package geth

/*
#include <stddef.h>
#include <stdbool.h>
extern bool StatusServiceSignalEvent( const char *jsonEvent );
*/
import "C"
import (
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"path/filepath"
	"runtime"
	"sync"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/cmd/utils"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/les"
	"github.com/ethereum/go-ethereum/logger"
	"github.com/ethereum/go-ethereum/logger/glog"
	"github.com/ethereum/go-ethereum/node"
	"github.com/ethereum/go-ethereum/p2p/discover"
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/rpc"
	"github.com/ethereum/go-ethereum/whisper"
	"gopkg.in/urfave/cli.v1"
)

const (
	clientIdentifier = "Geth"     // Client identifier to advertise over the network
	versionMajor     = 1          // Major version component of the current release
	versionMinor     = 5          // Minor version component of the current release
	versionPatch     = 0          // Patch version component of the current release
	versionMeta      = "unstable" // Version metadata to append to the version string

	RPCPort = 8545 // RPC port (replaced in unit tests)

	EventNodeStarted = "node.started"
)

var (
	ErrDataDirPreprocessingFailed  = errors.New("failed to pre-process data directory")
	ErrInvalidGethNode             = errors.New("no running geth node detected")
	ErrInvalidAccountManager       = errors.New("could not retrieve account manager")
	ErrInvalidWhisperService       = errors.New("whisper service is unavailable")
	ErrInvalidLightEthereumService = errors.New("can not retrieve LES service")
	ErrInvalidClient               = errors.New("RPC client is not properly initialized")
	ErrInvalidJailedRequestQueue   = errors.New("Jailed request queue is not properly initialized")
	ErrNodeStartFailure            = errors.New("could not create the in-memory node object")
)

type SelectedExtKey struct {
	Address     common.Address
	AccountKey  *accounts.Key
	SubAccounts []accounts.Account
}

type NodeManager struct {
	currentNode        *node.Node          // currently running geth node
	ctx                *cli.Context        // the CLI context used to start the geth node
	lightEthereum      *les.LightEthereum  // LES service
	accountManager     *accounts.Manager   // the account manager attached to the currentNode
	jailedRequestQueue *JailedRequestQueue // bridge via which jail notifies node of incoming requests
	SelectedAccount    *SelectedExtKey     // account that was processed during the last call to SelectAccount()
	whisperService     *whisper.Whisper    // Whisper service
	client             *rpc.Client         // RPC client
	nodeStarted        chan struct{}       // channel to wait for node to start
}

var (
	UseTestnet          = "true" // can be overridden via -ldflags '-X geth.UseTestnet'
	nodeManagerInstance *NodeManager
	createOnce          sync.Once
)

func NewNodeManager(datadir string, rpcport int) *NodeManager {
	createOnce.Do(func() {
		nodeManagerInstance = &NodeManager{
			jailedRequestQueue: NewJailedRequestsQueue(),
		}
		nodeManagerInstance.MakeNode(datadir, rpcport)
	})

	return nodeManagerInstance
}

func GetNodeManager() *NodeManager {
	return nodeManagerInstance
}

// createAndStartNode creates a node entity and starts the
// node running locally exposing given RPC port
func CreateAndRunNode(datadir string, rpcport int) error {
	nodeManager := NewNodeManager(datadir, rpcport)

	if nodeManager.HasNode() {
		nodeManager.RunNode()

		<-nodeManager.nodeStarted // block until node is ready
		return nil
	}

	return ErrNodeStartFailure
}

// MakeNode create a geth node entity
func (m *NodeManager) MakeNode(datadir string, rpcport int) *node.Node {
	// TODO remove admin rpcapi flag
	set := flag.NewFlagSet("test", 0)
	set.Bool("lightkdf", true, "Reduce key-derivation RAM & CPU usage at some expense of KDF strength")
	set.Bool("shh", true, "whisper")
	set.Bool("light", true, "disable eth")
	if UseTestnet == "true" {
		set.Bool("testnet", true, "light test network")
	}
	set.Bool("rpc", true, "enable rpc")
	set.String("rpcaddr", "localhost", "host for RPC")
	set.Int("rpcport", rpcport, "rpc port")
	set.String("rpccorsdomain", "*", "allow all domains")
	set.String("verbosity", "3", "verbosity level")
	set.String("rpcapi", "db,eth,net,web3,shh,personal,admin", "rpc api(s)")
	set.String("datadir", datadir, "data directory for geth")
	set.String("logdir", datadir, "log dir for glog")
	m.ctx = cli.NewContext(nil, set, nil)

	utils.DebugSetup(m.ctx)

	// create node and start requested protocols
	m.currentNode = utils.MakeNode(m.ctx, clientIdentifier, "")
	utils.RegisterEthService(m.ctx, m.currentNode, makeDefaultExtra())

	// Whisper must be explicitly enabled, but is auto-enabled in --dev mode.
	shhEnabled := m.ctx.GlobalBool(utils.WhisperEnabledFlag.Name)
	shhAutoEnabled := !m.ctx.GlobalIsSet(utils.WhisperEnabledFlag.Name) && m.ctx.GlobalIsSet(utils.DevModeFlag.Name)
	if shhEnabled || shhAutoEnabled {
		utils.RegisterShhService(m.currentNode)
	}

	m.accountManager = m.currentNode.AccountManager()
	m.nodeStarted = make(chan struct{})

	return m.currentNode
}

// StartNode starts a geth node entity
func (m *NodeManager) RunNode() {
	go func() {
		utils.StartNode(m.currentNode)

		if m.currentNode.AccountManager() == nil {
			glog.V(logger.Warn).Infoln("cannot get account manager")
		}
		if err := m.currentNode.Service(&m.whisperService); err != nil {
			glog.V(logger.Warn).Infoln("cannot get whisper service:", err)
		}
		if err := m.currentNode.Service(&m.lightEthereum); err != nil {
			glog.V(logger.Warn).Infoln("cannot get light ethereum service:", err)
		}

		// setup handlers
		m.lightEthereum.StatusBackend.SetTransactionQueueHandler(onSendTransactionRequest)
		m.lightEthereum.StatusBackend.SetAccountsFilterHandler(onAccountsListRequest)
		m.lightEthereum.StatusBackend.SetTransactionReturnHandler(onSendTransactionReturn)

		var err error
		m.client, err = m.currentNode.Attach()
		if err != nil {
			glog.V(logger.Warn).Infoln("cannot get RPC client service:", ErrInvalidClient)
		}

		// @TODO Remove after LES supports discover out of box
		m.populateStaticPeers()

		m.onNodeStarted() // node started, notify listeners
		m.currentNode.Wait()
	}()
}

func (m *NodeManager) onNodeStarted() {
	// notify local listener
	m.nodeStarted <- struct{}{}
	close(m.nodeStarted)

	// send signal up to native app
	event := GethEvent{
		Type:  EventNodeStarted,
		Event: struct{}{},
	}

	body, _ := json.Marshal(&event)
	C.StatusServiceSignalEvent(C.CString(string(body)))
}

func (m *NodeManager) AddPeer(url string) (bool, error) {
	if m == nil || !m.HasNode() {
		return false, ErrInvalidGethNode
	}

	server := m.currentNode.Server()
	if server == nil {
		return false, errors.New("node not started")
	}
	// Try to add the url as a static peer and return
	parsedNode, err := discover.ParseNode(url)
	if err != nil {
		return false, fmt.Errorf("invalid enode: %v", err)
	}
	server.AddPeer(parsedNode)

	return true, nil
}

func (m *NodeManager) HasNode() bool {
	return m != nil && m.currentNode != nil
}

func (m *NodeManager) HasAccountManager() bool {
	return m.accountManager != nil
}

func (m *NodeManager) AccountManager() (*accounts.Manager, error) {
	if m == nil || !m.HasNode() {
		return nil, ErrInvalidGethNode
	}

	if !m.HasAccountManager() {
		return nil, ErrInvalidAccountManager
	}

	return m.accountManager, nil
}

func (m *NodeManager) HasWhisperService() bool {
	return m.whisperService != nil
}

func (m *NodeManager) WhisperService() (*whisper.Whisper, error) {
	if m == nil || !m.HasNode() {
		return nil, ErrInvalidGethNode
	}

	if !m.HasWhisperService() {
		return nil, ErrInvalidWhisperService
	}

	return m.whisperService, nil
}

func (m *NodeManager) HasLightEthereumService() bool {
	return m.lightEthereum != nil
}

func (m *NodeManager) LightEthereumService() (*les.LightEthereum, error) {
	if m == nil || !m.HasNode() {
		return nil, ErrInvalidGethNode
	}

	if !m.HasLightEthereumService() {
		return nil, ErrInvalidLightEthereumService
	}

	return m.lightEthereum, nil
}

func (m *NodeManager) HasRPCClient() bool {
	return m.client != nil
}

func (m *NodeManager) RPCClient() (*rpc.Client, error) {
	if m == nil || !m.HasNode() {
		return nil, ErrInvalidGethNode
	}

	if !m.HasRPCClient() {
		return nil, ErrInvalidClient
	}

	return m.client, nil
}

func (m *NodeManager) HasJailedRequestQueue() bool {
	return m.jailedRequestQueue != nil
}

func (m *NodeManager) JailedRequestQueue() (*JailedRequestQueue, error) {
	if m == nil || !m.HasNode() {
		return nil, ErrInvalidGethNode
	}

	if !m.HasJailedRequestQueue() {
		return nil, ErrInvalidJailedRequestQueue
	}

	return m.jailedRequestQueue, nil
}

func makeDefaultExtra() []byte {
	var clientInfo = struct {
		Version   uint
		Name      string
		GoVersion string
		Os        string
	}{uint(versionMajor<<16 | versionMinor<<8 | versionPatch), clientIdentifier, runtime.Version(), runtime.GOOS}
	extra, err := rlp.EncodeToBytes(clientInfo)
	if err != nil {
		glog.V(logger.Warn).Infoln("error setting canonical miner information:", err)
	}

	if uint64(len(extra)) > params.MaximumExtraDataSize.Uint64() {
		glog.V(logger.Warn).Infoln("error setting canonical miner information: extra exceeds", params.MaximumExtraDataSize)
		glog.V(logger.Debug).Infof("extra: %x\n", extra)
		return nil
	}

	return extra
}

func (m *NodeManager) populateStaticPeers() {
	// manually add static nodes (LES auto-discovery is not stable yet)
	configFile, err := ioutil.ReadFile(filepath.Join("../data", "static-nodes.json"))
	if err != nil {
		return
	}
	var enodes []string
	if err = json.Unmarshal(configFile, &enodes); err != nil {
		return
	}

	for _, enode := range enodes {
		m.AddPeer(enode)
	}
}