backend/internal/service/helpers.go

package service

import (
	"carrotskin/internal/model"
	"carrotskin/internal/repository"
	"errors"
	"fmt"

	"gorm.io/gorm"
)

// 通用错误
var (
	ErrProfileNotFound    = errors.New("档案不存在")
	ErrProfileNoPermission = errors.New("无权操作此档案")
	ErrTextureNotFound    = errors.New("材质不存在")
	ErrTextureNoPermission = errors.New("无权操作此材质")
	ErrUserNotFound       = errors.New("用户不存在")
)

// NormalizePagination 规范化分页参数
func NormalizePagination(page, pageSize int) (int, int) {
	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = 20
	}
	if pageSize > 100 {
		pageSize = 100
	}
	return page, pageSize
}

// GetProfileWithPermissionCheck 获取档案并验证权限
// 返回档案，如果不存在或无权限则返回相应错误
func GetProfileWithPermissionCheck(uuid string, userID int64) (*model.Profile, error) {
	profile, err := repository.FindProfileByUUID(uuid)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrProfileNotFound
		}
		return nil, fmt.Errorf("查询档案失败: %w", err)
	}

	if profile.UserID != userID {
		return nil, ErrProfileNoPermission
	}

	return profile, nil
}

// GetTextureWithPermissionCheck 获取材质并验证权限
// 返回材质，如果不存在或无权限则返回相应错误
func GetTextureWithPermissionCheck(textureID, userID int64) (*model.Texture, error) {
	texture, err := repository.FindTextureByID(textureID)
	if err != nil {
		return nil, err
	}
	if texture == nil {
		return nil, ErrTextureNotFound
	}

	if texture.UploaderID != userID {
		return nil, ErrTextureNoPermission
	}

	return texture, nil
}

// EnsureTextureExists 确保材质存在
func EnsureTextureExists(textureID int64) (*model.Texture, error) {
	texture, err := repository.FindTextureByID(textureID)
	if err != nil {
		return nil, err
	}
	if texture == nil {
		return nil, ErrTextureNotFound
	}
	if texture.Status == -1 {
		return nil, errors.New("材质已删除")
	}
	return texture, nil
}

// EnsureUserExists 确保用户存在
func EnsureUserExists(userID int64) (*model.User, error) {
	user, err := repository.FindUserByID(userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return nil, ErrUserNotFound
	}
	return user, nil
}

// WrapError 包装错误，添加上下文信息
func WrapError(err error, message string) error {
	if err == nil {
		return nil
	}
	return fmt.Errorf("%s: %w", message, err)
}