/**
  * Composes a send transaction
  * @param  string $asset                     A counterparty asset name or BTC
  * @param  mixed  $quantity                  Quantity of asset to send.  Accepts a float or a Tokenly\CounterpartyTransactionComposer\Quantity or Tokenly\CryptoQuantity\CryptoQuantity object.  Use a Quantity object for indivisible assets.
  * @param  mixed  $destination               A single destination bitcoin address.  For BTC sends an array of [[address, amount], [address, amount]] is also allowed.  Amounts should be float values.
  * @param  string $private_key_wif           The private key in ASCII WIF format.  This can be null to compose an unsigned transaction.
  * @param  array  $utxos                     An array of UTXOs.  Each UTXO should be ['txid' => txid, 'n' => n, 'amount' => amount (in satoshis), 'script' => script hexadecimal string]
  * @param  mixed  $change_address_collection a single address string to receive all change. Or an array of [[address, amount], [address, amount], [address]].  Amounts should be float values.  An address with no amount for the last entry will send the remaining change to that address.
  * @param  float  $fee                       A fee
  * @param  float  $btc_dust                  Amount of BTC dust to send with the Counterparty transaction.
  * @return Array returns a ComposedTransaction object
  */
 public function composeSend($asset, $quantity, $destination, $private_key_wif, $utxos, $change_address_collection = null, $fee = null, $btc_dust = null)
 {
     if ($asset == 'BTC') {
         return $this->composeBTCSend($quantity, $destination, $private_key_wif, $utxos, $change_address_collection, $fee);
     }
     $fee_satoshis = $fee === null ? self::DEFAULT_FEE : intval(round($fee * self::SATOSHI));
     $btc_dust_satoshis = $btc_dust === null ? self::DEFAULT_BTC_DUST : intval(round($btc_dust * self::SATOSHI));
     // get total and change amount
     $change_amounts = $this->calculateAndValidateChange($utxos, $btc_dust_satoshis, $fee_satoshis, $change_address_collection);
     $tx_builder = TransactionFactory::build();
     // add the UTXO inputs
     $transaction_outputs = $this->addInputsAndReturnPreviousOutputs($utxos, $tx_builder);
     // pay the btc_dust to the destination
     if (is_array($destination)) {
         throw new Exception("Multiple destinations are not supported for counterparty sends", 1);
     }
     $tx_builder->payToAddress($btc_dust_satoshis, AddressFactory::fromString($destination));
     // build the OP_RETURN script
     $op_return_builder = new OpReturnBuilder();
     $op_return = $op_return_builder->buildOpReturn($quantity, $asset, $utxos[0]['txid']);
     $script = ScriptFactory::create()->op('OP_RETURN')->push(Buffer::hex($op_return, 28))->getScript();
     $tx_builder->output(0, $script);
     // pay the change to self
     $this->payChange($change_amounts, $tx_builder);
     // sign
     if ($private_key_wif !== null) {
         $signed_transaction = $this->signTx($private_key_wif, $tx_builder, $transaction_outputs);
         return $this->buildReturnValuesFromTransactionAndInputs($signed_transaction, $utxos, true);
     }
     return $this->buildReturnValuesFromTransactionAndInputs($tx_builder->get(), $utxos, false);
 }
 /**
  * @expectedException        Exception
  * @expectedExceptionMessage Asset ID was too low
  */
 public function testComposeTooSmallNumericAssetID()
 {
     $op_return_builder = new OpReturnBuilder();
     $fake_txid = 'deadbeef00000000000000000000000000000000000000000000000000001111';
     $op_return_builder->buildOpReturn(100, 'A95428956661682176', $fake_txid);
 }