Move `utils.proxy_user` to Converters and do minor refactoring

The `proxy_user` function now belongs to the `Converters` module,
since its use is directly related to it. `FetchedUser` uses this
function if there's an error trying to fetch and it  doesn't indicate
a non existing user.

Technically finished and working.

3 files changed, 29 insertions, 55 deletions

diff --git a/bot/cogs/moderation/management.py b/bot/cogs/moderation/management.py
index 9605d47b2..fff86e9ea 100644
--- a/bot/cogs/moderation/management.py
+++ b/bot/cogs/moderation/management.py
@@ -10,7 +10,7 @@ from discord.ext.commands import Context
 
 from bot import constants
 from bot.bot import Bot
-from bot.converters import InfractionSearchQuery, allowed_strings
+from bot.converters import InfractionSearchQuery, allowed_strings, proxy_user
 from bot.pagination import LinePaginator
 from bot.utils import time
 from bot.utils.checks import in_channel_check, with_role_check
@@ -20,7 +20,7 @@ from .modlog import ModLog
 
 log = logging.getLogger(__name__)
 
-UserConverter = t.Union[discord.User, utils.proxy_user]
+UserConverter = t.Union[discord.User, proxy_user]
 
 
 class ModManagement(commands.Cog):
diff --git a/bot/cogs/moderation/utils.py b/bot/cogs/moderation/utils.py
index 604ce5ce4..5b5aacb16 100644
--- a/bot/cogs/moderation/utils.py
+++ b/bot/cogs/moderation/utils.py
@@ -4,7 +4,6 @@ import typing as t
 from datetime import datetime
 
 import discord
-from discord.ext import commands
 from discord.ext.commands import Context
 
 from bot.api import ResponseCodeError
@@ -42,45 +41,23 @@ async def post_user(ctx: Context, user: t.Union[discord.User, discord.Object]) -
     if not isinstance(user, discord.User):
         log.warn("The given user is not a discord.User object.")
 
-    # XXX: Not sure if these default values are ideal.
     payload = {
         'avatar_hash': getattr(user, 'avatar', 0),
         'discriminator': int(getattr(user, 'discriminator', 0)),
         'id': user.id,
         'in_guild': False,
-        'name': getattr(user, 'name', 'No name'),
+        'name': getattr(user, 'name', 'Name unknown'),
         'roles': []
     }
 
     try:
         response = await ctx.bot.api_client.post('bot/users', json=payload)
+        log.trace(f"User {user.id} added to the DB.")
         return response
     except ResponseCodeError as e:
-        # TODO: Add details, and specific information per possible situation.
-        #  Potential race condition if someone joins and the bot syncs before the API replies!
-        log.info("Couldn't post user.")
-        # NOTE: `e.status` is probably not enough for a good message
-        await ctx.send(f"The attempt to add the user to the DB failed: {e.status}")
-
-
-def proxy_user(user_id: str) -> discord.Object:
-    """
-    Create a proxy user object from the given id.
-
-    Used when a Member or User object cannot be resolved.
-    """
-    log.trace(f"Attempting to create a proxy user for the user id {user_id}.")
-
-    try:
-        user_id = int(user_id)
-    except ValueError:
-        raise commands.BadArgument
-
-    user = discord.Object(user_id)
-    user.mention = user.id
-    user.avatar_url_as = lambda static_format: None
-
-    return user
+        log.warn("Couldn't post user.")
+        await ctx.send("The attempt to add the user to the DB failed: "
+                       f"{e.status}, {e.response_text if e.response_text else 'no message received'}.")
 
 
 async def post_infraction(
diff --git a/bot/converters.py b/bot/converters.py
index b33229cc7..28bf58cf4 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -280,36 +280,34 @@ class ISODateTime(Converter):
         return dt
 
 
-class FetchedUser(Converter):
+def proxy_user(user_id: str) -> discord.Object:
     """
-    Fetches from the Discord API and returns a `discord.User` or `discord.Object` object, given an ID.
+    Create a proxy user object from the given id.
 
-    If the fetching is successful, a `discord.User` object is returned. If it fails and
-    the error doesn't imply the user doesn't exist, then a `discord.Object` is returned
-    via the `user_proxy` function.
+    Used when a Member or User object cannot be resolved.
     """
+    log.trace(f"Attempting to create a proxy user for the user id {user_id}.")
 
-    # XXX: `proxy_user` shouldn't be here as a helper.
-    #  Should wait for PR #651 to import from bot.utils.whatever, maybe?
-    @staticmethod
-    def proxy_user(user_id: str) -> discord.Object:
-        """
-        Create a proxy user object from the given id.
+    try:
+        user_id = int(user_id)
+    except ValueError:
+        raise BadArgument
 
-        Used when a Member or User object cannot be resolved.
-        """
-        log.trace(f"Attempting to create a proxy user for the user id {user_id}.")
+    user = discord.Object(user_id)
+    user.mention = user.id
+    user.avatar_url_as = lambda static_format: None
 
-        try:
-            user_id = int(user_id)
-        except ValueError:
-            raise BadArgument
+    return user
 
-        user = discord.Object(user_id)
-        user.mention = user.id
-        user.avatar_url_as = lambda static_format: None
 
-        return user
+class FetchedUser(Converter):
+    """
+    Fetches from the Discord API and returns a `discord.User` or `discord.Object` object, given an ID.
+
+    If the fetching is successful, a `discord.User` object is returned. If it fails and
+    the error doesn't imply the user doesn't exist, then a `discord.Object` is returned
+    via the `user_proxy` function.
+    """
 
     @staticmethod
     async def convert(ctx: Context, user_id: str) -> t.Union[discord.User, discord.Object]:
@@ -320,11 +318,10 @@ class FetchedUser(Converter):
         except ValueError:
             raise BadArgument(f"The provided argument can't be turned into integer: `{user_id}`")
         except discord.HTTPException as e:
-            # If the Discord error isn't `Unknown user`, save it in the log and return a proxy
+            # If the Discord error isn't `Unknown user`, save it in the log and return a proxy instead
             if e.code != 10013:
                 log.warning("Failed to fetch user, returning a proxy instead.")
-                # XXX:
-                return FetchedUser.proxy_user(user_id)
+                return proxy_user(user_id)
             raise BadArgument
 
         return user