  Copyright ( c ) 2009
    <  >
    <  >
%% 
%% Permission is hereby granted, free of charge, to any person
%% obtaining a copy of this software and associated documentation
  files ( the " Software " ) , to deal in the Software without
%% restriction, including without limitation the rights to use,
%% copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software , and to permit persons to whom the
%% Software is furnished to do so, subject to the following
%% conditions:
%% 
%% The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software .
%% 
  THE SOFTWARE IS PROVIDED " AS IS " , WITHOUT WARRANTY OF ANY KIND ,
%% EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
%% OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
%% NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
%% HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
%% WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
%% FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
%% OTHER DEALINGS IN THE SOFTWARE.
-module(emysql_statements).
-behaviour(gen_server).

-export([start_link/0, init/1, handle_call/3, handle_cast/2]).
-export([handle_info/2, terminate/2, code_change/3]).

-export([all/0, fetch/1, add/2, version/2, prepare/3, remove/1]).

-include("emysql.hrl").

-record(state, {statements=gb_trees:empty(), prepared=gb_trees:empty()}).

%%====================================================================
%% API
%%====================================================================
%%--------------------------------------------------------------------
  Function : start_link ( ) - > { ok , Pid } | ignore | { error , Error }
%% Description: Starts the server
%%--------------------------------------------------------------------
start_link() ->
	gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
	
all() ->
	State = gen_server:call(?MODULE, all, infinity),
	[{statements, [StmtName || {StmtName, _} <- gb_trees:to_list(State#state.statements)]},
	 {prepared, gb_trees:to_list(State#state.prepared)}].
	
fetch(StmtName) ->
	gen_server:call(?MODULE, {fetch, StmtName}, infinity).
	
add(StmtName, Statement) ->
	gen_server:call(?MODULE, {add, StmtName, Statement}, infinity).
	
version(ConnId, StmtName) ->
	gen_server:call(?MODULE, {version, ConnId, StmtName}, infinity).
	
prepare(ConnId, StmtName, Version) ->
	gen_server:call(?MODULE, {prepare, ConnId, StmtName, Version}, infinity).

remove(ConnId) ->
	gen_server:call(?MODULE, {remove, ConnId}, infinity).	
%%====================================================================
%% gen_server callbacks
%%====================================================================

%%--------------------------------------------------------------------
%% Function: init(Args) -> {ok, State} |
                          { ok , State , Timeout } |
%%                         ignore               |
%%                         {stop, Reason}
%% Description: Initiates the server
%%--------------------------------------------------------------------
init([]) ->
	{ok, #state{}}.

%%--------------------------------------------------------------------
  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(all, _From, State) ->
	{reply, State, State};
	
handle_call({fetch, StmtName}, _From, State) ->
	{reply, lookup(StmtName, State#state.statements), State};

handle_call({add, StmtName, Statement}, _From, State) ->
	State1 =
		case lookup(StmtName, State#state.statements) of
			undefined ->
				State#state{
					statements = gb_trees:enter(StmtName, {1, Statement}, State#state.statements)
				};
			{_, Statement} ->
				State;
			{Version, _} ->
				State#state{
					statements = gb_trees:enter(StmtName, {Version+1, Statement}, State#state.statements)
				}
		end,
	{reply, ok, State1};

handle_call({version, ConnId, StmtName}, _From, State) ->
	Version = 
		case lookup(ConnId, State#state.prepared) of
			undefined -> undefined;
			Versions -> lookup(StmtName, Versions)
		end,
	{reply, Version, State};
	
handle_call({prepare, ConnId, StmtName, Version}, _From, State) ->
	Versions = 
		case lookup(ConnId, State#state.prepared) of
			undefined ->
				gb_trees:enter(StmtName, Version, gb_trees:empty());
			Versions1 ->
				gb_trees:enter(StmtName, Version, Versions1)
		end,
	Prepared = gb_trees:enter(ConnId, Versions, State#state.prepared),
	{reply, ok, State#state{prepared=Prepared}};

handle_call({remove, ConnId}, _From, State) ->
	StmtNames = 
		case lookup(ConnId, State#state.prepared) of
			undefined -> [];
			Versions -> gb_trees:keys(Versions)
		end,
	Prepared = gb_trees:delete_any(ConnId, State#state.prepared),
	{reply, StmtNames, State#state{prepared=Prepared}};
			
handle_call(_, _From, State) -> {reply, {error, invalid_call}, State}.

%%--------------------------------------------------------------------
  Function : handle_cast(Msg , State ) - > { noreply , State } |
                                       { noreply , State , Timeout } |
%%                                      {stop, Reason, State}
%% Description: Handling cast messages
%%--------------------------------------------------------------------
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
%%--------------------------------------------------------------------
lookup(Key, Tree) ->
	case gb_trees:lookup(Key, Tree) of
		{value, Val} -> Val;
		none -> undefined
	end.
 
 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation
 restriction, including without limitation the rights to use,
 copy, modify, merge, publish, distribute, sublicense, and/or sell
 Software is furnished to do so, subject to the following
 conditions:
 
 The above copyright notice and this permission notice shall be
 
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 OTHER DEALINGS IN THE SOFTWARE.
====================================================================
 API
====================================================================
--------------------------------------------------------------------
 Description: Starts the server
--------------------------------------------------------------------
====================================================================
 gen_server callbacks
====================================================================
--------------------------------------------------------------------
 Function: init(Args) -> {ok, State} |
                         ignore               |
                         {stop, Reason}
 Description: Initiates the server
--------------------------------------------------------------------
--------------------------------------------------------------------
 % handle_call(Request , From , State ) - > { reply , Reply , State } |
                                      {stop, Reason, Reply, State} |
                                      {stop, Reason, State}
 Description: Handling call messages
--------------------------------------------------------------------
--------------------------------------------------------------------
                                      {stop, Reason, State}
 Description: Handling cast messages
--------------------------------------------------------------------
--------------------------------------------------------------------
                                       {stop, Reason, State}
 Description: Handling all non call/cast messages
--------------------------------------------------------------------
--------------------------------------------------------------------
 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.
--------------------------------------------------------------------
--------------------------------------------------------------------
 Description: Convert process state when code is changed
--------------------------------------------------------------------
--------------------------------------------------------------------
--------------------------------------------------------------------
  Copyright ( c ) 2009
    <  >
    <  >
  files ( the " Software " ) , to deal in the Software without
  copies of the Software , and to permit persons to whom the
  included in all copies or substantial portions of the Software .
  THE SOFTWARE IS PROVIDED " AS IS " , WITHOUT WARRANTY OF ANY KIND ,
-module(emysql_statements).
-behaviour(gen_server).

-export([start_link/0, init/1, handle_call/3, handle_cast/2]).
-export([handle_info/2, terminate/2, code_change/3]).

-export([all/0, fetch/1, add/2, version/2, prepare/3, remove/1]).

-include("emysql.hrl").

-record(state, {statements=gb_trees:empty(), prepared=gb_trees:empty()}).

  Function : start_link ( ) - > { ok , Pid } | ignore | { error , Error }
start_link() ->
	gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
	
all() ->
	State = gen_server:call(?MODULE, all, infinity),
	[{statements, [StmtName || {StmtName, _} <- gb_trees:to_list(State#state.statements)]},
	 {prepared, gb_trees:to_list(State#state.prepared)}].
	
fetch(StmtName) ->
	gen_server:call(?MODULE, {fetch, StmtName}, infinity).
	
add(StmtName, Statement) ->
	gen_server:call(?MODULE, {add, StmtName, Statement}, infinity).
	
version(ConnId, StmtName) ->
	gen_server:call(?MODULE, {version, ConnId, StmtName}, infinity).
	
prepare(ConnId, StmtName, Version) ->
	gen_server:call(?MODULE, {prepare, ConnId, StmtName, Version}, infinity).

remove(ConnId) ->
	gen_server:call(?MODULE, {remove, ConnId}, infinity).	

                          { ok , State , Timeout } |
init([]) ->
	{ok, #state{}}.

                                       { reply , Reply , State , Timeout } |
                                       { noreply , State } |
                                       { noreply , State , Timeout } |
handle_call(all, _From, State) ->
	{reply, State, State};
	
handle_call({fetch, StmtName}, _From, State) ->
	{reply, lookup(StmtName, State#state.statements), State};

handle_call({add, StmtName, Statement}, _From, State) ->
	State1 =
		case lookup(StmtName, State#state.statements) of
			undefined ->
				State#state{
					statements = gb_trees:enter(StmtName, {1, Statement}, State#state.statements)
				};
			{_, Statement} ->
				State;
			{Version, _} ->
				State#state{
					statements = gb_trees:enter(StmtName, {Version+1, Statement}, State#state.statements)
				}
		end,
	{reply, ok, State1};

handle_call({version, ConnId, StmtName}, _From, State) ->
	Version = 
		case lookup(ConnId, State#state.prepared) of
			undefined -> undefined;
			Versions -> lookup(StmtName, Versions)
		end,
	{reply, Version, State};
	
handle_call({prepare, ConnId, StmtName, Version}, _From, State) ->
	Versions = 
		case lookup(ConnId, State#state.prepared) of
			undefined ->
				gb_trees:enter(StmtName, Version, gb_trees:empty());
			Versions1 ->
				gb_trees:enter(StmtName, Version, Versions1)
		end,
	Prepared = gb_trees:enter(ConnId, Versions, State#state.prepared),
	{reply, ok, State#state{prepared=Prepared}};

handle_call({remove, ConnId}, _From, State) ->
	StmtNames = 
		case lookup(ConnId, State#state.prepared) of
			undefined -> [];
			Versions -> gb_trees:keys(Versions)
		end,
	Prepared = gb_trees:delete_any(ConnId, State#state.prepared),
	{reply, StmtNames, State#state{prepared=Prepared}};
			
handle_call(_, _From, State) -> {reply, {error, invalid_call}, State}.

  Function : handle_cast(Msg , State ) - > { noreply , State } |
                                       { noreply , State , Timeout } |
handle_cast(_Msg, State) ->
    {noreply, State}.

  Function : handle_info(Info , State ) - > { noreply , State } |
                                        { noreply , State , Timeout } |
handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

  Func : code_change(OldVsn , State , Extra ) - > { ok , NewState }
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

  Internal functions
lookup(Key, Tree) ->
	case gb_trees:lookup(Key, Tree) of
		{value, Val} -> Val;
		none -> undefined
	end.