package authentication

import (
	"errors"
	"fmt"
	"math/rand"
	"netina/models"
	"time"

	"netina/validation"

	"gorm.io/gorm"
)

type GenerateCode struct {
    DB *gorm.DB
}

func NewGenerateCode(db *gorm.DB) *GenerateCode {
    return &GenerateCode{DB: db}
}

// Generate a random 6-digit code
func generateCode() string {
    rand.Seed(time.Now().UnixNano())
    return fmt.Sprintf("%06d", rand.Intn(1000000))
}

// CreateLoginCode generates a login code and stores it in the database
func (s *GenerateCode) CreateLoginCode(phoneNumber string) (string, error) {
    var code string
    var isUnique bool

    // Try to generate a unique code
    for !isUnique {
        code = generateCode()
        isUnique, _ = s.isCodeUnique(code)
    }

    now := time.Now()
    expiresAt := now.Add(2 * time.Minute)

    loginCode := &models.LoginCode{
        PhoneNumber: phoneNumber,
        Code:        code,
        CreatedAt:   now,
        ExpiresAt:   expiresAt,
    }

    if err := validation.ValidateStruct(loginCode); err != nil {
		return "" , err
	}

    if err := s.DB.Create(loginCode).Error; err != nil {
        return "", err
    }

    return code, nil
}

// Check if the generated code is unique
func (s *GenerateCode) isCodeUnique(code string) (bool, error) {
    var loginCode models.LoginCode
    if err := s.DB.Where("code = ?", code).First(&loginCode).Error; err != nil {
        if errors.Is(err, gorm.ErrRecordNotFound) {
            return true, nil
        }
        return false, err
    }
    return false, nil
}

// VerifyLoginCode verifies the login code and checks if it is still valid
func (s *GenerateCode) VerifyLoginCode(phoneNumber, code string) error {
    var loginCode models.LoginCode

    // Find the login code
    if err := s.DB.Where("phone_number = ? AND code = ?", phoneNumber, code).First(&loginCode).Error; err != nil {
        if errors.Is(err, gorm.ErrRecordNotFound) {
            return errors.New("code not found")
        }
        return err
    }

    // Check if the code has expired
    if time.Now().After(loginCode.ExpiresAt) {
        return errors.New("code expired")
    }

    return nil
}