package ticket_service

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"errors"
	"fmt"
	"net/url"
	"strings"

	"evening_detective_server/internal/repos/tickets_repo"
)

const maxTicketsPerRequest = 100

var (
	ErrInvalidTicketCount = errors.New("количество билетов должно быть от 1 до 100")
	ErrInvalidBaseURL     = errors.New("необходимо настроить APP_BASE_URL — публичный адрес приложения")
)

type Ticket struct {
	ID  int
	URL string
}

type Service struct {
	repo       *tickets_repo.Repo
	appBaseURL string
}

func New(repo *tickets_repo.Repo, appBaseURL string) *Service {
	return &Service{repo: repo, appBaseURL: appBaseURL}
}

func (s *Service) Issue(ctx context.Context, gameID, count int) ([]*Ticket, error) {
	if count < 1 || count > maxTicketsPerRequest {
		return nil, ErrInvalidTicketCount
	}

	base, err := parseBaseURL(s.appBaseURL)
	if err != nil {
		return nil, err
	}

	hashes := make([][]byte, count)
	tokens := make([]string, count)
	for i := range count {
		token, err := newToken()
		if err != nil {
			return nil, err
		}
		hash := sha256.Sum256([]byte(token))
		tokens[i] = token
		hashes[i] = hash[:]
	}

	ids, err := s.repo.CreateBatch(ctx, gameID, hashes)
	if err != nil {
		return nil, err
	}

	tickets := make([]*Ticket, count)
	for i, id := range ids {
		link := *base
		link.Path = strings.TrimRight(base.Path, "/") + "/tickets/" + tokens[i]
		link.RawPath = ""
		tickets[i] = &Ticket{ID: id, URL: link.String()}
	}
	return tickets, nil
}

func newToken() (string, error) {
	data := make([]byte, 32)
	if _, err := rand.Read(data); err != nil {
		return "", fmt.Errorf("generate ticket token: %w", err)
	}
	return base64.RawURLEncoding.EncodeToString(data), nil
}

func parseBaseURL(value string) (*url.URL, error) {
	base, err := url.Parse(strings.TrimSpace(value))
	if err != nil || base.Host == "" || (base.Scheme != "http" && base.Scheme != "https") || base.User != nil || base.RawQuery != "" || base.Fragment != "" {
		return nil, ErrInvalidBaseURL
	}
	return base, nil
}