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%%%-------------------------------------------------------------------
%%% File : eb_server.erl
%%% Author : Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
%%% Editr : Charles Feduke
%%% Description : The ErlyBank account server.
%%%
%%% Created : 5 Sep 2008 by Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
%%% Modified: 16 Jun 2012
%%%-------------------------------------------------------------------
-module(eb_server).
-behaviour(gen_server).
%% API
-export([start_link/0,
create_account/2,
destroy_account/1,
deposit/2,
withdraw/2,
authorize/2]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-record(state, {}).
-define(SERVER, ?MODULE).
%%====================================================================
%% API
%%====================================================================
%%--------------------------------------------------------------------
%% Function: start_link() -> {ok,Pid} | ignore | {error,Error}
%% Description: Starts the server
%%--------------------------------------------------------------------
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%%====================================================================
%% gen_server callbacks
%%====================================================================
%%--------------------------------------------------------------------
%% Function: init(Args) -> {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%% Description: Initiates the server
%%--------------------------------------------------------------------
init(_Args) ->
{ok, dict:new()}.
%%--------------------------------------------------------------------
%% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} |
%% {stop, Reason, State}
%% Description: Handling call messages
%%--------------------------------------------------------------------
handle_call({authorize, Name, Pin}, _From, State) ->
case dict:find(Name, State) of
{ok, {{pin, Pin}, _}} ->
{reply, ok, State};
{ok, _} ->
{reply, {error, invalid_pin}, State};
error ->
{reply, {error, account_does_not_exist}, State}
end;
handle_call({deposit, Name, Amount}, _From, State) ->
case dict:find(Name, State) of
{ok, {Pin, {balance, Value}}} ->
NewBalance = Value + Amount,
Response = {ok, NewBalance},
NewState = dict:store(Name, {Pin, {balance, NewBalance}}, State),
{reply, Response, NewState};
error ->
{reply, {error, account_does_not_exist}, State}
end;
handle_call({withdraw, Name, Amount}, _From, State) ->
case dict:find(Name, State) of
{ok, {_, {balance, Value}}} when Value < Amount ->
{reply, {error, not_enough_funds}, State};
{ok, {Pin, {balance, Value}}} ->
NewBalance = Value - Amount,
Response = {ok, NewBalance},
NewState = dict:store(Name, {Pin, {balance, NewBalance}}, State),
{reply, Response, NewState};
error ->
{reply, {error, account_does_not_exist}, State}
end;
handle_call(_Request, _From, State) ->
Reply = ok,
{reply, Reply, State}.
%%--------------------------------------------------------------------
%% Function: handle_cast(Msg, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% Description: Handling cast messages
%%--------------------------------------------------------------------
handle_cast({create, Name, Pin}, State) ->
{noreply, dict:store(Name, {{pin, Pin}, {balance, 0}}, State)};
handle_cast({destroy, Name}, State) ->
{noreply, dict:erase(Name, State)};
handle_cast(_Msg, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: handle_info(Info, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% Description: Handling all non call/cast messages
%%--------------------------------------------------------------------
handle_info(_Info, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: terminate(Reason, State) -> void()
%% Description: This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any necessary
%% cleaning up. When it returns, the gen_server terminates with Reason.
%% The return value is ignored.
%%--------------------------------------------------------------------
terminate(_Reason, _State) ->
ok.
%%--------------------------------------------------------------------
%% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
%% Description: Convert process state when code is changed
%%--------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
create_account(Name, Pin) ->
gen_server:cast(?SERVER, {create, Name, Pin}).
authorize(Name, Pin) ->
gen_server:call(?SERVER, {authorize, Name, Pin}).
deposit(Name, Amount) ->
gen_server:call(?SERVER, {deposit, Name, Amount}).
withdraw(Name, Amount) ->
gen_server:call(?SERVER, {withdraw, Name, Amount}).
destroy_account(Name) ->
gen_server:cast(?SERVER, {destroy, Name}).
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