backend/internal/repository/material_repo.go

package repository

import (
	"carrot_bbs/internal/model"

	"gorm.io/gorm"
)

// MaterialSubjectRepository 学科分类仓储
type MaterialSubjectRepository struct {
	db *gorm.DB
}

func NewMaterialSubjectRepository(db *gorm.DB) *MaterialSubjectRepository {
	return &MaterialSubjectRepository{db: db}
}

// ListActive 获取所有启用的学科分类
func (r *MaterialSubjectRepository) ListActive() ([]*model.MaterialSubject, error) {
	var subjects []*model.MaterialSubject
	err := r.db.
		Where("is_active = ?", true).
		Order("sort_order ASC, created_at ASC").
		Find(&subjects).Error
	return subjects, err
}

// ListAll 获取所有学科分类（管理端用）
func (r *MaterialSubjectRepository) ListAll() ([]*model.MaterialSubject, error) {
	var subjects []*model.MaterialSubject
	err := r.db.
		Order("sort_order ASC, created_at ASC").
		Find(&subjects).Error
	return subjects, err
}

// GetByID 根据ID获取学科分类
func (r *MaterialSubjectRepository) GetByID(id string) (*model.MaterialSubject, error) {
	var subject model.MaterialSubject
	if err := r.db.First(&subject, "id = ?", id).Error; err != nil {
		return nil, err
	}
	return &subject, nil
}

// Create 创建学科分类
func (r *MaterialSubjectRepository) Create(subject *model.MaterialSubject) error {
	return r.db.Create(subject).Error
}

// Update 更新学科分类
func (r *MaterialSubjectRepository) Update(subject *model.MaterialSubject) error {
	return r.db.Save(subject).Error
}

// Delete 删除学科分类
func (r *MaterialSubjectRepository) Delete(id string) error {
	return r.db.Delete(&model.MaterialSubject{}, "id = ?", id).Error
}

// CountMaterials 统计学科下的资料数量
func (r *MaterialSubjectRepository) CountMaterials(subjectID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.MaterialFile{}).Where("subject_id = ?", subjectID).Count(&count).Error
	return count, err
}

// MaterialFileRepository 文件资料仓储
type MaterialFileRepository struct {
	db *gorm.DB
}

func NewMaterialFileRepository(db *gorm.DB) *MaterialFileRepository {
	return &MaterialFileRepository{db: db}
}

// ListQueryParams 查询参数
type MaterialFileQueryParams struct {
	SubjectID string
	FileType  string
	Status    string
	Keyword   string
	Page      int
	PageSize  int
	SortBy    string
	SortOrder string
}

// List 获取资料列表（支持筛选和分页）
func (r *MaterialFileRepository) List(params MaterialFileQueryParams) ([]*model.MaterialFile, int64, error) {
	var files []*model.MaterialFile
	var total int64

	query := r.db.Model(&model.MaterialFile{})

	// 筛选条件
	if params.SubjectID != "" {
		query = query.Where("subject_id = ?", params.SubjectID)
	}
	if params.FileType != "" {
		query = query.Where("file_type = ?", params.FileType)
	}
	if params.Status != "" {
		query = query.Where("status = ?", params.Status)
	}
	if params.Keyword != "" {
		keyword := "%" + params.Keyword + "%"
		query = query.Where("title LIKE ? OR description LIKE ?", keyword, keyword)
	}

	// 统计总数
	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	// 排序
	sortBy := params.SortBy
	if sortBy == "" {
		sortBy = "created_at"
	}
	sortOrder := params.SortOrder
	if sortOrder == "" {
		sortOrder = "DESC"
	}
	orderClause := sortBy + " " + sortOrder

	// 分页
	page := params.Page
	if page < 1 {
		page = 1
	}
	pageSize := params.PageSize
	if pageSize < 1 {
		pageSize = 20
	}
	offset := (page - 1) * pageSize

	// 查询
	if err := query.Order(orderClause).Offset(offset).Limit(pageSize).Find(&files).Error; err != nil {
		return nil, 0, err
	}

	return files, total, nil
}

// GetByID 根据ID获取资料详情
func (r *MaterialFileRepository) GetByID(id string) (*model.MaterialFile, error) {
	var file model.MaterialFile
	if err := r.db.First(&file, "id = ?", id).Error; err != nil {
		return nil, err
	}
	return &file, nil
}

// GetByIDWithSubject 根据ID获取资料详情（包含学科信息）
func (r *MaterialFileRepository) GetByIDWithSubject(id string) (*model.MaterialFile, error) {
	var file model.MaterialFile
	if err := r.db.Preload("Subject").First(&file, "id = ?", id).Error; err != nil {
		return nil, err
	}
	return &file, nil
}

// Create 创建资料
func (r *MaterialFileRepository) Create(file *model.MaterialFile) error {
	return r.db.Create(file).Error
}

// Update 更新资料
func (r *MaterialFileRepository) Update(file *model.MaterialFile) error {
	return r.db.Save(file).Error
}

// Delete 删除资料
func (r *MaterialFileRepository) Delete(id string) error {
	return r.db.Delete(&model.MaterialFile{}, "id = ?", id).Error
}

// IncrementDownloadCount 增加下载次数
func (r *MaterialFileRepository) IncrementDownloadCount(id string) error {
	return r.db.Model(&model.MaterialFile{}).Where("id = ?", id).
		UpdateColumn("download_count", gorm.Expr("download_count + ?", 1)).Error
}

// GetBySubjectID 根据学科ID获取资料列表
func (r *MaterialFileRepository) GetBySubjectID(subjectID string, page, pageSize int) ([]*model.MaterialFile, int64, error) {
	var files []*model.MaterialFile
	var total int64

	query := r.db.Model(&model.MaterialFile{}).Where("subject_id = ? AND status = ?", subjectID, model.MaterialStatusActive)

	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	offset := (page - 1) * pageSize
	if err := query.Order("created_at DESC").Offset(offset).Limit(pageSize).Find(&files).Error; err != nil {
		return nil, 0, err
	}

	return files, total, nil
}

// Search 搜索资料
func (r *MaterialFileRepository) Search(keyword string, page, pageSize int) ([]*model.MaterialFile, int64, error) {
	var files []*model.MaterialFile
	var total int64

	query := r.db.Model(&model.MaterialFile{}).Where("status = ?", model.MaterialStatusActive)
	if keyword != "" {
		kw := "%" + keyword + "%"
		query = query.Where("title LIKE ? OR description LIKE ?", kw, kw)
	}

	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	offset := (page - 1) * pageSize
	if err := query.Order("created_at DESC").Offset(offset).Limit(pageSize).Find(&files).Error; err != nil {
		return nil, 0, err
	}

	return files, total, nil
}

// GetHotMaterials 获取热门资料（按下载次数排序）
func (r *MaterialFileRepository) GetHotMaterials(limit int) ([]*model.MaterialFile, error) {
	var files []*model.MaterialFile
	err := r.db.
		Where("status = ?", model.MaterialStatusActive).
		Order("download_count DESC").
		Limit(limit).
		Find(&files).Error
	return files, err
}

// GetLatestMaterials 获取最新资料
func (r *MaterialFileRepository) GetLatestMaterials(limit int) ([]*model.MaterialFile, error) {
	var files []*model.MaterialFile
	err := r.db.
		Where("status = ?", model.MaterialStatusActive).
		Order("created_at DESC").
		Limit(limit).
		Find(&files).Error
	return files, err
}