-module(cavv_user).

-behavior(gen_server).

-define(SERVER(UserId), {via, gproc, {n, l, {?MODULE, UserId}}}).

start_link(UserId) ->
    gen_server:start_link(?SERVER(UserId), ?MODULE, [UserId], []).

change_email_address(UserId, EmailAddress) ->
    gen_server:call(?SERVER(AggregateId), {execute_command, #change_user_email_address{user_id=UserId, email_address=EmailAddress}}).

-module(cavv_user_sup).

-behaviour(supervisor).

-define(CHILD(ChildName, Type, Args), {ChildName, {ChildName, start_link, Args}, temporary, 5000, Type, [ChildName]}).

start_link() ->
    supervisor:start_link({local, ?SERVER}, ?MODULE, []).

start_child(UserId) ->
    supervisor:start_child(?SERVER, [UserId]).

init([]) ->
    RestartStrategy = {simple_one_for_one, 1, 5},

    Children = [?CHILD(cavv_user, worker, [])],

    {ok, { RestartStrategy, Children} }.

cavv_user_dispatch_sup
            |               |
 cavv_user_dispatcher       |
       (gen_server)         |
                            |
                            |
                      cavv_user_sup
                        |   |   |
                 cavv_user_1...cavv_user_N

-module(cavv_user_dispatcher).

dispatch_command(UserId, Fun) ->
    gen_server:call(?SERVER, {dispatch_command, {UserId, Fun}}).

handle_call({dispatch_command, {UserId, Fun}}, _From, State) ->
    cavv_user_sup:start_child(UserId),
    Fun(), %% How to pass: cavv_user:change_email_address(..,..)?
    {reply, ok, State};

-module(cavv_user_dispatcher).

change_user_email_address(UserId, EmailAddress) ->
    gen_server:call(?SERVER, {change_user_email_address, {UserId, EmailAddress}}).

handle_call({change_user_email_address, {UserId, EmailAddress}}, _From, State) ->
    cavv_user_sup:start_child(UserId),
    cavv_user:change_email_address(UserId, EmailAddress),
    {reply, ok, State};