// Copyright (c) 2019-2020 The Zcash developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or https://www.opensource.org/licenses/mit-license.php .

syntax = "proto3";
package cash.z.wallet.sdk.rpc;
option go_package = "lightwalletd/walletrpc";
option swift_prefix = "";
// Remember that proto3 fields are all optional. A field that is not present will be set to its zero value.
// bytes fields of hashes are in canonical little-endian format.

// 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 {
    uint32 protoVersion = 1;    // the version of this wire format, for storage
    uint64 height = 2;          // the height of this block
    bytes hash = 3;             // the ID (hash) of this block, same as in block explorers
    bytes prevHash = 4;         // the ID (hash) of this block's predecessor
    uint32 time = 5;            // Unix epoch time when the block was mined
    bytes header = 6;           // (hash, prevHash, and time) OR (full header)
    repeated CompactTx vtx = 7; // zero or more compact transactions from this block
}

// CompactTx contains the minimum information for a wallet to know if this transaction
// is relevant to it (either pays to it or spends from it) via shielded elements
// only. This message will not encode a transparent-to-transparent transaction.
message CompactTx {
    uint64 index = 1;   // the index within the full block
    bytes hash = 2;     // the ID (hash) of this transaction, same as in block explorers

    // The transaction fee: present if server can provide. In the case of a
    // stateless server and a transaction with transparent inputs, this will be
    // unset because the calculation requires reference to prior transactions.
    // in a pure-Sapling context, the fee will be calculable as:
    //    valueBalance + (sum(vPubNew) - sum(vPubOld) - sum(tOut))
    uint32 fee = 3;

    repeated CompactSpend spends = 4;   // inputs
    repeated CompactOutput outputs = 5; // outputs
}

// CompactSpend is a Sapling Spend Description as described in 7.3 of the Zcash
// protocol specification.
message CompactSpend {
    bytes nf = 1;   // nullifier (see the Zcash protocol specification)
}

// output is a Sapling Output Description as described in section 7.4 of the
// Zcash protocol spec. Total size is 948.
message CompactOutput {
    bytes cmu = 1;          // note commitment u-coordinate
    bytes epk = 2;          // ephemeral public key
    bytes ciphertext = 3;   // ciphertext and zkproof
}