added that only logged_in clients get vote points, added comments

4 files changed, 156 insertions, 48 deletions

diff --git a/server/cldb.erl b/server/cldb.erl
index d1daaa9..28815a6 100644
--- a/server/cldb.erl
+++ b/server/cldb.erl
@@ -1,8 +1,8 @@
 % The clientdatabase
 
 -module(cldb).
--export([init/0,all/0, ask/2, login/2, decVote/1, incVote/1, register/3, check_rights/1, give_votes/1]).
--record(user, {name, passwd, votes, rights}).
+-export([init/0, all/0, find/1, login/2, dec_vote/1, inc_vote/1, register/3, check_rights/1, update_votes/0, logout/1, set_client_pid/2]).
+-record(user, {name, passwd, votes, logged_in, pid, rights}).
 
 init() ->
     mnesia:create_schema([node()]),
@@ -10,44 +10,121 @@ init() ->
     mnesia:create_table(user, [{attributes, record_info(fields, user)}]),
     io:format("Userdb up and running \n").
 
-ask(User, Pwd) ->
+find(User) when is_list(User) ->
+    find(User, '_');
+find(User) ->
+    find(User#user.name, '_').
+
+find(User, Pwd) ->
     F = fun() ->
-        mnesia:match_object({user, User, Pwd, '_', '_'})
+		mnesia:match_object({user, User, Pwd, '_', '_', '_', '_'})
         end,
     mnesia:transaction(F).
 
+find_logged_in_user() ->
+    F = fun() ->
+		mnesia:match_object({user, '_', '_', '_', true, '_', '_'})
+        end,
+    case mnesia:transaction(F) of
+	{atomic, List} -> {ok, List};
+	_ -> {error}
+    end.
+
+find_user_by_pid(Pid) ->
+    F = fun() ->
+		mnesia:match_object({user, '_', '_', '_', '_', Pid, '_'})
+        end,
+    case mnesia:transaction(F) of
+	{atomic, List} -> {ok, List};
+	_ -> {error}
+    end.
+
 all() ->
-	F = fun() ->
-        mnesia:match_object({user, '_', '_', '_', '_'})
+    F = fun() ->
+		mnesia:match_object({user, '_', '_', '_', '_', '_', '_'})
         end,
-    {atomic, List} =  mnesia:transaction(F),
-	List.
-	
+    case mnesia:transaction(F) of
+	{atomic, List} -> {ok, List};
+	_ -> {error}
+    end.
+
+login(User, Pwd) when is_list(User) and is_list(Pwd) ->
+    case find(User, Pwd) of
+	{atomic, [UserRow|_]} ->
+	    NewUserRow = UserRow#user{logged_in = true},
+	    F = fun() ->
+			mnesia:write(NewUserRow)
+		end,
+	    case mnesia:transaction(F) of
+		{atomic, ok} ->
+		    {ok, NewUserRow};
+		{atomic, Why} ->
+		    {error, Why}
+	    end;
 
-login(User, Pwd) ->
-    case ask(User, Pwd) of
-	{atomic, [UserRow|_]} -> {ok, UserRow};
 	_-> {error}
+    end;
+
+login(_, _) ->
+    {error}.
+
+set_client_pid(User, Pid) ->
+    case find(User) of
+	{atomic, [UserRow|_]} ->
+	    NewUserRow = UserRow#user{pid = Pid},
+	    F = fun() ->
+			mnesia:write(NewUserRow)
+		end,
+	    case mnesia:transaction(F) of
+		{atomic, ok} ->
+		    {ok, pid_updated};
+		{atomic, Why} ->
+		    {error, Why}
+	    end;
+	_ ->
+	    {error, user_not_found}
     end.
 
-register(User, Pwd, Root) ->
-    case ask(User, '_') of
+logout(Pid) ->
+    case find_user_by_pid(Pid) of
+	{atomic, [UserRow|_]} ->
+	    F = fun() ->
+			New = UserRow#user{logged_in = false},
+			mnesia:write(New)
+		end,
+	    case mnesia:transaction(F) of
+		{atomic, ok} ->
+		    {ok, logged_out};
+		{atomic, Why} ->
+		    {error, Why}
+	    end;
+
+	_ ->
+	    {error, invalid_user}
+    end.
+
+register(User, Pwd, Root) when is_list(User) and is_list(Pwd) ->
+    case find(User) of
 	{atomic, []} ->
 	    F = fun() ->
-			mnesia:write(#user{name = User, passwd = Pwd, votes = 5, rights = Root})
+			mnesia:write(#user{name = User, passwd = Pwd, votes = 5, logged_in = false, pid = undef, rights = Root})
 		end,
 	    case mnesia:transaction(F) of
 		{atomic, ok} ->
+		    io:format("User created: ~s~n", [User]),
 		    {ok, user_created};
 		{atomic, Why} ->
 		    {error, Why}
 	    end;
 	_ ->
 	    {error, duplicated_user}
-    end.
+    end;
+
+register(_,_,_) ->
+    {error, invalid_username}.
 
-decVote(User) when is_list(User) ->
-    {atomic, [Head|_]} = ask(User, '_'),
+dec_vote(User) when is_list(User) ->
+    {atomic, [Head|_]} = find(User),
     if Head#user.votes > 0 ->
         F = fun() ->
                     Votes = Head#user.votes - 1,
@@ -58,12 +135,12 @@ decVote(User) when is_list(User) ->
         {ok};
         true -> {error}
     end;
-decVote(User) ->
-    decVote(User#user.name).
+dec_vote(User) ->
+    dec_vote(User#user.name).
 
-incVote(User) ->
+inc_vote(User) ->
     F = fun() ->
-                {atomic, [Head|_]} = ask(User, '_'),
+                {atomic, [Head|_]} = find(User),
                 Votes = Head#user.votes + 1,
                 New = Head#user{votes = Votes},
                 mnesia:write(New)
@@ -71,13 +148,18 @@ incVote(User) ->
     mnesia:transaction(F).
 
 check_rights(User) ->
-    {_, _, Rights} = ask(User, '_'),
-    Rights.
+    {atomic, [UserRow|_]} = find(User),
+    UserRow#user.rights.
 
-% after a song every client gets on more vote
-give_votes([Head|Rest]) -> 
-	User = Head#user.name,
-	incVote(User),
+update_votes() ->
+    %% after a song every logged_in client gets on more vote
+    case find_logged_in_user() of
+	{ok, List} ->
+	    give_votes(List);
+	_ -> error
+    end.
+
+give_votes([User|Rest]) ->
+	inc_vote(User#user.name),
 	give_votes(Rest);
 give_votes([]) -> ok.
-
diff --git a/server/client.erl b/server/client.erl
index 7cee336..421280b 100644
--- a/server/client.erl
+++ b/server/client.erl
@@ -2,11 +2,19 @@
 -export([start/2, loop/2, register/2, login/2]).
 
 start(Node, User) ->
+    %% start linked processes on client and server to get noticed if
+    %% client disconnects and properly handle the logged in status
     process_flag(trap_exit, true),
     Client = server:start_on_node(Node, client, undef),
     link(Client),
+    %% store the client pid in the client database to find the correct
+    %% user on the exit message from the client
+    cldb:set_client_pid(User, Client),
     Server = spawn_link(client, loop, [Client, User]),
 
+    %% update the server process_id in the state of the client process,
+    %% so that the client process know directly its counterpart on the
+    %% server
     case server:rpc(Client, {change_state, Server}) of
 	{ok} ->
 	    {ok, Client};
@@ -26,12 +34,12 @@ execute(Client, F) ->
     end.
 
 loop(Client, User) ->
-    %% mainloop for client modul in server
+    %% mainloop for client modul in server, handle the commands form
+    %% the logged_in client
     receive
 	{register, Name, Password} ->
-	    case User of
-		{user, _, _, _, admin} ->
-		    execute(Client, fun() -> cldb:register(Name, Password, none) end);
+	    case cldb:check_rights(User) of
+		admin -> execute(Client, fun() -> cldb:register(Name, Password, none) end);
 		_ -> Client ! {error, {no_rights}}
 	    end;
 
@@ -42,21 +50,30 @@ loop(Client, User) ->
 	    execute(Client, fun() -> media:getVotes(Client) end);
 
 	{vote, Artist, Title} ->
-	    case cldb:decVote(User) of
+	    %% only allow vote if user has vote to give away
+	    case cldb:dec_vote(User) of
 	        {ok} -> execute(Client, fun() -> media:vote(Artist, Title) end);
 	        _ -> Client ! {error, no_votes_available}
-	    end; 
+	    end;
 
 	{devote, Artist, Title} ->
-	    execute(Client, fun() -> media:devote(Artist, Title) end);
+	    %% only allow devote if user has vote to give away
+	    case cldb:dec_vote(User) of
+	        {ok} -> execute(Client, fun() -> media:devote(Artist, Title) end);
+	        _ -> Client ! {error, no_votes_available}
+	    end;
 
 	Cmd ->
+	    %% fallback for error messages
 	    Client ! {error, {unknown_command, Cmd}}
     end,
     loop(Client, User).
 
 register(Client, {Name, Password}) ->
+    %% forward the register messages to the dispatcher (if user is not
+    %% logged in)
     dis ! {Client, {register, {Name, Password}}}.
 
 login(Client, {Node, Name, Password}) ->
+    %% forward the login messages to the dispatcher
     dis ! {Client, {login, {Node, Name, Password}}}.
diff --git a/server/dispatcher.erl b/server/dispatcher.erl
index 3806ef7..27c2d4c 100644
--- a/server/dispatcher.erl
+++ b/server/dispatcher.erl
@@ -1,7 +1,8 @@
 -module(dispatcher).
--export([start/0, handle/2, checkUserExists/1]).
+-export([start/0, handle/2]).
 
 checkUserExists([_|_]) ->
+    %% helper function to check if given array contains at least one element
     false;
 checkUserExists(_) ->
     true.
@@ -12,6 +13,7 @@ start() ->
     code:purge(server),
     code:load_abs("../common/server"),
 
+    %% initalize database
     cldb:init(),
 
     %% spawn media backend in seperat process
@@ -24,13 +26,15 @@ start() ->
 	    exit(1)
     end,
 
-    %% start server (registered as dis)
-    %% server-module will call handle if message arrives and init to
-    %% initialize the status
-    UserExists = checkUserExists(cldb:ask('_', '_')),
+    %% 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 admit and after the first
+    %% registration only the admit could register the other user
+    UserExists = checkUserExists(cldb:all()),
     try server:start(dis, dispatcher, UserExists) of
 	true ->
-	    io:format("Server started: ~w!~n", [UserExists]),
+	    io:format("Server started!~n"),
 	    true
     catch
 	_ ->
@@ -39,14 +43,16 @@ start() ->
     end.
 
 handle({register, {User, Password}}, true) ->
-    io:format("User created: ~s~n", [User]),
-    cldb:register(User, Password, admin),
-    {{ok, user_created}, false};
+    %% first registration
+    {cldb:register(User, Password, admin), false};
 
 handle({register, _}, false) ->
+    %% if state of the server is false, no registration allowed,
+    %% because the admin user allready exists
     {{error, no_rights}, false};
 
 handle({login, {Node, User, Password}}, State) ->
+    %% login user if Password match
     case cldb:login(User, Password) of
 	{ok, UserRow} ->
 	    case client:start(Node, UserRow) of
@@ -59,9 +65,12 @@ handle({login, {Node, User, Password}}, State) ->
 	    {{error, {user_or_password_invalid, Why}}, State}
     end;
 
-handle({'EXIT', _, _}, State) ->
+handle({'EXIT', From, _}, State) ->
+    %% handle the exit messages from the client, so that the client
+    %% logouts if the connection between server and client breaks
+    cldb:logout(From),
     State;
 
 handle(Cmd, State) ->
-    %% standard command, to find transmission errors
+    %% standard command, to find invalid commands and emit an error
     {{error, {unknown_command, Cmd}}, State}.
diff --git a/server/media.erl b/server/media.erl
index 5148edc..14aa53e 100644
--- a/server/media.erl
+++ b/server/media.erl
@@ -112,7 +112,7 @@ play(Artist, Title) ->
     
     io:format("playing: ~s, Artist: ~s~n", [Title, Artist]),
     receive
-		{Port, {exit_status, 0}} -> cldb:give_votes(cldb:all()), start_playing();
+		{Port, {exit_status, 0}} -> cldb:update_votes(), start_playing();
 		{Port, {exit_status, S}} -> throw({commandfailed, S})
 end.