package logic

import (
	"context"
	"errors"
	"regexp"
	"strconv"
	"strings"

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

var (
	lookupEmailRe  = regexp.MustCompile(`^[^@\s]+@[^@\s]+\.[^@\s]+$`)
	lookupDigitsRe = regexp.MustCompile(`^[0-9]+$`)
)

// LookupInput finds a user to add. Q is email, uid, spark_id, or qrcode.
type LookupInput struct {
	Q string `json:"q" validate:"required,max=255" label:"field.friend_query" errmsg:"required:validate.friend.query_required"`
}

func (s *Service) Lookup(ctx context.Context, userID int64, in LookupInput) (*FriendView, error) {
	if !s.ready() || userID <= 0 {
		return nil, errs.ErrUnauthorized
	}
	target, err := s.resolveLookupQuery(ctx, strings.TrimSpace(in.Q))
	if err != nil {
		return nil, err
	}
	blockedBy, err := s.repo.IsBlocked(ctx, target.ID, userID)
	if err != nil {
		return nil, err
	}
	if blockedBy {
		return nil, errs.ErrNotFound
	}
	rel, err := s.repo.GetRelation(ctx, userID, target.ID)
	if err != nil && !errors.Is(err, errs.ErrNotFound) {
		return nil, err
	}
	if errors.Is(err, errs.ErrNotFound) {
		rel = nil
	}
	friend, err := s.AreFriends(ctx, userID, target.ID)
	if err != nil {
		return nil, err
	}
	blockedMe := rel != nil && rel.Blocked
	view := viewOf(target, rel)
	view.Relation = entity.ViewRelation(friend, blockedMe)
	if !friend {
		view.CreatedAt = 0
		view.Pinned = false
		if rel == nil {
			view.Remark = ""
		}
	}
	return view, nil
}

func (s *Service) resolveLookupQuery(ctx context.Context, q string) (*userentity.User, error) {
	if q == "" {
		return nil, errs.ErrInvalidArgument.WithMsg(i18n.T(reqctx.Lang(ctx), i18n.KeyFriendQueryRequired, nil))
	}
	switch {
	case lookupEmailRe.MatchString(q):
		u, err := s.users.GetByEmail(ctx, userentity.NormalizeEmail(q))
		u, _, err = s.ensureActive(ctx, u, err, entity.SourceEmail)
		return u, err
	case lookupDigitsRe.MatchString(q):
		id, err := strconv.ParseInt(q, 10, 64)
		if err != nil || id <= 0 {
			return nil, errs.ErrNotFound
		}
		return s.activeUser(ctx, id)
	default:
		return s.lookupSparkIDThenQR(ctx, q)
	}
}

func (s *Service) lookupSparkIDThenQR(ctx context.Context, q string) (*userentity.User, error) {
	u, err := s.users.GetBySparkID(ctx, q)
	u, _, err = s.ensureActive(ctx, u, err, entity.SourceSparkID)
	if err == nil {
		return u, nil
	}
	if !errors.Is(err, errs.ErrNotFound) {
		return nil, err
	}
	u, err = s.users.GetByQRCode(ctx, q)
	u, _, err = s.ensureActive(ctx, u, err, entity.SourceQRCode)
	return u, err
}