realm-emoji: Add realm emoji uploading instead url providing.

- Add file_name field to `RealmEmoji` model and migration.
- Add emoji upload supporting to Upload backends.
- Add uploaded file processing to emoji views.
- Use emoji source url as based for display url.
- Change emoji form for image uploading.
- Fix back-end tests.
- Fix front-end tests.
- Add tests for emoji uploading.

Fixes #1134

zerver/views/realm_emoji.py

@@ -1,15 +1,20 @@
 from __future__ import absolute_import
 
+from django.conf import settings
+from django.core.exceptions import ValidationError
 from django.http import HttpRequest, HttpResponse
 from django.utils.translation import ugettext as _
 from typing import Text
 
+from zerver.lib.upload import upload_emoji_image
 from zerver.models import UserProfile
-from zerver.lib.emoji import check_emoji_admin, check_valid_emoji_name, check_valid_emoji
+from zerver.lib.emoji import check_emoji_admin, check_valid_emoji_name, check_valid_emoji, \
+    get_emoji_file_name
 from zerver.lib.request import JsonableError, REQ, has_request_variables
-from zerver.lib.response import json_success
+from zerver.lib.response import json_success, json_error
 from zerver.lib.actions import check_add_realm_emoji, do_remove_realm_emoji
 
+
 def list_emoji(request, user_profile):
     # type: (HttpRequest, UserProfile) -> HttpResponse
 
@@ -17,14 +22,27 @@ def list_emoji(request, user_profile):
     # emoji is public.
     return json_success({'emoji': user_profile.realm.get_emoji()})
 
+
 @has_request_variables
-def upload_emoji(request, user_profile, emoji_name, url=REQ()):
-    # type: (HttpRequest, UserProfile, Text, Text) -> HttpResponse
+def upload_emoji(request, user_profile, emoji_name=REQ()):
+    # type: (HttpRequest, UserProfile, Text) -> HttpResponse
     check_valid_emoji_name(emoji_name)
     check_emoji_admin(user_profile)
-    check_add_realm_emoji(user_profile.realm, emoji_name, url, author=user_profile)
+    if len(request.FILES) != 1:
+        return json_error(_("You must upload exactly one file."))
+    emoji_file = list(request.FILES.values())[0]
+    if (settings.MAX_EMOJI_FILE_SIZE * 1024 * 1024) < emoji_file.size:
+        return json_error(_("Uploaded file is larger than the allowed limit of %s MB") % (
+            settings.MAX_EMOJI_FILE_SIZE))
+    emoji_file_name = get_emoji_file_name(emoji_file.name, emoji_name)
+    upload_emoji_image(emoji_file, emoji_file_name, user_profile)
+    try:
+        check_add_realm_emoji(user_profile.realm, emoji_name, emoji_file_name, author=user_profile)
+    except ValidationError as e:
+        return json_error(e.messages[0])
     return json_success()
 
+
 def delete_emoji(request, user_profile, emoji_name):
     # type: (HttpRequest, UserProfile, Text) -> HttpResponse
     check_emoji_admin(user_profile)