/* openbills - Server for web based Libre Billing Software
 * Copyright (C) 2023-2024  Vidhu Kant Sharma <vidhukant@vidhukant.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package user

import (
	"strings"
	e "errors"
	"github.com/spf13/viper"
	"vidhukant.com/openbills/errors"
	"vidhukant.com/openbills/util"
)

func validatePassword(pass string) error {
	// check if password is too short
	if len(pass) < viper.GetInt("security.min_password_length") {
		return errors.ErrPasswordTooShort
	}

	// check if password is too long
	if len(pass) > viper.GetInt("security.max_password_length") {
		return errors.ErrPasswordTooLong
	}

	return nil
}

func validateUsername(username string) error {
	// check if username is too short
	if len(username) < viper.GetInt("username.min_username_length") {
		return errors.ErrUsernameTooShort
	}

	// check if username is too long
	if len(username) > viper.GetInt("username.max_username_length") {
		return errors.ErrUsernameTooLong
	}

  for _, char := range username {
    if !strings.Contains(username, string(char)) {
      return errors.ErrInvalidUsername
    }
  }

  return nil
}

// NOTE: very inefficient and really really really dumb but it works
// TODO: find a better (or even a remotely good) way
func validateUserField(field, value string) error {
	if value != "" {
		var count int64
		err := db.Model(&User{}).
			Where(field + " = ?", value).
			Count(&count).
			Error

		if err != nil {
			return err
		}

		if count > 0 {
			switch(field) {
			case "username":
				return errors.ErrNonUniqueUsername
      case "phone":
        return errors.ErrNonUniquePhone
			case "email":
				return errors.ErrNonUniqueEmail
      case "website":
        return errors.ErrNonUniqueWebsite
      case "gstin":
        return errors.ErrNonUniqueGSTIN
			default:
				return e.New(field + " is not unique")
			}
		}
	}

	return nil
}

func (u *User) validate() error {
	u.Username = strings.TrimSpace(u.Username)
	u.Email = strings.TrimSpace(u.Email)
  u.Phone = strings.TrimSpace(u.Phone)
  u.Website = strings.TrimSpace(u.Website)
  u.Gstin = strings.TrimSpace(u.Gstin)
	u.IsVerified = false

	// TODO: validate username length and stuff
  
  // don't validate if GSTIN is empty
  if u.Gstin != "" && !util.ValidateGstin(u.Gstin) {
    return errors.ErrInvalidGSTIN
  }

  // don't validate if phone is empty
  if u.Phone != "" && !util.ValidatePhone(u.Phone) {
    return errors.ErrInvalidPhone
  }

  // don't validate if website is empty
  if u.Website != "" && !util.ValidateWebsite(u.Website) {
    return errors.ErrInvalidWebsite
  }

  // don't accept empty email
  if u.Email == "" {
    return errors.ErrEmptyEmail
  } else {
    // validate email
    if !util.ValidateEmail(u.Email) {
      return errors.ErrInvalidEmail
    }
  }

  // don't accept empty username
  if u.Username == "" {
    return errors.ErrEmptyUsername
  } else {
    // validate username
    err := validateUsername(u.Username)
    if err != nil {
      return err
    }
  }

  // validate password
  err := validatePassword(u.Password)
  if err != nil {
    return err
  }

	for _, i := range [][]string{{"username", u.Username}, {"email", u.Email}, {"website", u.Website}, {"gstin", u.Gstin}, {"phone", u.Phone}} {
    err := validateUserField(i[0], i[1])
		if err != nil {
			return err
		}
	}

	return nil
}