package permissions

import (
	"encoding/json"
	"io/ioutil"
	"path/filepath"
	"os"
	"sync"

	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/eth"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/node"
	"github.com/ethereum/go-ethereum/cmd/utils"
	"github.com/ethereum/go-ethereum/raft"
	"gopkg.in/urfave/cli.v1"
)
const (
	PERMISSIONED_CONFIG = "permissioned-nodes.json"
	BLACKLIST_CONFIG = "disallowed-nodes.json"
	RAFT = "raft"
	ISTANBUL = "istanbul"
)

type NodeOperation uint8
const (
	NodeAdd NodeOperation = iota
	NodeDelete
)

// This function first adds the node list from permissioned-nodes.json to
// the permissiones contract deployed as a precompile via genesis.json
func QuorumPermissioning(ctx *cli.Context, stack *node.Node ) error {
	// Create a new ethclient to for interfacing with the contract
	stateReader, err := createEthClient(stack)
	if err != nil {
		log.Error ("Unable to create ethereum client for permissions check : ", "err" , err)
		return err
	}

	// check if permissioning contract is there at address. If not return from here
	if _ , err = NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader); err != nil {
		log.Error ("Permissions not enabled for the network : ", "err" , err)
		return nil
	}
	consensusEngine := ISTANBUL
	if ctx.GlobalBool(utils.RaftModeFlag.Name) {
		consensusEngine = RAFT
	} 
	// Monitors node addition and decativation from network
	manageNodePermissions(stack, stateReader, consensusEngine);

	// Monitors account level persmissions  update from smart contarct 
	manageAccountPermissions(stack, stateReader);

	return nil
}

// Create an RPC client for the contract interface
func createEthClient(stack *node.Node ) (*ethclient.Client, error){
	var e *eth.Ethereum
	if err := stack.Service(&e); err != nil {
		return nil, err
	}

	rpcClient, err := stack.Attach()
	if err != nil {
		return nil, err
	}
	return ethclient.NewClient(rpcClient), nil
}

// Manages node addition and decavtivation from network
func manageNodePermissions(stack *node.Node, stateReader *ethclient.Client, consensusEngine string) {
	//monitor for new nodes addition via smart contract
	go monitorNewNodeAdd(stack, stateReader)

	//monitor for nodes deletiin via smart contract
	go monitorNodeDeactivation(stack, stateReader)

	//monitor for nodes blacklisting via smart contract
	go monitorNodeBlacklisting(stack, stateReader, consensusEngine)
}

// This functions listens on the channel for new node approval via smart contract and
// adds the same into permissioned-nodes.json
func monitorNewNodeAdd(stack *node.Node, stateReader *ethclient.Client) {
	permissions, err := NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader)
	if err != nil {
		log.Error ("failed to monitor new node add : ", "err" , err)
	}
	datadir := stack.DataDir()

	ch := make(chan *PermissionsNodeApproved, 1)

	opts := &bind.WatchOpts{}
	var blockNumber uint64 = 1
	opts.Start = &blockNumber
	var nodeAddEvent *PermissionsNodeApproved 

	_, err = permissions.WatchNodeApproved(opts, ch)
	if err != nil {
		log.Info("Failed WatchNodeApproved: %v", err)
	}

	for {
		select {
		case nodeAddEvent = <-ch:
			updatePermissionedNodes(nodeAddEvent.EnodeId, nodeAddEvent.IpAddrPort, nodeAddEvent.DiscPort, nodeAddEvent.RaftPort, datadir, NodeAdd)
		}
    }
}

// This functions listens on the channel for new node approval via smart contract and
// adds the same into permissioned-nodes.json
func monitorNodeDeactivation(stack *node.Node, stateReader *ethclient.Client) {
	permissions, err := NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader)
	if err != nil {
		log.Error ("Failed to monitor node delete: ", "err" , err)
	}
	datadir := stack.DataDir()

	ch := make(chan *PermissionsNodeDeactivated)

	opts := &bind.WatchOpts{}
	var blockNumber uint64 = 1
	opts.Start = &blockNumber
	var newNodeDeleteEvent *PermissionsNodeDeactivated 

	_, err = permissions.WatchNodeDeactivated(opts, ch)
	if err != nil {
		log.Info("Failed NodeDeactivated: %v", err)
	}

	for {
		select {
		case newNodeDeleteEvent = <-ch:
			updatePermissionedNodes(newNodeDeleteEvent.EnodeId, newNodeDeleteEvent.IpAddrPort, newNodeDeleteEvent.DiscPort, newNodeDeleteEvent.RaftPort, datadir, NodeDelete)
	  }

	}
}

// This function listnes on the channel for any node blacklisting event via smart contract
// and adds the same disallowed-nodes.json
func monitorNodeBlacklisting(stack *node.Node, stateReader *ethclient.Client, consensusEngine string) {
	permissions, err := NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader)
	if err != nil {
		log.Error ("failed to monitor new node add : ", "err" , err)
	}
	ch := make(chan *PermissionsNodeBlacklisted, 1)

	opts := &bind.WatchOpts{}
	var blockNumber uint64 = 1
	opts.Start = &blockNumber
	var nodeBlacklistEvent *PermissionsNodeBlacklisted 

	_, err = permissions.WatchNodeBlacklisted(opts, ch)
	if err != nil {
		log.Info("Failed WatchNodeBlacklisted: %v", err)
	}

	for {
		select {
		case nodeBlacklistEvent = <-ch:
			updateDisallowedNodes(nodeBlacklistEvent, stack, consensusEngine)
		}
    }
}

//this function populates the new node information into the permissioned-nodes.json file
func updatePermissionedNodes(enodeId , ipAddrPort, discPort, raftPort, dataDir string, operation NodeOperation){
	log.Debug("updatePermissionedNodes", "DataDir", dataDir, "file", PERMISSIONED_CONFIG)

	path := filepath.Join(dataDir, PERMISSIONED_CONFIG)
	if _, err := os.Stat(path); err != nil {
		log.Error("Read Error for permissioned-nodes.json file. This is because 'permissioned' flag is specified but no permissioned-nodes.json file is present.", "err", err)
		return 
	}
	// Load the nodes from the config file
	blob, err := ioutil.ReadFile(path)
	if err != nil {
		log.Error("updatePermissionedNodes: Failed to access permissioned-nodes.json", "err", err)
		return
	}

	nodelist := []string{}
	if err := json.Unmarshal(blob, &nodelist); err != nil {
		log.Error("updatePermissionedNodes: Failed to load nodes list", "err", err)
		return 
	}
	newEnodeId := "enode://" + enodeId + "@" + ipAddrPort + "?discPort=" + discPort + "&raftport=" + raftPort

	if (operation == NodeAdd){
		nodelist = append(nodelist, newEnodeId)
	} else {
		index := 0
		for i, enodeId := range nodelist {
			if (enodeId == newEnodeId){
				index = i
				break
			}
		}
		nodelist = append(nodelist[:index], nodelist[index+1:]...)
	}

	mu := sync.RWMutex{}
	blob, _ = json.Marshal(nodelist)

	mu.Lock()
	if err:= ioutil.WriteFile(path, blob, 0644); err!= nil{
		log.Error("updatePermissionedNodes: Error writing new node info to file", "err", err)
	}
	mu.Unlock()
}

//this function populates the new node information into the permissioned-nodes.json file
func updateDisallowedNodes(nodeBlacklistEvent *PermissionsNodeBlacklisted, stack *node.Node, consensusEngine string){
	dataDir := stack.DataDir()
	log.Debug("updateDisallowedNodes", "DataDir", dataDir, "file", BLACKLIST_CONFIG)

	fileExisted := true
	path := filepath.Join(dataDir, BLACKLIST_CONFIG)
	// Check if the file is existing. If the file is not existing create the file
	if _, err := os.Stat(path); err != nil {
		log.Error("Read Error for disallowed-nodes.json file." , "err", err)
		if _, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0644); err != nil {
			log.Error("Failed to create disallowed-nodes.json file ", "err", err)
			return 
		}
		fileExisted = false
	}

	nodelist := []string{}
	// Load the nodes from the config file
	if fileExisted == true {
		blob, err := ioutil.ReadFile(path)
		if err != nil {
			log.Error("updateDisallowedNodes Failed to access disallowed-nodes.json", "err", err)
			return
		}
		if (blob != nil) {
			if err := json.Unmarshal(blob, &nodelist); err != nil {
				log.Error("updateDisallowedNodes: Failed to load nodes list", "err", err)
				return 
			}
		}
	}
	newEnodeId := "enode://" + nodeBlacklistEvent.EnodeId + "@" + nodeBlacklistEvent.IpAddrPort + "?discPort=" + nodeBlacklistEvent.DiscPort + "&raftport=" + nodeBlacklistEvent.RaftPort

	nodelist = append(nodelist, newEnodeId)

	mu := sync.RWMutex{}
	blob, _ := json.Marshal(nodelist)
	mu.Lock()
	if err:= ioutil.WriteFile(path, blob, 0644); err!= nil{
		log.Error("updateDisallowedNodes: Error writing new node info to file", "err", err)
	}
	mu.Unlock()

	// Disconnect the peer if it is already connected
	if consensusEngine == RAFT {
		var raftService *raft.RaftService
		if err := stack.Service(&raftService); err == nil {
			raftApi := raft.NewPublicRaftAPI(raftService)

			//get the raftId for the given enodeId
			raftId, err := raftApi.GetRaftId(newEnodeId)
			if err == nil {
				raftApi.RemovePeer(raftId)
			}
		}
	}
}

// Manages account level permissions update
func manageAccountPermissions(stack *node.Node, stateReader *ethclient.Client) error {
	//call populate nodes to populate the nodes into contract
	if err := populateAcctPermissions (stack, stateReader); err != nil {
		return err;
	}
	//monitor for nodes deletiin via smart contract
	go monitorAccountPermissions(stack, stateReader)
	return nil
}

// populates the nodes list from permissioned-nodes.json into the permissions
// smart contract
func populateAcctPermissions(stack *node.Node, stateReader *ethclient.Client) error{
	permissions, err := NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader)
	if err != nil {
		log.Error ("Failed to monitor node delete: ", "err" , err)
		return err
	}

	opts := &bind.FilterOpts{}
	pastEvents, err := permissions.FilterAccountAccessModified(opts)

	recExists := true
	for recExists {
		recExists = pastEvents.Next()
		if recExists {
			types.AddAccountAccess(pastEvents.Event.Address, pastEvents.Event.Access)
		}
	}
	return nil
}


// Monitors permissions changes at acount level and uodate the global permissions
// map with the same
func monitorAccountPermissions(stack *node.Node, stateReader *ethclient.Client) {
	permissions, err := NewPermissionsFilterer(params.QuorumPermissionsContract, stateReader)
	if err != nil {
		log.Error ("Failed to monitor Account permissions : ", "err" , err)
	}
	ch := make(chan *PermissionsAccountAccessModified)

	opts := &bind.WatchOpts{}
	var blockNumber uint64 = 1
	opts.Start = &blockNumber
	var newEvent *PermissionsAccountAccessModified

	_, err = permissions.WatchAccountAccessModified(opts, ch)
	if err != nil {
		log.Info("Failed NewNodeProposed: %v", err)
	}

	for {
		select {
		case newEvent = <-ch:
			types.AddAccountAccess(newEvent.Address, newEvent.Access)
		}
    }
}