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|
-module(dispatcher).
-export([start/0, handle/2]).
checkUserExists([_|_]) ->
%% helper function to check if given array contains at least one element
false;
checkUserExists(_) ->
true.
start() ->
%% load server module from common directory,
%% used form server and client
code:purge(server),
code:load_abs("../common/server"),
%% initalize client database
cldb:init(),
%% spawn media backend in seperate process
try spawn(media, init, []) of
_ ->
io:format("Media-Backend started!~n")
catch
_: Why ->
io:format("Error starting media backend: ~w! Exiting.~n", [Why]),
exit(1)
end,
%% start server (registered as "dis", arriving messages will call
%% the handle function to get the result)
%% The state of the server is true if register is allowed (no user
%% exists) -> first created user is admin and after the first
%% registration only the admin can register other users
UserExists = checkUserExists(cldb:all()),
try server:start(dis, dispatcher, UserExists) of
true ->
io:format("Server started!~n"),
true
catch
_ ->
io:format("Error starting server! Exiting.~n"),
exit(1)
end.
handle({register, {User, Password}}, true) ->
%% first registration
{cldb:register(User, Password, admin), false};
handle({register, _}, false) ->
%% if state of the server is false, registration is not allowed,
%% because the admin user already exists
{{error, no_rights}, false};
handle({login, {Node, User, Password}}, State) ->
%% login user if password correct
case cldb:login(User, Password) of
{ok, UserRow} ->
case client:start(Node, UserRow) of
{ok, Pid} ->
{{ok, {logged_in, Pid}}, State};
Why ->
{{error, {unable_to_login, Why}}, State}
end;
{error, Why} ->
{{error, Why}, State};
_ ->
{{error, user_or_password_invalid}, State}
end;
handle({'EXIT', From, _}, State) ->
%% handle the exit messages from the client, so that the client
%% logs out if the connection between server and client breaks
cldb:logout(From),
State;
handle(Cmd, State) ->
%% standard command to find invalid commands and emit an error
{{error, {unknown_command, Cmd}}, State}.
|
