Allow send_interactive to upload a file containing all content (#5902)

Co-authored-by: Flame442 <34169552+Flame442@users.noreply.github.com>

redbot/core/commands/context.py

@@ -9,7 +9,7 @@ import discord
 from discord.ext.commands import Context as DPYContext
 
 from .requires import PermState
-from ..utils.chat_formatting import box
+from ..utils.chat_formatting import box, text_to_file
 from ..utils.predicates import MessagePredicate
 from ..utils import can_user_react_in, common_filters
 
@@ -150,7 +150,11 @@ class Context(DPYContext):
             return True
 
     async def send_interactive(
-        self, messages: Iterable[str], box_lang: str = None, timeout: int = 15
+        self,
+        messages: Iterable[str],
+        box_lang: str = None,
+        timeout: int = 15,
+        join_character: str = "",
     ) -> List[discord.Message]:
         """Send multiple messages interactively.
 
@@ -168,6 +172,9 @@ class Context(DPYContext):
         timeout : int
             How long the user has to respond to the prompt before it times out.
             After timing out, the bot deletes its prompt message.
+        join_character : str
+            The character used to join all the messages when the file output
+            is selected.
 
         """
         messages = tuple(messages)
@@ -189,13 +196,14 @@ class Context(DPYContext):
                     is_are = "are"
                 query = await self.send(
                     "There {} still {} message{} remaining. "
-                    "Type `more` to continue."
+                    "Type `more` to continue or `file` to upload all contents as a file."
                     "".format(is_are, n_remaining, plural)
                 )
+                pred = MessagePredicate.lower_contained_in(("more", "file"), self)
                 try:
                     resp = await self.bot.wait_for(
                         "message",
-                        check=MessagePredicate.lower_equal_to("more", self),
+                        check=pred,
                         timeout=timeout,
                     )
                 except asyncio.TimeoutError:
@@ -211,6 +219,9 @@ class Context(DPYContext):
                         # or channel is a DM
                         with contextlib.suppress(discord.HTTPException):
                             await query.delete()
+                    if pred.result == 1:
+                        await self.send(file=text_to_file(join_character.join(messages)))
+                        break
         return ret
 
     async def embed_colour(self):