package main

import (
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"io"
	"net/http"
	"time"

	"golang.org/x/crypto/bcrypt"

	dbtypes "git.andr3h3nriqu3s.com/andr3/fyp/logic/db_types"
	"git.andr3h3nriqu3s.com/andr3/fyp/logic/utils"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/utils"
)

func generateSalt() string {
	salt := make([]byte, 4)
	_, err := io.ReadFull(rand.Reader, salt)
	if err != nil {
		panic("TODO handle this better")
	}
	return hex.EncodeToString(salt)
}

func hashPassword(password string, salt string) (string, error) {
	bytes_salt, err := hex.DecodeString(salt)
	if err != nil {
		return "", err
	}
	bytes, err := bcrypt.GenerateFromPassword(append([]byte(password), bytes_salt...), 14)
	return string(bytes), err
}

func genToken() string {
	token := make([]byte, 60)
	_, err := io.ReadFull(rand.Reader, token)
	if err != nil {
		panic("TODO handle this better")
	}
	return hex.EncodeToString(token)
}

func deleteToken(db *sql.DB, userId string, time time.Time) (err error) {
	_, err = db.Exec("delete from tokens where emit_day=$1 and user_id=$2", time, userId)
	return
}

func generateToken(db *sql.DB, email string, password string, name string) (string, bool) {
	row, err := db.Query("select id, salt, password from users where email = $1;", email)
	if err != nil || !row.Next() {
		return "", false
	}

	var db_id string
	var db_salt string
	var db_password string
	err = row.Scan(&db_id, &db_salt, &db_password)
	if err != nil {
		return "", false
	}

	bytes_salt, err := hex.DecodeString(db_salt)
	if err != nil {
		panic("TODO handle better! Somethign is wrong with salt being stored in the database")
	}

	if err = bcrypt.CompareHashAndPassword([]byte(db_password), append([]byte(password), bytes_salt...)); err != nil {
		return "", false
	}

	token := genToken()

	_, err = db.Exec("insert into tokens (user_id, token, name) values ($1, $2, $3);", db_id, token, name)
	if err != nil {
		return "", false
	}

	return token, true
}

func usersEndpints(db *sql.DB, handle *Handle) {
	handle.Post("/login", func(c *Context) *Error {
		type UserLogin struct {
			Email    string `json:"email"`
			Password string `json:"password"`
		}

		var dat UserLogin

		if err := c.ToJSON(&dat); err != nil {
			return err
		}

		// TODO Give this to the generateToken function
		token, login := generateToken(db, dat.Email, dat.Password, "Logged in user")
		if !login {
			return c.SendJSONStatus(http.StatusUnauthorized, "Email or password are incorrect")
		}

		user, err := dbtypes.UserFromToken(c.Db, token)
		if err != nil {
			return c.Error500(err)
		}

		type UserReturn struct {
			Token    string `json:"token"`
			Id       string `json:"id"`
			UserType int    `json:"user_type"`
			Username string `json:"username"`
			Email    string `json:"email"`
		}

		userReturn := UserReturn{
			Token:    token,
			Id:       user.Id,
			UserType: user.UserType,
			Username: user.Username,
			Email:    user.Email,
		}

		return c.SendJSON(userReturn)
	})

	handle.Post("/register", func(c *Context) *Error {
		type UserLogin struct {
			Username string `json:"username"`
			Email    string `json:"email"`
			Password string `json:"password"`
		}

		var dat UserLogin

		if err := c.ToJSON(&dat); err != nil {
			return err
		}

		if len(dat.Username) == 0 || len(dat.Password) == 0 || len(dat.Email) == 0 {
			return c.SendJSONStatus(http.StatusBadRequest, "Please provide a valid json")
		}

		rows, err := db.Query("select username, email from users where username=$1 or email=$2;", dat.Username, dat.Email)
		if err != nil {
			return c.Error500(err)
		}
		defer rows.Close()

		if rows.Next() {
			var db_username string
			var db_email string
			err = rows.Scan(&db_username, &db_email)
			if err != nil {
				return c.Error500(err)
			}
			if db_email == dat.Email {
				return c.SendJSONStatus(http.StatusBadRequest, "Email already in use!")
			}
			if db_username == dat.Username {
				return c.SendJSONStatus(http.StatusBadRequest, "Username already in use!")
			}
			panic("Unrechable")
		}

		if len([]byte(dat.Password)) > 68 {
			return c.JsonBadRequest("Password is to long!")
		}

		salt := generateSalt()
		hash_password, err := hashPassword(dat.Password, salt)
		if err != nil {
			return c.Error500(err)
		}

		_, err = db.Exec("insert into users (username, email, salt, password) values ($1, $2, $3, $4);", dat.Username, dat.Email, salt, hash_password)
		if err != nil {
			return c.Error500(err)
		}

		// TODO Give this to the generateToken function
		token, login := generateToken(db, dat.Email, dat.Password, "User Login")
		if !login {
			return c.SendJSONStatus(500, "Could not login after creatting account please try again later")
		}

		user, err := dbtypes.UserFromToken(c.Db, token)
		if err != nil {
			return c.Error500(err)
		}

		type UserReturn struct {
			Token    string `json:"token"`
			Id       string `json:"id"`
			UserType int    `json:"user_type"`
			Username string `json:"username"`
			Email    string `json:"email"`
		}

		userReturn := UserReturn{
			Token:    token,
			Id:       user.Id,
			UserType: user.UserType,
			Username: user.Username,
			Email:    user.Email,
		}

		return c.SendJSON(userReturn)
	})

	// TODO allow admin users to update this data
	handle.Get("/user/info", func(c *Context) *Error {
		if !c.CheckAuthLevel(1) {
			return nil
		}

		user, err := dbtypes.UserFromToken(c.Db, *c.Token)
		if err != nil {
			return c.Error500(err)
		}

		type UserReturn struct {
			Id       string `json:"id"`
			UserType int    `json:"user_type"`
			Username string `json:"username"`
			Email    string `json:"email"`
		}

		userReturn := UserReturn{
			Id:       user.Id,
			UserType: user.UserType,
			Username: user.Username,
			Email:    user.Email,
		}

		return c.SendJSON(userReturn)
	})

	// Handles updating users
	handle.Post("/user/info", func(c *Context) *Error {
		if !c.CheckAuthLevel(int(dbtypes.User_Normal)) {
			return nil
		}

		type UserData struct {
			Id    string `json:"id"`
			Email string `json:"email"`
		}

		var dat UserData

		if err := c.ToJSON(&dat); err != nil {
			return err
		}

		if dat.Id != c.User.Id && c.User.UserType != int(dbtypes.User_Admin) {
			return c.SendJSONStatus(403, "You need to be an admin to update another users account")
		}

		if dat.Id != c.User.Id {
			var data struct {
				Id string
			}

			err := utils.GetDBOnce(c, &data, "users where id=$1", dat.Id)
			if err == NotFoundError {
				return c.JsonBadRequest("User does not exist")
			} else if err != nil {
				return c.Error500(err)
			}
		}

		var data struct {
			Id string
		}

		err := utils.GetDBOnce(c, &data, "users where email=$1", dat.Email)
		if err != nil && err != NotFoundError {
			return c.Error500(err)
		}

		if err != NotFoundError {
			if data.Id == dat.Id {
				return c.JsonBadRequest("Email is the name as the previous one!")
			} else {
				return c.JsonBadRequest("Email already in use")
			}
		}

		_, err = c.Db.Exec("update users set email=$2 where id=$1", dat.Id, dat.Email)
		if err != nil {
			return c.Error500(err)
		}

		var user struct {
			Id        string
			Username  string
			Email     string
			User_Type int
		}

		err = utils.GetDBOnce(c, &user, "users where id=$1", dat.Id)
		if err != nil {
			return c.Error500(err)
		}

		toReturnUser := dbtypes.User{
			Id:       user.Id,
			Username: user.Username,
			Email:    user.Email,
			UserType: user.User_Type,
		}

		return c.SendJSON(toReturnUser)
	})

	handle.Post("/user/info/password", func(c *Context) *Error {
		if !c.CheckAuthLevel(1) {
			return nil
		}

		var dat struct {
			Old_Password string `json:"old_password"`
			Password     string `json:"password"`
			Password2    string `json:"password2"`
		}

		if err := c.ToJSON(&dat); err != nil {
			return err
		}

		if dat.Password == "" {
			return c.JsonBadRequest("Password can not be empty")
		}

		if dat.Password != dat.Password2 {
			return c.JsonBadRequest("New passwords did not match")
		}

		// TODO remote token
		_, login := generateToken(db, c.User.Email, dat.Old_Password, "Update password Token")
		if !login {
			return c.JsonBadRequest("Password is incorrect")
		}

		salt := generateSalt()
		hash_password, err := hashPassword(dat.Password, salt)
		if err != nil {
			return c.Error500(err)
		}

		_, err = db.Exec("update users set salt=$1, password=$2 where id=$3", salt, hash_password, c.User.Id)
		if err != nil {
			return c.Error500(err)
		}

		return c.SendJSON(c.User.Id)
	})

	type TokenList struct {
		Id   string `json:"id"`
		Page int    `json:"page"`
	}
	PostAuthJson[TokenList](handle, "/user/token/list", 1, func(c *Context, obj *TokenList) *Error {
		if obj.Id == "" {
			obj.Id = c.User.Id
		}

		if obj.Id != c.User.Id && c.User.UserType < int(dbtypes.User_Admin) {
			return c.JsonBadRequest("Could not find user tokens")
		}

		type Token struct {
			CreationDate time.Time `json:"create_date" db:"emit_day"`
			TimeToLive   int       `json:"time_to_live" db:"time_to_live"`
			Name         string    `json:"name"`
		}

		tokens, err := GetDbMultitple[Token](c, "tokens where user_id=$1 order by emit_day desc limit 11 offset $2;", obj.Id, 10*obj.Page)
		if err != nil {
			return c.E500M("Failed get tokens", err)
		}

		max_len := min(11, len(tokens))

		c.ShowMessage = false
		return c.SendJSON(struct {
			TokenList []*Token `json:"token_list"`
			ShowNext  bool     `json:"show_next"`
		}{
			tokens[0:max_len],
			len(tokens) > 10,
		})
	})

	type TokenDelete struct {
		Time time.Time `json:"time" validate:"required"`
	}
	DeleteAuthJson(handle, "/user/token", 1, func(c *Context, obj *TokenDelete) *Error {
		// TODO allow admin user to delete to other persons token

		err := deleteToken(c.Db, c.User.Id, obj.Time)
		if err != nil {
			return c.E500M("Could not delete token", err)
		}

		return c.SendJSON("Ok")
	})

	// TODO create function to remove token
}