Contractless/src/orphans/undo_transactions/undo_borrower.rs

use crate::blocks::loan_payment::ContractPaymentTransaction;
use crate::blocks::loans::LoanContractTransaction;
use crate::common::network_paths_and_settings::block_extension_and_paths;
use crate::decode;
use crate::records::balance_sheet::operations::balance_sheet_operation_with_db;
use crate::records::record_chain::add_payments_db::remove_payment;
use crate::records::record_chain::nft_provenance::remove_nft_history_entry;
use crate::rpc::commands::transaction_by_txid::request_transaction_by_txid;
use crate::rpc::responses::RpcResponse;
use crate::sled::Db;

pub async fn undo_borrower_transaction(
    transaction: ContractPaymentTransaction,
    mining_receiver: &str,
    db: &Db,
) -> Result<(), String> {
    // restore balances and database state for a contract payment
    // that is being removed during orphan rollback
    let operand_subtraction = "subtraction";
    let operand_addition = "addition";
    let (
        _network_name,
        _padded_base_coin,
        type_str,
        _torrentpath,
        _wallet_path,
        _blockpath,
        _db_path,
        _balance_path,
        _log_path,
    ) = block_extension_and_paths();

    // reload the original loan contract so the rollback uses the
    // same lender and asset information the payment was based on
    let contract_hash = decode(&transaction.unsigned_contract_payment.contract_hash)
        .map_err(|e| format!("Error decoding contract hash: {e}"))?;
    let contract = request_transaction_by_txid(db, contract_hash.clone()).await;

    let loan_txtype = 7;
    let loan_tx = match contract {
        RpcResponse::Binary(contract_bytes) => {
            if contract_bytes.is_empty() {
                return Err("Invalid loan contract: empty transaction bytes".to_string());
            }
            if contract_bytes[0] != loan_txtype {
                return Err(
                    "Invalid loan contract: referenced transaction is not a loan contract"
                        .to_string(),
                );
            }
            LoanContractTransaction::from_bytes(loan_txtype, &contract_bytes[1..])
                .await
                .map_err(|e| e.to_string())?
        }
    };

    let lender = loan_tx.unsigned_loan_contract.lender;
    let loan_coin = loan_tx.unsigned_loan_contract.loan_coin;
    let borrower = &transaction.unsigned_contract_payment.address;
    let payback_amount = transaction.unsigned_contract_payment.payback_amount;
    let tip = transaction.unsigned_contract_payment.tip;
    let txfee = transaction.unsigned_contract_payment.txfee;

    // reverse the fee, tip, and repayment movements that were
    // applied when the borrower payment was originally saved
    let _ =
        balance_sheet_operation_with_db(db, mining_receiver, txfee, &type_str, operand_subtraction);
    let _ = balance_sheet_operation_with_db(db, borrower, txfee, &type_str, operand_addition);
    let _ =
        balance_sheet_operation_with_db(db, mining_receiver, tip, &loan_coin, operand_subtraction);
    let _ = balance_sheet_operation_with_db(db, borrower, tip, &loan_coin, operand_addition);
    let _ = balance_sheet_operation_with_db(
        db,
        &lender,
        payback_amount,
        &loan_coin,
        operand_subtraction,
    );
    let _ =
        balance_sheet_operation_with_db(db, borrower, payback_amount, &loan_coin, operand_addition);

    // Remove the payment transaction lookup from the txid tree.
    let txid_tree = db
        .open_tree("txid")
        .map_err(|e| format!("Failed to open txid tree: {e}"))?;
    let tx_hash = transaction.unsigned_contract_payment.hash().await;
    txid_tree
        .remove(decode(&tx_hash).map_err(|e| format!("Error decoding txid: {e}"))?)
        .map_err(|e| format!("Failed to remove borrower txid: {e}"))?;

    // Loan payments involving NFTs also add a provenance entry for the loan
    // asset, so remove it if this loan coin is tracked as an NFT.
    let nft_tree = db
        .open_tree("nfts")
        .map_err(|e| format!("Failed to open nfts tree: {e}"))?;
    let tx_hash_bytes = decode(&tx_hash).map_err(|e| format!("Error decoding txid: {e}"))?;
    if nft_tree.contains_key(loan_coin.as_bytes()).unwrap_or(false) {
        let _ = remove_nft_history_entry(db, &loan_coin, &tx_hash_bytes);
    }

    // The aggregate payment record is reduced by the payment being undone.
    let _ = remove_payment(db, contract_hash, payback_amount);

    Ok(())
}