package logic

import (
	"context"
	"crypto/subtle"
	"errors"
	"strings"
	"time"

	"spark-server/internal/module/user/entity"
	"spark-server/internal/pkg/errs"
	"spark-server/internal/pkg/i18n"
	"spark-server/internal/pkg/reqctx"
)

// AuthenticateEmail verifies OTP (test01–test10@spark.com accept any code),
// creates the user on first login, and upserts the login device.
func (s *Service) AuthenticateEmail(ctx context.Context, email, verifyCode string, device *entity.LoginDevice) (*entity.User, error) {
	if s == nil || s.repo == nil || s.ids == nil {
		return nil, errs.ErrUnauthorized
	}
	email = entity.NormalizeEmail(email)
	if email == "" {
		return nil, errs.ErrUnauthorized
	}
	if err := s.checkVerifyCode(ctx, email, verifyCode); err != nil {
		return nil, err
	}
	u, err := s.getOrCreate(ctx, email)
	if err != nil {
		return nil, err
	}
	if err := s.ensureQRCode(ctx, u); err != nil {
		return nil, err
	}
	s.ensureDefaultAvatar(ctx, u)
	if u.Status != entity.StatusActive {
		return nil, errs.ErrForbidden
	}
	if err := s.touchDevice(ctx, u.ID, device); err != nil {
		return nil, err
	}
	if err := s.recordLogin(ctx, u.ID, device); err != nil {
		return nil, err
	}
	now := time.Now()
	if err := s.repo.TouchLogin(ctx, u.ID, now); err != nil {
		return nil, err
	}
	u.LastLoginAt = now
	u.LastActiveAt = now
	return u, nil
}

func (s *Service) checkVerifyCode(ctx context.Context, email, verifyCode string) error {
	if entity.IsTestEmail(email) {
		return nil
	}
	want, err := s.codes.Get(ctx, email)
	if err != nil {
		return err
	}
	if want == "" || subtle.ConstantTimeCompare([]byte(want), []byte(verifyCode)) != 1 {
		return errs.ErrUnauthorized
	}
	_ = s.codes.Del(ctx, email)
	return nil
}

func (s *Service) getOrCreate(ctx context.Context, email string) (*entity.User, error) {
	u, err := s.repo.GetByEmail(ctx, email)
	if err == nil {
		return u, nil
	}
	if !errors.Is(err, errs.ErrNotFound) {
		return nil, err
	}
	return s.createWithEmail(ctx, email)
}

func (s *Service) createWithEmail(ctx context.Context, email string) (*entity.User, error) {
	id, err := s.ids.NextID()
	if err != nil {
		return nil, err
	}
	now := time.Now()
	qr, err := entity.NewQRCode()
	if err != nil {
		return nil, err
	}
	nick := nicknameFromEmail(email)
	u := &entity.User{
		ID:           id,
		SparkID:      entity.DefaultSparkID(id),
		Nickname:     nick,
		Avatar:       entity.LetterAvatarDataURI(nick),
		Gender:       entity.GenderUnknown,
		Status:       entity.StatusActive,
		QRCode:       qr,
		LastLoginAt:  now,
		LastActiveAt: now,
		CreatedAt:    now,
		UpdatedAt:    now,
	}
	if err := s.repo.CreateWithEmail(ctx, u, email); err != nil {
		if errors.Is(err, errs.ErrDuplicate) {
			return s.repo.GetByEmail(ctx, email)
		}
		return nil, err
	}
	s.stampDefaultAvatar(ctx, u)
	return u, nil
}

func (s *Service) ensureQRCode(ctx context.Context, u *entity.User) error {
	if u == nil || entity.ValidQRCode(u.QRCode) {
		return nil
	}
	qr, err := entity.NewQRCode()
	if err != nil {
		return err
	}
	u.QRCode = qr
	return s.repo.UpdateQRCode(ctx, u.ID, u.QRCode)
}

func (s *Service) touchDevice(ctx context.Context, userID int64, device *entity.LoginDevice) error {
	if device == nil || device.DeviceID == 0 {
		return errs.ErrInvalidArgument
	}
	typ := entity.DeviceTypeOf(device)
	if !entity.ValidDeviceType(typ) {
		return errs.ErrInvalidArgument.WithMsg(i18n.T(reqctx.Lang(ctx), i18n.KeyLoginDeviceTypeRequired, nil))
	}
	now := time.Now()
	ip := strings.TrimSpace(device.RealIP)
	if ip == "" {
		ip = reqctx.RealIP(ctx)
	}
	lang := strings.TrimSpace(device.Language)
	if lang == "" {
		lang = reqctx.Language(ctx)
	}
	return s.repo.UpsertDevice(ctx, &entity.Device{
		UserID:      userID,
		DeviceID:    device.DeviceID,
		DeviceType:  typ,
		DeviceName:  device.DeviceName,
		AppVersion:  device.AppVersion,
		Language:    lang,
		LastIP:      ip,
		LastLoginAt: now,
		CreatedAt:   now,
	})
}

func (s *Service) recordLogin(ctx context.Context, userID int64, device *entity.LoginDevice) error {
	if device == nil {
		return errs.ErrInvalidArgument
	}
	ip := strings.TrimSpace(device.RealIP)
	if ip == "" {
		ip = reqctx.RealIP(ctx)
	}
	lang := strings.TrimSpace(device.Language)
	if lang == "" {
		lang = reqctx.Language(ctx)
	}
	return s.repo.InsertLoginLog(ctx, &entity.LoginLog{
		UserID:     userID,
		DeviceID:   device.DeviceID,
		DeviceType: entity.DeviceTypeOf(device),
		DeviceName: device.DeviceName,
		AppVersion: device.AppVersion,
		Language:   lang,
		IP:         ip,
		CreatedAt:  time.Now(),
	})
}

func nicknameFromEmail(email string) string {
	local, _, _ := strings.Cut(email, "@")
	local = strings.TrimSpace(local)
	if local == "" {
		return "user"
	}
	if len(local) > 64 {
		return local[:64]
	}
	return local
}