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server.go
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server.go
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package main
import (
"encoding/json"
"fmt"
"hash/fnv"
"net/http"
"strconv"
"github.com/gorilla/websocket"
)
type Server struct {
wsUpgrader websocket.Upgrader
wsSubMap WebSocketSubMap
topicSubscribers SubStorage
idSubscribers SubStorage
schemas Schemas
instances Instances
}
func respond(sub *Sub, req *ReqJson, msg json.RawMessage) {
res := &ResJson{
Type: req.Type,
Id: req.Id,
Msg: msg,
}
sub.ws.WriteJSON(res)
}
func respondError(sub *Sub, req *ReqJson, errorString string) {
res := &ResJson{
Type: req.Type,
Id: req.Id,
Msg: nil,
Error: errorString,
}
sub.ws.WriteJSON(res)
}
func calcUniqueInstanceId(schemaId SchemaId, count int) InstanceId {
str := string(schemaId) + ":" + strconv.Itoa(count)
h := fnv.New32a()
h.Write([]byte(str))
hash := int(h.Sum32())
return InstanceId(strconv.Itoa(hash))
}
func (s *Server) handle_sub_msg(sub *Sub, raw []byte, msgType int) {
if msgType != 1 {
return
}
req := &ReqJson{}
err := json.Unmarshal(raw, &req)
if err != nil {
fmt.Println(err)
return
}
if req.Type == "auth" {
msg := &ReqAuth{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(msg)
} else if req.Type == "sub" {
msg := &ReqSub{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
isTopic := msg.IsTopic == true
s.setSubscribe(msg.Id, isTopic, sub, true)
} else if req.Type == "unsub" {
msg := &ReqSub{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
isTopic := msg.IsTopic == true
s.setSubscribe(msg.Id, isTopic, sub, false)
} else if req.Type == "list" {
rmsg := &ResList{
Topics: []SchemaId{},
}
for k := range s.schemas {
rmsg.Topics = append(rmsg.Topics, k)
}
Msg, err := json.Marshal(rmsg)
if err != nil {
fmt.Println("list rmsg marshal", err)
return
}
res := &ResJson{
Id: req.Id,
Type: req.Type,
Msg: Msg,
}
sub.ws.WriteJSON(res)
} else if req.Type == "schema-set" {
msg := &ReqSchemaSet{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
s.schemas[msg.SchemaId] = msg.Schema
} else if req.Type == "schema-get" {
msg := &ReqSchemaGet{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
rmsg := &ResSchemaGet{
Id: msg.Id,
Schema: s.schemas[msg.Id],
}
Msg, err := json.Marshal(rmsg)
if err != nil {
fmt.Println("list rmsg marshal", err)
return
}
res := &ResJson{
Id: req.Id,
Type: req.Type,
Msg: Msg,
}
sub.ws.WriteJSON(res)
} else if req.Type == "mut" {
msg := &ReqMut{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
//what instance are we talking about?
instance, isValidInstanceId := s.instances[msg.Id]
//make sure an instance already exists with the id for mutation
if !isValidInstanceId {
//if instance doesn't exist, don't try to apply changes
return
}
//get the schema for this instance
// instanceSchema := s.schemas[msg.Change.SchemaId]
instanceSchema := s.schemas[instance.SchemaId]
//get the change
Change := msg.Change
AppliedChanges := map[FieldId]any{}
//loop over each key in Change Data
for ChangeFieldId, ChangeFieldValue := range Change {
//get the field type
SchemaFieldType, isValidField := instanceSchema.Fields[ChangeFieldId]
// fmt.Println(instance, ChangeFieldId, ChangeFieldValue)
//schema must have field, and it's type must match the change data
if isValidField {
if valueIsFieldType(ChangeFieldValue, SchemaFieldType, false) {
//apply the change of this field to the instance
AppliedChanges[ChangeFieldId] = ChangeFieldValue
instance.Data[ChangeFieldId] = ChangeFieldValue
// fmt.Println("Applied", instance, ChangeFieldId, ChangeFieldValue)
} else {
fmt.Println("invalid field value", ChangeFieldValue, SchemaFieldType)
}
} else {
fmt.Println("invalid field", ChangeFieldId)
}
}
//re-apply the instance to the store (we're not using pointers)
s.instances[msg.Id] = instance
//push changes to subscribers
resmsg := &ResPub{
Id: msg.Id,
Change: AppliedChanges,
}
ResMsg, err := json.Marshal(resmsg)
if err != nil {
fmt.Println("list rmsg marshal", err)
return
}
res := &ResJson{
Id: req.Id,
Type: req.Type,
Msg: ResMsg,
}
Res, err := json.Marshal(res)
if err != nil {
fmt.Println("RMsg marshal", err)
return
}
s.walkSubs(msg.Id, false, func(sub *Sub) {
sub.ws.WriteMessage(websocket.TextMessage, Res)
})
} else if req.Type == "inst" {
msg := &ReqInst{}
err = json.Unmarshal(req.Msg, &msg)
if err != nil {
fmt.Println(err)
return
}
schema, isValidSchema := s.schemas[msg.SchemaId]
if !isValidSchema {
respondError(sub, req, "unknown schema, cannot instance")
return
}
Data := InstanceData{}
for FieldId, FieldType := range schema.Fields {
Data[FieldId] = FieldDefaultForType(FieldType)
}
Instance := Instance{
SchemaId: msg.SchemaId,
Data: Data,
}
count := len(s.instances)
InstanceId := calcUniqueInstanceId(msg.SchemaId, count)
resinst := &ResInst{
Instance: Instance,
InstanceId: InstanceId,
}
Msg, err := json.Marshal(resinst)
if err != nil {
respondError(sub, req, "server error: couldn't marshal instance json")
return
}
respond(sub, req, Msg)
s.instances[InstanceId] = Instance
} else {
fmt.Println("Unhandled json Type:", req.Type)
}
}
func (s *Server) handle_http(w http.ResponseWriter, r *http.Request) {
c, err := s.wsUpgrader.Upgrade(w, r, nil)
if err != nil {
// log.Print("upgrade:", err)
return
}
defer c.Close()
s.wsSubMap[c] = makeSub(c)
for {
mt, message, err := c.ReadMessage()
if err != nil {
delete(s.wsSubMap, c)
// log.Println("read:", err)
break
}
s.handle_sub_msg(s.wsSubMap[c], message, mt)
}
}
func makeServer() *Server {
result := new(Server)
result.wsSubMap = make(map[*websocket.Conn]*Sub)
result.topicSubscribers = make(SubStorage)
result.idSubscribers = make(SubStorage)
result.schemas = make(Schemas)
result.instances = make(Instances)
return result
}
func (s *Server) subsGetOrCreate(topicOrId InstanceId, isTopic bool) Subs {
var result Subs = nil
if isTopic {
result = s.topicSubscribers[string(topicOrId)]
} else {
result = s.idSubscribers[string(topicOrId)]
}
if result == nil {
result = make(Subs)
if isTopic {
s.topicSubscribers[string(topicOrId)] = result
} else {
s.idSubscribers[string(topicOrId)] = result
}
}
return result
}
func (s *Server) setSubscribe(topicOrId InstanceId, isTopic bool, sub *Sub, isSub bool) {
subs := s.subsGetOrCreate(topicOrId, isTopic)
if isSub {
subs[sub] = true
} else {
delete(subs, sub)
}
// fmt.Println(topicOrId, isTopic, *sub, isSub)
}
type walkSubsCb = func(sub *Sub)
func (s *Server) walkSubs(topicOrId InstanceId, isTopic bool, cb walkSubsCb) {
var subs Subs = nil
if isTopic {
subs = s.subsGetOrCreate(topicOrId, isTopic)
} else {
subs = s.subsGetOrCreate(topicOrId, isTopic)
}
for k := range subs {
cb(k)
}
}
func (s *Server) init(addr string) {
s.wsUpgrader = websocket.Upgrader{}
//allow cross origin
s.wsUpgrader.CheckOrigin = func(r *http.Request) bool {
return true
}
http.HandleFunc("/", s.handle_http)
http.ListenAndServe(addr, nil)
}