SFM-loan-Rest-Api/apiv1.go

package main

import (
	"biukop/sfm/loan"
	"database/sql"
	"encoding/json"
	"fmt"
	log "github.com/sirupsen/logrus"
	"net/http"
	"net/http/httputil"
	"strings"
	"time"
)

const apiV1Prefix = "/api/v1/"

type apiV1HandlerMap struct {
	Method  string
	Path    string //regex
	Handler func(http.ResponseWriter, *http.Request, *loan.Session)
}

var apiV1Handler = []apiV1HandlerMap{
	{"POST", "login", apiV1Login},
	{"GET", "login", apiV1DumpRequest},
}

//apiV1Main  version 1 main entry for all REST API
//
func apiV1Main(w http.ResponseWriter, r *http.Request) {
	logRequestDebug(httputil.DumpRequest(r, true))
	w.Header().Set("Content-Type", "application/json;charset=UTF-8")

	//try session login first, if not an empty session will be created
	session, e := apiV1InitSession(r)
	if e != nil {
		log.Warnf("Fail to InitSession %+v", session)
		apiV1Client403Error(w, r)
		return
	}
	session.RenewIfExpireSoon()

	//we have a session now, either guest or valid user
	//search through handler
	path := r.URL.Path[len(apiV1Prefix):] //strip API prefix
	for _, node := range apiV1Handler {
		if r.Method == node.Method && path == node.Path {
			node.Handler(w, r, &session)
			e = session.Write() //finish this session to DB
			if e != nil {
				log.Warnf("Failed to Save Session %+v \n reason \n%s\n", session, e.Error())
			}
			return
		}
	}
	//Catch for all
	apiV1DumpRequest(w, r, &session)
}

func apiV1InitSession(r *http.Request) (session loan.Session, e error) {
	session = loan.Session{}
	sid := r.Header.Get("Biukop-Session")
	e = session.Retrieve(r)
	if e == nil { //we got existing session
		e = session.ValidateRequest(r)
		if e != nil { // not successfully validated
			log.Warnf("failed session login %+v, %s", session, time.Now().Format(time.RFC1123))
			session.InitGuest(time.Now().Add(loan.DefaultSessionDuration))
			e = nil
		} //else, we have logged this user in
	} else if e == sql.ErrNoRows {
		log.Warn("DB has no corresponding session ", sid)
		session.InitGuest(time.Now().Add(loan.DefaultSessionDuration))
		e = nil //we try to init an empty one
	} else {
		log.Warnf("Retrieve Session %s encountered error %s", sid, e.Error())
	}
	session.SetRemote(r) //make sure they are using latest remote
	return
}

func apiV1ErrorCheck(e error) {
	if nil != e {
		panic(e.Error()) //TODO: detailed error check, truck all caller
	}
}

func apiV1Server500Error(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(500)
	fmt.Fprintf(w, "Server Internal Error  "+time.Now().Format(time.RFC1123))

	//write log
	dump := logRequestDebug(httputil.DumpRequest(r, true))
	dump = strings.TrimSpace(dump)
	log.Warnf("Unhandled Protocol = %s path= %s", r.Method, r.URL.Path)
}

func apiV1Client403Error(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(403)
	type struct403 struct {
		Error    int
		ErrorMsg string
	}
	e403 := struct403{Error: 403, ErrorMsg: "Not Authorized " + time.Now().Format(time.RFC1123)}
	msg403, _ := json.Marshal(e403)
	fmt.Fprintln(w, string(msg403))

	//write log
	dump := logRequestDebug(httputil.DumpRequest(r, true))
	dump = strings.TrimSpace(dump)
	log.Warnf("Not authorized   http(%s) path= %s, %s", r.Method, r.URL.Path, dump)
}