/*
    * create, sign and send a transaction
    *
    * @param array     $outputs            [address => value, ] or [[address, value], ] or [['address' => address, 'value' => value], ] coins to send
    *                                      value should be INT
    * @param string    $changeAddress      change address to use (autogenerated if NULL)
    * @param bool      $allowZeroConf
    * @param bool      $randomizeChangeIdx randomize the location of the change (for increased privacy / anonimity)
    * @param null|int  $forceFee           set a fixed fee instead of automatically calculating the correct fee, not recommended!
    * @return string the txid / transaction hash
    * @throws \Exception
    */
     
    public function pay(array $outputs, $changeAddress = null, $allowZeroConf = false, $randomizeChangeIdx = true, $forceFee = null) {
        if ($this->locked) {
            throw new \Exception("Wallet needs to be unlocked to pay");
        }

        $outputs = self::normalizeOutputsStruct($outputs);

        $txBuilder = new TransactionBuilder();
        $txBuilder->randomizeChangeOutput($randomizeChangeIdx);

        foreach ($outputs as $output) {
            $txBuilder->addRecipient($output['address'], $output['value']);
        }

        $this->coinSelectionForTxBuilder($txBuilder, true, $allowZeroConf, $forceFee);

        $apiCheckFee = $forceFee === null;

        return $this->sendTx($txBuilder, $apiCheckFee);
    }