function FMainClass::FindSourceDestination(cargo_id, desired_distance) {
    local cargo_entry = cargoes[cargo_id];
    if (cargo_entry.freight) { // Freight cargo, find an industry accepting it.
        local accept_inds = GSIndustryList_CargoAccepting(cargo_id);
        local prod_inds = GSIndustryList_CargoProducing(cargo_id);

        local accept_ind, prod_ind;
        foreach (accept_ind in accept_inds) {
            GSLog.Info("accept " + GSCargo.GetCargoLabel(cargo_entry.cid) + GSIndustry.GetName(accept_ind));
            local accept_tile = GSIndustry.GetLocation(accept_ind);

            foreach (prod_ind in prod_inds) {
                if (prod_ind == accept_ind) continue;
                local prod_tile = GSIndustry.GetLocation(prod_ind);
                local dist = GSTile.GetDistanceManhattanToTile(accept_tile, prod_tile);

                GSLog.Info("produce " + GSCargo.GetCargoLabel(cargo_entry.cid) + GSIndustry.GetName(prod_ind) + "@" + dist);
                // GSIndustry.GetDistanceManhattan(accept_tile)
            }

        }
    }
}