package repository

import (
	"seeyon-filesystem/config"
	"seeyon-filesystem/model"

	"gorm.io/gorm"
)

// FileRepository 文件数据访问
type FileRepository struct{}

// NewFileRepository 创建文件Repository实例
func NewFileRepository() *FileRepository {
	return &FileRepository{}
}

// Create 创建文件记录
func (r *FileRepository) Create(file *model.File) error {
	return config.DB.Create(file).Error
}

// FindByID 根据ID查找文件
func (r *FileRepository) FindByID(id uint64) (*model.File, error) {
	var file model.File
	err := config.DB.First(&file, id).Error
	if err != nil {
		return nil, err
	}
	return &file, nil
}

// FindByMD5 根据MD5查找文件(用于秒传)
func (r *FileRepository) FindByMD5(md5 string) (*model.File, error) {
	var file model.File
	err := config.DB.Where("md5 = ? AND status = 1", md5).First(&file).Error
	if err != nil {
		return nil, err
	}
	return &file, nil
}

// ListByFolder 查询文件夹下的文件列表(基于权限)
// 使用 LEFT JOIN 一次性查出, 避免子查询
func (r *FileRepository) ListByFolder(folderID uint64, userID uint64, roleIDs []uint64) ([]model.File, error) {
	var files []model.File

	query := r.buildListByFolderQuery(folderID, userID, roleIDs)
	err := query.Order("f.extension ASC, f.name ASC").Find(&files).Error
	return files, err
}

// ListByFolderPaginated 分页查询文件夹下的文件列表(基于权限)
func (r *FileRepository) ListByFolderPaginated(folderID uint64, userID uint64, roleIDs []uint64, page, pageSize int) ([]model.File, int64, error) {
	var files []model.File
	var total int64

	query := r.buildListByFolderQuery(folderID, userID, roleIDs)

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

	// 分页查询
	offset := (page - 1) * pageSize
	err := query.Order("f.extension ASC, f.name ASC").Offset(offset).Limit(pageSize).Find(&files).Error
	return files, total, err
}

// buildListByFolderQuery 构建文件夹文件查询(公共逻辑)
// 可见性: 管理员看全部 | 自己的 | 直接授权 | 角色授权
func (r *FileRepository) buildListByFolderQuery(folderID uint64, userID uint64, roleIDs []uint64) *gorm.DB {
	// 检查是否为管理员
	isAdmin := r.isAdmin(roleIDs)

	// 管理员: 无额外条件, 看所有文件
	if isAdmin {
		query := config.DB.Table("fs_file f").
			Where("f.folder_id = ? AND f.status = 1", folderID)
		return query
	}

	// 非管理员: 自己的 + 直接授权 + 角色授权
	permCond := "f.owner_id = ?"
	args := []interface{}{userID}

	permCond += " OR fp_user.user_id = ?"
	args = append(args, userID)

	if len(roleIDs) > 0 {
		permCond += " OR fp_role.role_id IN ?"
		args = append(args, roleIDs)
	}

	query := config.DB.Table("fs_file f").
		Select("DISTINCT f.*").
		Joins("LEFT JOIN fs_file_permission fp_user ON fp_user.file_id = f.id AND fp_user.user_id = ?", userID)

	if len(roleIDs) > 0 {
		query = query.Joins("LEFT JOIN fs_file_permission fp_role ON fp_role.file_id = f.id AND fp_role.role_id IN ?", roleIDs)
	}

	query = query.Where("f.folder_id = ? AND f.status = 1 AND ("+permCond+")", append([]interface{}{folderID}, args...)...)
	return query
}

// isAdmin 检查用户角色中是否包含 admin
func (r *FileRepository) isAdmin(roleIDs []uint64) bool {
	if len(roleIDs) == 0 {
		return false
	}
	var count int64
	config.DB.Model(&model.Role{}).Where("id IN ? AND name = ?", roleIDs, "admin").Count(&count)
	return count > 0
}

// ListByOwner 查询用户的所有文件(仅自己的)
func (r *FileRepository) ListByOwner(ownerID uint64) ([]model.File, error) {
	var files []model.File
	err := config.DB.Where("owner_id = ? AND status = 1", ownerID).
		Order("created_at DESC").Find(&files).Error
	return files, err
}

// SearchByName 按文件名搜索(基于权限, 使用JOIN优化)
func (r *FileRepository) SearchByName(userID uint64, roleIDs []uint64, keyword string) ([]model.File, error) {
	var files []model.File

	isAdmin := r.isAdmin(roleIDs)

	var query *gorm.DB

	if isAdmin {
		// 管理员: 搜所有文件
		query = config.DB.Table("fs_file f").
			Where("f.status = 1")
	} else {
		// 非管理员: 自己的 + 直接授权 + 角色授权
		permCond := "f.owner_id = ? OR fp_user.user_id = ?"
		args := []interface{}{userID, userID}
		if len(roleIDs) > 0 {
			permCond += " OR fp_role.role_id IN ?"
			args = append(args, roleIDs)
		}

		query = config.DB.Table("fs_file f").
			Select("DISTINCT f.*").
			Joins("LEFT JOIN fs_file_permission fp_user ON fp_user.file_id = f.id AND fp_user.user_id = ?", userID)

		if len(roleIDs) > 0 {
			query = query.Joins("LEFT JOIN fs_file_permission fp_role ON fp_role.file_id = f.id AND fp_role.role_id IN ?", roleIDs)
		}

		query = query.Where("f.status = 1 AND ("+permCond+")", args...)
	}

	// 多关键词: 用|分隔, OR匹配
	if keyword != "" {
		keywords := splitKeywords(keyword)
		if len(keywords) > 1 {
			conditions := make([]string, 0, len(keywords))
			args := make([]interface{}, 0, len(keywords))
			for _, kw := range keywords {
				conditions = append(conditions, "name LIKE ?")
				args = append(args, "%"+kw+"%")
			}
			query = query.Where("("+joinStrings(conditions, " OR ")+")", args...)
		} else {
			query = query.Where("name LIKE ?", "%"+keywords[0]+"%")
		}
	}

	err := query.Order("created_at DESC").Limit(200).Find(&files).Error
	return files, err
}

// SearchByType 按文件类型搜索
func (r *FileRepository) SearchByType(ownerID uint64, extensions []string) ([]model.File, error) {
	var files []model.File
	err := config.DB.Where("owner_id = ? AND status = 1 AND extension IN ?", ownerID, extensions).
		Order("created_at DESC").Limit(200).Find(&files).Error
	return files, err
}

// SearchByPolicy 按存储策略搜索(管理员用)
func (r *FileRepository) SearchByPolicy(policyID uint64) ([]model.File, error) {
	var files []model.File
	err := config.DB.Where("storage_policy_id = ? AND status = 1", policyID).
		Order("created_at DESC").Limit(500).Find(&files).Error
	return files, err
}

func splitKeywords(s string) []string {
	var result []string
	for _, kw := range splitByChar(s, '|') {
		kw = trimSpace(kw)
		if kw != "" {
			result = append(result, kw)
		}
	}
	if len(result) == 0 {
		result = []string{s}
	}
	return result
}

func splitByChar(s string, sep byte) []string {
	var result []string
	start := 0
	for i := 0; i < len(s); i++ {
		if s[i] == sep {
			result = append(result, s[start:i])
			start = i + 1
		}
	}
	result = append(result, s[start:])
	return result
}

func trimSpace(s string) string {
	start, end := 0, len(s)
	for start < end && s[start] == ' ' {
		start++
	}
	for end > start && s[end-1] == ' ' {
		end--
	}
	return s[start:end]
}

func joinStrings(strs []string, sep string) string {
	if len(strs) == 0 {
		return ""
	}
	result := strs[0]
	for i := 1; i < len(strs); i++ {
		result += sep + strs[i]
	}
	return result
}

// ListTrashed 查询回收站文件
func (r *FileRepository) ListTrashed(ownerID uint64) ([]model.File, error) {
	var files []model.File
	err := config.DB.Where("owner_id = ? AND status = 0", ownerID).
		Order("updated_at DESC").Find(&files).Error
	return files, err
}

// Update 更新文件信息
func (r *FileRepository) Update(file *model.File) error {
	return config.DB.Save(file).Error
}

// SoftDelete 软删除(移入回收站)
func (r *FileRepository) SoftDelete(id uint64) error {
	return config.DB.Model(&model.File{}).Where("id = ?", id).Update("status", 0).Error
}

// Restore 从回收站恢复
func (r *FileRepository) Restore(id uint64) error {
	return config.DB.Model(&model.File{}).Where("id = ?", id).Update("status", 1).Error
}

// HardDelete 永久删除
func (r *FileRepository) HardDelete(id uint64) error {
	return config.DB.Unscoped().Delete(&model.File{}, id).Error
}

// IncrementDownloadCount 增加下载次数
func (r *FileRepository) IncrementDownloadCount(id uint64) error {
	return config.DB.Model(&model.File{}).Where("id = ?", id).
		Update("download_count", config.DB.Raw("download_count + 1")).Error
}

// CountByOwner 统计用户文件数
func (r *FileRepository) CountByOwner(ownerID uint64) (int64, error) {
	var count int64
	err := config.DB.Model(&model.File{}).Where("owner_id = ? AND status = 1", ownerID).Count(&count).Error
	return count, err
}

// SumSizeByOwner 统计用户文件总大小
func (r *FileRepository) SumSizeByOwner(ownerID uint64) (int64, error) {
	var total int64
	err := config.DB.Model(&model.File{}).Where("owner_id = ? AND status = 1", ownerID).
		Select("COALESCE(SUM(size), 0)").Scan(&total).Error
	return total, err
}

// PolicyStats 存储策略统计
type PolicyStats struct {
	PolicyID   uint64 `json:"policy_id"`
	PolicyName string `json:"policy_name"`
	PolicyType string `json:"policy_type"`
	FileCount  int64  `json:"file_count"`
	TotalSize  int64  `json:"total_size"`
	UserCount  int64  `json:"user_count"`
}

// GetPolicyStats 获取所有存储策略的使用统计
func (r *FileRepository) GetPolicyStats() ([]PolicyStats, error) {
	var stats []PolicyStats
	err := config.DB.Raw(`
		SELECT
			f.storage_policy_id as policy_id,
			COALESCE(sp.name, '未知') as policy_name,
			COALESCE(sp.policy_type, '') as policy_type,
			COUNT(*) as file_count,
			COALESCE(SUM(f.size), 0) as total_size,
			COUNT(DISTINCT f.owner_id) as user_count
		FROM fs_file f
		LEFT JOIN fs_storage_policy sp ON sp.id = f.storage_policy_id
		WHERE f.status = 1
		GROUP BY f.storage_policy_id, sp.name, sp.policy_type
		ORDER BY total_size DESC
	`).Scan(&stats).Error
	return stats, err
}

// GetGlobalStats 获取全局统计
func (r *FileRepository) GetGlobalStats() (map[string]interface{}, error) {
	var totalFiles int64
	var totalSize int64
	var totalUsers int64

	config.DB.Model(&model.File{}).Where("status = 1").Count(&totalFiles)
	config.DB.Model(&model.File{}).Where("status = 1").Select("COALESCE(SUM(size), 0)").Scan(&totalSize)
	config.DB.Model(&model.File{}).Where("status = 1").Distinct("owner_id").Count(&totalUsers)

	var totalFolders int64
	config.DB.Model(&model.Folder{}).Where("status = 1").Count(&totalFolders)

	return map[string]interface{}{
		"total_files":   totalFiles,
		"total_size":    totalSize,
		"total_folders": totalFolders,
		"total_users":   totalUsers,
	}, nil
}