// Copyright 2023 LiveKit, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package signalling

import (
	"fmt"

	"github.com/livekit/protocol/livekit"
	"github.com/livekit/protocol/logger"
	"github.com/livekit/protocol/utils"
	"github.com/livekit/psrpc"

	"github.com/livekit/livekit-server/pkg/routing"
	"github.com/livekit/livekit-server/pkg/rtc/types"

	"google.golang.org/protobuf/proto"
)

var _ ParticipantSignaller = (*signallerAsync)(nil)

type SignallerAsyncParams struct {
	Logger            logger.Logger
	Participant       types.LocalParticipant
	OnHandshakeOpened func()
}

type signallerAsync struct {
	params SignallerAsyncParams

	*signallerAsyncBase
}

func NewSignallerAsync(params SignallerAsyncParams) ParticipantSignaller {
	return &signallerAsync{
		params: params,
		signallerAsyncBase: newSignallerAsyncBase(signallerAsyncBaseParams{
			Logger:            params.Logger,
			OnHandshakeOpened: params.OnHandshakeOpened,
		}),
	}
}

func (s *signallerAsync) WriteMessage(msg proto.Message) error {
	if msg == nil {
		return nil
	}

	getMessageType := func(msg proto.Message) string {
		messageType := "unknown"
		if typed, ok := msg.(*livekit.SignalResponse); ok {
			messageType = fmt.Sprintf("%T", typed.Message)
		}
		return messageType
	}

	if s.params.Participant.IsDisconnected() {
		s.params.Logger.Debugw(
			"could not send message to participant, participant disconnected",
			"messageType", getMessageType(msg),
		)
		return nil
	}

	// a signal connection opens with a join response, or with a reconnect response when
	// it is resumed or migrated in. The client reads that first message as the handshake,
	// so nothing may go out ahead of it.
	isHandshake := false
	isSdp := false
	if typed, ok := msg.(*livekit.SignalResponse); !ok {
		s.params.Logger.Warnw(
			"unknown message type", nil,
			"messageType", fmt.Sprintf("%T", msg),
		)
	} else {
		isHandshake = typed.GetJoin() != nil || typed.GetReconnect() != nil
		isSdp = typed.GetOffer() != nil || typed.GetAnswer() != nil
	}

	if !isHandshake && (!s.params.Participant.IsReady() || s.HandshakePending()) {
		logFunc := s.params.Logger.Debugw
		if isSdp {
			// a dropped SDP leaves the negotiation waiting for the peer until the
			// negotiation state machine recovers it, so make it visible
			logFunc = func(msg string, keysAndValues ...any) {
				s.params.Logger.Infow(msg, keysAndValues...)
			}
		}
		logFunc(
			"dropping message, connection has not opened yet",
			"messageType", getMessageType(msg),
		)
		return nil
	}

	sink := s.GetResponseSink()
	if sink == nil {
		s.params.Logger.Debugw(
			"could not send message to participant, no sink",
			"messageType", getMessageType(msg),
		)
		return nil
	}

	err := sink.WriteMessage(msg)
	if err != nil {
		if utils.ErrorIsOneOf(err, psrpc.Canceled, routing.ErrChannelClosed) {
			s.params.Logger.Debugw(
				"could not send message to participant",
				"error", err,
				"messageType", getMessageType(msg),
			)
			return nil
		} else {
			s.params.Logger.Warnw(
				"could not send message to participant", err,
				"messageType", getMessageType(msg),
			)
			return err
		}
	} else {
		if isHandshake {
			// the connection is open, hold nothing back any more
			s.OpenHandshake()
		}
		s.params.Logger.Debugw("sent signal response", "response", logger.Proto(msg))
	}
	return nil
}