package user

import (
	"crypto/rand"
	"database/sql"
	"encoding/base64"
	"fmt"
	"math/big"
	"regexp"
	"strings"
	"time"
	"unicode"

	"git.umbach.dev/app-idea/rest-api/modules/database"
	"github.com/gofiber/fiber/v2"
	"github.com/google/uuid"
	ua "github.com/mileusna/useragent"
	log "github.com/sirupsen/logrus"
	"golang.org/x/crypto/bcrypt"
)

type LoginInput struct {
	Username string `json:"username"`
	Email    string `json:"email"`
	Password string `json:"password"`
	Hashtag  string `json:"hashtag"`
}

func NewUser(c *fiber.Ctx) error {
	// swagger:operation POST /users usersNewUser
	// ---
	// summary: Create new user
	// produces:
	// - application/json
	// parameters:
	// - name: username
	//   in: query
	//   description: username of the user (length 3-30)
	//   type: string
	//   required: true
	// - name: email
	//   in: query
	//   description: email of the user (length 3-255)
	//   type: string
	//   required: true
	// - name: password
	//   in: query
	//   description: password (base64) of the user (length 6-250)
	//   type: string
	//   required: true
	// - name: hashtag
	//   in: query
	//   description: hashtag of the client (length 2-6, UPPERCASE)
	//   type: string
	// - name: avatar_url
	//   in: query
	//   description: avatar url of the client
	//   type: string
	// - name: location
	//   in: query
	//   description: location of the client (length 1-20) (for example Frankfurt)
	//   type: string
	// responses:
	//   '201':
	//     description: user created
	//   '400':
	//     description: format is not correct
	//   '422':
	//     description: username, email or/and hashtag already assigned

	var input LoginInput

	if err := c.BodyParser(&input); err != nil {
		log.Debugln("bodyParser failed:", err)
		return c.SendStatus(fiber.StatusBadRequest)
	}

	decodedPassword, err := base64.StdEncoding.DecodeString(input.Password)

	if err != nil {
		log.Debugln("base64 decoding failed:", err)
		return c.SendStatus(fiber.StatusBadRequest)
	}

	input.Password = string(decodedPassword)

	if !isValid(input.Username, 3, 30) || !isEmailValid(input.Email) || !isValid(input.Password, 6, 250) {
		return c.SendStatus(fiber.StatusForbidden)
	}

	db, err := database.GetDatabase()

	if db == nil || err != nil {
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	defer db.Close()

	if !isEmailAvailable(db, input.Email) {
		return c.SendStatus(fiber.StatusUnprocessableEntity)
	}

	if input.Hashtag == "" {
		input.Hashtag, err = generateRandomHashtag(db, 6)

		if err != nil {
			return c.SendStatus(fiber.StatusInternalServerError)
		}
	} else if !isHashtagValid(db, input.Hashtag) {
		return c.SendStatus(fiber.StatusUnprocessableEntity)
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(input.Password), bcrypt.DefaultCost)

	if err != nil {
		log.Warnln("Failed to bcrypt password", err)
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	userId := strings.Replace(uuid.New().String(), "-", "", -1)
	created := time.Now().Format("2006-01-02 15:04:05") // YYYY-MM-DD hh:mm:ss

	stmt, err := db.Prepare("INSERT INTO users (user_id, user_hashtag, username, email, password, created) VALUES (?, ?, ?, ?, ?, ?);")
	stmt.Exec(userId, input.Hashtag, input.Username, input.Email, hashedPassword, created)

	stmt.Close()

	if err != nil {
		log.Warnln("Failed to insert user to db:", err.Error())
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	sessionId, err := createUserSession(db, userId, c.IP(), string(c.Context().UserAgent()))

	if err != nil {
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	expires := getExpiresTime()

	c.Cookie(&fiber.Cookie{Name: "session_id", Value: sessionId, Secure: true, HTTPOnly: true, Expires: expires})
	c.Cookie(&fiber.Cookie{Name: "username", Value: input.Username, Secure: true, Expires: expires})
	c.Cookie(&fiber.Cookie{Name: "user_hashtag", Value: input.Hashtag, Secure: true, Expires: expires})

	log.Debugln("user created", userId, input.Hashtag, input.Username, input.Email)

	return c.SendStatus(fiber.StatusCreated)
}

func generateRandomString(n int) (string, error) {
	const letters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
	r := make([]byte, n)

	for i := 0; i < n; i++ {
		num, err := rand.Int(rand.Reader, big.NewInt(int64(len(letters))))
		if err != nil {
			return "", err
		}
		r[i] = letters[num.Int64()]
	}

	return string(r), nil
}

func generateRandomHashtag(db *sql.DB, n int) (string, error) {
	c := make(chan bool)
	var s string
	var err error

	for {
		s, err = generateRandomString(6)

		if err != nil {
			log.Warnln("Error generating Hashtag:", err)
			return "", err
		}

		go func() {
			err := db.QueryRow("SELECT user_hashtag FROM users WHERE user_hashtag = ?", s).Scan(&s)

			if err == sql.ErrNoRows {
				c <- true
			} else {
				c <- false
			}
		}()

		if msg := <-c; msg {
			break
		}
	}

	return s, nil
}

func isHashtagValid(db *sql.DB, h string) bool {
	if !isUpper(h) || len(h) < 2 || len(h) > 6 {
		return false
	}

	err := db.QueryRow("SELECT user_hashtag FROM users WHERE user_hashtag = ?", h).Scan(&h)

	if err == sql.ErrNoRows {
		return true
	}
	return false
}

func isUpper(s string) bool {
	for _, r := range s {
		if !unicode.IsUpper(r) && unicode.IsLetter(r) {
			return false
		}
	}
	return true
}

func isValid(s string, min int, max int) bool {
	if len(s) < min || len(s) > max {
		return false
	}
	return true
}

var emailRegex = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")

func isEmailValid(e string) bool {
	if len(e) < 3 || len(e) > 255 {
		return false
	}
	return emailRegex.MatchString(e)
}

func isEmailAvailable(db *sql.DB, e string) bool {
	err := db.QueryRow("SELECT email FROM users WHERE email = ?", e).Scan(&e)

	if err == sql.ErrNoRows {
		return true
	}
	return false
}

func SessionIdCheck(c *fiber.Ctx) error {
	sessionId := c.Cookies("session_id")

	if sessionId == "" {
		return fiber.ErrUnauthorized
	}

	valid, err := isSessionIdValid(sessionId)

	if err != nil {
		return fiber.ErrInternalServerError
	}

	if valid {
		return c.Next()
	}

	return fiber.ErrUnauthorized
}

func isSessionIdValid(sessionId string) (bool, error) {
	db, err := database.GetDatabase()

	if db == nil || err != nil {
		log.Warn("DB error:", err)
		return false, err
	}

	defer db.Close()

	var expires string

	err = db.QueryRow("SELECT session_id, expires FROM sessions WHERE session_id = ?", sessionId).Scan(&sessionId, &expires)

	if err == sql.ErrNoRows {
		return false, nil
	}

	t, err := time.Parse("2006-01-02 15:04:05", expires)

	log.Infoln("expires", expires, time.Now().Add(time.Hour*73).Unix(), t.Unix())

	if err != nil {
		log.Warn("Failed to parse session datetime", err)
		return false, err
	}

	// session has expired
	if time.Now().Add(time.Hour*73).Unix() > t.Unix() {
		log.Info("bigger")
		deleteSession(db, sessionId)

		return false, err
	}

	log.Info("not bigger")
	return true, nil
}

func deleteSession(db *sql.DB, sessionId string) {
	res, err := db.Exec("DELETE FROM sessions WHERE session_id = ?", sessionId)

	if err != nil {
		log.Infoln("err delete session", err)
	}

	log.Infoln("delete session res", res)
}

func createUserSession(db *sql.DB, userId string, ip string, userAgent string) (string, error) {
	sessionId, err := generateRandomString(32)

	if err != nil {
		log.Warnln("Failed to generate user session:", err)
		return "", err
	}

	stmt, err := db.Prepare("INSERT INTO sessions (user_id, session_id, ip, user_agent, last_login, expires) VALUES (?, ?, ?, ?, ?, ?);")

	if err != nil {
		log.Warnln("Failed to insert user into db:", err)
		return "", err
	}

	ua := ua.Parse(userAgent)

	stmt.Exec(userId, sessionId, ip, ua.OS+" "+ua.Name, time.Now(), getExpiresTime())
	stmt.Close()

	return sessionId, nil
}

func getExpiresTime() time.Time {
	// TODO: db default
	return time.Now().Add(time.Hour * 72)
}

func Login(c *fiber.Ctx) error {
	// swagger:operation POST /user/login userLogin
	// ---
	// summary: Login a user
	// produces:
	// - application/json
	// parameters:
	// - name: username or email
	//   in: query
	//   description: username or email
	//   type: string
	//   required: true
	// - name: password
	//   in: query
	//   description: password (base64) of the user
	//   type: string
	//   required: true
	// responses:
	//   '200':
	//     description: login success
	//   '401':
	//     description: login credentials not correct

	var input LoginInput

	if err := c.BodyParser(&input); err != nil {
		return c.SendStatus(fiber.StatusBadRequest)
	}

	log.Println(input)

	if input.Username != "" && !isValid(input.Username, 3, 30) || input.Email != "" && !isEmailValid(input.Email) || input.Username == "" && input.Email == "" || input.Password == "" {
		return c.SendStatus(fiber.StatusBadRequest)
	}

	decodedPassword, err := base64.StdEncoding.DecodeString(input.Password)

	if err != nil {
		log.Debugln("base64 decoding failed:", err)
		return c.SendStatus(fiber.StatusBadRequest)
	}

	input.Password = string(decodedPassword)

	db, err := database.GetDatabase()

	if db == nil || err != nil {
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	defer db.Close()

	var userId string
	var username string
	var userHashtag string
	var hashedPassword string

	if input.Username != "" {
		err = db.QueryRow("SELECT user_id, user_hashtag, password FROM users WHERE username = ?", input.Username).Scan(&userId, &userHashtag, &hashedPassword)
	} else {
		err = db.QueryRow("SELECT user_id, user_hashtag, username, password FROM users WHERE email = ?", input.Email).Scan(&userId, &userHashtag, &username, &hashedPassword)
	}

	if err != nil {
		return c.SendStatus(fiber.StatusUnauthorized)
	}

	err = bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(input.Password))

	if err != nil {
		log.Warnln("Failed to comapare bcrypt password", err)
		return c.SendStatus(fiber.StatusUnauthorized)
	}

	sessionId, err := createUserSession(db, userId, c.IP(), string(c.Context().UserAgent()))

	if err != nil {
		return c.SendStatus(fiber.StatusInternalServerError)
	}

	expires := getExpiresTime()

	c.Cookie(&fiber.Cookie{Name: "session_id", Value: sessionId, Secure: true, HTTPOnly: true, Expires: expires})
	if username != "" {
		c.Cookie(&fiber.Cookie{Name: "username", Value: username, Secure: true, Expires: expires})
	}
	c.Cookie(&fiber.Cookie{Name: "user_hashtag", Value: userHashtag, Secure: true, Expires: expires})

	return c.SendStatus(fiber.StatusCreated)
}

func GetUser(c *fiber.Ctx) error {
	return c.SendString("user")
}

func GetUsers(c *fiber.Ctx) error {
	cookie := c.Cookies("session_id")

	log.Infoln("cookies", cookie)

	db, err := database.GetDatabase()

	// c.Params("id")

	if db == nil || err != nil {
		return c.SendString("db error")
	}

	list := []string{}

	var (
		name string
	)

	rows, err := db.Query("SELECT username FROM users;")
	fmt.Println("err", err)
	defer rows.Close()
	fmt.Println("reading data:")
	for rows.Next() {
		err := rows.Scan(&name)
		fmt.Printf("Data row = (%s, %s)\n", name, err)
		list = append(list, name)
	}
	err = rows.Err()
	fmt.Println("Done")

	return c.JSON(list)
}