// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package node

import (
	"crypto/ecdsa"
	"fmt"
	"io/ioutil"
	"net"
	"os"
	"path/filepath"
	"runtime"
	"strings"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/accounts/keystore"
	"github.com/ethereum/go-ethereum/accounts/usbwallet"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/p2p/discover"
	"github.com/ethereum/go-ethereum/p2p/discv5"
	"github.com/ethereum/go-ethereum/p2p/nat"
	"github.com/ethereum/go-ethereum/p2p/netutil"
)

var (
	datadirPrivateKey      = "nodekey"            // Path within the datadir to the node's private key
	datadirDefaultKeyStore = "keystore"           // Path within the datadir to the keystore
	datadirStaticNodes     = "static-nodes.json"  // Path within the datadir to the static node list
	datadirTrustedNodes    = "trusted-nodes.json" // Path within the datadir to the trusted node list
	datadirNodeDatabase    = "nodes"              // Path within the datadir to store the node infos
)

// Config represents a small collection of configuration values to fine tune the
// P2P network layer of a protocol stack. These values can be further extended by
// all registered services.
type Config struct {
	// Name sets the instance name of the node. It must not contain the / character and is
	// used in the devp2p node identifier. The instance name of geth is "geth". If no
	// value is specified, the basename of the current executable is used.
	Name string

	// UserIdent, if set, is used as an additional component in the devp2p node identifier.
	UserIdent string

	// Version should be set to the version number of the program. It is used
	// in the devp2p node identifier.
	Version string

	// DataDir is the file system folder the node should use for any data storage
	// requirements. The configured data directory will not be directly shared with
	// registered services, instead those can use utility methods to create/access
	// databases or flat files. This enables ephemeral nodes which can fully reside
	// in memory.
	DataDir string

	// KeyStoreDir is the file system folder that contains private keys. The directory can
	// be specified as a relative path, in which case it is resolved relative to the
	// current directory.
	//
	// If KeyStoreDir is empty, the default location is the "keystore" subdirectory of
	// DataDir. If DataDir is unspecified and KeyStoreDir is empty, an ephemeral directory
	// is created by New and destroyed when the node is stopped.
	KeyStoreDir string

	// UseLightweightKDF lowers the memory and CPU requirements of the key store
	// scrypt KDF at the expense of security.
	UseLightweightKDF bool

	// IPCPath is the requested location to place the IPC endpoint. If the path is
	// a simple file name, it is placed inside the data directory (or on the root
	// pipe path on Windows), whereas if it's a resolvable path name (absolute or
	// relative), then that specific path is enforced. An empty path disables IPC.
	IPCPath string

	// This field should be a valid secp256k1 private key that will be used for both
	// remote peer identification as well as network traffic encryption. If no key
	// is configured, the preset one is loaded from the data dir, generating it if
	// needed.
	PrivateKey *ecdsa.PrivateKey

	// NoDiscovery specifies whether the peer discovery mechanism should be started
	// or not. Disabling is usually useful for protocol debugging (manual topology).
	NoDiscovery bool

	// DiscoveryV5 specifies whether the the new topic-discovery based V5 discovery
	// protocol should be started or not.
	DiscoveryV5 bool

	// Listener address for the V5 discovery protocol UDP traffic.
	DiscoveryV5Addr string

	// Restrict communication to white listed IP networks.
	// The whitelist only applies when non-nil.
	NetRestrict *netutil.Netlist

	// BootstrapNodes used to establish connectivity with the rest of the network.
	BootstrapNodes []*discover.Node

	// BootstrapNodesV5 used to establish connectivity with the rest of the network
	// using the V5 discovery protocol.
	BootstrapNodesV5 []*discv5.Node

	// Network interface address on which the node should listen for inbound peers.
	ListenAddr string

	// If set to a non-nil value, the given NAT port mapper is used to make the
	// listening port available to the Internet.
	NAT nat.Interface

	// If Dialer is set to a non-nil value, the given Dialer is used to dial outbound
	// peer connections.
	Dialer *net.Dialer

	// If NoDial is true, the node will not dial any peers.
	NoDial bool

	// MaxPeers is the maximum number of peers that can be connected. If this is
	// set to zero, then only the configured static and trusted peers can connect.
	MaxPeers int

	// MaxPendingPeers is the maximum number of peers that can be pending in the
	// handshake phase, counted separately for inbound and outbound connections.
	// Zero defaults to preset values.
	MaxPendingPeers int

	// HTTPHost is the host interface on which to start the HTTP RPC server. If this
	// field is empty, no HTTP API endpoint will be started.
	HTTPHost string

	// HTTPPort is the TCP port number on which to start the HTTP RPC server. The
	// default zero value is/ valid and will pick a port number randomly (useful
	// for ephemeral nodes).
	HTTPPort int

	// HTTPCors is the Cross-Origin Resource Sharing header to send to requesting
	// clients. Please be aware that CORS is a browser enforced security, it's fully
	// useless for custom HTTP clients.
	HTTPCors string

	// HTTPModules is a list of API modules to expose via the HTTP RPC interface.
	// If the module list is empty, all RPC API endpoints designated public will be
	// exposed.
	HTTPModules []string

	// WSHost is the host interface on which to start the websocket RPC server. If
	// this field is empty, no websocket API endpoint will be started.
	WSHost string

	// WSPort is the TCP port number on which to start the websocket RPC server. The
	// default zero value is/ valid and will pick a port number randomly (useful for
	// ephemeral nodes).
	WSPort int

	// WSOrigins is the list of domain to accept websocket requests from. Please be
	// aware that the server can only act upon the HTTP request the client sends and
	// cannot verify the validity of the request header.
	WSOrigins string

	// WSModules is a list of API modules to expose via the websocket RPC interface.
	// If the module list is empty, all RPC API endpoints designated public will be
	// exposed.
	WSModules []string
}

// IPCEndpoint resolves an IPC endpoint based on a configured value, taking into
// account the set data folders as well as the designated platform we're currently
// running on.
func (c *Config) IPCEndpoint() string {
	// Short circuit if IPC has not been enabled
	if c.IPCPath == "" {
		return ""
	}
	// On windows we can only use plain top-level pipes
	if runtime.GOOS == "windows" {
		if strings.HasPrefix(c.IPCPath, `\\.\pipe\`) {
			return c.IPCPath
		}
		return `\\.\pipe\` + c.IPCPath
	}
	// Resolve names into the data directory full paths otherwise
	if filepath.Base(c.IPCPath) == c.IPCPath {
		if c.DataDir == "" {
			return filepath.Join(os.TempDir(), c.IPCPath)
		}
		return filepath.Join(c.DataDir, c.IPCPath)
	}
	return c.IPCPath
}

// NodeDB returns the path to the discovery node database.
func (c *Config) NodeDB() string {
	if c.DataDir == "" {
		return "" // ephemeral
	}
	return c.resolvePath("nodes")
}

// DefaultIPCEndpoint returns the IPC path used by default.
func DefaultIPCEndpoint(clientIdentifier string) string {
	if clientIdentifier == "" {
		clientIdentifier = strings.TrimSuffix(filepath.Base(os.Args[0]), ".exe")
		if clientIdentifier == "" {
			panic("empty executable name")
		}
	}
	config := &Config{DataDir: DefaultDataDir(), IPCPath: clientIdentifier + ".ipc"}
	return config.IPCEndpoint()
}

// HTTPEndpoint resolves an HTTP endpoint based on the configured host interface
// and port parameters.
func (c *Config) HTTPEndpoint() string {
	if c.HTTPHost == "" {
		return ""
	}
	return fmt.Sprintf("%s:%d", c.HTTPHost, c.HTTPPort)
}

// DefaultHTTPEndpoint returns the HTTP endpoint used by default.
func DefaultHTTPEndpoint() string {
	config := &Config{HTTPHost: DefaultHTTPHost, HTTPPort: DefaultHTTPPort}
	return config.HTTPEndpoint()
}

// WSEndpoint resolves an websocket endpoint based on the configured host interface
// and port parameters.
func (c *Config) WSEndpoint() string {
	if c.WSHost == "" {
		return ""
	}
	return fmt.Sprintf("%s:%d", c.WSHost, c.WSPort)
}

// DefaultWSEndpoint returns the websocket endpoint used by default.
func DefaultWSEndpoint() string {
	config := &Config{WSHost: DefaultWSHost, WSPort: DefaultWSPort}
	return config.WSEndpoint()
}

// NodeName returns the devp2p node identifier.
func (c *Config) NodeName() string {
	name := c.name()
	// Backwards compatibility: previous versions used title-cased "Geth", keep that.
	if name == "geth" || name == "geth-testnet" {
		name = "Geth"
	}
	if c.UserIdent != "" {
		name += "/" + c.UserIdent
	}
	if c.Version != "" {
		name += "/v" + c.Version
	}
	name += "/" + runtime.GOOS
	name += "/" + runtime.Version()
	return name
}

func (c *Config) name() string {
	if c.Name == "" {
		progname := strings.TrimSuffix(filepath.Base(os.Args[0]), ".exe")
		if progname == "" {
			panic("empty executable name, set Config.Name")
		}
		return progname
	}
	return c.Name
}

// These resources are resolved differently for "geth" instances.
var isOldGethResource = map[string]bool{
	"chaindata":          true,
	"nodes":              true,
	"nodekey":            true,
	"static-nodes.json":  true,
	"trusted-nodes.json": true,
}

// resolvePath resolves path in the instance directory.
func (c *Config) resolvePath(path string) string {
	if filepath.IsAbs(path) {
		return path
	}
	if c.DataDir == "" {
		return ""
	}
	// Backwards-compatibility: ensure that data directory files created
	// by geth 1.4 are used if they exist.
	if c.name() == "geth" && isOldGethResource[path] {
		oldpath := ""
		if c.Name == "geth" {
			oldpath = filepath.Join(c.DataDir, path)
		}
		if oldpath != "" && common.FileExist(oldpath) {
			// TODO: print warning
			return oldpath
		}
	}
	return filepath.Join(c.instanceDir(), path)
}

func (c *Config) instanceDir() string {
	if c.DataDir == "" {
		return ""
	}
	return filepath.Join(c.DataDir, c.name())
}

// NodeKey retrieves the currently configured private key of the node, checking
// first any manually set key, falling back to the one found in the configured
// data folder. If no key can be found, a new one is generated.
func (c *Config) NodeKey() *ecdsa.PrivateKey {
	// Use any specifically configured key.
	if c.PrivateKey != nil {
		return c.PrivateKey
	}
	// Generate ephemeral key if no datadir is being used.
	if c.DataDir == "" {
		key, err := crypto.GenerateKey()
		if err != nil {
			log.Crit(fmt.Sprintf("Failed to generate ephemeral node key: %v", err))
		}
		return key
	}

	keyfile := c.resolvePath(datadirPrivateKey)
	if key, err := crypto.LoadECDSA(keyfile); err == nil {
		return key
	}
	// No persistent key found, generate and store a new one.
	key, err := crypto.GenerateKey()
	if err != nil {
		log.Crit(fmt.Sprintf("Failed to generate node key: %v", err))
	}
	instanceDir := filepath.Join(c.DataDir, c.name())
	if err := os.MkdirAll(instanceDir, 0700); err != nil {
		log.Error(fmt.Sprintf("Failed to persist node key: %v", err))
		return key
	}
	keyfile = filepath.Join(instanceDir, datadirPrivateKey)
	if err := crypto.SaveECDSA(keyfile, key); err != nil {
		log.Error(fmt.Sprintf("Failed to persist node key: %v", err))
	}
	return key
}

// StaticNodes returns a list of node enode URLs configured as static nodes.
func (c *Config) StaticNodes() []*discover.Node {
	return c.parsePersistentNodes(c.resolvePath(datadirStaticNodes))
}

// TrusterNodes returns a list of node enode URLs configured as trusted nodes.
func (c *Config) TrusterNodes() []*discover.Node {
	return c.parsePersistentNodes(c.resolvePath(datadirTrustedNodes))
}

// parsePersistentNodes parses a list of discovery node URLs loaded from a .json
// file from within the data directory.
func (c *Config) parsePersistentNodes(path string) []*discover.Node {
	// Short circuit if no node config is present
	if c.DataDir == "" {
		return nil
	}
	if _, err := os.Stat(path); err != nil {
		return nil
	}
	// Load the nodes from the config file.
	var nodelist []string
	if err := common.LoadJSON(path, &nodelist); err != nil {
		log.Error(fmt.Sprintf("Can't load node file %s: %v", path, err))
		return nil
	}
	// Interpret the list as a discovery node array
	var nodes []*discover.Node
	for _, url := range nodelist {
		if url == "" {
			continue
		}
		node, err := discover.ParseNode(url)
		if err != nil {
			log.Error(fmt.Sprintf("Node URL %s: %v\n", url, err))
			continue
		}
		nodes = append(nodes, node)
	}
	return nodes
}

func makeAccountManager(conf *Config) (*accounts.Manager, string, error) {
	scryptN := keystore.StandardScryptN
	scryptP := keystore.StandardScryptP
	if conf.UseLightweightKDF {
		scryptN = keystore.LightScryptN
		scryptP = keystore.LightScryptP
	}

	var (
		keydir    string
		ephemeral string
		err       error
	)
	switch {
	case filepath.IsAbs(conf.KeyStoreDir):
		keydir = conf.KeyStoreDir
	case conf.DataDir != "":
		if conf.KeyStoreDir == "" {
			keydir = filepath.Join(conf.DataDir, datadirDefaultKeyStore)
		} else {
			keydir, err = filepath.Abs(conf.KeyStoreDir)
		}
	case conf.KeyStoreDir != "":
		keydir, err = filepath.Abs(conf.KeyStoreDir)
	default:
		// There is no datadir.
		keydir, err = ioutil.TempDir("", "go-ethereum-keystore")
		ephemeral = keydir
	}
	if err != nil {
		return nil, "", err
	}
	if err := os.MkdirAll(keydir, 0700); err != nil {
		return nil, "", err
	}
	// Assemble the account manager and supported backends
	backends := []accounts.Backend{
		keystore.NewKeyStore(keydir, scryptN, scryptP),
	}
	if ledgerhub, err := usbwallet.NewLedgerHub(); err != nil {
		log.Warn(fmt.Sprintf("Failed to start Ledger hub, disabling: %v", err))
	} else {
		backends = append(backends, ledgerhub)
	}
	return accounts.NewManager(backends...), ephemeral, nil
}