Skip to content

Commit

Permalink
Merge pull request #1 from jpg-store/kwhitemsg/dev-245-add-change-spl…
Browse files Browse the repository at this point in the history 
…itting-to-the

Kwhitemsg/dev 245 add change splitting to the
  • Loading branch information
@MartinSchere
MartinSchere authored Apr 20, 2022
2 parents 9e28003 + a7bc2fa commit 08c4918
Showing 1 changed file with 137 additions and 7 deletions.
144 changes: 137 additions & 7 deletions rust/src/tx_builder.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -282,6 +282,10 @@ pub struct TransactionBuilderConfig {
costmdls: Costmdls, // protocol parameter
blockfrost: Blockfrost,
prefer_pure_change: bool,
collateral_amount: BigNum,
min_split_amount_ada: BigNum,
prefer_split_change: bool,
native_asset_chunk_size: u32,
}

#[wasm_bindgen]
Expand All @@ -297,6 +301,10 @@ pub struct TransactionBuilderConfigBuilder {
costmdls: Option<Costmdls>, // protocol parameter
blockfrost: Option<Blockfrost>,
prefer_pure_change: bool,
collateral_amount: BigNum,
min_split_amount_ada: BigNum,
prefer_split_change: bool,
native_asset_chunk_size: Option<u32>,
}

#[wasm_bindgen]
Expand All @@ -313,6 +321,10 @@ impl TransactionBuilderConfigBuilder {
costmdls: None,
blockfrost: None,
prefer_pure_change: false,
collateral_amount: to_bignum(5000000),
min_split_amount_ada: to_bignum(100),
prefer_split_change: false,
native_asset_chunk_size: None,
}
}

Expand Down Expand Up @@ -376,6 +388,21 @@ impl TransactionBuilderConfigBuilder {
cfg
}

pub fn prefer_split_change(
&self,
prefer_split_change: bool,
collateral_amount: BigNum,
min_split_amount_ada: BigNum,
native_asset_chunk_size: u32,
) -> Self {
let mut cfg = self.clone();
cfg.prefer_split_change = prefer_split_change;
cfg.collateral_amount = collateral_amount;
cfg.min_split_amount_ada = min_split_amount_ada;
cfg.native_asset_chunk_size = Some(native_asset_chunk_size);
cfg
}

pub fn build(&self) -> Result<TransactionBuilderConfig, JsError> {
let cfg = self.clone();
Ok(TransactionBuilderConfig {
Expand Down Expand Up @@ -411,6 +438,10 @@ impl TransactionBuilderConfigBuilder {
Blockfrost::new("".to_string(), "".to_string())
},
prefer_pure_change: cfg.prefer_pure_change,
prefer_split_change: cfg.prefer_split_change,
collateral_amount: cfg.collateral_amount,
min_split_amount_ada: cfg.min_split_amount_ada,
native_asset_chunk_size: cfg.native_asset_chunk_size,
})
}
}
Expand Down Expand Up @@ -1817,8 +1848,15 @@ impl TransactionBuilder {
.as_ref()
.map_or_else(|| None, |ma| ma.partial_cmp(&MultiAsset::new()))
{
//Use pack_nfts_for_change with different params to easily split nft change.
let max_value_size_change = if self.config.prefer_split_change {
self.config.native_asset_chunk_size
} else {
self.config.max_value_size
};

let nft_changes = pack_nfts_for_change(
self.config.max_value_size,
max_value_size_change,
&self.config.coins_per_utxo_word,
address,
&change_left,
Expand Down Expand Up @@ -1858,7 +1896,73 @@ impl TransactionBuilder {
change_left = change_left.checked_sub(&Value::new(&new_fee))?;
// add potentially a separate pure ADA change output
let left_above_minimum = change_left.coin.compare(&minimum_utxo_val) > 0;
if self.config.prefer_pure_change && left_above_minimum {
// calculate the fee for two outputs for split outputs which creates at least 2 outputs
let fee_for_outputs = self
.fee_for_output(&TransactionOutput {
address: address.clone(),
amount: Value::new(&self.config.collateral_amount.clone()),
datum: datum.clone(),
script_ref: script_ref.clone(),
})?
.checked_mul(&BigNum::from_str(&"2")?)?;
let above_collateral_minimum = change_left.coin.compare(
&self
.config
.collateral_amount
.checked_add(&minimum_utxo_val)?
.checked_add(&fee_for_outputs)?,
) > 0;
if self.config.prefer_split_change && above_collateral_minimum {
// Create collateral output and subtract from change left
change_left =
change_left.checked_sub(&Value::new(&self.config.collateral_amount))?;
let collateral_transaction = TransactionOutput {
address: address.clone(),
amount: Value::new(&self.config.collateral_amount.clone()),
datum: datum.clone(),
script_ref: script_ref.clone(),
};
self.add_change_output(&collateral_transaction)?;
// add on fee for collateral
let fee_for_change = self.fee_for_output(&collateral_transaction)?;
new_fee = new_fee.checked_add(&fee_for_change)?;

//Split the rest of the change into decreasing outputs / 2, but if 100 ada or under stop splitting based on default config
while change_left
.coin
.checked_div(&BigNum::from_str(&"2")?)?
.compare(
&minimum_utxo_val.checked_mul(&self.config.min_split_amount_ada)?,
)
>= 0
{
let half = change_left.coin.checked_div(&BigNum::from_str(&"2")?)?;
change_left = change_left.checked_sub(&Value::new(&half))?;
let half_output = TransactionOutput {
address: address.clone(),
amount: Value::new(&half.clone()),
datum: datum.clone(),
script_ref: script_ref.clone(),
};
self.add_change_output(&half_output)?;
let fee_for_change = self.fee_for_output(&half_output)?;
new_fee = new_fee.checked_add(&fee_for_change)?;
}

//deal with change left before exiting if statement
if !change_left.is_zero() {
change_left = change_left.checked_sub(&change_left)?;
let leftover_output = TransactionOutput {
address: address.clone(),
amount: change_left,
datum: datum.clone(),
script_ref: script_ref.clone(),
};
self.add_change_output(&leftover_output)?;
let fee_for_change = self.fee_for_output(&leftover_output)?;
new_fee = new_fee.checked_add(&fee_for_change)?;
}
} else if self.config.prefer_pure_change && left_above_minimum {
let pure_output = TransactionOutput {
address: address.clone(),
amount: change_left.clone(),
Expand Down Expand Up @@ -2149,13 +2253,13 @@ impl TransactionBuilder {
get_ex_units(full_tx.clone(), &this.config.blockfrost).await?;
this.redeemers = Some(updated_redeemers);

//set new fee and and subract remaining amount from a change output
// set new fee and and subract remaining amount from a change output
let old_fee = full_tx.body.fee.clone();
let new_fee = min_fee(this)?;
this.set_fee(&new_fee);
let amount_to_subtract = new_fee.checked_sub(&old_fee)?;
// //get index of a change output which has sufficient balance
let index = this
// get index of a change output which has sufficient balance and is not collateral change output
let mut index_or_error = this
.change_outputs
.0
.iter()
Expand All @@ -2174,9 +2278,35 @@ impl TransactionBuilder {
.unwrap(),
)
.is_positive()
&& output.amount.coin.compare(&self.config.collateral_amount) != 0
})
.ok_or_else(|| JsError::from_str("No change output found"))
.unwrap();
.ok_or_else(|| JsError::from_str("No change output found"));

// didn't find any other outputs with enough lovelaces so now check all change outputs one more time
if index_or_error.is_err() {
index_or_error = this
.change_outputs
.0
.iter()
.position(|output| {
output
.amount
.coin
.checked_sub(&amount_to_subtract)
.unwrap_or(to_bignum(0))
.compare(
&min_ada_required(
&output.amount(),
output.datum.is_some(),
&this.config.coins_per_utxo_word,
)
.unwrap(),
)
.is_positive()
})
.ok_or_else(|| JsError::from_str("No change output found"));
}
let index = index_or_error.unwrap();

this.change_outputs.0[index].amount = this.change_outputs.0[index]
.amount
Expand Down

0 comments on commit 08c4918

Please sign in to comment.