package main

import (
	"biukop.com/sfm/loan"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/brianvoe/gofakeit/v6"
	log "github.com/sirupsen/logrus"
	"net/http"
	"net/http/httputil"
	"strings"
	"time"
)

const apiV1Prefix = "/api/v1/"
const apiV1WebSocket = apiV1Prefix + "ws"

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

var apiV1Handler = setupApiV1Handler()

func setupApiV1Handler() []apiV1HandlerMap {
	if config.Debug { //debug only
		return []apiV1HandlerMap{
			{"POST", "login", apiV1Login},
			{"*", "logout", apiV1Logout},
			{"GET", "chart/type-of-loans", apiV1ChartTypeOfLoans},
			{"GET", "chart/amount-of-loans", apiV1ChartTypeOfLoans},
			{"GET", "chart/past-year-monthly", apiV1ChartPastYearMonthly},
			{"GET", "chart/recent-10-loans", apiV1ChartRecent10Loans},
			{"GET", "chart/top-broker", apiV1ChartTopBroker},
			{"POST", "grid/loan/full-loan-overview", apiV1GridLoanFullOverview},
			{"GET", "loan/", apiV1LoanSingleGet},
			{"POST", "loan/basic/", apiV1LoanSinglePostBasic},
			{"GET", "avatar/", apiV1Avatar},
			{"GET", "login", apiV1DumpRequest},
		}
	} else { //production
		return []apiV1HandlerMap{
			{"POST", "login", apiV1Login},
			{"*", "logout", apiV1Logout},
			{"GET", "chart/type-of-loans", apiV1ChartTypeOfLoans},
			{"GET", "chart/amount-of-loans", apiV1ChartTypeOfLoans},
			{"GET", "chart/past-year-monthly", apiV1ChartPastYearMonthly},
			{"GET", "chart/recent-10-loans", apiV1ChartRecent10Loans},
			{"GET", "chart/top-broker", apiV1ChartTopBroker},
			{"POST", "grid/loan/full-loan-overview", apiV1GridLoanFullOverview},
			{"GET", "loan/", apiV1LoanSingleGet},
			{"POST", "loan/basic/", apiV1LoanSinglePostBasic},
			{"GET", "avatar/", apiV1Avatar},
			{"GET", "login", apiV1EmptyResponse},
		}
	}
}

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

	//CORS setup
	setupCrossOriginResponse(&w, r)

	//if its options then we don't bother with other issues
	if r.Method == "OPTIONS" {
		apiV1EmptyResponse(w, r, nil)
		return //stop processing
	}

	if config.Debug {
		logRequestDebug(httputil.DumpRequest(r, true))
	}

	session := apiV1InitSession(r)
	if config.Debug {
		log.Debugf("session : %+v", session)
	}

	//search through handler
	path := r.URL.Path[len(apiV1Prefix):] //strip API prefix
	for _, node := range apiV1Handler {
		//log.Println(node, path, strings.HasPrefix(path, node.Path))
		if (r.Method == node.Method || node.Method == "*") && strings.HasPrefix(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 UnHandled Request
	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())
	}
	if config.Debug {
		apiV1DumpRequest(w, r, &session)
	} else {
		apiV1EmptyResponse(w, r, &session)
	}

}

func apiV1InitSession(r *http.Request) (session loan.Session) {
	session.MarkEmpty()

	//track browser, and take session from cookie
	cookieSession, e := apiV1InitSessionByBrowserId(r)
	if e == nil {
		session = cookieSession
	}

	//try session login first, if not an empty session will be created
	headerSession, e := apiV1InitSessionByHttpHeader(r)
	if e == nil {
		session = headerSession
	}

	if session.IsEmpty() {
		session.InitGuest(time.Now().Add(loan.DefaultSessionDuration))
	} else {
		session.RenewIfExpireSoon()
	}
	//we have a session anyway
	session.Add("Biukop-Mid", apiV1GetMachineId(r)) //set machine id
	session.SetRemote(r)                            //make sure they are using latest remote
	return
}

func setupCrossOriginResponse(w *http.ResponseWriter, r *http.Request) {
	origin := r.Header.Get("Origin")
	if origin == "" {
		origin = "*"
	}
	requestedHeaders := r.Header.Get("Access-control-Request-Headers")
	method := r.Header.Get("Access-Control-Request-Method")
	(*w).Header().Set("Access-Control-Allow-Origin", origin) //for that specific origin
	(*w).Header().Set("Access-Control-Allow-Credentials", "true")
	(*w).Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, "+method)
	(*w).Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, Cookie, Biukop-Session, Biukop-Session-Token, Biukop-Session-Expire, "+requestedHeaders)
}

func apiV1GetMachineId(r *http.Request) string {
	var mid string
	inCookie, e := r.Cookie("Biukop-Mid")
	if e == nil {
		mid = inCookie.Value
	} else {
		mid = gofakeit.UUID()
	}

	headerMid := r.Header.Get("Biukop-Mid")
	if headerMid != "" {
		mid = headerMid
	}
	return mid
}

func apiV1InitSessionByBrowserId(r *http.Request) (session loan.Session, e error) {
	var sid string
	mid := apiV1GetMachineId(r)
	inCookie, e := r.Cookie("Biukop-Session")
	if e == nil {
		sid = inCookie.Value
		if sid != "" {
			e = session.Read(sid)
			if e == nil {
				if mid != session.Get("Biukop-Mid") {
					session.MarkEmpty()
				}
			}
		}
	}
	return
}

func apiV1AddTrackingCookie(w http.ResponseWriter, r *http.Request, session *loan.Session) {
	//set session header too.
	w.Header().Add("Access-Control-Expose-Headers", "Biukop-Session")
	if session == nil {
		w.Header().Add("Biukop-Session", "")
	} else {
		w.Header().Add("Biukop-Session", session.Id)
	}

	//add tracking cookie
	expiration := time.Now().Add(365 * 24 * time.Hour)
	mid := apiV1GetMachineId(r)
	cookie := http.Cookie{Name: "Biukop-Mid", Value: mid, Expires: expiration, Path: "/", Secure: true, SameSite: http.SameSiteNoneMode}
	http.SetCookie(w, &cookie)

	if session != nil {
		cookie = http.Cookie{Name: "Biukop-Session", Value: session.Id, Expires: expiration, Path: "/", Secure: true, SameSite: http.SameSiteNoneMode}
		http.SetCookie(w, &cookie)
	}
}

func apiV1InitSessionByHttpHeader(r *http.Request) (ss loan.Session, e error) {
	sid := r.Header.Get("Biukop-Session")
	ss.MarkEmpty()
	//make sure session id is given
	if sid != "" {
		e = ss.Retrieve(r)
		if e == sql.ErrNoRows { //db does not have required session.
			log.Warn("DB has no corresponding session ", sid)
		} else if e != nil { // retrieve DB has error
			log.Errorf("Retrieve Session %s encountered error %s", sid, e.Error())
		}
	} else {
		e = errors.New("session not found: " + sid)
	}
	return
	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)
	apiV1AddTrackingCookie(w, r, nil) //always the last one to set cookies
	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, ss *loan.Session) {
	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)

	//before send out
	apiV1AddTrackingCookie(w, r, ss) //always the last one to set cookies
	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)
}

func apiV1Client404Error(w http.ResponseWriter, r *http.Request, ss *loan.Session) {
	w.WriteHeader(404)
	type struct404 struct {
		Error    int
		ErrorMsg string
	}
	e404 := struct404{Error: 404, ErrorMsg: "Not Found " + time.Now().Format(time.RFC1123)}
	msg404, _ := json.Marshal(e404)

	//before send out
	apiV1AddTrackingCookie(w, r, ss) //always the last one to set cookies
	fmt.Fprintln(w, string(msg404))

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

func apiV1DumpRequest(w http.ResponseWriter, r *http.Request, ss *loan.Session) {
	dump := logRequestDebug(httputil.DumpRequest(r, true))
	dump = strings.TrimSpace(dump)
	msg := fmt.Sprintf("Unhandled Protocol = %s path= %s", r.Method, r.URL.Path)
	dumpLines := strings.Split(dump, "\r\n")
	ar := apiV1ResponseBlank()
	ar.Env.Msg = msg
	ar.Env.Session = *ss
	ar.Env.Session.Bin = []byte("masked data") //clear
	ar.Env.Session.Secret = "***********"
	ar.add("Body", dumpLines)
	ar.add("Biukop-Mid", ss.Get("Biukop-Mid"))
	b, _ := ar.toJson()

	apiV1AddTrackingCookie(w, r, ss) //always the last one to set cookies
	fmt.Fprintf(w, "%s\n", b)
}

func apiV1EmptyResponse(w http.ResponseWriter, r *http.Request, ss *loan.Session) {
	apiV1AddTrackingCookie(w, r, ss) //always the last one to set cookies
	fmt.Fprintf(w, "")
}