Add optional password to the download url

app/templates/downloadPassword.js

@@ -0,0 +1,41 @@
+const html = require('choo/html');
+
+module.exports = function(state, emit) {
+  const fileInfo = state.fileInfo;
+  const label =
+    fileInfo.password === null
+      ? html`
+          <label class="red"
+            for="unlock-input">${state.translate('incorrectPassword')}</label>`
+      : html`
+          <label for="unlock-input">
+            ${state.translate('unlockInputLabel')}
+          </label>`;
+  const div = html`
+    <div class="enterPassword">
+      ${label}
+      <form id="unlock" onsubmit=${checkPassword}>
+        <input id="unlock-input"
+          autocomplete="off"
+          placeholder="${state.translate('unlockInputPlaceholder')}"
+          type="password"/>
+        <input type="submit"
+          id="unlock-btn"
+          class="btn"
+          value="${state.translate('unlockButtonLabel')}"/>
+      </form>
+    </div>`;
+
+  function checkPassword(event) {
+    event.preventDefault();
+    const password = document.getElementById('unlock-input').value;
+    if (password.length > 0) {
+      document.getElementById('unlock-btn').disabled = true;
+      state.fileInfo.url = window.location.href;
+      state.fileInfo.password = password;
+      emit('preview');
+    }
+  }
+
+  return div;
+};