Make ResourceMapper interpret URLs ending with '/' as index pages

Essentially, URLs ending with a '/' will internally be translated
to paths such as 'index.html', 'index.ttl', ...
depending on the content type

Author: rubensworks

lib/resource-mapper.js

@@ -8,12 +8,13 @@ const readdir = promisify(fs.readdir)
 // following the principles of the “sweet spot” discussed in
 // https://www.w3.org/DesignIssues/HTTPFilenameMapping.html
 class ResourceMapper {
-  constructor ({ rootUrl, rootPath, includeHost, defaultContentType }) {
+  constructor ({ rootUrl, rootPath, includeHost, defaultContentType, indexName = 'index' }) {
     this._rootUrl = this._removeTrailingSlash(rootUrl)
     this._rootPath = this._removeTrailingSlash(rootPath)
     this._includeHost = includeHost
     this._readdir = readdir
     this._defaultContentType = defaultContentType
+    this._indexName = indexName
 
     // If the host needs to be replaced on every call, pre-split the root URL
     if (includeHost) {
@@ -29,16 +30,28 @@ class ResourceMapper {
   }
 
   // Maps the request for a given resource and representation format to a server file
+  // When the URL ends with a '/', then files with the prefix 'index.' will be matched,
+  // such as 'index.html' and 'index.ttl'.
   async mapUrlToFile ({ url, contentType, createIfNotExists }) {
-    const fullPath = this._getFullPath(url)
+    let fullPath = this._getFullPath(url)
+    let isIndex = fullPath.endsWith('/')
     let path
 
+    // Append index filename if the URL ends with a '/'
+    if (isIndex) {
+      fullPath += this._indexName
+    }
+
     // Create the path for a new file
     if (createIfNotExists) {
       path = fullPath
       // If the extension is not correct for the content type, append the correct extension
       if (this._getContentTypeByExtension(path) !== contentType) {
-        path += contentType in extensions ? `$.${extensions[contentType][0]}` : '$.unknown'
+        // Append a '$', unless we map for the index
+        if (!isIndex) {
+          path += '$'
+        }
+        path += contentType in extensions ? `.${extensions[contentType][0]}` : '.unknown'
       }
     // Determine the path of an existing file
     } else {
@@ -48,7 +61,8 @@ class ResourceMapper {
       const files = await this._readdir(folder)
 
       // Find a file with the same name (minus the dollar extension)
-      const match = files.find(f => this._removeDollarExtension(f) === filename)
+      const match = files.find(f => this._removeDollarExtension(f) === filename ||
+        (isIndex && f.startsWith(this._indexName + '.')))
       if (!match) {
         throw new Error('File not found')
       }

test/unit/resource-mapper-test.js

@@ -192,6 +192,54 @@ describe('ResourceMapper', () => {
         contentType: 'text/html'
       })
 
+    itMapsUrl(mapper, 'a URL ending with a slash to an index file when index.html is available',
+      {
+        url: 'http://localhost/space/'
+      },
+      [
+        `${rootPath}space/index.html`,
+        `${rootPath}space/index$.ttl`
+      ],
+      {
+        path: `${rootPath}space/index.html`,
+        contentType: 'text/html'
+      })
+
+    itMapsUrl(mapper, 'a URL ending with a slash to an index file when index$.html is available',
+      {
+        url: 'http://localhost/space/'
+      },
+      [
+        `${rootPath}space/index$.html`,
+        `${rootPath}space/index$.ttl`
+      ],
+      {
+        path: `${rootPath}space/index$.html`,
+        contentType: 'text/html'
+      })
+
+    itMapsUrl(mapper, 'a URL ending with a slash to an index file for text/html when index.html not is available',
+      {
+        url: 'http://localhost/space/',
+        contentType: 'text/html',
+        createIfNotExists: true
+      },
+      {
+        path: `${rootPath}space/index.html`,
+        contentType: 'text/html'
+      })
+
+    itMapsUrl(mapper, 'a URL ending with a slash to an index file for text/turtle when index.ttl not is available',
+      {
+        url: 'http://localhost/space/',
+        contentType: 'text/turtle',
+        createIfNotExists: true
+      },
+      {
+        path: `${rootPath}space/index.ttl`,
+        contentType: 'text/turtle'
+      })
+
     // Security cases
 
     itMapsUrl(mapper, 'a URL with an unknown content type',
@@ -448,7 +496,7 @@ function mapsUrl (it, mapper, label, options, files, expected) {
   // Mock filesystem
   function mockReaddir () {
     mapper._readdir = async (path) => {
-      expect(path).to.equal(`${rootPath}space/`)
+      expect(path.startsWith(`${rootPath}space/`)).to.equal(true)
       return files.map(f => f.replace(/.*\//, ''))
     }
   }