go-ethereum/p2p/simulations/session_controller.go

package simulations

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"reflect"
	"sync"
	"time"

	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/logger/glog"
	"github.com/ethereum/go-ethereum/p2p/discover"
)

type returnHandler func(io.Reader) (io.ReadSeeker, error)

type ResourceHandler struct {
	Handle func(interface{}, *ResourceController) (interface{}, error)
	Type   reflect.Type
}

type ResourceHandlers struct {
	Create, Retrieve, Update, Destroy *ResourceHandler
}

type ResourceController struct {
	lock        sync.Mutex
	controllers map[string]Controller
	id          int
	methods     []string
	*ResourceHandlers
}

var methodsAvailable = []string{"POST", "GET", "PUT", "DELETE"}

func (self *ResourceHandlers) handler(method string) *ResourceHandler {
	var h *ResourceHandler
	switch method {
	case "POST":
		h = self.Create
	case "GET":
		h = self.Retrieve
	case "PUT":
		h = self.Update
	case "DELETE":
		h = self.Destroy
	}
	return h
}

func NewResourceContoller(c *ResourceHandlers) *ResourceController {
	var methods []string
	for _, method := range methodsAvailable {
		if c.handler(method) != nil {
			methods = append(methods, method)
		}
	}
	return &ResourceController{
		ResourceHandlers: c,
		controllers:      make(map[string]Controller),
		methods:          methods,
	}
}

func NewSessionController() (*ResourceController, chan bool) {
	quitc := make(chan bool)
	return NewResourceContoller(
		&ResourceHandlers{

			Create: &ResourceHandler{
				Handle: func(msg interface{}, parent *ResourceController) (interface{}, error) {
					// TODO: take config for type of network
					eventer := &event.TypeMux{}
					ticker := time.NewTicker(1000 * time.Millisecond)
					journal := NewJournal(eventer, &Entry{})

					m := NewMockNetworkController(journal, func() { ticker.Stop() })
					if parent != nil {
						parent.SetResource(fmt.Sprintf("%d", parent.id), m)
					}
					go MockNetwork(eventer, ticker.C)
					parent.id++
					return m, nil
				},
			},

			Destroy: &ResourceHandler{
				Handle: func(msg interface{}, parent *ResourceController) (interface{}, error) {
					glog.V(6).Infof("destroy handler called")
					// this can quit the entire app (shut down the backend server)
					quitc <- true
					return nil, nil
				},
			},
		},
	), quitc
}

func (self *ResourceController) Handle(method string) (returnHandler, error) {
	h := self.handler(method)
	if h == nil {
		return nil, fmt.Errorf("allowed methods: %v", self.methods)
	}
	glog.V(6).Infof("get handler callback for method %v", method)
	rh := func(r io.Reader) (io.ReadSeeker, error) {
		input, err := ioutil.ReadAll(r)
		if err != nil {
			glog.V(6).Infof("reading json body: %v", err)
			return nil, err
		}
		glog.V(6).Infof("decode json request body")
		var arg interface{}
		if h.Type != nil {
			val := reflect.New(h.Type)
			req := val.Elem()
			req.Set(reflect.Zero(h.Type))
			err = json.Unmarshal(input, val.Interface())
			if err != nil {
				return nil, err
			}
			arg = req.Interface()
		}
		glog.V(6).Infof("calling handler")
		res, err := h.Handle(arg, self)
		if err != nil {
			return nil, err
		}
		resp, err := json.MarshalIndent(res, "", "  ")
		return bytes.NewReader(resp), nil
	}
	return rh, nil
}

func (self *ResourceController) Resource(id string) (Controller, error) {
	self.lock.Lock()
	defer self.lock.Unlock()
	c, ok := self.controllers[id]
	glog.V(6).Infof("resource for id %v", id)
	if !ok {
		return nil, fmt.Errorf("not found")
	}
	return c, nil
}

func (self *ResourceController) SetResource(id string, c Controller) {
	self.lock.Lock()
	defer self.lock.Unlock()
	if c == nil {
		delete(self.controllers, id)
	} else {
		self.controllers[id] = c
	}
}

func RandomNodeID() *discover.NodeID {
	key, err := crypto.GenerateKey()
	if err != nil {
		panic("unable to generate key")
	}
	var id discover.NodeID
	pubkey := crypto.FromECDSAPub(&key.PublicKey)
	copy(id[:], pubkey[1:])
	return &id
}

func RandomNodeIDs(n int) []*discover.NodeID {
	var ids []*discover.NodeID
	for i := 0; i < n; i++ {
		ids = append(ids, RandomNodeID())
	}
	return ids
}