%%%-------------------------------------------------------------------
%%% Author: Niclas Axelsson <niclas@burbas.se>
%%% Created : 10 Aug 2024 by Niclas Axelsson <niclas@burbas.se>
%%%-------------------------------------------------------------------
-module(nova_plugin_manager).
-moduledoc "Main manager for handling plugins".
-behaviour(gen_server).
%% API
-export([
start_link/0,
add_plugin/1,
add_plugin/3,
get_state/1,
set_state/2
]).
%% gen_server callbacks
-export([
init/1,
handle_call/3,
handle_cast/2,
handle_info/2,
terminate/2,
code_change/3
]).
-include_lib("kernel/include/logger.hrl").
-define(TABLE, '__nova_plugins__').
-define(SERVER, ?MODULE).
-record(state, {}).
-record(plugin, {
module :: atom(),
name :: binary(),
version :: binary(),
state :: nova:state()
}).
%%%===================================================================
%%% API
%%%===================================================================
%%--------------------------------------------------------------------
-doc "Starts the server".
-spec start_link() -> {ok, Pid :: pid()} |
{error, Error :: {already_started, pid()}} |
{error, Error :: term()} |
ignore.
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%%--------------------------------------------------------------------
-doc """
Adds a plugin to the manager. The plugin module must implement the plugin_info/0 function returning #\{title := Title, version := Version\}. Optionally it can implement init/0 returning the initial state for the plugin, and stop/0 for cleaning up when the manager terminates.
""".
-spec add_plugin({Class :: atom(), Module :: atom(), Opts :: map()} |
Module :: atom() | Callback :: function()) ->
ok | {error, Reason :: term()}.
add_plugin({_Class, Module, _Opts}) ->
add_plugin(Module);
add_plugin(Module) when is_atom(Module) ->
#{title := Title, version := Version} = case Module:plugin_info() of
{Title0, Version0, _, _, _} -> #{title => Title0, version => Version0};
PluginInfo -> PluginInfo
end,
add_plugin(Module, Title, Version);
add_plugin(Callback) when is_function(Callback) ->
Info = erlang:fun_info(Callback),
Module = proplists:get_value(module, Info),
add_plugin(Module).
-spec add_plugin(Module :: atom(), Name :: binary(), Version :: binary()) ->
ok | {error, Reason :: term()}.
add_plugin(Module, Name, Version) ->
case ets:lookup(?TABLE, Module) of
[#plugin{}] ->
?LOG_DEBUG(<<"Plugin ~p already initialized.">>, [Module]),
ok;
[] ->
gen_server:cast(?SERVER, {add_plugin, Module, Name, Version})
end.
%%--------------------------------------------------------------------
-doc "Gets the state of a plugin. The plugin can be specified either as a module or as a callback function. The callback function is used to extract the module name in order to retrieve the state.".
-spec get_state(Module :: atom() | Callback :: function()) ->
{ok, State :: nova:state()} | {error, not_found}.
get_state(Module) when is_atom(Module) ->
case ets:lookup(?TABLE, Module) of
[#plugin{state = State}] ->
{ok, State};
_ ->
?LOG_DEBUG(<<"Plugin ~p not found. get_state/1 failed.">>, [Module]),
{error, not_found}
end;
get_state(Callback) when is_function(Callback) ->
Info = erlang:fun_info(Callback),
Module = proplists:get_value(module, Info),
get_state(Module).
%%--------------------------------------------------------------------
-doc "Sets the state of a plugin. The plugin can be specified either as a module or as a callback function. The callback function is used to extract the module name in order to set the state.".
-spec set_state(Module :: atom() | Callback :: function(),
NewState :: term()) ->
ok | {error, not_found}.
set_state(Module, NewState) when is_atom(Module) ->
case ets:lookup(?TABLE, Module) of
[#plugin{} = P] ->
gen_server:call(?SERVER, {set_state, Module, P, NewState});
_ ->
?LOG_DEBUG(<<"Plugin ~p not found. set_state/2 failed.">>, [Module]),
{error, not_found}
end;
set_state(Callback, NewState) when is_function(Callback) ->
Info = erlang:fun_info(Callback),
Module = proplists:get_value(module, Info),
set_state(Module, NewState).
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
%%--------------------------------------------------------------------
%% Initializes the server
-doc false.
-spec init(Args :: term()) -> {ok, State :: term()} |
{ok, State :: term(), Timeout :: timeout()} |
{ok, State :: term(), hibernate} |
{stop, Reason :: term()} |
ignore.
init([]) ->
process_flag(trap_exit, true),
ets:new(?TABLE, [named_table, set, protected, {keypos, #plugin.module}]),
Plugins = nova_router:plugins(),
[ add_plugin(Callback) || Callback <- Plugins ],
{ok, #state{}}.
%%--------------------------------------------------------------------
%% Handling call messages
-doc false.
-spec handle_call(Request :: term(), From :: {pid(), term()}, State :: term()) ->
{reply, Reply :: term(), NewState :: term()} |
{reply, Reply :: term(), NewState :: term(), Timeout :: timeout()} |
{reply, Reply :: term(), NewState :: term(), hibernate} |
{noreply, NewState :: term()} |
{noreply, NewState :: term(), Timeout :: timeout()} |
{noreply, NewState :: term(), hibernate} |
{stop, Reason :: term(), Reply :: term(), NewState :: term()} |
{stop, Reason :: term(), NewState :: term()}.
handle_call({set_state, Module, P, NewState}, _From, State) ->
?LOG_DEBUG(<<"Set state for plugin ~p; NewState: ~p">>, [Module, NewState]),
ets:insert(?TABLE, P#plugin{state = NewState}),
{reply, ok, State};
handle_call(_Request, _From, State) ->
Reply = ok,
{reply, Reply, State}.
%%--------------------------------------------------------------------
%% Handling cast messages
-doc false.
-spec handle_cast(Request :: term(), State :: term()) ->
{noreply, NewState :: term()} |
{noreply, NewState :: term(), Timeout :: timeout()} |
{noreply, NewState :: term(), hibernate} |
{stop, Reason :: term(), NewState :: term()}.
handle_cast({add_plugin, Module, Name, Version}, State) ->
PluginState =
case erlang:function_exported(Module, init, 0) of
true ->
?LOG_INFO(<<"Initializing plugin ~p">>, [Module]),
Module:init();
_ ->
?LOG_DEBUG(<<"Plugin ~p has no init/0 function. Defaulting to empty map #{}">>, [Module]),
#{}
end,
ets:insert(?TABLE, #plugin{module = Module, name = Name, version = Version, state = PluginState}),
{noreply, State};
handle_cast(_Request, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Handling all non call/cast messages
-doc false.
-spec handle_info(Info :: timeout() | term(), State :: term()) ->
{noreply, NewState :: term()} |
{noreply, NewState :: term(), Timeout :: timeout()} |
{noreply, NewState :: term(), hibernate} |
{stop, Reason :: normal | term(), NewState :: term()}.
handle_info(_Info, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% 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.
-doc false.
-spec terminate(Reason :: normal | shutdown | {shutdown, term()} | term(),
State :: term()) -> any().
terminate(_Reason, _State) ->
%% Stop all plugins and clean state
Plugins = ets:tab2list(?TABLE),
[ Plugin:stop() || #plugin{module = Plugin} <- Plugins,
erlang:function_exported(Plugin, stop, 0) ],
ets:delete(?TABLE),
ok.
%%--------------------------------------------------------------------
%% Convert process state when code is changed
-doc false.
-spec code_change(OldVsn :: term() | {down, term()},
State :: term(),
Extra :: term()) -> {ok, NewState :: term()} |
{error, Reason :: term()}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================