Introduce a concept of 'storage backend'; add fs backend

components/storage-backends/filesystem.js

+const Promise = require('bluebird');
+const fs = require('fs-extra');
+const crypto = require('crypto');
+const path = require('path');
+const logging = require('../logging').getWrapperForModule('filesystem');
+
+
+const HASH_ALGORITHM = 'sha256';
+
+class FilesystemStorage {
+  /**
+   * @param {string} basePath - A root directory for all stored files
+   */
+  constructor (basePath) {
+    this.basePath = basePath;
+  }
+
+  /**
+   * Uploads attachment to file storage.
+   * @param {File} file Multipart/form-data file.
+   * @return {Promise<string>} Hash of uploaded attachment.
+   */
+  add (file) {
+    logging.verbose(`Uploading '${file.originalFilename}' to filesystem`);
+
+    const hash = this.computeHash(file);
+    const filePath = this.getFilePath(hash);
+
+    return fs.outputFile(filePath, file).then(() => hash);
+  }
+
+  /**
+   * Deletes a file.
+   * 
+   * @param {string} hash - Hash of file to delete
+   * @return {Promise<void>}
+   */
+  delete (hash) {
+    logging.verbose(`Deleting file ${hash} from filesystem`);
+    
+    const filePath = this.getFilePath(hash);
+    return fs.remove(filePath);
+  }
+
+  /**
+   * Gets file from IPFS.
+   * @param  {String} hash IPFS hash.
+   * @return {Promise<ReadableStream>} Readable Stream of attachment.
+   */
+  get (hash) {
+    logging.verbose(`Serving attachment for ${hash} from filesystem`);
+
+    const filePath = this.getFilePath(hash);
+    return fs.readFile(filePath);
+  }
+
+
+  computeHash (file) {
+    const hash = crypto.createHash(HASH_ALGORITHM);
+    hash.update(file);
+    return hash.digest('hex');
+  }
+
+  getFilePath (hash) {
+    const dirName = hash.slice(0, 2);
+    const fileName = hash.slice(2);
+    return path.join(this.basePath, dirName, fileName);
+  }
+}
\ No newline at end of file

components/ipfs.js → components/storage-backends/ipfs.js

-'use strict';
-
 const fs = require('fs');
 const ipfsAPI = require('ipfs-api');
 const path = require('path');
 
-const FileNotFoundError = require('./errors').FileNotFoundError;
-const logging = require('./logging').getWrapperForModule('ipfs');
-const settings = require('./settings');
+const FileNotFoundError = require('../errors').FileNotFoundError;
+const logging = require('../logging').getWrapperForModule('ipfs');
+const settings = require('../settings');
 
 /**
  * Represents an interface to interact with IPFS daemon to download and upload
@@ -16,67 +14,69 @@ class Ipfs {
   /**
    * constructor for Ipfs class.
    */
-  constructor() {
-    this.ipfs = ipfsAPI(settings.ipfs.url);
+  constructor (url) {
+    this.ipfs = ipfsAPI(url);
   }
 
   /**
-   * Stores an IPFS object from a given path locally to disk.
-   * @param  {String}  hash IPFS hash.
-   * @return {Promise}      Pinned object.
+   * Uploads attachment to IPFS.
+   * @param  {File} file Multipart/form-data file.
+   * @return {Promise<string>} IPFS hash of uploaded attachment.
    */
-  pin(hash) {
-    logging.verbose(`Pinning object ${hash} to local storage`);
-    return this.ipfs.pin.add(hash);
+  add (file) {
+    logging.verbose(`Uploading '${file.originalFilename}' to IPFS`);
+    
+    let files = [{
+      path: path.basename(file.path),
+      content: fs.createReadStream(file.path),
+    }];
+
+    let hash;
+    return this.ipfs.files.add(files).then((res) => {
+      hash = res;
+      return this.pin(hash);
+    }).then(() => {
+      return Promise.resolve(hash);
+    });
+  }
+
+  /**
+   * Unpins a file from IPFS - it will be deleted during next `ipfs repo gc`
+   * 
+   * @param {string} hash - Hash of file to delete
+   * @return {Promise<void>}
+   */
+  delete (hash) {
+    logging.verbose(`Unpinning object ${hash} from local storage`);
+    return this.ipfs.pin.rm(hash);
   }
 
   /**
-   * Serves attachment to the client.
+   * Gets file from IPFS.
    * @param  {String} hash IPFS hash.
-   * @return {Promise}     Readable Stream of attachment.
+   * @return {Promise<ReadableStream>} Readable Stream of attachment.
    */
-  serve(hash) {
+  get (hash) {
     logging.verbose(`Serving attachment for ${hash}`);
 
     return this.ipfs.files.cat(hash).then((stream) => {
-      if (!(stream && stream.pipe))
+      if (!(stream && stream.pipe)) {
         throw new FileNotFoundError('No file or stream provided');
+      }
 
       return stream;
     });
   }
 
-  /**
-   * Removes the pin from the given object allowing it to be garbage
-   * collected if needed.
-   * @param  {String}  hash IPFS hash.
-   * @return {Promise}      Unpinned object.
-   */
-  unpin(hash) {
-    logging.verbose(`Unpinning object ${hash} from local storage`);
-    return this.ipfs.pin.rm(hash);
-  }
 
   /**
-   * Uploads attachment to IPFS.
-   * @param  {File}     file Multipart/form-data file.
-   * @return {Promise}       IPFS hash of uploaded attachment.
+   * Pins a file by hash.
+   * @param  {String} hash IPFS hash.
+   * @return {Promise<void>}
    */
-  upload(file) {
-    logging.verbose(`Uploading '${file.originalFilename}' to IPFS`);
-
-    let files = [{
-      path: path.basename(file.path),
-      content: fs.createReadStream(file.path),
-    }];
-
-    let hash;
-    return this.ipfs.files.add(files).then((res) => {
-      hash = res;
-      return this.pin(hash);
-    }).then(() => {
-      return Promise.resolve(hash);
-    });
+  pin (hash) {
+    logging.verbose(`Pinning object ${hash} to local storage`);
+    return this.ipfs.pin.add(hash);
   }
 }