Atomic_Swap_Order.py

from pyteal import *

def create_atomic_swap_order():
    # Args
    recovery_account = Arg(0)
    buyer = Arg(1)
    asset_id = Btoi(Arg(2))
    price_per_unit = Btoi(Arg(3))
    max_payment_fee = Int(2000)

    # Gtx[0] pays seller for asset
    payment = Gtxn[0]
    # Gtx[1] delivers asset to buyer
    delivery = Gtxn[1]

    is_valid_payment = And(
        Txn.fee() < max_payment_fee,
        Txn.type_enum() == TxnType.Payment,
        payment.amount() == delivery.asset_amount() * price_per_unit,
    )

    # Gtx[1] delivers asset to buyer
    is_valid_delivery = And(
        Txn.type_enum() == TxnType.AssetTransfer,
        delivery.asset_receiver() == buyer,
        delivery.xfer_asset() == asset_id,
        delivery.asset_amount() == payment.amount() / price_per_unit,
    )

    is_fulfillment = And(
        Global.group_size() == Int(2),
        is_valid_payment,
        is_valid_delivery
    )

    is_recovery = And(
        Global.group_size() == Int(1),
        Txn.type_enum() == TxnType.Payment,
        Or(Txn.receiver() == recovery_account, Txn.close_remainder_to() == recovery_account),
    )

    program = Or(is_recovery, is_fulfillment)

    return program