feat: File Manager (wip)

- 用于集中管理各类文件, 并清理长期未被访问的文件

src/data/FileManager.ts

@@ -1,5 +1,76 @@
+import { DatabaseSync } from "node:sqlite"
 import { Buffer } from "node:buffer"
 import path from 'node:path'
 import crypto from 'node:crypto'
+import fs from 'node:fs/promises'
 
+import { fileTypeFromBuffer } from 'file-type'
 
+export default class FileManager {
+    static FileBean = interface {
+        count: number,
+        name: string,
+        hash: string,
+        mime: string,
+    }
+    
+    static File = class {
+        declare bean: FileManager.FileBean
+        constructor(bean: UserBean) {
+            this.bean = bean
+        }
+        getMime(): string {
+            return this.bean.mime
+        }
+        getName(): string {
+            return this.bean.name
+        }
+        getFilePath(): string {
+            const hash = this.bean.hash
+            return path.join(
+                config.data_path, 
+                "files",
+                hash.substring(0, 1),
+                hash.substring(2, 3),
+                hash.substring(3, 4),
+                this.bean.hash
+            )
+        }
+        async readAsync(): Buffer {
+            return await fs.readFile(this.getFilePath())
+        }
+    }
+
+    static table_name: string = "FileReferences"
+    private static database: DatabaseSync = FileManager.init()
+    private static init(): DatabaseSync {
+        const db: DatabaseSync = new DatabaseSync(path.join(config.data_path, FileManager.table_name + '.db'))
+        db.exec(`
+            CREATE TABLE IF NOT EXISTS ${FileManager.table_name} (
+                /* 序号 */ count INTEGER PRIMARY KEY AUTOINCREMENT,
+                /* 文件名称 */ name TEXT NOT NULL,
+                /* 文件哈希 */ hash TEXT NOT NULL,
+                /* MIME 类型 */ mime TEXT NOT NULL
+            );
+       `)
+       return db
+    }
+    
+    static uploadFile(fileName: string, data: Buffer) {
+        const hash = crypto.createHash('sha256').update(data).digest('hex')
+        mime = fileTypeFromBuffer(data)
+        
+    }
+    
+    private static findAllBeansByCondition(condition: string, ...args: unknown[]): FileManager.FileBean[] {
+        return FileManager.database.prepare(`SELECT * FROM ${FileManager.table_name} WHERE ${condition};`).all(...args)
+    }
+    static findByHash(hash: string): FileManager.File {
+        const beans = FileManager.findAllBeansByCondition('hash = ?', hash)
+        if (beans.length == 0)
+            throw new Error(`找不到 hash 为 ${hash} 的文件`)
+        else if (beans.length > 1)
+            console.error(chalk.red(`警告: 查询 hash = ${id} 时, 查询到多个相同 Hash 的文件`))
+        return new FileManager.File(beans[0])
+    }
+}