Improved sKai support and overall download algo

js/app.js

@@ -1,5 +1,20 @@
 // Kopher UI logic
 
+function saveBlob(blob, fname, successCb, errorCb) {
+  var storage = navigator.getDeviceStorage(blob.type.startsWith('image/') ? 'pictures' : 'sdcard'),
+      freeSpaceReq = storage.freeSpace()
+  freeSpaceReq.onsuccess = function() {
+    var freeSize = freeSpaceReq.result
+    if(freeSize > blob.size) {
+      var req = storage.addNamed(blob, fname)
+      req.onsuccess = successCb
+      req.onerror = errorCb
+    }
+    else errorCb(new Error('No free space available'))
+  }
+  freeSpaceReq.onerror = errorCb
+}
+
 function openURL(url, successCb, errorCb) {
   if(url.startsWith('about:')) { // handle about: pages first
     var pageName = url.split(':')[1], allowedPageNames = ['kopher', 'blank', 'help']
@@ -27,8 +42,14 @@ function openURL(url, successCb, errorCb) {
     if(resource.length > 4) input = resource[4]
     Hi01379.load(resource, input, function(res) {
       if(res.content && res.content instanceof Blob) { // handle the download here
-        successCb({content: null, serviceMsg: 'Downloaded ' + res.contentName, updateAddr: false})
-        window.open(URL.createObjectURL(res.content))
+        if(res.contentType.startsWith('image/') && confirm('View the image? (press Cancel to save it)')) { // try to open it in an external image viewer
+          window.open(URL.createObjectURL(res.content))
+          successCb({content: null, serviceMsg: 'Viewed ' + res.contentName, updateAddr: false})
+        } else // proceed with storing the file
+          saveBlob(res.content, res.contentName, function() {
+            successCb({content: null, serviceMsg: 'Saved ' + res.contentName, updateAddr: false})
+            navigator.mozNotification.createNotification('File saved', res.contentName).show()
+          }, errorCb)
       }
       else successCb(res) // proceed to UI with non-downloads
     }, errorCb)