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223 | class LoanWriter():
"""Loan Writer.
ipfs filename:
loan/borrower_<id>.lender_<id>.loan_<id>/created_<timestamp>
"""
loan_id: str
borrower: str
lender: str
index: Index
data: Loan
ipfsclient: Ipfs
borrower_wallet: str
lender_wallet: str
def __init__(
self: Self,
ipfs: Ipfs,
borrower: str,
lender: str,
principal_amount: int,
repayment_schedule: List[LoanPayment],
offer_expiry: datetime.date,
secret_manager: SecretManager,
project: str) -> None:
"""Construct a new unaccepted loan and write it.
The loan is not accepted until the borrower signs it.
Args:
ipfs: the ipfs client
borrower: the borrower id
lender: the lender id
principal_amount: the principal amount of the loan
repayment_schedule: the repayment schedule of the loan
offer_expiry: the expiry date of the loan offer
secret_manager: the secret manager to use for
storing wallet private keys
project: the project to use for wallet creation (the project to
use in Google Secret Manager for storing the private keys
of the created wallets)
"""
self.loan_id = str(uuid.uuid4())
self.borrower = borrower
self.lender = lender
self.ipfsclient = ipfs
timestamp = Timestamp()
timestamp.FromDatetime(offer_expiry)
# Create deposit wallets
self._create_wallets(secret_manager, project)
self.data = Loan(
principal_amount=principal_amount,
repayment_schedule=repayment_schedule,
offer_expiry=timestamp,
accepted=False,
borrower_deposit_wallet=self.borrower_wallet,
lender_deposit_wallet=self.lender_wallet
)
@staticmethod
def from_data(
ipfs: Ipfs,
data: Store,
wallet_manager: WalletManager,
secret_manager: SecretManager,
project: str) -> Self:
"""Construct a new loan from existing data.
Args:
ipfs: the ipfs client
data: the loan data
wallet_manager: the wallet manager
secret_manager: the secret manager to use for
storing wallet private keys
project: the project to use for wallet creation (the project to
use in Google Secret Manager for storing the private keys
of the created wallets)
Returns:
LoanWriter: the loan writer
"""
writer = LoanWriter(
ipfs=ipfs,
borrower=data.index["borrower"],
lender=data.index["lender"],
principal_amount=data.reader.principal_amount,
repayment_schedule=data.reader.repayment_schedule,
offer_expiry=data.reader.offer_expiry,
wallet_manager=wallet_manager,
secret_manager=secret_manager,
project=project
)
return writer
def _create_wallets(
self: Self,
secret_manager: SecretManager,
project: str) -> None:
"""Create deposit wallets for borrower and lender.
The borrower deposit wallet is for the principal and
the lender deposit wallet is for the repayments.
Args:
secret_manager: the secret manager to use for
storing wallet private keys
project: the project to use for wallet creation (the project to
use in Google Secret Manager for storing the private keys
of the created wallets)
"""
# Borrower's deposit wallet
borrower_wallet_name = f"{self.loan_id}_borrower_deposit_wallet"
borrower_wallet_id, borrower_account_address = \
WalletManager(secret_manager).create_wallet(
project, borrower_wallet_name
)
# Lender's deposit wallet
lender_wallet_name = f"{self.loan_id}_lender_deposit_wallet"
lender_wallet_id, lender_account_address = \
WalletManager(secret_manager).create_wallet(
project, lender_wallet_name
)
# Check if wallets created successfully
if not all([
borrower_wallet_id,
lender_wallet_id,
borrower_account_address,
lender_account_address]):
raise Exception("Error during wallets creation. Loan initiation failed.")
self.borrower_wallet = borrower_account_address
self.lender_wallet = lender_account_address
def write(self: Self) -> None:
"""Write the loan to IPFS."""
self._generate_index()
store = Store(
index=self.index,
ipfs=self.ipfsclient,
writer=self.data
)
store.add()
def _generate_index(self: Self) -> None:
"""Generate the index for the loan."""
self.index = Index(
prefix=PREFIX,
index={
"borrower": self.borrower,
"lender": self.lender,
"loan": self.loan_id
},
subindex=Index(
index={
"created": str(time.time_ns())
}
)
)
def accept_terms(self: Self) -> None:
"""Accept the loan terms."""
self.data = Loan(
principal_amount=self.data.principal_amount,
repayment_schedule=self.data.repayment_schedule,
offer_expiry=self.data.offer_expiry,
accepted=True
)
def register_payment(
self: Self,
payment_id: str,
transaction: str) -> None:
"""Register a payment.
Args:
payment_id: the payment id
transaction: the transaction id
"""
new_repayment_schedule = []
for payment in self.data.repayment_schedule:
if payment.payment_id == payment_id:
new_repayment_schedule.append(LoanPayment(
payment_id=payment_id,
amount_due=payment.amount_due_each_payment,
due_date=payment.timestamp,
transaction=transaction
))
else:
new_repayment_schedule.append(payment)
self.data = Loan(
principal_amount=self.data.principal_amount,
repayment_schedule=self.data.repayment_schedule,
offer_expiry=self.data.offer_expiry,
accepted=self.data.accepted
)
|