bill.erl

-module(bill).
-export([
    database/0,
    bill/0,
    print_bill/1
]).

database() -> [
    {4719, "Fish Fingers" , 121},
    {5643, "Nappies" , 1010},
    {3814, "Orange Jelly", 56},
    {1111, "Hula Hoops", 21},
    {1112, "Hula Hoops (Giant)", 133},
    {1234, "Dry Sherry, 1lt", 540}
].

bill() -> [1234,4719,3814,1112,1113,1234].

%%
%% find_item(Number, Database) -> Record
%%
find_item(Item, []) -> {Item, "Unknown Item", 0};
find_item(Item, [{Item, _Description, _Value}=Record | _Records]) -> Record;
find_item(Item, [_Record | Records]) -> find_item(Item, Records).

%%
%% print_bill(Bill) -> ok
%%
print_bill(Bill) ->
    print_header(),
    Total = print_line(Bill, 0),
    print_total(Total).

print_header() ->
    io:format("~s~n~n", [string:pad("Erlang Stores", 40, both)]).

print_line([], Total) -> Total;
print_line([Item | Items], Total) ->
    {_, Description, Value} = find_item(Item, database()),
    io:format("~-30...s~10.2..f~n", [Description, Value/100]),
    print_line(Items, Total + Value).

print_total(Total) ->
    io:format("~n~-30...s~10.2..f~n", ["Total", Total/100]).