// package peer implements an object used to represent peers in the ipfs network.
package peer

import (
	"encoding/hex"
	"encoding/json"
	"fmt"
	"strings"

	b58 "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-base58"
	ma "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr"
	mh "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"

	ic "github.com/ipfs/go-ipfs/p2p/crypto"
	u "github.com/ipfs/go-ipfs/util"
)

var log = u.Logger("peer")

// ID represents the identity of a peer.
type ID string

// Pretty returns a b58-encoded string of the ID
func (id ID) Pretty() string {
	return IDB58Encode(id)
}

func (id ID) Loggable() map[string]interface{} {
	return map[string]interface{}{
		"peerID": id.Pretty(),
	}
}

// String prints out the peer.
//
// TODO(brian): ensure correctness at ID generation and
// enforce this by only exposing functions that generate
// IDs safely. Then any peer.ID type found in the
// codebase is known to be correct.
func (id ID) String() string {
	pid := id.Pretty()

	//All sha256 nodes start with Qm
	//We can skip the Qm to make the peer.ID more useful
	if strings.HasPrefix(pid, "Qm") {
		pid = pid[2:]
	}

	maxRunes := 6
	if len(pid) < maxRunes {
		maxRunes = len(pid)
	}
	return fmt.Sprintf("<peer.ID %s>", pid[:maxRunes])
}

// MatchesPrivateKey tests whether this ID was derived from sk
func (id ID) MatchesPrivateKey(sk ic.PrivKey) bool {
	return id.MatchesPublicKey(sk.GetPublic())
}

// MatchesPublicKey tests whether this ID was derived from pk
func (id ID) MatchesPublicKey(pk ic.PubKey) bool {
	oid, err := IDFromPublicKey(pk)
	if err != nil {
		return false
	}
	return oid == id
}

// IDFromString cast a string to ID type, and validate
// the id to make sure it is a multihash.
func IDFromString(s string) (ID, error) {
	if _, err := mh.Cast([]byte(s)); err != nil {
		return ID(""), err
	}
	return ID(s), nil
}

// IDFromBytes cast a string to ID type, and validate
// the id to make sure it is a multihash.
func IDFromBytes(b []byte) (ID, error) {
	if _, err := mh.Cast(b); err != nil {
		return ID(""), err
	}
	return ID(b), nil
}

// IDB58Decode returns a b58-decoded Peer
func IDB58Decode(s string) (ID, error) {
	m, err := mh.FromB58String(s)
	if err != nil {
		return "", err
	}
	return ID(m), err
}

// IDB58Encode returns b58-encoded string
func IDB58Encode(id ID) string {
	return b58.Encode([]byte(id))
}

// IDHexDecode returns a b58-decoded Peer
func IDHexDecode(s string) (ID, error) {
	m, err := mh.FromHexString(s)
	if err != nil {
		return "", err
	}
	return ID(m), err
}

// IDHexEncode returns b58-encoded string
func IDHexEncode(id ID) string {
	return hex.EncodeToString([]byte(id))
}

// IDFromPublicKey returns the Peer ID corresponding to pk
func IDFromPublicKey(pk ic.PubKey) (ID, error) {
	b, err := pk.Bytes()
	if err != nil {
		return "", err
	}
	hash := u.Hash(b)
	return ID(hash), nil
}

// IDFromPrivateKey returns the Peer ID corresponding to sk
func IDFromPrivateKey(sk ic.PrivKey) (ID, error) {
	return IDFromPublicKey(sk.GetPublic())
}

// Map maps a Peer ID to a struct.
type Set map[ID]struct{}

// PeerInfo is a small struct used to pass around a peer with
// a set of addresses (and later, keys?). This is not meant to be
// a complete view of the system, but rather to model updates to
// the peerstore. It is used by things like the routing system.
type PeerInfo struct {
	ID    ID
	Addrs []ma.Multiaddr
}

func (pi *PeerInfo) MarshalJSON() ([]byte, error) {
	out := make(map[string]interface{})
	out["ID"] = IDB58Encode(pi.ID)
	var addrs []string
	for _, a := range pi.Addrs {
		addrs = append(addrs, a.String())
	}
	out["Addrs"] = addrs
	return json.Marshal(out)
}

func (pi *PeerInfo) UnmarshalJSON(b []byte) error {
	var data map[string]interface{}
	err := json.Unmarshal(b, &data)
	if err != nil {
		return err
	}
	pid, err := IDB58Decode(data["ID"].(string))
	if err != nil {
		return err
	}
	pi.ID = pid
	addrs, ok := data["Addrs"].([]interface{})
	if ok {
		for _, a := range addrs {
			pi.Addrs = append(pi.Addrs, ma.StringCast(a.(string)))
		}
	}
	return nil
}

// IDSlice for sorting peers
type IDSlice []ID

func (es IDSlice) Len() int           { return len(es) }
func (es IDSlice) Swap(i, j int)      { es[i], es[j] = es[j], es[i] }
func (es IDSlice) Less(i, j int) bool { return string(es[i]) < string(es[j]) }