package user

import (
	"context"
	"errors"

	"bindbox-game/internal/repository/mysql/dao"
	"bindbox-game/internal/repository/mysql/model"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// BindInviterInput 绑定邀请人输入
type BindInviterInput struct {
	InviteCode string // 邀请人的邀请码
}

// BindInviterOutput 绑定邀请人输出
type BindInviterOutput struct {
	InviterID       int64  `json:"inviter_id"`
	InviterNickname string `json:"inviter_nickname"`
}

var (
	ErrAlreadyBound     = errors.New("already_bound")
	ErrInvalidCode      = errors.New("invalid_code")
	ErrCannotInviteSelf = errors.New("cannot_invite_self")
)

// BindInviter 用户主动绑定邀请人（仅限未绑定过的用户）
func (s *service) BindInviter(ctx context.Context, userID int64, in BindInviterInput) (*BindInviterOutput, error) {
	var result *BindInviterOutput

	err := s.writeDB.Transaction(func(tx *dao.Query) error {
		// 1. 获取当前用户，加行锁
		user, err := tx.Users.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).
			Where(tx.Users.ID.Eq(userID)).First()
		if err != nil {
			return err
		}

		// 2. 检查是否已绑定邀请人
		if user.InviterID != 0 {
			return ErrAlreadyBound
		}

		// 3. 查找邀请人
		inviter, err := tx.Users.WithContext(ctx).Where(tx.Users.InviteCode.Eq(in.InviteCode)).First()
		if err != nil {
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return ErrInvalidCode
			}
			return err
		}

		// 4. 不能邀请自己
		if inviter.ID == userID {
			return ErrCannotInviteSelf
		}

		// 5. 创建邀请记录
		invite := &model.UserInvites{
			InviterID:  inviter.ID,
			InviteeID:  userID,
			InviteCode: in.InviteCode,
		}
		if err := tx.UserInvites.WithContext(ctx).Create(invite); err != nil {
			return err
		}

		// 6. 更新用户的邀请人ID
		if _, err := tx.Users.WithContext(ctx).Where(tx.Users.ID.Eq(userID)).
			UpdateColumn(tx.Users.InviterID, inviter.ID); err != nil {
			return err
		}

		result = &BindInviterOutput{
			InviterID:       inviter.ID,
			InviterNickname: inviter.Nickname,
		}

		return nil
	})

	if err != nil {
		return nil, err
	}

	return result, nil
}