mecenas_locktime.cash

pragma cashscript ^0.10.0;

// This is an experimental contract for a more "streaming" Mecenas experience
// Completely untested, just a concept
contract Mecenas(
    bytes20 recipient,
    bytes20 funder,
    int pledgePerBlock,
    bytes8 initialBlock,
) {
    function receive() {
        // Check that the first output sends to the recipient
        bytes25 recipientLockingBytecode = new LockingBytecodeP2PKH(recipient);
        require(tx.outputs[0].lockingBytecode == recipientLockingBytecode);

        // Check that time has passed and that time locks are enabled
        int initial = int(initialBlock);
        require(tx.time >= initial);

        // Calculate the amount that has accrued since last claim
        int passedBlocks = tx.locktime - initial;
        int pledge = passedBlocks * pledgePerBlock;

        // Calculate the leftover amount
        int minerFee = 1000;
        int currentValue = tx.inputs[this.activeInputIndex].value;
        int changeValue = currentValue - pledge - minerFee;

        // If there is not enough left for *another* block after this one,
        // we send the remainder to the recipient. Otherwise we send the
        // remainder to the recipient and the change back to the contract
        if (changeValue <= pledgePerBlock + minerFee) {
            require(tx.outputs[0].value == currentValue - minerFee);
        } else {
            // Check that the outputs send the correct amounts
            require(tx.outputs[0].value == pledge);
            require(tx.outputs[1].value == changeValue);

            // Cut out old initialBlock (OP_PUSHBYTES_8 <initialBlock>)
            // Insert new initialBlock (OP_PUSHBYTES_8 <tx.locktime>)
            // Note that constructor parameters are added in reverse order,
            // so initialBlock is the first statement in the contract bytecode.
            bytes newContract = 0x08 + bytes8(tx.locktime) + this.activeBytecode.split(9)[1];

            // Create the locking bytecode for the new contract and check that
            // the change output sends to that contract
            bytes23 newContractLock = new LockingBytecodeP2SH20(hash160(newContract));
            require(tx.outputs[1].lockingBytecode == newContractLock);
        }
    }

    function reclaim(pubkey pk, sig s) {
        require(hash160(pk) == funder);
        require(checkSig(s, pk));
    }
}