Add `.aoc link` command

This new command will allow people to associate their Discord ID with
their Advent of Code name. This Redis Cache idea was taken from the
hacktoberfest stats command, which allows people to associate their
github username to then pull the correct stats.

This does not check if the name exists on the leaderboard and that is
intentional. Due to the cooldown on the leaderboard I don't want to rely
on that before someone can link their account. Additionally, someone
may change their display name on the Advent of Code side and I don't
think validation of it existing on the leaderboard gets us anything.

The usefulness of this function will not be apparent in this cog, but it
is necessary for something fun I'd like to do.

1 files changed, 69 insertions, 0 deletions

diff --git a/bot/exts/events/advent_of_code/_cog.py b/bot/exts/events/advent_of_code/_cog.py
index af1cbcf5..1b1cd9f8 100644
--- a/bot/exts/events/advent_of_code/_cog.py
+++ b/bot/exts/events/advent_of_code/_cog.py
@@ -6,6 +6,7 @@ from typing import Optional
 
 import arrow
 import discord
+from async_rediscache import RedisCache
 from discord.ext import commands
 
 from bot.bot import Bot
@@ -29,6 +30,8 @@ AOC_WHITELIST = AOC_WHITELIST_RESTRICTED + (Channels.advent_of_code,)
 class AdventOfCode(commands.Cog):
     """Advent of Code festivities! Ho Ho Ho!"""
 
+    account_links = RedisCache()
+
     def __init__(self, bot: Bot):
         self.bot = bot
 
@@ -172,6 +175,72 @@ class AdventOfCode(commands.Cog):
         else:
             await ctx.message.add_reaction(Emojis.envelope)
 
+    @in_month(Month.NOVEMBER, Month.DECEMBER)
+    @adventofcode_group.command(
+        name="link",
+        aliases=("connect",),
+        brief="Tie your Discord account with your Advent of Code name."
+    )
+    @whitelist_override(channels=AOC_WHITELIST)
+    async def aoc_link_account(self, ctx: commands.Context, aoc_name: str = None) -> None:
+        """
+        Link your Discord Account to your Advent of Code name.
+
+        Stored in a Redis Cache, Discord ID: Advent of Code Name
+        """
+        cache_items = await self.account_links.items()
+
+        # A short circuit in case the cache is empty
+        if len(cache_items) == 0 and aoc_name:
+            log.info(f"{ctx.author} ({ctx.author.id}) is now linked to {aoc_name}.")
+            await self.account_links.set(ctx.author.id, aoc_name)
+            await ctx.reply(f"You have linked your Discord ID to {aoc_name}.")
+            return
+        elif len(cache_items) == 0:
+            await ctx.reply(
+                "You have not linked an Advent of Code account."
+                "Please re-run the command with one specified."
+            )
+            return
+
+        cache_aoc_name = [value for _, value in cache_items]
+
+        if aoc_name:
+            # Let's check the current values in the cache to make sure it isn't already tied to a different account
+            if aoc_name == await self.account_links.get(ctx.author.id):
+                await ctx.reply(f"{aoc_name} is already tied to your account.")
+                return
+            elif aoc_name in cache_aoc_name:
+                log.info(
+                    f"{ctx.author} ({ctx.author.id}) tried to connect their account to {aoc_name},"
+                    " but it's already connected to another user."
+                )
+                await ctx.reply(
+                    f"{aoc_name} is already tied to another account."
+                    " Please contact an admin if you believe this is an error."
+                )
+                return
+
+            # Update an existing link
+            if old_aoc_name := await self.account_links.get(ctx.author.id):
+                log.info(f"{ctx.author} ({ctx.author.id}) has changed their link from {old_aoc_name} to {aoc_name}.")
+                await self.account_links.set(ctx.author.id, aoc_name)
+                await ctx.reply(f"Your linked account has been changed to {aoc_name}.")
+            else:
+                # Create a new link
+                log.info(f"{ctx.author} ({ctx.author.id}) is now linked to {aoc_name}.")
+                await self.account_links.set(ctx.author.id, aoc_name)
+                await ctx.reply(f"You have linked your Discord ID to {aoc_name}.")
+        else:
+            # User has not supplied a name, let's check if they're in the cache or not
+            if cache_name := await self.account_links.get(ctx.author.id):
+                await ctx.reply(f"You have already linked an Advent of Code account: {cache_name}.")
+            else:
+                await ctx.reply(
+                    "You have not linked an Advent of Code account."
+                    " Please re-run the command with one specified."
+                )
+
     @in_month(Month.DECEMBER)
     @adventofcode_group.command(
         name="dayandstar",