// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.

package node

import (
	"crypto/tls"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"io/ioutil"
	"net"
	"os"
	"path"
	"sync"
	"time"

	"github.com/ava-labs/gecko/api"
	"github.com/ava-labs/gecko/api/admin"
	"github.com/ava-labs/gecko/api/health"
	"github.com/ava-labs/gecko/api/info"
	"github.com/ava-labs/gecko/api/ipcs"
	"github.com/ava-labs/gecko/api/keystore"
	"github.com/ava-labs/gecko/api/metrics"
	"github.com/ava-labs/gecko/chains"
	"github.com/ava-labs/gecko/chains/atomic"
	"github.com/ava-labs/gecko/database"
	"github.com/ava-labs/gecko/database/prefixdb"
	"github.com/ava-labs/gecko/genesis"
	"github.com/ava-labs/gecko/ids"
	"github.com/ava-labs/gecko/network"
	"github.com/ava-labs/gecko/snow/triggers"
	"github.com/ava-labs/gecko/snow/validators"
	"github.com/ava-labs/gecko/utils"
	"github.com/ava-labs/gecko/utils/hashing"
	"github.com/ava-labs/gecko/utils/logging"
	"github.com/ava-labs/gecko/utils/wrappers"
	"github.com/ava-labs/gecko/version"
	"github.com/ava-labs/gecko/vms"
	"github.com/ava-labs/gecko/vms/avm"
	"github.com/ava-labs/gecko/vms/nftfx"
	"github.com/ava-labs/gecko/vms/platformvm"
	"github.com/ava-labs/gecko/vms/propertyfx"
	"github.com/ava-labs/gecko/vms/rpcchainvm"
	"github.com/ava-labs/gecko/vms/secp256k1fx"
	"github.com/ava-labs/gecko/vms/spchainvm"
	"github.com/ava-labs/gecko/vms/spdagvm"
	"github.com/ava-labs/gecko/vms/timestampvm"
)

// Networking constants
const (
	TCP = "tcp"
)

var (
	genesisHashKey = []byte("genesisID")

	// Version is the version of this code
	Version       = version.NewDefaultVersion("avalanche", 0, 5, 7)
	versionParser = version.NewDefaultParser()
)

// Node is an instance of an Ava node.
type Node struct {
	Log        logging.Logger
	LogFactory logging.Factory
	HTTPLog    logging.Logger

	// This node's unique ID used when communicating with other nodes
	// (in consensus, for example)
	ID ids.ShortID

	// Storage for this node
	DB database.Database

	// Handles calls to Keystore API
	keystoreServer keystore.Keystore

	// Manages shared memory
	sharedMemory atomic.SharedMemory

	// Manages creation of blockchains and routing messages to them
	chainManager chains.Manager

	// Manages Virtual Machines
	vmManager vms.Manager

	// dispatcher for events as they happen in consensus
	DecisionDispatcher  *triggers.EventDispatcher
	ConsensusDispatcher *triggers.EventDispatcher

	// Net runs the networking stack
	Net network.Network

	// this node's initial connections to the network
	beacons validators.Set

	// current validators of the network
	vdrs validators.Manager

	// Handles HTTP API calls
	APIServer api.Server

	// This node's configuration
	Config *Config

	// channel for closing the node
	nodeCloser chan<- os.Signal
}

/*
 ******************************************************************************
 *************************** P2P Networking Section ***************************
 ******************************************************************************
 */

func (n *Node) initNetworking() error {
	listener, err := net.Listen(TCP, fmt.Sprintf(":%d", n.Config.StakingLocalPort))
	if err != nil {
		return err
	}
	dialer := network.NewDialer(TCP)

	var serverUpgrader, clientUpgrader network.Upgrader
	if n.Config.EnableP2PTLS {
		cert, err := tls.LoadX509KeyPair(n.Config.StakingCertFile, n.Config.StakingKeyFile)
		if err != nil {
			return err
		}

		tlsConfig := &tls.Config{
			Certificates: []tls.Certificate{cert},
			ClientAuth:   tls.RequireAnyClientCert,
			// We do not use TLS's CA functionality, we just require an
			// authenticated channel. Therefore, we can safely skip verification
			// here.
			//
			// TODO: Security audit required
			InsecureSkipVerify: true,
		}

		serverUpgrader = network.NewTLSServerUpgrader(tlsConfig)
		clientUpgrader = network.NewTLSClientUpgrader(tlsConfig)
	} else {
		serverUpgrader = network.NewIPUpgrader()
		clientUpgrader = network.NewIPUpgrader()
	}

	// Initialize validator manager and default subnet's validator set
	defaultSubnetValidators := validators.NewSet()
	if !n.Config.EnableStaking {
		defaultSubnetValidators.Add(validators.NewValidator(n.ID, 1))
	}
	n.vdrs = validators.NewManager()
	n.vdrs.PutValidatorSet(platformvm.DefaultSubnetID, defaultSubnetValidators)

	n.Net = network.NewDefaultNetwork(
		n.Config.ConsensusParams.Metrics,
		n.Log,
		n.ID,
		n.Config.StakingIP,
		n.Config.NetworkID,
		Version,
		versionParser,
		listener,
		dialer,
		serverUpgrader,
		clientUpgrader,
		defaultSubnetValidators,
		n.beacons,
		n.Config.ConsensusRouter,
	)

	if !n.Config.EnableStaking {
		n.Net.RegisterHandler(&insecureValidatorManager{
			vdrs: defaultSubnetValidators,
		})
	}

	n.nodeCloser = utils.HandleSignals(func(os.Signal) {
		n.Net.Close()
	}, os.Interrupt, os.Kill)

	return nil
}

type insecureValidatorManager struct {
	vdrs validators.Set
}

func (i *insecureValidatorManager) Connected(vdrID ids.ShortID) bool {
	i.vdrs.Add(validators.NewValidator(vdrID, 1))
	return false
}

func (i *insecureValidatorManager) Disconnected(vdrID ids.ShortID) bool {
	i.vdrs.Remove(vdrID)
	return false
}

// Dispatch starts the node's servers.
// Returns when the node exits.
func (n *Node) Dispatch() error {
	// Add bootstrap nodes to the peer network
	for _, peer := range n.Config.BootstrapPeers {
		if !peer.IP.Equal(n.Config.StakingIP) {
			n.Net.Track(peer.IP)
		} else {
			n.Log.Error("can't add self as a bootstrapper")
		}
	}

	return n.Net.Dispatch()
}

/*
 ******************************************************************************
 *********************** End P2P Networking Section ***************************
 ******************************************************************************
 */

func (n *Node) initDatabase() error {
	n.DB = n.Config.DB

	expectedGenesis, err := genesis.Genesis(n.Config.NetworkID)
	if err != nil {
		return err
	}
	rawExpectedGenesisHash := hashing.ComputeHash256(expectedGenesis)

	rawGenesisHash, err := n.DB.Get(genesisHashKey)
	if err == database.ErrNotFound {
		rawGenesisHash = rawExpectedGenesisHash
		err = n.DB.Put(genesisHashKey, rawGenesisHash)
	}
	if err != nil {
		return err
	}

	genesisHash, err := ids.ToID(rawGenesisHash)
	if err != nil {
		return err
	}
	expectedGenesisHash, err := ids.ToID(rawExpectedGenesisHash)
	if err != nil {
		return err
	}

	if !genesisHash.Equals(expectedGenesisHash) {
		return fmt.Errorf("db contains invalid genesis hash. DB Genesis: %s Generated Genesis: %s", genesisHash, expectedGenesisHash)
	}
	return nil
}

// Initialize this node's ID
// If staking is disabled, a node's ID is a hash of its IP
// Otherwise, it is a hash of the TLS certificate that this node
// uses for P2P communication
func (n *Node) initNodeID() error {
	if !n.Config.EnableP2PTLS {
		n.ID = ids.NewShortID(hashing.ComputeHash160Array([]byte(n.Config.StakingIP.String())))
		n.Log.Info("Set the node's ID to %s", n.ID)
		return nil
	}

	stakeCert, err := ioutil.ReadFile(n.Config.StakingCertFile)
	if err != nil {
		return fmt.Errorf("problem reading staking certificate: %w", err)
	}

	block, _ := pem.Decode(stakeCert)
	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		return fmt.Errorf("problem parsing staking certificate: %w", err)
	}
	n.ID, err = ids.ToShortID(hashing.PubkeyBytesToAddress(cert.Raw))
	if err != nil {
		return fmt.Errorf("problem deriving staker ID from certificate: %w", err)
	}
	n.Log.Info("Set node's ID to %s", n.ID)
	return nil
}

// Create the IDs of the peers this node should first connect to
func (n *Node) initBeacons() {
	n.beacons = validators.NewSet()
	for _, peer := range n.Config.BootstrapPeers {
		n.beacons.Add(validators.NewValidator(peer.ID, 1))
	}
}

// Create the vmManager and register the following vms:
// AVM, Simple Payments DAG, Simple Payments Chain
// The Platform VM is registered in initStaking because
// its factory needs to reference n.chainManager, which is nil right now
func (n *Node) initVMManager() error {
	avaAssetID, err := genesis.AVAAssetID(n.Config.NetworkID)
	if err != nil {
		return err
	}

	n.vmManager = vms.NewManager(&n.APIServer, n.HTTPLog)

	errs := wrappers.Errs{}
	errs.Add(
		n.vmManager.RegisterVMFactory(avm.ID, &avm.Factory{
			AVA:      avaAssetID,
			Platform: ids.Empty,
		}),
		n.vmManager.RegisterVMFactory(genesis.EVMID, &rpcchainvm.Factory{Path: path.Join(n.Config.PluginDir, "evm")}),
		n.vmManager.RegisterVMFactory(spdagvm.ID, &spdagvm.Factory{TxFee: n.Config.AvaTxFee}),
		n.vmManager.RegisterVMFactory(spchainvm.ID, &spchainvm.Factory{}),
		n.vmManager.RegisterVMFactory(timestampvm.ID, &timestampvm.Factory{}),
		n.vmManager.RegisterVMFactory(secp256k1fx.ID, &secp256k1fx.Factory{}),
		n.vmManager.RegisterVMFactory(nftfx.ID, &nftfx.Factory{}),
		n.vmManager.RegisterVMFactory(propertyfx.ID, &propertyfx.Factory{}),
	)
	return errs.Err
}

// Create the EventDispatcher used for hooking events
// into the general process flow.
func (n *Node) initEventDispatcher() {
	n.DecisionDispatcher = &triggers.EventDispatcher{}
	n.DecisionDispatcher.Initialize(n.Log)

	n.ConsensusDispatcher = &triggers.EventDispatcher{}
	n.ConsensusDispatcher.Initialize(n.Log)

	n.Log.AssertNoError(n.ConsensusDispatcher.Register("gossip", n.Net))
}

// Initializes the Platform chain.
// Its genesis data specifies the other chains that should
// be created.
func (n *Node) initChains() error {
	n.Log.Info("initializing chains")

	vdrs := n.vdrs

	// If staking is disabled, ignore updates to Subnets' validator sets
	// Instead of updating node's validator manager, platform chain makes changes
	// to its own local validator manager (which isn't used for sampling)
	if !n.Config.EnableStaking {
		defaultSubnetValidators := validators.NewSet()
		defaultSubnetValidators.Add(validators.NewValidator(n.ID, 1))
		vdrs = validators.NewManager()
		vdrs.PutValidatorSet(platformvm.DefaultSubnetID, defaultSubnetValidators)
	}

	avaAssetID, err := genesis.AVAAssetID(n.Config.NetworkID)
	if err != nil {
		return err
	}
	createAVMTx, err := genesis.VMGenesis(n.Config.NetworkID, avm.ID)
	if err != nil {
		return err
	}

	err = n.vmManager.RegisterVMFactory(
		/*vmID=*/ platformvm.ID,
		/*vmFactory=*/ &platformvm.Factory{
			ChainManager:   n.chainManager,
			Validators:     vdrs,
			StakingEnabled: n.Config.EnableStaking,
			AVA:            avaAssetID,
			AVM:            createAVMTx.ID(),
		},
	)
	if err != nil {
		return err
	}

	genesisBytes, err := genesis.Genesis(n.Config.NetworkID)
	if err != nil {
		return err
	}

	// Create the Platform Chain
	n.chainManager.ForceCreateChain(chains.ChainParameters{
		ID:            ids.Empty,
		SubnetID:      platformvm.DefaultSubnetID,
		GenesisData:   genesisBytes, // Specifies other chains to create
		VMAlias:       platformvm.ID.String(),
		CustomBeacons: n.beacons,
	})

	return nil
}

// initAPIServer initializes the server that handles HTTP calls
func (n *Node) initAPIServer() {
	n.Log.Info("Initializing API server")

	n.APIServer.Initialize(n.Log, n.LogFactory, n.Config.HTTPHost, n.Config.HTTPPort)

	go n.Log.RecoverAndPanic(func() {
		if n.Config.EnableHTTPS {
			n.Log.Debug("Initializing API server with TLS Enabled")
			err := n.APIServer.DispatchTLS(n.Config.HTTPSCertFile, n.Config.HTTPSKeyFile)
			n.Log.Warn("Secure API server initialization failed with %s, attempting to create insecure API server", err)
		}

		n.Log.Debug("Initializing API server")
		err := n.APIServer.Dispatch()

		n.Log.Fatal("API server initialization failed with %s", err)
		n.Net.Close()
	})
}

// Assumes n.DB, n.vdrs all initialized (non-nil)
func (n *Node) initChainManager() {
	n.chainManager = chains.New(
		n.Config.EnableStaking,
		n.Log,
		n.LogFactory,
		n.vmManager,
		n.DecisionDispatcher,
		n.ConsensusDispatcher,
		n.DB,
		n.Config.ConsensusRouter,
		n.Net,
		n.Config.ConsensusParams,
		n.vdrs,
		n.ID,
		n.Config.NetworkID,
		&n.APIServer,
		&n.keystoreServer,
		&n.sharedMemory,
	)

	n.chainManager.AddRegistrant(&n.APIServer)
}

// initSharedMemory initializes the shared memory for cross chain interation
func (n *Node) initSharedMemory() {
	n.Log.Info("initializing SharedMemory")
	sharedMemoryDB := prefixdb.New([]byte("shared memory"), n.DB)
	n.sharedMemory.Initialize(n.Log, sharedMemoryDB)
}

// initKeystoreAPI initializes the keystore service
// Assumes n.APIServer is already set
func (n *Node) initKeystoreAPI() {
	n.Log.Info("initializing Keystore API")
	keystoreDB := prefixdb.New([]byte("keystore"), n.DB)
	n.keystoreServer.Initialize(n.Log, keystoreDB)
	keystoreHandler := n.keystoreServer.CreateHandler()
	if n.Config.KeystoreAPIEnabled {
		n.APIServer.AddRoute(keystoreHandler, &sync.RWMutex{}, "keystore", "", n.HTTPLog)
	}
}

// initMetricsAPI initializes the Metrics API
// Assumes n.APIServer is already set
func (n *Node) initMetricsAPI() {
	n.Log.Info("initializing Metrics API")
	registry, handler := metrics.NewService()
	if n.Config.MetricsAPIEnabled {
		n.APIServer.AddRoute(handler, &sync.RWMutex{}, "metrics", "", n.HTTPLog)
	}
	n.Config.ConsensusParams.Metrics = registry
}

// initAdminAPI initializes the Admin API service
// Assumes n.log, n.chainManager, and n.ValidatorAPI already initialized
func (n *Node) initAdminAPI() {
	if n.Config.AdminAPIEnabled {
		n.Log.Info("initializing Admin API")
		service := admin.NewService(Version, n.ID, n.Config.NetworkID, n.Log, n.chainManager, n.Net, &n.APIServer)
		n.APIServer.AddRoute(service, &sync.RWMutex{}, "admin", "", n.HTTPLog)
	}
}

func (n *Node) initInfoAPI() {
	if n.Config.InfoAPIEnabled {
		n.Log.Info("initializing Info API")
		service := info.NewService(n.Log, Version, n.ID, n.Config.NetworkID, n.chainManager, n.Net)
		n.APIServer.AddRoute(service, &sync.RWMutex{}, "info", "", n.HTTPLog)
	}
}

// initHealthAPI initializes the Health API service
// Assumes n.Log, n.ConsensusAPI, and n.ValidatorAPI already initialized
func (n *Node) initHealthAPI() {
	if !n.Config.HealthAPIEnabled {
		return
	}

	n.Log.Info("initializing Health API")
	service := health.NewService(n.Log)
	service.RegisterHeartbeat("network.validators.heartbeat", n.Net, 5*time.Minute)
	n.APIServer.AddRoute(service.Handler(), &sync.RWMutex{}, "health", "", n.HTTPLog)
}

// initIPCAPI initializes the IPC API service
// Assumes n.log and n.chainManager already initialized
func (n *Node) initIPCAPI() {
	if n.Config.IPCEnabled {
		n.Log.Info("initializing IPC API")
		service := ipcs.NewService(n.Log, n.chainManager, n.DecisionDispatcher, &n.APIServer)
		n.APIServer.AddRoute(service, &sync.RWMutex{}, "ipcs", "", n.HTTPLog)
	}
}

// Give chains and VMs aliases as specified by the genesis information
func (n *Node) initAliases() error {
	n.Log.Info("initializing aliases")
	defaultAliases, chainAliases, vmAliases, err := genesis.Aliases(n.Config.NetworkID)
	if err != nil {
		return err
	}

	for chainIDKey, aliases := range chainAliases {
		chainID := ids.NewID(chainIDKey)
		for _, alias := range aliases {
			if err := n.chainManager.Alias(chainID, alias); err != nil {
				return err
			}
		}
	}
	for vmIDKey, aliases := range vmAliases {
		vmID := ids.NewID(vmIDKey)
		for _, alias := range aliases {
			if err := n.vmManager.Alias(vmID, alias); err != nil {
				return err
			}
		}
	}
	for url, aliases := range defaultAliases {
		if err := n.APIServer.AddAliases(url, aliases...); err != nil {
			return err
		}
	}
	return nil
}

// Initialize this node
func (n *Node) Initialize(Config *Config, logger logging.Logger, logFactory logging.Factory) error {
	n.Log = logger
	n.LogFactory = logFactory
	n.Config = Config
	n.Log.Info("Gecko version is: %s", Version)

	httpLog, err := logFactory.MakeSubdir("http")
	if err != nil {
		return fmt.Errorf("problem initializing HTTP logger: %w", err)
	}
	n.HTTPLog = httpLog

	if err := n.initDatabase(); err != nil { // Set up the node's database
		return fmt.Errorf("problem initializing database: %w", err)
	}

	if err = n.initNodeID(); err != nil { // Derive this node's ID
		return fmt.Errorf("problem initializing staker ID: %w", err)
	}

	n.initBeacons()

	// Start HTTP APIs
	n.initAPIServer()   // Start the API Server
	n.initKeystoreAPI() // Start the Keystore API
	n.initMetricsAPI()  // Start the Metrics API

	// initialize shared memory
	n.initSharedMemory()

	if err = n.initNetworking(); err != nil { // Set up all networking
		return fmt.Errorf("problem initializing networking: %w", err)
	}

	if err := n.initVMManager(); err != nil { // Set up the vm manager
		return fmt.Errorf("problem initializing the VM manager: %w", err)
	}

	n.initEventDispatcher() // Set up the event dipatcher
	n.initChainManager()    // Set up the chain manager

	n.initAdminAPI()  // Start the Admin API
	n.initInfoAPI()   // Start the Info API
	n.initHealthAPI() // Start the Health API
	n.initIPCAPI()    // Start the IPC API

	if err := n.initAliases(); err != nil { // Set up aliases
		return err
	}
	return n.initChains() // Start the Platform chain
}

// Shutdown this node
func (n *Node) Shutdown() {
	n.Log.Info("shutting down the node")
	n.Net.Close()
	n.chainManager.Shutdown()
	utils.ClearSignals(n.nodeCloser)
	n.Log.Info("node shut down successfully")
}