feat: add independent direct-link sharing flow

backend/database.js

@@ -236,6 +236,28 @@ function initDatabase() {
     )
   `);
 
+  // 分享直链表（与 shares 独立，互不影响）
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS direct_links (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      user_id INTEGER NOT NULL,
+      link_code TEXT UNIQUE NOT NULL,
+      file_path TEXT NOT NULL,
+      file_name TEXT,
+      storage_type TEXT DEFAULT 'oss',
+
+      -- 直链统计
+      download_count INTEGER DEFAULT 0,
+      last_accessed_at DATETIME,
+
+      -- 时间戳
+      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+      expires_at DATETIME,
+
+      FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE CASCADE
+    )
+  `);
+
   // 系统设置表
   db.exec(`
     CREATE TABLE IF NOT EXISTS system_settings (
@@ -254,6 +276,9 @@ function initDatabase() {
     CREATE INDEX IF NOT EXISTS idx_shares_code ON shares(share_code);
     CREATE INDEX IF NOT EXISTS idx_shares_user ON shares(user_id);
     CREATE INDEX IF NOT EXISTS idx_shares_expires ON shares(expires_at);
+    CREATE INDEX IF NOT EXISTS idx_direct_links_code ON direct_links(link_code);
+    CREATE INDEX IF NOT EXISTS idx_direct_links_user ON direct_links(user_id);
+    CREATE INDEX IF NOT EXISTS idx_direct_links_expires ON direct_links(expires_at);
 
     -- ===== 性能优化：复合索引（P0 优先级修复） =====
 
@@ -262,6 +287,10 @@ function initDatabase() {
     -- 使用场景：ShareDB.findByCode, 分享访问验证
     CREATE INDEX IF NOT EXISTS idx_shares_code_expires ON shares(share_code, expires_at);
 
+    -- 直链复合索引：link_code + expires_at
+    -- 使用场景：DirectLinkDB.findByCode
+    CREATE INDEX IF NOT EXISTS idx_direct_links_code_expires ON direct_links(link_code, expires_at);
+
     -- 注意：system_logs 表的复合索引在表创建后创建（第372行之后）
     -- 2. 活动日志复合索引：user_id + created_at
     -- 优势：快速查询用户最近的活动记录，支持时间范围过滤
@@ -276,6 +305,7 @@ function initDatabase() {
 
   console.log('[数据库性能优化] ✓ 基础索引已创建');
   console.log('  - idx_shares_code_expires: 分享码+过期时间');
+  console.log('  - idx_direct_links_code_expires: 直链码+过期时间');
 
   // 数据库迁移：添加upload_api_key字段（如果不存在）
   try {
@@ -1265,6 +1295,127 @@ const ShareDB = {
   }
 };
 
+// 分享直链相关操作（与 ShareDB 独立）
+const DirectLinkDB = {
+  // 生成随机直链码
+  generateLinkCode(length = 10) {
+    const chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
+    const bytes = crypto.randomBytes(length);
+    let code = '';
+    for (let i = 0; i < length; i++) {
+      code += chars[bytes[i] % chars.length];
+    }
+    return code;
+  },
+
+  create(userId, options = {}) {
+    const {
+      file_path = '',
+      file_name = '',
+      storage_type = 'oss',
+      expiry_days = null
+    } = options;
+
+    let linkCode;
+    let attempts = 0;
+    do {
+      linkCode = this.generateLinkCode();
+      attempts++;
+      if (attempts > 10) {
+        linkCode = this.generateLinkCode(14);
+      }
+    } while (
+      db.prepare('SELECT 1 FROM direct_links WHERE link_code = ?').get(linkCode)
+      && attempts < 20
+    );
+
+    let expiresAt = null;
+    if (expiry_days) {
+      const expireDate = new Date();
+      expireDate.setDate(expireDate.getDate() + parseInt(expiry_days, 10));
+      const year = expireDate.getFullYear();
+      const month = String(expireDate.getMonth() + 1).padStart(2, '0');
+      const day = String(expireDate.getDate()).padStart(2, '0');
+      const hours = String(expireDate.getHours()).padStart(2, '0');
+      const minutes = String(expireDate.getMinutes()).padStart(2, '0');
+      const seconds = String(expireDate.getSeconds()).padStart(2, '0');
+      expiresAt = `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`;
+    }
+
+    const result = db.prepare(`
+      INSERT INTO direct_links (user_id, link_code, file_path, file_name, storage_type, expires_at)
+      VALUES (?, ?, ?, ?, ?, ?)
+    `).run(
+      userId,
+      linkCode,
+      file_path,
+      file_name || null,
+      storage_type || 'oss',
+      expiresAt
+    );
+
+    return {
+      id: result.lastInsertRowid,
+      link_code: linkCode,
+      file_path,
+      file_name: file_name || null,
+      storage_type: storage_type || 'oss',
+      expires_at: expiresAt
+    };
+  },
+
+  findByCode(linkCode) {
+    return db.prepare(`
+      SELECT
+        dl.*,
+        u.username,
+        u.is_banned
+      FROM direct_links dl
+      JOIN users u ON dl.user_id = u.id
+      WHERE dl.link_code = ?
+        AND (dl.expires_at IS NULL OR dl.expires_at > datetime('now', 'localtime'))
+        AND u.is_banned = 0
+    `).get(linkCode);
+  },
+
+  findById(id) {
+    return db.prepare('SELECT * FROM direct_links WHERE id = ?').get(id);
+  },
+
+  getUserLinks(userId) {
+    return db.prepare(`
+      SELECT *
+      FROM direct_links
+      WHERE user_id = ?
+      ORDER BY created_at DESC
+    `).all(userId);
+  },
+
+  incrementDownloadCount(linkCode) {
+    return db.prepare(`
+      UPDATE direct_links
+      SET download_count = download_count + 1,
+          last_accessed_at = CURRENT_TIMESTAMP
+      WHERE link_code = ?
+    `).run(linkCode);
+  },
+
+  touchAccess(linkCode) {
+    return db.prepare(`
+      UPDATE direct_links
+      SET last_accessed_at = CURRENT_TIMESTAMP
+      WHERE link_code = ?
+    `).run(linkCode);
+  },
+
+  delete(id, userId = null) {
+    if (userId) {
+      return db.prepare('DELETE FROM direct_links WHERE id = ? AND user_id = ?').run(id, userId);
+    }
+    return db.prepare('DELETE FROM direct_links WHERE id = ?').run(id);
+  }
+};
+
 // 系统设置管理
 const SettingsDB = {
   // 获取设置
@@ -2091,17 +2242,21 @@ const TransactionDB = {
       // 1. 删除用户的所有分享
       const sharesDeleted = db.prepare('DELETE FROM shares WHERE user_id = ?').run(userId);
 
-      // 2. 删除密码重置令牌
+      // 2. 删除用户的所有直链
+      const directLinksDeleted = db.prepare('DELETE FROM direct_links WHERE user_id = ?').run(userId);
+
+      // 3. 删除密码重置令牌
       const tokensDeleted = db.prepare('DELETE FROM password_reset_tokens WHERE user_id = ?').run(userId);
 
-      // 3. 更新日志中的用户引用（设为 NULL，保留日志记录）
+      // 4. 更新日志中的用户引用（设为 NULL，保留日志记录）
       db.prepare('UPDATE system_logs SET user_id = NULL WHERE user_id = ?').run(userId);
 
-      // 4. 删除用户记录
+      // 5. 删除用户记录
       const userDeleted = db.prepare('DELETE FROM users WHERE id = ?').run(userId);
 
       return {
         sharesDeleted: sharesDeleted.changes,
+        directLinksDeleted: directLinksDeleted.changes,
         tokensDeleted: tokensDeleted.changes,
         userDeleted: userDeleted.changes
       };
@@ -2123,6 +2278,7 @@ module.exports = {
   db,
   UserDB,
   ShareDB,
+  DirectLinkDB,
   SettingsDB,
   VerificationDB,
   PasswordResetTokenDB,