package bzz

/*
BZZ implements the bzz wire protocol of swarm
routing decoded storage and retrieval requests
registering peers with the DHT
*/

import (
	"net"
	"time"

	"github.com/ethereum/go-ethereum/p2p"
)

const (
	Version            = 0
	ProtocolLength     = uint64(8)
	ProtocolMaxMsgSize = 10 * 1024 * 1024
	NetworkId          = 0
	strategy           = 0
)

// bzz protocol message codes
const (
	statusMsg          = iota // 0x01
	storeRequestMsg           // 0x02
	retrieveRequestMsg        // 0x03
	peersMsg                  // 0x04
)

// bzzProtocol represents the swarm wire protocol
// instance is running on each peer
type bzzProtocol struct {
	netStore *netStore
	hive     *hive
	peer     *p2p.Peer
	rw       p2p.MsgReadWriter
}

/*
 message structs used for rlp decoding
Handshake

[0x01, Version: B_32, strategy: B_32, capacity: B_64, peers: B_8]

Storing

[+0x02, key: B_256, metadata: [], data: B_4k]: the data chunk to be stored, preceded by its key.

Retrieving

[0x03, key: B_256, timeout: B_64, metadata: []]: key of the data chunk to be retrieved, timeout in milliseconds. Note that zero timeout retrievals serve also as messages to retrieve peers.

Peers

[0x04, key: B_256, timeout: B_64, peers: [[peer], [peer], .... ]] the encoding of a peer is identical to that in the devp2p base protocol peers messages: [IP, Port, NodeID] note that a node's DPA address is not the NodeID but the hash of the NodeID. Timeout serves to indicate whether the responder is forwarding the query within the timeout or not.

*/

type statusMsgData struct {
	Version   uint64
	ID        string
	NodeID    []byte
	NetworkId uint64
	Caps      []p2p.Cap
	// Strategy  uint64
}

/*
 Given the chunker I see absolutely no reason why not allow storage and delivery of larger data . See my discussion on flexible chunking.
 store requests are forwarded to the peers in their cademlia proximity bin if they are distant
 if they are within our storage radius or have any incentive to store it then attach your nodeID to the metadata
 if the storage request is sufficiently close (within our proximity range (the last row of the routing table), then sending it to all peers will not guarantee convergence, so there needs to be an absolute expiry of the request too. Maybe the protocol should specify a forward probability exponentially declining with age.
*/
type storeRequestMsgData struct {
	Key  Key    // hash of datasize | data
	Size int64  // size of data in bytes
	Data []byte // is this needed?
	// optional
	Id             int64     //
	RequestTimeout time.Time // expiry for forwarding
	StorageTimeout time.Time // expiry of content
	Metadata       metaData  //
	//
	peer peer
}

/*
Root key retrieve request
Timeout in milliseconds. Note that zero timeout retrieval requests do not request forwarding, but prompt for a peers message response. therefore they also serve also as messages to retrieve peers.
MaxSize specifies the maximum size that the peer will accept. This is useful in particular if we allow storage and delivery of multichunk payload representing the entire or partial subtree unfolding from the requested root key. So when only interested in limited part of a stream (infinite trees) or only testing chunk availability etc etc, we can indicate it by limiting the size here.
In the special case that the key is identical to the peers own address (hash of NodeID) the message is to be handled as a self lookup. The response is a PeersMsg with the peers in the cademlia proximity bin corresponding to the address.
It is unclear if a retrieval request with an empty target is the same as a self lookup
*/
type retrieveRequestMsgData struct {
	Key Key
	// optional
	Id       int64     //
	MaxSize  int64     //  maximum size of delivery accepted
	Timeout  time.Time //
	Metadata metaData  //
	//
	peer peer
}

type peerAddr struct {
	IP     net.IP
	Port   uint64
	Pubkey []byte
}

/*
one response to retrieval, always encouraged after a retrieval request to respond with a list of peers in the same cademlia proximity bin.
The encoding of a peer is identical to that in the devp2p base protocol peers messages: [IP, Port, NodeID]
note that a node's DPA address is not the NodeID but the hash of the NodeID.
Timeout serves to indicate whether the responder is forwarding the query within the timeout or not.
The Key is the target (if response to a retrieval request) or peers address (hash of NodeID) if retrieval request was a self lookup.
It is unclear if PeersMsg with an empty Key has a special meaning or just mean the same as with the peers address as Key (cademlia bin)
*/
type peersMsgData struct {
	Peers   []*peerAddr //
	Timeout time.Time   // indicate whether responder is expected to deliver content
	Key     Key         // if a response to a retrieval request
	Id      int64       // if a response to a retrieval request
	//
	peer peer
}

/*
metadata is as yet a placeholder
it will likely contain info about hops or the entire forward chain of node IDs
this may allow some interesting schemes to evolve optimal routing strategies
metadata for storage and retrieval requests could specify format parameters relevant for the (blockhashing) chunking scheme used (for chunks corresponding to a treenode). For instance all runtime params for the chunker (hashing algorithm used, branching etc.)
Finally metadata can hold info relevant to some reward or compensation scheme that may be used to incentivise peers.
*/
type metaData struct{}

/*
main entrypoint, wrappers starting a server running the bzz protocol
use this constructor to attach the protocol ("class") to server caps
the Dev p2p layer then runs the protocol instance on each peer
*/
func BzzProtocol(netStore *netStore, hive *hive) p2p.Protocol {
	return p2p.Protocol{
		Name:    "bzz",
		Version: Version,
		Length:  ProtocolLength,
		Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
			return runBzzProtocol(netStore, hive, p, rw)
		},
	}
}

// the main loop that handles incoming messages
// note RemovePeer in the post-disconnect hook
func runBzzProtocol(netStore *netStore, hive *hive, p *p2p.Peer, rw p2p.MsgReadWriter) (err error) {
	self := &bzzProtocol{
		netStore: netStore,
		hive:     hive,
		rw:       rw,
		peer:     p,
	}
	err = self.handleStatus()
	if err == nil {
		for {
			err = self.handle()
			if err != nil {
				self.hive.removePeer(peer{bzzProtocol: self})
				break
			}
		}
	}
	return
}

func (self *bzzProtocol) handle() error {
	msg, err := self.rw.ReadMsg()
	if err != nil {
		return err
	}
	if msg.Size > ProtocolMaxMsgSize {
		return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
	}
	// make sure that the payload has been fully consumed
	defer msg.Discard()
	/*
	   statusMsg          = iota // 0x01
	   storeRequestMsg           // 0x02
	   retrieveRequestMsg        // 0x03
	   peersMsg                  // 0x04
	*/
	switch msg.Code {
	case statusMsg:
		return self.protoError(ErrExtraStatusMsg, "")

	case storeRequestMsg:
		var req storeRequestMsgData
		if err := msg.Decode(&req); err != nil {
			return self.protoError(ErrDecode, "msg %v: %v", msg, err)
		}
		req.peer = peer{bzzProtocol: self}
		self.netStore.addStoreRequest(&req)

	case retrieveRequestMsg:
		var req retrieveRequestMsgData
		if err := msg.Decode(&req); err != nil {
			return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
		}
		req.peer = peer{bzzProtocol: self}
		self.netStore.addRetrieveRequest(&req)

	case peersMsg:
		var req peersMsgData
		if err := msg.Decode(&req); err != nil {
			return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
		}
		req.peer = peer{bzzProtocol: self}
		self.hive.addPeers(&req)

	default:
		return self.protoError(ErrInvalidMsgCode, "%v", msg.Code)
	}
	return nil
}

func (self *bzzProtocol) statusMsg() p2p.Msg {

	return p2p.NewMsg(statusMsg,
		uint32(Version),
		uint32(NetworkId),
		"honey",
		[]p2p.Cap{},
		strategy,
	)
}

func (self *bzzProtocol) handleStatus() error {
	// send precanned status message
	if err := self.rw.WriteMsg(self.statusMsg()); err != nil {
		return err
	}

	// read and handle remote status
	msg, err := self.rw.ReadMsg()
	if err != nil {
		return err
	}

	if msg.Code != statusMsg {
		return self.protoError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, statusMsg)
	}

	if msg.Size > ProtocolMaxMsgSize {
		return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
	}

	var status statusMsgData
	if err := msg.Decode(&status); err != nil {
		return self.protoError(ErrDecode, "msg %v: %v", msg, err)
	}

	if status.NetworkId != NetworkId {
		return self.protoError(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, NetworkId)
	}

	if Version != status.Version {
		return self.protoError(ErrVersionMismatch, "%d (!= %d)", status.Version, Version)
	}

	self.peer.Infof("Peer is [bzz] capable (%d/%d)\n", status.Version, status.NetworkId)

	req := &peersMsgData{
		// Peers: []*peerAddr{self.peer.Address()}, // not implemented in p2p, should be the same as node discovery cademlia
		// Key:   nil,
		peer: peer{bzzProtocol: self, pubkey: status.NodeID},
	}

	self.hive.addPeers(req)

	return nil
}

// outgoing messages
func (self *bzzProtocol) retrieve(req *retrieveRequestMsgData) {
	p2p.EncodeMsg(self.rw, retrieveRequestMsg, req)
}

func (self *bzzProtocol) store(req *storeRequestMsgData) {
	p2p.EncodeMsg(self.rw, storeRequestMsg, req)
}

func (self *bzzProtocol) peers(req *peersMsgData) {
	p2p.EncodeMsg(self.rw, peersMsg, req)
}

// errors
// TODO: should be reworked using errs pkg
func (self *bzzProtocol) protoError(code int, format string, params ...interface{}) (err *protocolError) {
	err = ProtocolError(code, format, params...)
	if err.Fatal() {
		self.peer.Errorln("err %v", err)
		// disconnect
	} else {
		self.peer.Debugf("fyi %v", err)
	}
	return
}

func (self *bzzProtocol) protoErrorDisconnect(code int, format string, params ...interface{}) {
	err := ProtocolError(code, format, params...)
	if err.Fatal() {
		self.peer.Errorln("err %v", err)
		// disconnect
	} else {
		self.peer.Debugf("fyi %v", err)
	}

}