package yggdrasil

import (
	"encoding/hex"
	"io/ioutil"
	"net"
	"time"

	"github.com/gologme/log"

	"github.com/yggdrasil-network/yggdrasil-go/src/address"
	"github.com/yggdrasil-network/yggdrasil-go/src/config"
	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
	"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
)

var buildName string
var buildVersion string

type module interface {
	init(*Core, *config.NodeConfig) error
	start() error
}

// The Core object represents the Yggdrasil node. You should create a Core
// object for each Yggdrasil node you plan to run.
type Core struct {
	// This is the main data structure that holds everything else for a node
	// We're going to keep our own copy of the provided config - that way we can
	// guarantee that it will be covered by the mutex
	config      config.NodeState // Config
	boxPub      crypto.BoxPubKey
	boxPriv     crypto.BoxPrivKey
	sigPub      crypto.SigPubKey
	sigPriv     crypto.SigPrivKey
	switchTable switchTable
	peers       peers
	sessions    sessions
	router      router
	dht         dht
	admin       admin
	searches    searches
	link        link
	log         *log.Logger
}

func (c *Core) init() error {
	// TODO separate init and start functions
	//  Init sets up structs
	//  Start launches goroutines that depend on structs being set up
	// This is pretty much required to completely avoid race conditions
	if c.log == nil {
		c.log = log.New(ioutil.Discard, "", 0)
	}

	current, _ := c.config.Get()

	boxPubHex, err := hex.DecodeString(current.EncryptionPublicKey)
	if err != nil {
		return err
	}
	boxPrivHex, err := hex.DecodeString(current.EncryptionPrivateKey)
	if err != nil {
		return err
	}
	sigPubHex, err := hex.DecodeString(current.SigningPublicKey)
	if err != nil {
		return err
	}
	sigPrivHex, err := hex.DecodeString(current.SigningPrivateKey)
	if err != nil {
		return err
	}

	copy(c.boxPub[:], boxPubHex)
	copy(c.boxPriv[:], boxPrivHex)
	copy(c.sigPub[:], sigPubHex)
	copy(c.sigPriv[:], sigPrivHex)

	c.admin.init(c)
	c.searches.init(c)
	c.dht.init(c)
	c.sessions.init(c)
	//c.multicast.init(c)
	c.peers.init(c)
	c.router.init(c)
	c.switchTable.init(c) // TODO move before peers? before router?

	return nil
}

// If any static peers were provided in the configuration above then we should
// configure them. The loop ensures that disconnected peers will eventually
// be reconnected with.
func (c *Core) addPeerLoop() {
	for {
		// Get the peers from the config - these could change!
		current, _ := c.config.Get()

		// Add peers from the Peers section
		for _, peer := range current.Peers {
			c.AddPeer(peer, "")
			time.Sleep(time.Second)
		}

		// Add peers from the InterfacePeers section
		for intf, intfpeers := range current.InterfacePeers {
			for _, peer := range intfpeers {
				c.AddPeer(peer, intf)
				time.Sleep(time.Second)
			}
		}

		// Sit for a while
		time.Sleep(time.Minute)
	}
}

// UpdateConfig updates the configuration in Core and then signals the
// various module goroutines to reconfigure themselves if needed
func (c *Core) UpdateConfig(config *config.NodeConfig) {
	c.log.Infoln("Reloading configuration...")

	c.config.Replace(*config)

	errors := 0

	components := []chan chan error{
		c.admin.reconfigure,
		c.searches.reconfigure,
		c.dht.reconfigure,
		c.sessions.reconfigure,
		c.peers.reconfigure,
		c.router.reconfigure,
		c.router.cryptokey.reconfigure,
		c.switchTable.reconfigure,
		c.link.reconfigure,
	}

	for _, component := range components {
		response := make(chan error)
		component <- response
		if err := <-response; err != nil {
			c.log.Errorln(err)
			errors++
		}
	}

	if errors > 0 {
		c.log.Warnln(errors, "modules reported errors during configuration reload")
	} else {
		c.log.Infoln("Configuration reloaded successfully")
	}
}

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

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

// Set the router adapter
func (c *Core) SetRouterAdapter(adapter adapterImplementation) {
	c.router.tun = adapter
}

// Starts up Yggdrasil using the provided NodeState, and outputs debug logging
// through the provided log.Logger. The started stack will include TCP and UDP
// sockets, a multicast discovery socket, an admin socket, router, switch and
// DHT node.
func (c *Core) Start(nc *config.NodeConfig, log *log.Logger) error {
	c.log = log

	c.config = config.NodeState{
		Current:  *nc,
		Previous: *nc,
	}

	if name := GetBuildName(); name != "unknown" {
		c.log.Infoln("Build name:", name)
	}
	if version := GetBuildVersion(); version != "unknown" {
		c.log.Infoln("Build version:", version)
	}

	c.log.Infoln("Starting up...")

	c.init()

	if err := c.link.init(c); err != nil {
		c.log.Errorln("Failed to start link interfaces")
		return err
	}

	c.config.Mutex.RLock()
	if c.config.Current.SwitchOptions.MaxTotalQueueSize >= SwitchQueueTotalMinSize {
		c.switchTable.queueTotalMaxSize = c.config.Current.SwitchOptions.MaxTotalQueueSize
	}
	c.config.Mutex.RUnlock()

	if err := c.switchTable.start(); err != nil {
		c.log.Errorln("Failed to start switch")
		return err
	}

	if err := c.router.start(); err != nil {
		c.log.Errorln("Failed to start router")
		return err
	}

	if err := c.admin.start(); err != nil {
		c.log.Errorln("Failed to start admin socket")
		return err
	}

	if err := c.router.tun.Start(c.router.addr, c.router.subnet); err != nil {
		c.log.Errorln("Failed to start TUN/TAP")
		return err
	}

	go c.addPeerLoop()

	c.log.Infoln("Startup complete")
	return nil
}

// Stops the Yggdrasil node.
func (c *Core) Stop() {
	c.log.Infoln("Stopping...")
	c.router.tun.Close()
	c.admin.close()
}

// ListenOn starts a new listener
func (c *Core) ListenTCP(uri string) (*TcpListener, error) {
	return c.link.tcp.listen(uri)
}

// 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()
}

// 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()
}

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

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

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

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

// Gets the nodeinfo.
func (c *Core) GetNodeInfo() nodeinfoPayload {
	return c.router.nodeinfo.getNodeInfo()
}

// Sets the nodeinfo.
func (c *Core) SetNodeInfo(nodeinfo interface{}, nodeinfoprivacy bool) {
	c.router.nodeinfo.setNodeInfo(nodeinfo, nodeinfoprivacy)
}

// 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
}

// Adds a peer. This should be specified in the peer URI format, i.e.
// tcp://a.b.c.d:e, udp://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 {
	return c.admin.addPeer(addr, sintf)
}

// Calls a peer. This should be specified in the peer URI format, i.e.
// tcp://a.b.c.d:e, udp://a.b.c.d:e, socks://a.b.c.d:e/f.g.h.i:j. This calls the
// peer once, and if the connection drops, it won't be called again.
func (c *Core) CallPeer(addr string, sintf string) error {
	return c.link.call(addr, sintf)
}

// 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)
}

// Gets the default admin listen address for your platform.
func (c *Core) GetAdminDefaultListen() string {
	return defaults.GetDefaults().DefaultAdminListen
}

// Gets the default TUN/TAP interface name for your platform.
func (c *Core) GetTUNDefaultIfName() string {
	return defaults.GetDefaults().DefaultIfName
}

// Gets the default TUN/TAP interface MTU for your platform. This can be as high
// as 65535, depending on platform, but is never lower than 1280.
func (c *Core) GetTUNDefaultIfMTU() int {
	return defaults.GetDefaults().DefaultIfMTU
}

// Gets the maximum supported TUN/TAP interface MTU for your platform. This
// can be as high as 65535, depending on platform, but is never lower than 1280.
func (c *Core) GetTUNMaximumIfMTU() int {
	return defaults.GetDefaults().MaximumIfMTU
}

// Gets the default TUN/TAP interface mode for your platform.
func (c *Core) GetTUNDefaultIfTAPMode() bool {
	return defaults.GetDefaults().DefaultIfTAPMode
}

// Gets the current TUN/TAP interface name.
func (c *Core) GetTUNIfName() string {
	//return c.router.tun.iface.Name()
	return c.router.tun.Name()
}

// Gets the current TUN/TAP interface MTU.
func (c *Core) GetTUNIfMTU() int {
	//return c.router.tun.mtu
	return c.router.tun.MTU()
}