add new check and error handler for the solved command (#28)

Author: AbstractUmbra

modules/help.py

@@ -50,6 +50,10 @@
 """.strip()
 
 
+class NotThreadOwner(commands.CheckFailure):
+    pass
+
+
 def is_forum_thread() -> Check[Context]:
     def predicate(ctx: Context) -> bool:
         channel = ctx.channel
@@ -67,6 +71,21 @@ def predicate(ctx: Context) -> bool:
     return commands.check(predicate)
 
 
+def can_close_thread() -> Check[Context]:
+    def predicate(ctx: core.GuildContext) -> bool:
+        assert isinstance(ctx.channel, discord.Thread)
+
+        if ctx.author_is_mod():
+            return True
+
+        if ctx.author == ctx.channel.owner:
+            return True
+
+        raise NotThreadOwner()
+
+    return commands.check(predicate)
+
+
 class Help(commands.Cog):
     """Commands relating to the help channels/forum of Pythonista."""
 
@@ -86,6 +105,7 @@ async def forum_post_created(self, thread: discord.Thread) -> None:
 
         await thread.send(FORUM_BLURB)
 
+    @can_close_thread()
     @is_forum_thread()
     @commands.command("solved", brief="Closes a forum post", short_doc="Closes a forum post in the help channels")
     async def solved(self, ctx: core.GuildContext) -> None:
@@ -97,10 +117,6 @@ async def solved(self, ctx: core.GuildContext) -> None:
         assert isinstance(ctx.channel, discord.Thread)  # guarded by the check
         assert isinstance(ctx.channel.parent, discord.ForumChannel)  # guarded by the check
 
-        if not ctx.author_is_mod() or ctx.author != ctx.channel.owner:
-            await ctx.send("You can only mark your own posts as solved")
-            return
-
         try:
             emoji = discord.utils.get(ctx.guild.emojis, id=578575442383208468)
             if emoji:
@@ -128,6 +144,16 @@ async def solved(self, ctx: core.GuildContext) -> None:
         msg: str = f"{ctx.author} ({ctx.author.id}) marked thread '{ctx.channel.name}' ({ctx.channel.id}) as solved."
         await channel.send(msg)
 
+    @solved.error
+    async def solved_error(self, ctx: Context, error: commands.CommandError) -> None:
+        error = getattr(error, "original", error)
+
+        if isinstance(error, NotThreadOwner):
+            await ctx.send("Sorry, you must be the owner of this thread to close it!")
+
+        elif isinstance(error, commands.CheckFailure):
+            await ctx.send("Sorry, this doesn't appear to be a forum thread?")
+
 
 async def setup(bot: core.Bot) -> None:
     await bot.add_cog(Help(bot))