how does one compute the amount to be repaid?

[vd1]

     repay(); // ***Step 2: Repay the aggregated flash loan + above fees
    /* Remember to factor in:
        + 6bps in Kollateral aggregation fee
        + 9bps in native Aave flash loan fee
        + 2 Wei in native DyDx floan loan fee
    */

it seems the repay function would need to know how the loan was routed - ie the fraction of tokenAmount sent to aave or dydx? Other question what happens if we repay too much?