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|
-module(client).
-export([register/2, register/3, login/3, list/0, handle/2, getVotes/0, vote/2, devote/2]).
checkLogin(Value) ->
%% check if user meets the requirements to be logged in or not by
%% logging in to the registered processes and checking if the cli
%% process is registered
LoggedIn = lists:member(cli, registered()),
if LoggedIn == Value ->
true;
true -> throw({error, login_state})
end.
buildNode(Server) ->
list_to_atom("distributed_music_system_main_node@" ++ Server).
rpc(Server, Function, Params) ->
rpc:call(buildNode(Server), client, Function, Params).
wait_for_reply() ->
receive
{_, Msg} ->
Msg;
Why -> Why
after 3000 ->
{error, timeout}
end.
register(Name, Password) ->
try checkLogin(true) of
_ ->
server:rpc(cli, {register, Name, Password})
catch
{error, login_state} ->
{error, not_logged_in}
end.
%register the client with the server
register(Server, Name, Password) ->
try checkLogin(false) of
_ ->
rpc(Server, register, [self(), {Name, Password}])
catch
{error, login_state} ->
{error, logged_in}
end,
wait_for_reply().
%login to the server
login(Server, Name, Password) ->
code:purge(server),
code:load_abs("../common/server"),
try checkLogin(false) of
_ ->
rpc(Server, login, [self(), {node(), Name, Password}]),
receive
{ok, {ok, {logged_in, Pid}}} ->
erlang:register(cli, Pid),
{ok, logged_in};
{_, Msg} ->
Msg;
Msg ->
Msg
after 3000 ->
{error, timeout}
end
catch
{error, login_state} ->
{error, logged_in}
end.
%request the playlist from the server
list() ->
try checkLogin(true) of
_ ->
server:rpc(cli, list)
catch
{error, login_state} ->
{error, not_logged_in}
end.
send_to_server(Cmd, Server) ->
Server ! Cmd,
receive
{ok, Msg} ->
{Msg, Server};
Msg ->
{Msg, Server}
end.
handle(list, Server) ->
send_to_server(list, Server);
handle(get_votes, Server) ->
send_to_server(get_votes, Server);
handle({vote, Artist, Title}, Server) ->
send_to_server({vote, Artist, Title}, Server);
handle({devote, Artist, Title}, Server) ->
send_to_server({devote, Artist, Title}, Server);
handle({register, Name, Password}, Server) ->
send_to_server({register, Name, Password}, Server);
handle({change_state, NewState}, _) ->
{{ok}, NewState};
handle(Cmd, Server) ->
{{error, {unknown_command, Cmd}}, Server}.
try_logged_in_rpc(Rpc) ->
%% tries to execute an rpc for logged in user and returns error
%% message if user is not logged in
try checkLogin(true) of
_ ->
server:rpc(cli, Rpc)
catch
{error, login_state} ->
{error, not_logged_in}
end.
getVotes() ->
%% queries the server for the current votes this client possesses
try_logged_in_rpc(get_votes).
vote(Artist, Title) ->
%% positive vote, increments the votes for {Artist, Title} by one
try_logged_in_rpc({vote, Artist, Title}).
devote(Artist, Title) ->
%% negative vote, decrements the votes for {Artist, Title} by one
try_logged_in_rpc({devote, Artist, Title}).
|
