web-demo: decode content

4 files changed, 57 insertions, 21 deletions

diff --git a/examples/web-demo/index.html b/examples/web-demo/index.html
index ff89441..4fa7e3a 100644
--- a/examples/web-demo/index.html
+++ b/examples/web-demo/index.html
@@ -60,12 +60,16 @@
               <option value="application/ld+json">JSON-LD</option>
             </select>
           </details>
+          <br>
+          <button id="controls-decode">Decode</button>
         </div>
 
         <div id="encoded">
           <h2>Encoded</h2>
-          <h3>ERIS URN</h3>
-          <input id="encoded-eris-urn" type="url" readonly>
+
+          <h3>Read capability</h3>
+          <input id="encoded-eris-read-cap" type="url">
+
           </input>
 
           <br>
diff --git a/examples/web-demo/src/index.js b/examples/web-demo/src/index.js
index cc66492..155fe1e 100644
--- a/examples/web-demo/src/index.js
+++ b/examples/web-demo/src/index.js
@@ -88,9 +88,12 @@ async function main () {
   const inputLoadAliceInWonderland = document.getElementById('input-load-alice-in-wonderland')
   const inputLoadSampleVocabulary = document.getElementById('input-load-sample-vocabulary')
   const inputLoadSampleActor = document.getElementById('input-load-sample-actor')
+
   const controlsEncode = document.getElementById('controls-encode')
+  const controlsDecode = document.getElementById('controls-decode')
   const controlsInputType = document.getElementById('controls-input-type')
-  const encodedErisUrn = document.getElementById('encoded-eris-urn')
+
+  const encodedErisReadCap = document.getElementById('encoded-eris-read-cap')
   const encodedData = document.getElementById('encoded-data')
 
   // a ContentAddressableStorage based on a JavaScipt Map
@@ -131,14 +134,30 @@ async function main () {
     return ERIS.put(input, cas)
   }
 
-  controlsEncode.onclick = function (e) {
-    encode().then((urn) => {
-      encodedErisUrn.value = urn
+  async function decode () {
+    const readCap = encodedErisReadCap.value
+    return ERIS.get(readCap, cas)
+  }
+
+  controlsEncode.onclick = async function (e) {
+    try {
+      const urn = await encode()
+      encodedErisReadCap.value = urn
       renderBlocks(cas)
-    }).catch((e) => {
-      console.error(e)
-      encodedErisUrn.value = 'ERROR (see console)'
-    })
+    } catch (err) {
+      console.error(err)
+      encodedErisReadCap.value = 'ERROR (see console)'
+    }
+  }
+
+  controlsDecode.onclick = async function (e) {
+    try {
+      const decoded = await decode()
+      inputTextarea.value = utf8Decoder.decode(decoded)
+    } catch (err) {
+      console.error(err)
+      inputTextarea.value = 'ERROR (see console)'
+    }
   }
 
   inputLoadSampleVocabulary.onclick = function (e) {
diff --git a/examples/web-demo/style.css b/examples/web-demo/style.css
index 4cb471c..95fc931 100644
--- a/examples/web-demo/style.css
+++ b/examples/web-demo/style.css
@@ -20,14 +20,13 @@ textarea {
 
 #input {
     background-color: #EEE;
-    flex-basis: 600px;
-    flex-grow: 3;
+    flex: 3 0;
     padding: 10px;
     margin: 10px;
 }
 
 #controls {
-    flex-basis: 200px;
+    flex: 1 0;
     padding: 10px;
     margin-top: 100px;
     text-align: center;
@@ -39,12 +38,11 @@ textarea {
 
 #encoded {
     background-color: #EEE;
-    flex-basis: 600px;
-    flex-grow: 3;
+    flex: 3 0;
     padding: 10px;
 }
 
-#encoded-eris-urn {
+#encoded-eris-read-cap {
     width: 90%;
 }
 
diff --git a/src/eris.js b/src/eris.js
index 7f37498..e82a521 100644
--- a/src/eris.js
+++ b/src/eris.js
@@ -198,12 +198,27 @@ function decodeCapability (cap) {
   if (cap.substring(0, 10) === 'urn:erisx:') {
     const buffer = base32.decode(cap.substring(10))
     const view = new Uint8Array(buffer)
+
+    const version = view[0]
+    if (version !== 0) throw new Error('Capability has unsupported ERIS version')
+
+    const type = view[1]
+    if (!(type === 0 || type === 1)) throw new Error('Unknown capability type')
+
+    const level = view[2]
+
+    const rootReference = view.slice(3,35)
+    if (rootReference.length !== 32) throw new Error('Could not extract root reference from ERIS capability')
+
+    const key = view.slice(35, 67)
+    if (key.length !== 32) throw new Error('Could not extract key from ERIS capability')
+   
     return {
-      version: view[0],
-      type: view[1],
-      level: view[2],
-      rootReference: view.slice(3, 35),
-      key: view.slice(35, 67)
+      version: version,
+      type: type,
+      level: level,
+      rootReference: rootReference,
+      key: key
     }
   } else {
     throw new Error('Can not decode ERIS URN.')