// Copyright (c) 2023 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.ffi;

// A data structure that describes a series of transactions to be created.
message Proposal {
    // The version of this serialization format.
    uint32 protoVersion = 1;
    // The fee rule used in constructing this proposal
    FeeRule feeRule = 2;
    // The target height for which the proposal was constructed
    //
    // The chain must contain at least this many blocks in order for the proposal to
    // be executed.
    uint32 minTargetHeight = 3;
    // The series of transactions to be created.
    repeated ProposalStep steps = 4;
}

// A data structure that describes the inputs to be consumed and outputs to
// be produced in a proposed transaction.
message ProposalStep {
    // ZIP 321 serialized transaction request
    string transactionRequest = 1;
    // The vector of selected payment index / output pool mappings. Payment index
    // 0 corresponds to the payment with no explicit index.
    repeated PaymentOutputPool paymentOutputPools = 2;
    // The anchor height to be used in creating the transaction, if any.
    // Setting the anchor height to zero will disallow the use of any shielded
    // inputs.
    uint32 anchorHeight = 3;
    // The inputs to be used in creating the transaction.
    repeated ProposedInput inputs = 4;
    // The total value, fee value, and change outputs of the proposed
    // transaction
    TransactionBalance balance = 5;
    // A flag indicating whether the step is for a shielding transaction,
    // used for determining which OVK to select for wallet-internal outputs.
    bool isShielding = 6;
}

enum ValuePool {
    // Protobuf requires that enums have a zero discriminant as the default
    // value. However, we need to require that a known value pool is selected,
    // and we do not want to fall back to any default, so sending the
    // PoolNotSpecified value will be treated as an error.
    PoolNotSpecified = 0;
    // The transparent value pool (P2SH is not distinguished from P2PKH)
    Transparent = 1;
    // The Sapling value pool
    Sapling = 2;
    // The Orchard value pool
    Orchard = 3;
}

// A mapping from ZIP 321 payment index to the output pool that has been chosen
// for that payment, based upon the payment address and the selected inputs to
// the transaction.
message PaymentOutputPool {
    uint32 paymentIndex = 1;
    ValuePool valuePool = 2;
}

// The unique identifier and value for each proposed input that does not
// require a back-reference to a prior step of the proposal.
message ReceivedOutput {
    bytes txid = 1;
    ValuePool valuePool = 2;
    uint32 index = 3;
    uint64 value = 4;
}

// A reference to a payment in a prior step of the proposal. This payment must
// belong to the wallet.
message PriorStepOutput {
    uint32 stepIndex = 1;
    uint32 paymentIndex = 2;
}

// A reference to a change or ephemeral output from a prior step of the proposal.
message PriorStepChange {
    uint32 stepIndex = 1;
    uint32 changeIndex = 2;
}

// The unique identifier and value for an input to be used in the transaction.
message ProposedInput {
    oneof value {
        ReceivedOutput receivedOutput = 1;
        PriorStepOutput priorStepOutput = 2;
        PriorStepChange priorStepChange = 3;
    }
}

// The fee rule used in constructing a Proposal
enum FeeRule {
    // Protobuf requires that enums have a zero discriminant as the default
    // value. However, we need to require that a known fee rule is selected,
    // and we do not want to fall back to any default, so sending the
    // FeeRuleNotSpecified value will be treated as an error.
    FeeRuleNotSpecified = 0;
    // 10000 ZAT
    PreZip313 = 1;
    // 1000 ZAT
    Zip313 = 2;
    // MAX(10000, 5000 * logical_actions) ZAT
    Zip317 = 3;
}

// The proposed change outputs and fee value.
message TransactionBalance {
    // A list of change or ephemeral output values.
    repeated ChangeValue proposedChange = 1;
    // The fee to be paid by the proposed transaction, in zatoshis.
    uint64 feeRequired = 2;
}

// A proposed change or ephemeral output. If the transparent value pool is
// selected, the `memo` field must be null.
//
// When the `isEphemeral` field of a `ChangeValue` is set, it represents
// an ephemeral output, which must be spent by a subsequent step. This is
// only supported for transparent outputs. Each ephemeral output will be
// given a unique t-address.
message ChangeValue {
    // The value of a change or ephemeral output to be created, in zatoshis.
    uint64 value = 1;
    // The value pool in which the change or ephemeral output should be created.
    ValuePool valuePool = 2;
    // The optional memo that should be associated with the newly created output.
    // Memos must not be present for transparent outputs.
    MemoBytes memo = 3;
    // Whether this is to be an ephemeral output.
    bool isEphemeral = 4;
}

// An object wrapper for memo bytes, to facilitate representing the
// `change_memo == None` case.
message MemoBytes {
    bytes value = 1;
}