package services

import (
	"context"
	"crypto/rand"
	"encoding/base64"
	"errors"
	"maot-shortner/internal/domain"
	"maot-shortner/internal/repositories"
	"strings"
	"time"
)

type LinkService struct {
	repo repositories.LinkRepository
}

func NewLinkService(repo repositories.LinkRepository) *LinkService {
	return &LinkService{
		repo: repo,
	}
}

func (s *LinkService) GetLinks(ctx context.Context) ([]*domain.Link, error) {
	return s.repo.GetLinks(ctx)
}

func (s *LinkService) CreateLink(ctx context.Context, longUrl string, redirectCode *string) (*domain.Link, error) {
	if !strings.Contains(longUrl, "http://") && !strings.Contains(longUrl, "https://") {
		return nil, errors.New("Invalid URL")
	}

	var shortUrl string

	if redirectCode != nil {
		shortUrl = *redirectCode
	} else {
		shortUrl = generateShortCode(5)
	}

	link := &domain.Link{
		LongURL:   longUrl,
		ShortURL:  shortUrl,
		CreatedAt: time.Now(),
	}

	return s.repo.CreateLink(ctx, link)
}

func generateShortCode(length int) string {
	b := make([]byte, length)
	rand.Read(b)
	if _, err := rand.Read(b); err != nil {
		return ""
	}

	return base64.RawURLEncoding.EncodeToString(b)
}

func (s *LinkService) GetLink(ctx context.Context, shortUrl string) (*domain.Link, error) {

	return s.repo.GetLinkByShortCode(ctx, shortUrl)
}