for primitive types).
    bytes value = 2;
    // Indicator that `key` is missing from the underlying map.
    google.protobuf.Empty no_value = 3;
  }
}

// Path to an intermediate Merkle Patricia tree node and a corresponding
// hash value.
message MapProofEntry {
  // Path to the node, expressed with the minimum necessary number of bytes.
  // Bits within each byte are indexed from the least significant to
  // the most significant.
  // The last byte may be padded with zeros if necessary.
  bytes path = 1;
  // Hash associated with the node.
  exonum.crypto.Hash hash = 2;
  // Number of zero bit padding at the end of the path. Must be in the `0..8`
  // interval.
  uint32 path_padding = 3;
}