added browserify, refactored code to separate UI and network logic

frontend/src/download.js

@@ -0,0 +1,132 @@
+const UIWrapper = require('./file').UIWrapper;
+
+let download = () => {
+
+  let xhr = new XMLHttpRequest();
+  xhr.open("get", "/assets" + location.pathname.slice(0, -1), true);
+  xhr.responseType = "blob";
+  
+  let listelem = setupUI();
+  xhr.addEventListener("progress", updateProgress.bind(null, listelem));
+  
+  xhr.onload = function(e) {
+
+    // maybe send a separate request before this one to get the filename?
+
+    // maybe render the html itself with the filename, since it's generated server side
+    // after a get request with the unique id
+    listelem.emit('name', xhr.getResponseHeader("Content-Disposition").match(/filename="(.+)"/)[1]);
+
+    if (this.status == 200) {
+      let self = this;
+      let blob = new Blob([this.response]);
+      let arrayBuffer;
+      let fileReader = new FileReader();
+      fileReader.onload = function() {
+        arrayBuffer = this.result;
+        let array = new Uint8Array(arrayBuffer);
+        salt = strToIv(location.pathname.slice(10, -1));
+
+        window.crypto.subtle.importKey(
+          "jwk",
+          {
+              kty: "oct",
+              k: location.hash.slice(1),
+              alg: "A128CBC",
+              ext: true,
+          },
+          {
+              name: "AES-CBC",
+          },
+          true,
+          ["encrypt", "decrypt"])
+        .then((key) => {  
+          return window.crypto.subtle.decrypt(
+              {
+                name: "AES-CBC",
+                iv: salt,
+              },
+              key,
+              array)
+        })
+        .then((decrypted) => {
+          let dataView = new DataView(decrypted);
+          let blob = new Blob([dataView]);
+          let downloadUrl = URL.createObjectURL(blob);
+          let a = document.createElement("a");
+          a.href = downloadUrl;
+          a.download = xhr.getResponseHeader("Content-Disposition").match(/filename="(.+)"/)[1];
+          document.body.appendChild(a);
+          a.click();
+        })
+        .catch((err) => {
+          alert("This link is either invalid or has expired, or the uploader has deleted the file.");
+          console.error(err);
+        });
+      };
+
+      fileReader.readAsArrayBuffer(blob);
+    } else {
+      alert("This link is either invalid or has expired, or the uploader has deleted the file.")
+    }
+  };
+  xhr.send();
+}
+
+window.download = download;
+
+let setupUI = () => {
+  let li = document.createElement("li");
+  let name = document.createElement("p");
+  li.appendChild(name);
+
+  let progress = document.createElement("p");
+  li.appendChild(progress);
+
+  document.getElementById("downloaded_files").appendChild(li);
+
+  return new UIWrapper(li, name, null, progress);
+}
+
+let ivToStr = (iv) => {
+  let hexStr = "";
+  for (let i in iv) {
+    if (iv[i] < 16) {
+      hexStr += "0" + iv[i].toString(16);
+    } else {
+      hexStr += iv[i].toString(16);
+    }
+  }
+  window.hexStr = hexStr;
+  return hexStr;
+}
+
+let strToIv = (str) => {
+  let iv = new Uint8Array(16);
+  for (let i = 0; i < str.length; i += 2) {
+    iv[i/2] = parseInt((str.charAt(i) + str.charAt(i + 1)), 16);
+  }
+
+  return iv;
+}
+
+let updateProgress = (UIelem, e) => {
+  if (e.lengthComputable) { 
+    let percentComplete = Math.floor((e.loaded / e.total) * 100);
+    UIelem.emit('progress', "Progress: " + percentComplete + "%");
+
+    if (percentComplete === 100) {
+      let finished = document.createElement("p");
+      finished.innerText = "Your download has finished.";
+      UIelem.li.appendChild(finished);
+
+      let close = document.createElement("button");
+      close.innerText = "Ok";
+      close.addEventListener("click", () => {
+        document.getElementById("downloaded_files").removeChild(UIelem.li);
+      });
+
+      UIelem.li.appendChild(close);
+    }
+  } 
+}