package yggdrasil

import (
	"encoding/hex"
	"errors"
	"net"
	"sort"
	"sync/atomic"
	"time"

	"github.com/gologme/log"
	"github.com/yggdrasil-network/yggdrasil-go/src/address"
	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
)

// Peer represents a single peer object. This contains information from the
// preferred switch port for this peer, although there may be more than one in
// reality.
type Peer struct {
	PublicKey  crypto.BoxPubKey
	Endpoint   string
	BytesSent  uint64
	BytesRecvd uint64
	Protocol   string
	Port       uint64
	Uptime     time.Duration
}

// SwitchPeer represents a switch connection to a peer. Note that there may be
// multiple switch peers per actual peer, e.g. if there are multiple connections
// to a given node.
type SwitchPeer struct {
	PublicKey  crypto.BoxPubKey
	Coords     []byte
	BytesSent  uint64
	BytesRecvd uint64
	Port       uint64
	Protocol   string
}

// DHTEntry represents a single DHT entry that has been learned or cached from
// DHT searches.
type DHTEntry struct {
	PublicKey crypto.BoxPubKey
	Coords    []byte
	LastSeen  time.Duration
}

// SwitchQueues represents information from the switch related to link
// congestion and a list of switch queues created in response to congestion on a
// given link.
type SwitchQueues struct {
	Queues       []SwitchQueue
	Count        uint64
	Size         uint64
	HighestCount uint64
	HighestSize  uint64
	MaximumSize  uint64
}

// SwitchQueue represents a single switch queue, which is created in response
// to congestion on a given link.
type SwitchQueue struct {
	ID      string
	Size    uint64
	Packets uint64
	Port    uint64
}

// Session represents an open session with another node.
type Session struct {
	PublicKey   crypto.BoxPubKey
	Coords      []byte
	BytesSent   uint64
	BytesRecvd  uint64
	MTU         uint16
	WasMTUFixed bool
}

// GetPeers returns one or more Peer objects containing information about active
// peerings with other Yggdrasil nodes, where one of the responses always
// includes information about the current node (with a port number of 0). If
// there is exactly one entry then this node is not connected to any other nodes
// and is therefore isolated.
func (c *Core) GetPeers() []Peer {
	ports := c.peers.ports.Load().(map[switchPort]*peer)
	var peers []Peer
	var ps []switchPort
	for port := range ports {
		ps = append(ps, port)
	}
	sort.Slice(ps, func(i, j int) bool { return ps[i] < ps[j] })
	for _, port := range ps {
		p := ports[port]
		info := Peer{
			Endpoint:   p.intf.name,
			BytesSent:  atomic.LoadUint64(&p.bytesSent),
			BytesRecvd: atomic.LoadUint64(&p.bytesRecvd),
			Protocol:   p.intf.info.linkType,
			Port:       uint64(port),
			Uptime:     time.Since(p.firstSeen),
		}
		copy(info.PublicKey[:], p.box[:])
		peers = append(peers, info)
	}
	return peers
}

// GetSwitchPeers returns zero or more SwitchPeer objects containing information
// about switch port connections with other Yggdrasil nodes. Note that, unlike
// GetPeers, GetSwitchPeers does not include information about the current node,
// therefore it is possible for this to return zero elements if the node is
// isolated or not connected to any peers.
func (c *Core) GetSwitchPeers() []SwitchPeer {
	var switchpeers []SwitchPeer
	table := c.switchTable.table.Load().(lookupTable)
	peers := c.peers.ports.Load().(map[switchPort]*peer)
	for _, elem := range table.elems {
		peer, isIn := peers[elem.port]
		if !isIn {
			continue
		}
		coords := elem.locator.getCoords()
		info := SwitchPeer{
			Coords:     coords,
			BytesSent:  atomic.LoadUint64(&peer.bytesSent),
			BytesRecvd: atomic.LoadUint64(&peer.bytesRecvd),
			Port:       uint64(elem.port),
			Protocol:   peer.intf.info.linkType,
		}
		copy(info.PublicKey[:], peer.box[:])
		switchpeers = append(switchpeers, info)
	}
	return switchpeers
}

// GetDHT returns zero or more entries as stored in the DHT, cached primarily
// from searches that have already taken place.
func (c *Core) GetDHT() []DHTEntry {
	var dhtentries []DHTEntry
	getDHT := func() {
		now := time.Now()
		var dhtentry []*dhtInfo
		for _, v := range c.dht.table {
			dhtentry = append(dhtentry, v)
		}
		sort.SliceStable(dhtentry, func(i, j int) bool {
			return dht_ordered(&c.dht.nodeID, dhtentry[i].getNodeID(), dhtentry[j].getNodeID())
		})
		for _, v := range dhtentry {
			info := DHTEntry{
				Coords:   v.coords,
				LastSeen: now.Sub(v.recv),
			}
			copy(info.PublicKey[:], v.key[:])
			dhtentries = append(dhtentries, info)
		}
	}
	c.router.doAdmin(getDHT)
	return dhtentries
}

// GetSwitchQueues returns information about the switch queues that are
// currently in effect. These values can change within an instant.
func (c *Core) GetSwitchQueues() SwitchQueues {
	var switchqueues SwitchQueues
	switchTable := &c.switchTable
	getSwitchQueues := func() {
		switchqueues = SwitchQueues{
			Count:        uint64(len(switchTable.queues.bufs)),
			Size:         switchTable.queues.size,
			HighestCount: uint64(switchTable.queues.maxbufs),
			HighestSize:  switchTable.queues.maxsize,
			MaximumSize:  switchTable.queueTotalMaxSize,
		}
		for k, v := range switchTable.queues.bufs {
			nexthop := switchTable.bestPortForCoords([]byte(k))
			queue := SwitchQueue{
				ID:      k,
				Size:    v.size,
				Packets: uint64(len(v.packets)),
				Port:    uint64(nexthop),
			}
			switchqueues.Queues = append(switchqueues.Queues, queue)
		}

	}
	c.switchTable.doAdmin(getSwitchQueues)
	return switchqueues
}

// GetSessions returns a list of open sessions from this node to other nodes.
func (c *Core) GetSessions() []Session {
	var sessions []Session
	getSessions := func() {
		for _, sinfo := range c.sessions.sinfos {
			// TODO? skipped known but timed out sessions?
			session := Session{
				Coords:      sinfo.coords,
				MTU:         sinfo.getMTU(),
				BytesSent:   sinfo.bytesSent,
				BytesRecvd:  sinfo.bytesRecvd,
				WasMTUFixed: sinfo.wasMTUFixed,
			}
			copy(session.PublicKey[:], sinfo.theirPermPub[:])
			sessions = append(sessions, session)
		}
	}
	c.router.doAdmin(getSessions)
	return sessions
}

// BuildName gets the current build name. This is usually injected if built
// from git, or returns "unknown" otherwise.
func BuildName() string {
	if buildName == "" {
		return "unknown"
	}
	return buildName
}

// BuildVersion gets the current build version. This is usually injected if
// built from git, or returns "unknown" otherwise.
func BuildVersion() string {
	if buildVersion == "" {
		return "unknown"
	}
	return buildVersion
}

// ListenConn returns a listener for Yggdrasil session connections.
func (c *Core) ConnListen() (*Listener, error) {
	c.sessions.listenerMutex.Lock()
	defer c.sessions.listenerMutex.Unlock()
	if c.sessions.listener != nil {
		return nil, errors.New("a listener already exists")
	}
	c.sessions.listener = &Listener{
		core:  c,
		conn:  make(chan *Conn),
		close: make(chan interface{}),
	}
	return c.sessions.listener, nil
}

// ConnDialer returns a dialer for Yggdrasil session connections.
func (c *Core) ConnDialer() (*Dialer, error) {
	return &Dialer{
		core: c,
	}, nil
}

// ListenTCP starts a new TCP listener. The input URI should match that of the
// "Listen" configuration item, e.g.
// 		tcp://a.b.c.d:e
func (c *Core) ListenTCP(uri string) (*TcpListener, error) {
	return c.link.tcp.listen(uri)
}

// NewEncryptionKeys generates a new encryption keypair. The encryption keys are
// used to encrypt traffic and to derive the IPv6 address/subnet of the node.
func (c *Core) NewEncryptionKeys() (*crypto.BoxPubKey, *crypto.BoxPrivKey) {
	return crypto.NewBoxKeys()
}

// NewSigningKeys generates a new signing keypair. The signing keys are used to
// derive the structure of the spanning tree.
func (c *Core) NewSigningKeys() (*crypto.SigPubKey, *crypto.SigPrivKey) {
	return crypto.NewSigKeys()
}

// NodeID gets the node ID.
func (c *Core) NodeID() *crypto.NodeID {
	return crypto.GetNodeID(&c.boxPub)
}

// TreeID gets the tree ID.
func (c *Core) TreeID() *crypto.TreeID {
	return crypto.GetTreeID(&c.sigPub)
}

// SigPubKey gets the node's signing public key.
func (c *Core) SigPubKey() string {
	return hex.EncodeToString(c.sigPub[:])
}

// BoxPubKey gets the node's encryption public key.
func (c *Core) BoxPubKey() string {
	return hex.EncodeToString(c.boxPub[:])
}

// Address gets the IPv6 address of the Yggdrasil node. This is always a /128
// address.
func (c *Core) Address() *net.IP {
	address := net.IP(address.AddrForNodeID(c.NodeID())[:])
	return &address
}

// Subnet gets the routed IPv6 subnet of the Yggdrasil node. This is always a
// /64 subnet.
func (c *Core) Subnet() *net.IPNet {
	subnet := address.SubnetForNodeID(c.NodeID())[:]
	subnet = append(subnet, 0, 0, 0, 0, 0, 0, 0, 0)
	return &net.IPNet{IP: subnet, Mask: net.CIDRMask(64, 128)}
}

// RouterAddresses returns the raw address and subnet types as used by the
// router
func (c *Core) RouterAddresses() (address.Address, address.Subnet) {
	return c.router.addr, c.router.subnet
}

// NodeInfo gets the currently configured nodeinfo.
func (c *Core) NodeInfo() nodeinfoPayload {
	return c.router.nodeinfo.getNodeInfo()
}

// SetNodeInfo the lcal nodeinfo. Note that nodeinfo can be any value or struct,
// it will be serialised into JSON automatically.
func (c *Core) SetNodeInfo(nodeinfo interface{}, nodeinfoprivacy bool) {
	c.router.nodeinfo.setNodeInfo(nodeinfo, nodeinfoprivacy)
}

// SetLogger sets the output logger of the Yggdrasil node after startup. This
// may be useful if you want to redirect the output later.
func (c *Core) SetLogger(log *log.Logger) {
	c.log = log
}

// AddPeer adds a peer. This should be specified in the peer URI format, e.g.:
// 		tcp://a.b.c.d:e
//		socks://a.b.c.d:e/f.g.h.i:j
// This adds the peer to the peer list, so that they will be called again if the
// connection drops.
func (c *Core) AddPeer(addr string, sintf string) error {
	if err := c.CallPeer(addr, sintf); err != nil {
		return err
	}
	c.config.Mutex.Lock()
	if sintf == "" {
		c.config.Current.Peers = append(c.config.Current.Peers, addr)
	} else {
		c.config.Current.InterfacePeers[sintf] = append(c.config.Current.InterfacePeers[sintf], addr)
	}
	c.config.Mutex.Unlock()
	return nil
}

// CallPeer calls a peer once. This should be specified in the peer URI format,
// e.g.:
// 		tcp://a.b.c.d:e
//		socks://a.b.c.d:e/f.g.h.i:j
// This does not add the peer to the peer list, so if the connection drops, the
// peer will not be called again automatically.
func (c *Core) CallPeer(addr string, sintf string) error {
	return c.link.call(addr, sintf)
}

// AddAllowedEncryptionPublicKey adds an allowed public key. This allow peerings
// to be restricted only to keys that you have selected.
func (c *Core) AddAllowedEncryptionPublicKey(boxStr string) error {
	return c.admin.addAllowedEncryptionPublicKey(boxStr)
}