From 4167558e07a702deb2e868f9c5ccf172cc133680 Mon Sep 17 00:00:00 2001
From: Patrick Peng Sun <patrick@lawipac.com>
Date: Fri, 26 May 2017 13:03:29 +1000
Subject: [PATCH] save, read session tested

---
 chagSession_test.go |  48 +++++++++++++++++
 chatSession.go      | 124 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 172 insertions(+)
 create mode 100644 chagSession_test.go
 create mode 100644 chatSession.go

diff --git a/chagSession_test.go b/chagSession_test.go
new file mode 100644
index 0000000..d203968
--- /dev/null
+++ b/chagSession_test.go
@@ -0,0 +1,48 @@
+package main
+
+import (
+	"log"
+	"testing"
+	"time"
+)
+
+func TestSession(t *testing.T) {
+	id := "testopenid"
+	state := "testsate"
+
+	//delete any existing
+	deleteSession(id)
+	path := getSessionPath(id)
+	AssertEqual(t, isFileExist(path), false, "Session file should not exist")
+
+	//create new
+	setSessionState(id, state, 100)
+
+	//wait 1 sec
+	log.Print("wait for 1 sec for testing timestamp ......")
+	time.Sleep(1 * time.Second)
+	log.Print("......waiting done")
+
+	//read back , check state
+	s, _ := getCurrentSesssion(id)
+	AssertEqual(t, s.State, state, "")
+	now := int32(time.Now().Unix())
+
+	//check timing
+	AssertEqual(t, s.Expire > now, true, "Expire should be in future")
+	AssertEqual(t, s.UpdateAt < now, true, "Update should be in pass")
+	AssertEqual(t, s.CreateAt == s.UpdateAt, true, "Update should be equal to create")
+	AssertEqual(t, isExpired(now), false, "current time should not be expired")
+
+	//update existing session
+	s, _ = setSessionState(id, state, 100)
+	//timeing should be exactly 1s diff
+	AssertEqual(t, s.CreateAt+1 == s.UpdateAt, true, "second Update should be bigger create")
+	n, _ := getCurrentSesssion(id)
+	AssertEqual(t, s, n, "session should be equal")
+
+	//delete session, for clean up
+	deleteSession(id)
+	path = getSessionPath(id)
+	AssertEqual(t, isFileExist(path), false, "Session file should not exist")
+}
diff --git a/chatSession.go b/chatSession.go
new file mode 100644
index 0000000..0d7eddd
--- /dev/null
+++ b/chatSession.go
@@ -0,0 +1,124 @@
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+//a state is a alphanumerical string lessthan 128 bytes.
+
+//when messages comes in we need to differentiate what state is this in.
+//default state is where command can happen
+
+//where the state is stored,
+// in  sessions/openID.json
+
+//if there is no such file, we are in default state.
+
+//First state is to record user's name, email, and phone number.
+// for individual state
+// state/statename/openID.json
+
+var sessionDir = "sessions"
+var stateDir = "state"
+
+//openIDSession  openID user's session
+type openIDSession struct {
+	State    string `json:"State"`    //name of the current state  alphanumerical string
+	CreateAt int32  `json:"CreateAt"` //when is this session created
+	UpdateAt int32  `json:"UpdateAt"` //when is this session updated
+	Expire   int32  `json:"Expire"`   //unix timestamp of when this state expires
+}
+
+//read sessions/openID.json to check whether its a state for ongoing dialog
+func getCurrentSesssion(openID string) (result openIDSession, err error) {
+	path := getSessionPath(openID)
+	log.Printf("read session from %s\r\n", path)
+	body, err := ioutil.ReadFile(path)
+	if err != nil { //read file error
+		if isFileExist(path) {
+			log.Println("Error session reading " + path)
+		}
+		return //empty and expired session
+	}
+	err = json.Unmarshal(body, &result)
+	if err != nil {
+		log.Printf("Session Content [path=%s] not correct: ", path)
+	}
+	//we don't check Expire, we give the caller full control on
+	//how to deal wiht expired session
+	return
+}
+
+func writeSession(openid string, ss openIDSession) (err error) {
+	path := getSessionPath(openid)
+	r, err := json.Marshal(ss)
+	if err == nil {
+		err = ioutil.WriteFile(path, r, 0600)
+		if err != nil {
+			log.Printf("Error writing session %s: \r\n %s \r\n", openid, r)
+			log.Println(err)
+		} else {
+			log.Println("write session to " + path)
+		}
+	} else {
+		log.Printf("Error encoding session %s ", openid)
+		log.Println(err)
+	}
+	return
+}
+
+//create if not available
+func setSessionState(openID, state string, expireAfter int32) (updatedSession openIDSession, err error) {
+	s, err := getCurrentSesssion(openID)
+	now := int32(time.Now().Unix())
+	if s.CreateAt == 0 {
+		s.CreateAt = now
+	}
+	s.UpdateAt = now
+	s.State = state
+	s.Expire = now + expireAfter
+	err = writeSession(openID, s)
+	return s, err
+}
+
+func isExpired(timestamp int32) bool {
+	now := int32(time.Now().Unix())
+	return now > timestamp
+}
+
+func getSessionPath(openID string) (path string) {
+	path = sessionDir + string(os.PathSeparator) + openID + ".json"
+	ensurePathExist(path)
+	return path
+}
+
+func getStatePath(openID, stateName string) (path string) {
+	path = stateDir + string(os.PathSeparator) + stateName + string(os.PathSeparator) + openID + ".json"
+	ensurePathExist(path)
+	return
+}
+
+func ensurePathExist(path string) {
+	d := filepath.Dir(path)
+	if !isFileExist(d) {
+		log.Println("Creating path [" + d + "]")
+		os.MkdirAll(d, 0700)
+	}
+}
+
+func deleteSession(openID string) {
+	path := getSessionPath(openID)
+	if isFileExist(path) {
+		err := os.Remove(path)
+		if err != nil {
+			log.Println(err)
+		} else {
+			log.Println("delete session :" + path)
+		}
+	}
+}