package routes

import (
	"backend/database"
	"backend/utils"
	"bytes"
	"database/sql"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/getsentry/sentry-go"
	"github.com/go-chi/chi/v5"
	"github.com/golang-jwt/jwt/v5"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"golang.org/x/crypto/bcrypt"
)

type Login struct {
	Login     string `json:"login"`
	Password  string `json:"password"`
	Recaptcha string `json:"recaptcha"`
}

type Register struct {
	Login     string `json:"login"`
	Email     string `json:"email"`
	Password  string `json:"password"`
	Recaptcha string `json:"recaptcha"`
}

type Activate struct {
	Token string `json:"token"`
}

func RegisterAuthRoutes(r chi.Router) {
	r.Post("/login", resolveGenerateNewToken)
	r.Post("/logout", resolveDeleteToken)
	r.Post("/register", resolveRegisterUser)
	r.Post("/register/vk", resolveRegisterUserVK)

	r.Post("/activate", resolveActivateUser)
	r.Post("/activateToken", resolveGenerateActivateToken)

	r.Post("/restore", resolveRestorePassword)
	r.Post("/restoreToken", resolveGenerateRestorePassword)
}

var (
	loginAttempts         = make(map[string][]time.Time)
	restoreGenerations    = make(map[int64]time.Time)
	activationGenerations = make(map[int]time.Time)
)

func resolveRegisterUserVK(w http.ResponseWriter, r *http.Request) {
	type Body struct {
		Code string `json:"code"`
	}
	body := new(Body)
	reqBody, err := ReadBody(r)
	if err != nil {
		Error(w, err)
		return
	}
	err = json.Unmarshal(reqBody, body)
	if err != nil {
		Error(w, err)
		return
	}

	req, err := http.Get("https://oauth.vk.com/access_token?client_id=7836090&client_secret=HqlMicDyJyq4E3SvsPba&redirect_uri=http://localhost:3000/vk_auth&code=" + body.Code)
	if err != nil {
		Error(w, err)
		return
	}

	b, err := io.ReadAll(req.Body)
	if err != nil {
		Error(w, err)
		return
	}
	log.Println(string(b))
}

func resolveRestorePassword(w http.ResponseWriter, r *http.Request) {
	type Restore struct {
		Token       string `json:"token"`
		NewPassword string `json:"new_password"`
	}

	restore := new(Restore)
	body, err := ReadBody(r)
	if err != nil {
		w.WriteHeader(400)
		Error(w, err)
	}
	err = json.Unmarshal(body, restore)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	tokenString, err := base64.StdEncoding.DecodeString(restore.Token)
	if err != nil {
		Error(w, err)
		return
	}

	token, err := jwt.Parse(string(tokenString), func(token *jwt.Token) (i interface{}, e error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return []byte(os.Getenv("ACTIVATE_TOKEN_SECRET")), nil
	})
	if err != nil {
		Error(w, err)
		return
	}
	if !token.Valid {
		RawError(w, "token not valid")
		return
	}

	claims, ok := token.Claims.(jwt.MapClaims)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	t, ok := claims["time"].(float64)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	id, ok := claims["id"].(float64)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	genTime := time.Unix(int64(t), 0)
	if time.Since(genTime) > time.Hour*1 {
		TokenExpired.Ferror(w)
		return
	}

	user, err := database.FetchUser(int(id))
	if err != nil {
		Error(w, err)
		return
	}
	samePassword := comparePasswords(restore.NewPassword, user.Password)
	if samePassword {
		SamePassword.Ferror(w)
		return
	}

	hashedPassword := hashAndSaltPassword([]byte(restore.NewPassword))

	err = database.UpdatePassword(int(id), hashedPassword)
	Response(w, err, "ok")
}

func resolveGenerateRestorePassword(w http.ResponseWriter, r *http.Request) {
	type Restore struct {
		Email     string `json:"email"`
		Recaptcha string `json:"recaptcha"`
	}

	var restore = &Restore{}
	body, err := ReadBody(r)
	if err != nil {
		w.WriteHeader(400)
		Error(w, err)
	}
	err = json.Unmarshal(body, restore)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	valid, err := validateRecaptcha(restore.Recaptcha, r.RemoteAddr)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		Error(w, err)
		return
	}
	if !valid {
		RecaptchaFailed.Ferror(w)
		return
	}

	user, err := database.FetchUserByLogin(restore.Email)
	if errors.Is(err, sql.ErrNoRows) {
		NotFound.Ferror(w)
		return
	}
	if err != nil {
		Error(w, err)
		return
	}

	t, ok := restoreGenerations[user.ID]
	if !ok {
		restoreGenerations[user.ID] = time.Now()
	} else {
		if t.Add(time.Minute * 5).After(time.Now()) {
			TooOftenGeneration.Ferror(w)
			return
		}
	}

	restoreToken := createActivateToken(user)
	var mailData = struct {
		Name string
		URL  string
	}{Name: user.Username, URL: fmt.Sprintf("%s/restore/%s", utils.GetFrontendURL(), restoreToken)}
	utils.SendMailTemplate(user.Email, "Восстановление пароля", "restore_password.html", mailData)
	Response(w, nil, "ok")
}

func resolveActivateUser(w http.ResponseWriter, r *http.Request) {
	var activate Activate
	body, err := ReadBody(r)
	if err != nil {
		w.WriteHeader(400)
		Error(w, err)
	}
	err = json.Unmarshal(body, &activate)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	tokenString, err := base64.StdEncoding.DecodeString(activate.Token)
	if err != nil {
		Error(w, err)
		return
	}

	token, err := jwt.Parse(string(tokenString), func(token *jwt.Token) (i interface{}, e error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return []byte(os.Getenv("ACTIVATE_TOKEN_SECRET")), nil
	})
	if err != nil {
		Error(w, err)
		return
	}

	if !token.Valid {
		RawError(w, "token not valid")
		return
	}

	claims, ok := token.Claims.(jwt.MapClaims)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	t, ok := claims["time"].(float64)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	id, ok := claims["id"].(float64)
	if !ok {
		RawError(w, "token not valid")
		return
	}

	genTime := time.Unix(int64(t), 0)
	if time.Since(genTime) > time.Hour*1 {
		TokenExpired.Ferror(w)
		return
	}

	user, err := database.FetchUser(int(id))
	if errors.Is(err, sql.ErrNoRows) {
		NotFound.Ferror(w)
		return
	}
	if err != nil {
		Error(w, err)
		return
	}
	if user.IsActivated {
		AlreadyActivated.Ferror(w)
		return
	}
	user, err = database.ActivateUser(int(id))
	Response(w, err, user)
}

func resolveRegisterUser(w http.ResponseWriter, r *http.Request) {
	var reg Register
	body, err := ReadBody(r)
	if err != nil {
		w.WriteHeader(400)
		Error(w, err)
	}
	_ = json.Unmarshal(body, &reg)

	if reg.Login == "" || reg.Password == "" || reg.Email == "" || reg.Recaptcha == "" {
		w.WriteHeader(http.StatusForbidden)
		RawError(w, "no")
		return
	}

	_, err = database.FetchUserByLogin(reg.Login)
	if !errors.Is(err, sql.ErrNoRows) {
		RawError(w, "User already register!")
		return
	}

	valid, err := validateRecaptcha(reg.Recaptcha, r.RemoteAddr)
	if err != nil || !valid {
		RecaptchaFailed.Ferror(w)
		return
	}

	user, err := database.CreateUser(reg.Login, hashAndSaltPassword([]byte(reg.Password)), reg.Email)
	Response(w, err, user)

	activateToken := createActivateToken(user)
	var mailData = struct {
		Name string
		URL  string
	}{Name: user.Username, URL: fmt.Sprintf("%s/activate/%s", utils.GetFrontendURL(), activateToken)}
	utils.SendMailTemplate(user.Email, "Активируйте аккаунт", "activate_account.html", mailData)

	embeds := make([]utils.Embed, 1)
	embeds = append(embeds, utils.Embed{
		Title:       "Nix13",
		Type:        "rich",
		Description: "Был зарегестрирован новый пользователь!",
		Timestamp:   time.Now(),
		URL:         fmt.Sprintf("%s/user/%d", utils.GetFrontendURL(), 1),
	})
	err = utils.ExecuteWebhook(
		"https://discord.com/api/webhooks/790593203862241320/vGyrLPzbmtKXHLaOpVrwNwn15tBK58CrsL3rQdAiUQSbi_jBvclpfUT1SoM75j98hBKY",
		utils.WebhookContent{Embeds: embeds},
	)
	if err != nil {
		sentry.CaptureException(err)
		log.Println(err)
	}
}

func resolveDeleteToken(w http.ResponseWriter, _ *http.Request) {
	cookie := &http.Cookie{
		Name:     "token",
		Value:    "",
		Path:     "/",
		SameSite: http.SameSiteLaxMode,
		Expires:  time.Time{},
	}
	http.SetCookie(w, cookie)
}

func resolveGenerateNewToken(w http.ResponseWriter, r *http.Request) {
	var login Login
	body, err := ReadBody(r)
	if err != nil {
		Error(w, err)
		return
	}
	err = json.Unmarshal(body, &login)
	if err != nil {
		Error(w, err)
		return
	}

	userAttempts := append(loginAttempts[r.RemoteAddr], time.Now())

	for index, t := range userAttempts {
		if t.Add(time.Hour).Before(time.Now()) {
			userAttempts = append(userAttempts[:index], userAttempts[index+1:]...)
		}
	}

	if len(loginAttempts[r.RemoteAddr])+1 >= 5 {
		if len(login.Recaptcha) == 0 {
			RecaptchaNeeded.Ferror(w)
			return
		}

		valid, err := validateRecaptcha(login.Recaptcha, r.RemoteAddr)
		if err != nil {
			Error(w, err)
			return
		}
		if !valid {
			RecaptchaFailed.Ferror(w)
			return
		}
	}

	if len(login.Password) == 0 || len(login.Login) == 0 {
		w.WriteHeader(http.StatusBadRequest)
		RawError(w, "No login or/and password")
		return
	}

	user, err := database.FetchUserByLogin(login.Login)
	log.Println(login.Login)
	if errors.Is(err, sql.ErrNoRows) || user == nil {
		WrongPassword.Ferror(w)
		return
	}

	if !comparePasswords(login.Password, user.Password) {
		WrongPassword.Ferror(w)
		return
	}

	claims := jwt.MapClaims{
		"id":           user.ID,
		"is_superuser": user.IsSuperuser,
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString([]byte(os.Getenv("AUTH_TOKEN_SECRET")))
	if err != nil {
		Error(w, err)
		return
	}
	expires := time.Now().Add(365 * 24 * time.Hour)
	cookie := &http.Cookie{
		Name:     "token",
		Value:    tokenString,
		Path:     "/",
		Expires:  expires,
		Secure:   false,
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
	}
	http.SetCookie(w, cookie)

	params := r.URL.Query()
	authType := params.Get("auth_type")

	switch authType {
	case "token":
		Response(w, err, tokenString)
	default:
		Response(w, err, user)
	}
}

func resolveGenerateActivateToken(w http.ResponseWriter, r *http.Request) {
	tokenCookie, err := r.Cookie("token")
	if errors.Is(err, http.ErrNoCookie) {
		w.WriteHeader(http.StatusUnauthorized)
		return
	}
	if err != nil {
		Error(w, err)
		return
	}

	token, err := jwt.Parse(tokenCookie.Value, func(token *jwt.Token) (i interface{}, e error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return []byte(os.Getenv("AUTH_TOKEN_SECRET")), nil
	})
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		Error(w, err)
		return
	}

	if !token.Valid {
		w.WriteHeader(http.StatusInternalServerError)
		RawError(w, "Unhandled exception!")
		return
	}

	claims := token.Claims.(jwt.MapClaims)
	id := int(claims["id"].(float64))

	t, ok := activationGenerations[id]
	if !ok {
		activationGenerations[id] = time.Now()
	} else {
		if t.Add(time.Minute * 5).After(time.Now()) {
			TooOftenGeneration.Ferror(w)
			return
		}
	}

	user, err := database.FetchUser(id)
	if err != nil {
		Error(w, err)
		return
	}
	if user.IsActivated {
		AlreadyActivated.Ferror(w)
		return
	}
	activateToken := createActivateToken(user)
	var mailData = struct {
		Name string
		URL  string
	}{Name: user.Username, URL: fmt.Sprintf("%s/activate/%s", utils.GetFrontendURL(), activateToken)}
	utils.SendMailTemplate(user.Email, "Активируйте аккаунт", "activate_account.html", mailData)
	Response(w, nil, "ok")
}

func hashAndSaltPassword(password []byte) string {
	hash, err := bcrypt.GenerateFromPassword(password, bcrypt.DefaultCost)
	if err != nil {
		log.Println(err)
		sentry.CaptureException(err)
	}
	return string(hash)
}

func comparePasswords(password, hashedPassword string) bool {
	return bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(password)) == nil
}

func createActivateToken(user *database.User) string {
	claims := jwt.MapClaims{
		"id":   user.ID,
		"time": time.Now().Unix(),
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, _ := token.SignedString([]byte(os.Getenv("ACTIVATE_TOKEN_SECRET")))
	hashed := base64.StdEncoding.EncodeToString([]byte(tokenString))
	return hashed
}

func hasPermission(user *database.User, permission string) bool {
	if user == nil {
		return false
	}
	permissions := strings.Split(user.Group.Permissions, ",")
	if user.IsSuperuser || user.Group.IsSuperuser {
		return true
	}
	for _, perm := range permissions {
		if perm == permission {
			return true
		}
	}
	return false
}

func validateRecaptcha(token string, ip string) (bool, error) {
	url := fmt.Sprintf("https://www.google.com/recaptcha/api/siteverify?secret=%s&response=%s&remoteip=%s", os.Getenv("RECAPTCHA_SECRET"), token, ip)

	resp, err := http.Post(url, "application/json", bytes.NewBuffer([]byte("")))
	if err != nil {
		return false, err
	}

	validateBody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return false, err
	}
	err = resp.Body.Close()
	if err != nil {
		return false, err
	}
	var validate map[string]interface{}
	err = json.Unmarshal(validateBody, &validate)
	if err != nil {
		return false, err
	}
	if !validate["success"].(bool) {
		return false, nil
	}
	return true, nil
}

func JWTMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodGet || r.Method == http.MethodOptions || strings.HasPrefix(r.URL.Path, "/v1/auth") {
			next.ServeHTTP(w, r)
			return
		}

		tokenCookie, err := r.Cookie("token")
		if errors.Is(err, http.ErrNoCookie) {
			w.WriteHeader(http.StatusUnauthorized)
			return
		}
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			Error(w, err)
			return
		}
		tokenString := tokenCookie.Value

		if len(tokenString) == 0 {
			w.WriteHeader(http.StatusUnauthorized)
			return
		}

		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (i interface{}, e error) {
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
			}
			return []byte(os.Getenv("AUTH_TOKEN_SECRET")), nil
		})

		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			Error(w, err)
			return
		}

		if !token.Valid {
			w.WriteHeader(http.StatusInternalServerError)
			RawError(w, "Unhandled exception!")
			return
		}

		if strings.HasSuffix(r.URL.Path, "comments") {
			next.ServeHTTP(w, r)
			return
		}

		claims := token.Claims.(jwt.MapClaims)

		user, err := GetCurrentUser(r)
		if err != nil {
			Error(w, err)
			return
		}

		if strings.HasPrefix(r.URL.Path, "/v1/users") {
			id := IURLParam(r, "userId")

			if !strings.HasPrefix(r.URL.Path, "/v1/users/me") && id != int(claims["id"].(float64)) && !hasPermission(user, "users") {
				NoAccess.Ferror(w)
				return
			}
		} else {
			path := strings.Split(r.URL.Path, "/")
			if len(path) < 3 {
				RawError(w, "something wrong")
				return
			}
			category := path[2]

			if !hasPermission(user, category) {
				NoAccess.Ferror(w)
				return
			}
		}

		next.ServeHTTP(w, r)
	})
}