fix: better handling of Accept headers (#20)

.eslintrc.json

@@ -10,6 +10,7 @@
   ],
   "rules": {
     "no-console": "off",
+    "import/prefer-default-export": "off",
     "no-restricted-syntax": [
         "error",
         {

src/index.js

@@ -11,6 +11,7 @@ const { Did, init, connect } = require('@kiltprotocol/sdk-js')
 
 const { PORT, BLOCKCHAIN_NODE } = require('./config')
 const { URI_DID } = require('./consts')
+const { processAcceptHeaders } = require('./utils')
 
 const driver = express()
 
@@ -25,7 +26,10 @@ async function start() {
       console.log('--------------------')
       console.info('\n→ Received headers:')
       console.info(JSON.stringify(req.headers, null, 2))
+      const { exportType, defaultExport, responseContentType } = processAcceptHeaders(req.headers.accept)
       const { did } = req.params
+      // Add queried DID to default export for deleted resolutions
+      defaultExport.id = did
 
       let didResolutionResult
       // Throws if the address is not a valid address
@@ -51,8 +55,8 @@ async function start() {
       // which is represented by the sole `id` property.
       // https://www.w3.org/TR/did-core/#did-document-properties
       const didDocument = didResolutionResult.details ?
-        Did.exportToDidDocument(didResolutionResult.details, 'application/ld+json') :
-        { id: did, '@context': ['https://www.w3.org/ns/did/v1'] }
+        Did.exportToDidDocument(didResolutionResult.details, exportType) :
+        defaultExport
 
       const exportedDidDocument = {
         didDocument,
@@ -62,6 +66,7 @@ async function start() {
       console.trace('\n← Exported DID document:')
       console.trace(JSON.stringify(exportedDidDocument, null, 2))
 
+      res.contentType(responseContentType)
       res.send(exportedDidDocument)
     } catch (error) {
       console.error("\n🚨 Could not satisfy request because of the following error:")

src/utils.js

@@ -0,0 +1,29 @@
+/**
+ * Copyright 2018-2021 BOTLabs GmbH.
+ *
+ * This source code is licensed under the BSD 4-Clause "Original" license
+ * found in the LICENSE file in the root directory of this source tree.
+ */
+
+function processAcceptHeaders(headers) {
+    const acceptedTypes = new Set([...headers.split(',').map((c) => c.trim())])
+    let exportType
+    let defaultExport
+    let responseContentType
+    if (acceptedTypes.has('application/did+json')) {
+        exportType = 'application/json'
+        defaultExport = {}
+        responseContentType = 'application/did+json'
+    } else {
+        exportType = 'application/ld+json'
+        defaultExport = { '@context': ['https://www.w3.org/ns/did/v1'] }
+        responseContentType = 'application/did+ld+json'
+    }
+    return {
+        exportType,
+        defaultExport,
+        responseContentType
+    }
+}
+
+module.exports = { processAcceptHeaders }