syntax = "proto3";
package proto;

// Remember that proto3 fields are all optional.

// A BlockFilter message contains identifiers to select a block: either a
// height or a hash.
message BlockFilter {
     uint64 blockHeight = 1;
     bytes blockHash = 2;
}

message RangeFilter {
    BlockFilter start = 1;
    BlockFilter end = 2;
}

// A TxFilter contains the information needed to identify a particular
// transaction: either a block and an index, or a direct transaction hash.
message TxFilter {
     BlockFilter blockID = 1;
     uint64 txIndex = 2;
     bytes txHash = 3;
}


// CompactBlock is a packaging of ONLY the data from a block that's needed to:
//   1. Detect a payment to your shielded Sapling address
//   2. Detect a spend of your shielded Sapling notes
//   3. Update your witnesses to generate new Sapling spend proofs.
message CompactBlock {
    BlockFilter blockID = 1;
    repeated CompactTx vtx = 3;
}

message CompactTx {
    // Index and hash will allow the receiver to call out to chain
    // explorers or other data structures to retrieve more information
    // about this transaction.
    uint64 index = 1;
    bytes hash = 2;

    repeated CompactSpend spends = 3;
    repeated CompactOutput outputs = 4;
}

message CompactSpend {
    bytes nf = 1;
}

message CompactOutput {
    bytes cmu = 1;
    bytes epk = 2;
    bytes ciphertext = 3;
}

// An opaque blob of full transaction data, for fetching anything that is not
// in the compact format (e.g. the memo field).
message FullTransaction {
    TxFilter txID = 1;
    bytes data = 2;
}

// Empty placeholder.
// Someday we may want to specify e.g. a particular chain fork.
message ChainSpec {}

service CompactTxStreamer {
    rpc GetLatestBlock(ChainSpec) returns (BlockFilter) {}
    rpc GetBlock(BlockFilter) returns (CompactBlock) {}
    rpc GetBlockRange(RangeFilter) returns (stream CompactBlock) {}
    rpc GetTransaction(TxFilter) returns (FullTransaction) {}
}