from sqlalchemy import and_, select, func
from sqlalchemy.orm import aliased

from ledger.schema import TransactionLedgerRead
from transaction.models import Split, Transaction



class LedgerResource:
    @classmethod
    def get_ledger(cls, session, account_id):
        split_account = aliased(Split)
        split_balance = aliased(Split)
        transaction_balance = aliased(Transaction)

        balance_stmt = select(func.sum(split_balance.amount)).join(transaction_balance).where(and_(split_balance.account_id == split_account.account_id, transaction_balance.sequence <= Transaction.sequence)).scalar_subquery()

        stmt = (select(
            Transaction,
            split_account,
            balance_stmt.label('balance')
        ).join(
            split_account,
            and_(Transaction.id == split_account.transaction_id, split_account.account_id == account_id)
        ))

        return [TransactionLedgerRead(transaction=transaction, account_split=split, balance=balance) for transaction, split, balance in session.exec(stmt).all()]