Implement ldp.fetchGraph and pass it in to ACLChecker

Author: dmitrizagidulin

lib/acl-checker.js

@@ -4,7 +4,6 @@ const PermissionSet = require('solid-permissions').PermissionSet
 const rdf = require('rdflib')
 const debug = require('./debug').ACL
 const HTTPError = require('./http-error')
-const { promisify } = require('util')
 
 const DEFAULT_ACL_SUFFIX = '.acl'
 
@@ -15,6 +14,7 @@ class ACLChecker {
     this.host = options.host
     this.origin = options.origin
     this.fetch = options.fetch
+    this.fetchGraph = options.fetchGraph
     this.strictOrigin = options.strictOrigin
     this.suffix = options.suffix || DEFAULT_ACL_SUFFIX
   }
@@ -33,7 +33,7 @@ class ACLChecker {
         .then(acl => this.getPermissionSet(acl))
     }
 
-    const options = { fetchGraph: promisify(this.fetch) }
+    const options = { fetchGraph: this.fetchGraph }
 
     // Check the resource's permissions
     return this._permissionSet
@@ -90,7 +90,7 @@ class ACLChecker {
 
   // Tests whether the permissions allow a given operation
   checkAccess (permissionSet, user, mode) {
-    const options = { fetchGraph: promisify(this.fetch) }
+    const options = { fetchGraph: this.fetchGraph }
     return permissionSet.checkAccess(this.resource, user, mode, options)
       .then(hasAccess => {
         if (hasAccess) {

lib/handlers/allow.js

@@ -39,6 +39,12 @@ function allow (mode) {
         origin: req.get('origin'),
         host: req.protocol + '://' + req.get('host'),
         fetch: fetchFromLdp(mapper, ldp),
+        fetchGraph: (uri, contentType) => {
+          // first try loading from local fs
+          return ldp.getGraph(uri, contentType)
+            // failing that, fetch remote graph
+            .catch(() => ldp.fetchGraph(uri, contentType))
+        },
         suffix: ldp.suffixAcl,
         strictOrigin: ldp.strictOrigin
       })

lib/ldp.js

@@ -14,6 +14,8 @@ const extend = require('extend')
 const rimraf = require('rimraf')
 const ldpContainer = require('./ldp-container')
 const parse = require('./utils').parse
+const fetch = require('node-fetch')
+const { promisify } = require('util')
 
 const DEFAULT_CONTENT_TYPE = 'text/turtle'
 
@@ -296,7 +298,36 @@ class LDP {
   }
 
   /**
-   * Fetches the graph at a given uri, parses it and and returns it.
+   * Remotely loads the graph at a given uri, parses it and and returns it.
+   * Usage:
+   *
+   *   ```
+   *   ldp.fetchGraph('https://example.com/contacts/card1.ttl')
+   *     .then(graph => {
+   *       // const matches = graph.match(...)
+   *     })
+   *   ```
+   *
+   * @param uri {string} Fully qualified uri of the request.
+   * @param [contentType] {string}
+   *
+   * @return {Promise<Graph>}
+   */
+  async fetchGraph (uri, contentType = DEFAULT_CONTENT_TYPE) {
+    const response = await fetch(uri)
+    if (!response.ok) {
+      const error = new Error(
+        `Error fetching ${uri}: ${response.status} ${response.statusText}`
+      )
+      error.statusCode = response.status || 400
+      throw error
+    }
+    const body = await response.text()
+    return promisify(parse)(body, uri, contentType)
+  }
+
+  /**
+   * Loads from fs the graph at a given uri, parses it and and returns it.
    * Usage:
    *
    *   ```