%%%-------------------------------------------------------------------
%%% @doc
%%% QUIC connection callback module for Macula.
%%% Implements quicer_connection behavior to handle connection lifecycle.
%%% @end
%%%-------------------------------------------------------------------
-module(macula_quic_conn_callback).

-behaviour(quicer_connection).

%% Callback init
-export([init/1]).

%% Connection Callbacks
-export([
    new_conn/3,
    connected/3,
    transport_shutdown/3,
    shutdown/3,
    closed/3,
    local_address_changed/3,
    peer_address_changed/3,
    streams_available/3,
    peer_needs_streams/3,
    resumed/3,
    nst_received/3,
    new_stream/3
]).

-export([handle_info/2]).

%%%===================================================================
%%% Callback Implementation
%%%===================================================================

%% @doc Initialize connection callback state
init(ConnOpts) when is_map(ConnOpts) ->
    io:format("[ConnCallback] Initializing with opts: ~p~n", [maps:keys(ConnOpts)]),
    {ok, ConnOpts};
init(ConnOpts) when is_list(ConnOpts) ->
    init(maps:from_list(ConnOpts)).

%% @doc Handle new connection
%% With quicer_server, streams are delivered automatically via new_stream/3
new_conn(Conn, #{version := Vsn}, #{gateway_pid := GatewayPid} = State) ->
    io:format("[ConnCallback] New connection: ~p (QUIC v~p)~n", [Conn, Vsn]),
    io:format("[ConnCallback] Gateway PID: ~p~n", [GatewayPid]),

    %% quicer_server will automatically deliver streams via new_stream/3 callback
    %% No need to spawn stream acceptor - quicer_server handles it
    io:format("[ConnCallback] Using quicer_server automatic stream delivery~n"),

    %% Store connection and gateway_pid in state
    {ok, State#{
        conn => Conn,
        gateway_pid => GatewayPid
    }};
new_conn(Conn, ConnProps, State) ->
    %% Fallback if gateway_pid not provided
    io:format("[ConnCallback] New connection without gateway_pid: ~p~n", [Conn]),
    new_conn(Conn, ConnProps, State#{gateway_pid => whereis(macula_gateway)}).

%% @doc Handle connection established
connected(_Conn, _Flags, State) ->
    io:format("[ConnCallback] Connection established~n"),
    {ok, State}.

%% @doc Handle transport shutdown
transport_shutdown(Conn, #{error := Error, status := Status}, State) ->
    io:format("[ConnCallback] Transport shutdown: Conn=~p, Error=~p, Status=~p~n",
              [Conn, Error, Status]),
    {ok, State}.

%% @doc Handle connection shutdown
shutdown(Conn, Reason, State) ->
    io:format("[ConnCallback] Connection shutdown: Conn=~p, Reason=~p~n", [Conn, Reason]),
    {ok, State}.

%% @doc Handle connection closed
closed(_Conn, _Flags, State) ->
    io:format("[ConnCallback] Connection closed~n"),
    {stop, normal, State}.

%% @doc Handle local address changed
local_address_changed(_Conn, _NewAddr, State) ->
    {ok, State}.

%% @doc Handle peer address changed
peer_address_changed(_Conn, _NewAddr, State) ->
    {ok, State}.

%% @doc Handle streams available
streams_available(_Conn, #{bidi_streams := Bidi, unidi_streams := Unidi}, State) ->
    io:format("[ConnCallback] Streams available: Bidi=~p, Unidi=~p~n", [Bidi, Unidi]),
    {ok, State}.

%% @doc Handle peer needs streams
peer_needs_streams(_Conn, _Undefined, State) ->
    {ok, State}.

%% @doc Handle connection resumed
resumed(_Conn, _Data, State) ->
    {ok, State}.

%% @doc Handle NST received (not used for server)
nst_received(_Conn, _Data, State) ->
    {stop, no_nst_for_server, State}.

%% @doc Handle new stream
%% With quicer_server, ALL streams are delivered here (not just orphans)
%% Forward them to the gateway for processing
new_stream(Stream, Props, #{gateway_pid := GatewayPid} = State) ->
    io:format("[ConnCallback] ========================================~n"),
    io:format("[ConnCallback] NEW STREAM RECEIVED!~n"),
    io:format("[ConnCallback] Stream: ~p~n", [Stream]),
    io:format("[ConnCallback] Props: ~p~n", [Props]),
    io:format("[ConnCallback] ========================================~n"),

    %% Forward stream to gateway
    io:format("[ConnCallback] Forwarding stream to gateway: ~p~n", [GatewayPid]),
    GatewayPid ! {quic_stream, Stream, Props},

    {ok, State};
new_stream(Stream, Props, State) ->
    %% Fallback if no gateway_pid in state
    io:format("[ConnCallback] WARNING: Stream received but no gateway_pid in state~n"),
    io:format("[ConnCallback] Stream: ~p, Props: ~p~n", [Stream, Props]),
    {ok, State}.

%% @doc Handle other messages
handle_info(Info, State) ->
    io:format("[ConnCallback] Unhandled info: ~p~n", [Info]),
    {ok, State}.