// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package adapters

import (
	"fmt"
	"sync"

	"github.com/ethereum/go-ethereum/logger/glog"
	"github.com/ethereum/go-ethereum/p2p"
	"github.com/ethereum/go-ethereum/p2p/discover"
)

func newPeer(m Messenger) *Peer {
	return &Peer{
		Messenger: m,
		Errc:   make(chan error, 1),
		Flushc: make(chan bool),
	}
}

type Peer struct {
	//RW     p2p.MsgReadWriter
	Messenger
	Errc   chan error
	Flushc chan bool
}

// Network interface to retrieve protocol runner to launch upon peer
// connection
type Network interface {
	GetNodeAdapter(id *NodeId) NodeAdapter
	Reporter
}

// SimNode is the network adapter that
type SimNode struct {
	lock      sync.RWMutex
	Id        *NodeId
	network   Network
	messenger func(p2p.MsgReadWriter) Messenger
	peerMap   map[discover.NodeID]int
	peers     []*Peer
	Run       ProtoCall
}

func (self *SimNode) Messenger(rw p2p.MsgReadWriter) Messenger {
	return self.messenger(rw)
}

func NewSimNode(id *NodeId, n Network, m func(p2p.MsgReadWriter) Messenger) *SimNode {
	return &SimNode{
		Id:        id,
		network:   n,
		messenger: m,
		peerMap:   make(map[discover.NodeID]int),
	}
}

func (self *SimNode) LocalAddr() []byte {
	return self.Id.Bytes()
}

func (self *SimNode) ParseAddr(p []byte, s string) ([]byte, error) {
	return p, nil
}

func (self *SimNode) GetPeer(id *NodeId) *Peer {
	self.lock.Lock()
	defer self.lock.Unlock()
	return self.getPeer(id)
}

func (self *SimNode) getPeer(id *NodeId) *Peer {
	i, found := self.peerMap[id.NodeID]
	if !found {
		return nil
	}
	return self.peers[i]
}

func (self *SimNode) SetPeer(id *NodeId, rw p2p.MsgReadWriter) {
	self.lock.Lock()
	defer self.lock.Unlock()
	self.setPeer(id, self.Messenger(rw))
}

func (self *SimNode) setPeer(id *NodeId, m Messenger) *Peer {
	i, found := self.peerMap[id.NodeID]
	if !found {
		i = len(self.peers)
		self.peerMap[id.NodeID] = i
		p := newPeer(m)
		self.peers = append(self.peers, p)
		return p
	}
	if self.peers[i] != nil && m != nil {
		panic(fmt.Sprintf("pipe for %v already set", id))
	}
	// legit reconnect reset disconnection error,
	p := self.peers[i]
	p.Messenger = m
	return p
}

func (self *SimNode) Disconnect(rid []byte) error {
	self.lock.Lock()
	defer self.lock.Unlock()
	id := NewNodeId(rid)
	peer := self.getPeer(id)
	if peer == nil || peer.Messenger == nil {
		return fmt.Errorf("already disconnected")
	}
	peer.Messenger.Close()
	peer.Messenger = nil
	// na := self.network.GetNodeAdapter(id)
	// peer = na.(*SimNode).GetPeer(self.Id)
	// peer.RW = nil
	glog.V(6).Infof("dropped peer %v", id)
	return self.network.DidDisconnect(self.Id, id)
}

func (self *SimNode) Connect(rid []byte) error {
	self.lock.Lock()
	defer self.lock.Unlock()
	id := NewNodeId(rid)
	na := self.network.GetNodeAdapter(id)
	if na == nil {
		return fmt.Errorf("node adapter for %v is missing", id)
	}
	rw, rrw := p2p.MsgPipe()
	runc := make(chan bool)
	defer close(runc)
	// run protocol on remote node with self as peer

	err := na.(ProtocolRunner).RunProtocol(self.Id, rrw, rw, runc)
	if err != nil {
		return fmt.Errorf("cannot run protocol (%v -> %v) %v", self.Id, id, err)
	}
	// run protocol on remote node with self as peer
	err = self.RunProtocol(id, rw, rrw, runc)
	if err != nil {
		return fmt.Errorf("cannot run protocol (%v -> %v): %v", id, self.Id, err)
	}
	self.network.DidConnect(self.Id, id)
	return nil
}

func (self *SimNode) RunProtocol(id *NodeId, rw, rrw p2p.MsgReadWriter, runc chan bool) error {
	if self.Run == nil {
		glog.V(6).Infof("no protocol starting on peer %v (connection with %v)", self.Id, id)
		return nil
	}
	glog.V(6).Infof("protocol starting on peer %v (connection with %v)", self.Id, id)
	peer := self.getPeer(id)
	if peer != nil && peer.Messenger != nil {
		return fmt.Errorf("already connected %v to peer %v", self.Id, id)
	}
	peer = self.setPeer(id, self.Messenger(rrw))
	p := p2p.NewPeer(id.NodeID, Name(id.Bytes()), []p2p.Cap{})
	go func() {
		err := self.Run(p, rw)
		glog.V(6).Infof("protocol quit on peer %v (connection with %v broken)", self.Id, id)
		<-runc
		self.Disconnect(id.Bytes())
		peer.Errc <- err
	}()
	return nil
}