Serena

%% Models module with record operations and business logic -module(models). -include("../include/records.hrl"). -include("../include/types.hrl"). %% Export functions -export([ create_user/4, update_user/2, get_user_by_id/1, create_order/3, add_item_to_order/3, calculate_order_total/1, validate_email/1, format_user_info/1 ]). %% User operations -spec create_user(integer(), string(), email(), integer()) -> #user{}. create_user(Id, Name, Email, Age) -> #user{ id = Id, name = Name, email = Email, age = Age, active = true }. -spec update_user(#user{}, [{atom(), term()}]) -> #user{}. update_user(User, Updates) -> lists:foldl(fun update_user_field/2, User, Updates). -spec get_user_by_id(user_id()) -> {ok, #user{}} | {error, not_found}. get_user_by_id(Id) -> %% Simulate database lookup case Id of 1 -> {ok, create_user(1, "John Doe", "john@example.com", 30)}; 2 -> {ok, create_user(2, "Jane Smith", "jane@example.com", 25)}; _ -> {error, not_found} end. %% Order operations -spec create_order(integer(), user_id(), list()) -> #order{}. create_order(Id, UserId, Items) -> #order{ id = Id, user_id = UserId, items = Items, total = 0.0, status = pending }. -spec add_item_to_order(#order{}, #item{}, quantity()) -> #order{}. add_item_to_order(Order, Item, Quantity) -> NewItem = Item#item{id = Quantity}, % Store quantity in id field for simplicity Order#order{items = [NewItem | Order#order.items]}. -spec calculate_order_total(#order{}) -> float(). calculate_order_total(#order{items = Items}) -> lists:foldl(fun(#item{price = Price, id = Qty}, Acc) -> Acc + (Price * Qty) end, 0.0, Items). %% Helper functions -spec update_user_field({atom(), term()}, #user{}) -> #user{}. update_user_field({name, Name}, User) -> User#user{name = Name}; update_user_field({email, Email}, User) -> User#user{email = Email}; update_user_field({age, Age}, User) -> User#user{age = Age}; update_user_field({active, Active}, User) -> User#user{active = Active}; update_user_field(_, User) -> User. -spec validate_email(string()) -> boolean(). validate_email(Email) -> string:str(Email, "@") > 0 andalso string:str(Email, ".") > 0. -spec format_user_info(#user{}) -> string(). format_user_info(#user{name = Name, email = Email, age = Age, active = Active}) -> Status = case Active of true -> "active"; false -> "inactive" end, lists:flatten(io_lib:format("~s (~s) - Age: ~w - Status: ~s", [Name, Email, Age, Status])).