Implement a BAI2 bank statement parser that loads daily balance and transaction data into a cash-position ledger with validation

Verified steps

1. Retrieve the BAI2 file from your bank's SFTP or file delivery channel; validate the file encoding (ASCII or UTF-8) and the presence of required record types: 01 File Header, 02 Group Header, 03 Account Identifier, 16 Transaction, 49 Account Trailer, 98 Group Trailer, 99 File Trailer
2. Parse each Account Identifier record (type 03) to extract the bank customer account number, currency code, and as-of date; create or match an internal account record for each
3. For each Transaction record (type 16), extract the BAI2 type code, amount, funds type, and text description; map the BAI2 type code to your internal transaction category (debit, credit, memo post, etc.)
4. Validate the Account Trailer (type 49) control totals: sum of credit amounts and debit amounts within each account must match the trailer's control totals; reject the account block if they do not match
5. Post the validated transactions to your internal cash-position ledger with the BAI2 as-of date as the value date; flag any transaction whose BAI2 type code does not appear in your type-code mapping table for manual review
6. Run a daily closing balance check: the closing ledger balance for each account must equal the BAI2 account-level closing balance figure; alert on any discrepancy