From c1c32e32689519ac0655b89f28832a51351fd5dd Mon Sep 17 00:00:00 2001
From: Timo Paulssen <timonator@perpetuum-immobile.de>
Date: Fri, 17 Apr 2020 00:09:56 +0200
Subject: [PATCH] Offer "alias" field in room create form

Tries its best to not allow aliases that are too
long (full alias including leading #, : in the
middle, and homeserver domain name must not exceed
255 bytes.

Change-Id: I1e784a94cb599eca7e30736d666b20e37aad5444
---
 src/components/rooms.js     | 57 +++++++++++++++++++++++++++++++++++--
 src/i18n/de.js              |  6 ++++
 src/i18n/en.js              |  6 ++++
 src/synapse/dataProvider.js |  2 ++
 4 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/src/components/rooms.js b/src/components/rooms.js
index f8612b6..57c113e 100644
--- a/src/components/rooms.js
+++ b/src/components/rooms.js
@@ -29,20 +29,73 @@ function generateRoomRecord() {
   return {
     room_name: "",
     public: true,
+    alias: "",
   }
 }
 
 const validateDisplayName = fieldval => fieldval === undefined ? "synapseadmin.rooms.room_name_required" : fieldval.length === 0 ? "synapseadmin.rooms.room_name_required" : undefined;
 
+function approximateAliasLength(alias, homeserver) {
+  /* TODO maybe handle punycode in homeserver URL */
+
+  var te;
+
+  // Support for TextEncoder is quite widespread, but the polyfill is
+  // pretty large; We will only underestimate the size with the regular
+  // length attribute of String, so we never prevent the user from using
+  // an alias that is short enough for the server, but too long for our
+  // heuristic.
+  try {
+    te = new TextEncoder();
+  }
+  catch (err) {
+    if (err instanceof ReferenceError) {
+      te = undefined;
+    }
+  }
+
+  const aliasLength = te === undefined ? alias.length : te.encode(alias).length;
+
+  return (
+    "#".length +
+      aliasLength +
+      ":".length +
+      homeserver.length
+  );
+}
+
+const validateAlias = fieldval => {
+  if (fieldval === undefined) {
+    return undefined;
+  }
+  const homeserver = localStorage.getItem("home_server");
+
+  if (approximateAliasLength(fieldval, homeserver) > 255) {
+    return "synapseadmin.rooms.alias_too_long";
+  }
+}
+
 const removeLeadingWhitespace = fieldVal => fieldVal === undefined ? undefined : fieldVal.trimStart();
 
+const validateHasAliasIfPublic = formdata => {
+  let errors = {};
+  if (formdata.public) {
+    if (formdata.alias === undefined || formdata.alias.trim().length === 0) {
+      errors.alias = "synapseadmin.rooms.alias_required_if_public"
+    }
+  }
+  return errors;
+}
+
 export const RoomCreate = props => (
   <Create record={generateRoomRecord()} {...props}>
-    <SimpleForm>
+    <SimpleForm validate={validateHasAliasIfPublic}>
       <TextInput source="room_name"
-                 label="synapseadmin.rooms.room_name"
                  parse={removeLeadingWhitespace}
                  validate={validateDisplayName}/>
+      <TextInput source="alias"
+                 parse={removeLeadingWhitespace}
+                 validate={validateAlias}/>
       <BooleanInput source="public"
                     label="synapseadmin.rooms.make_public"/>
     </SimpleForm>
diff --git a/src/i18n/de.js b/src/i18n/de.js
index 4e4b67c..452584b 100644
--- a/src/i18n/de.js
+++ b/src/i18n/de.js
@@ -21,6 +21,12 @@ export default {
       make_public: "Öffentlicher Raum",
       room_name_required:
         "Muss angegeben werden",
+      alias_required_if_public:
+        "Muss für öffentliche Räume angegeben werden.",
+      alias:
+        "Alias",
+      alias_too_long:
+        "Darf zusammen mit der Domain des Homeservers 255 bytes nicht überschreiten"
     }
   },
   resources: {
diff --git a/src/i18n/en.js b/src/i18n/en.js
index d8cb0a4..f6382d9 100644
--- a/src/i18n/en.js
+++ b/src/i18n/en.js
@@ -21,6 +21,12 @@ export default {
       make_public: "Make room public",
       room_name_required:
         "Must be provided",
+      alias_required_if_public:
+        "Must be provided for a public room",
+      alias:
+        "Alias",
+      alias_too_long:
+        "Must not exceed 255 bytes including the domain of the homeserver."
     }
   },
   resources: {
diff --git a/src/synapse/dataProvider.js b/src/synapse/dataProvider.js
index d47576d..0f24749 100644
--- a/src/synapse/dataProvider.js
+++ b/src/synapse/dataProvider.js
@@ -83,8 +83,10 @@ const roomCreationProvider = {
     const newParams = { ...params.data,
       public: undefined,
       room_name: undefined,
+      alias: undefined,
 
       name: params.data.room_name,
+      room_alias_name: params.data.alias,
       visibility: params.data.public ? "public" : "private",
     }