リアクションを押して展開されたメッセージを消去する機能の追加

README.md

@@ -21,11 +21,16 @@ bot.run(token)
 
 ## 関数として使用する場合
 
-on_message内のどこかで実行してください
+on_message内のどこかで実行してください。
+
+展開したメッセージを消去する機能を使用するには`on_reaction_add`イベントもしくは`on_raw_reaction_add`イベントのどちらかでdelete_dispand関数を実行してください。
+on_raw_reaction_addの場合はキーワード引数`payload`にRawReactionActionEventを、on_reaction_addの場合はキーワード引数`user`にUser、`reaction`にReactionを指定して下さい。
+
+消去の際のリアクションを変更したい場合は環境変数`DELETE_REACTION_EMOJI`に絵文字を設定してください。
 
 ```python
 import discord
-from dispander import dispand
+from dispander import dispand, delete_dispand
 
 client = discord.Client()
 
@@ -35,5 +40,11 @@ async def on_message(message):
         return
     await dispand(message)
 
+
+@client.event
+async def on_raw_reaction_add(payload):
+    await delete_dispand(client, payload=payload)
+
+
 client.run(token)
 ```

dispander/module.py

@@ -1,11 +1,22 @@
+from typing import Optional
+import os
+
+import discord
 from discord import Embed
+from discord.embeds import EmptyEmbed
 from discord.ext import commands
 import re
 
 regex_discord_message_url = (
     '(?!<)https://(ptb.|canary.)?discord(app)?.com/channels/'
     '(?P<guild>[0-9]{18})/(?P<channel>[0-9]{18})/(?P<message>[0-9]{18})(?!>)'
 )
+regex_extra_url = (
+    r'\?base_aid=(?P<base_author_id>[0-9]{18})'
+    '&aid=(?P<author_id>[0-9]{18})'
+    '&extra=(?P<extra_messages>(|[0-9,]+))'
+)
+DELETE_REACTION_EMOJI = os.environ.get("DELETE_REACTION_EMOJI", "\U0001f5d1")
 
 
 class ExpandDiscordMessageUrl(commands.Cog):
@@ -18,21 +29,87 @@ async def on_message(self, message):
             return
         await dispand(message)
 
+    @commands.Cog.listener()
+    async def on_raw_reaction_add(self, payload: discord.RawReactionActionEvent):
+        await delete_dispand(self.bot, payload=payload)
+
+
+async def delete_dispand(bot: discord.Client,
+                         *,
+                         payload: Optional[discord.RawReactionActionEvent] = None,
+                         reaction: Optional[discord.Reaction] = None,
+                         user: Optional[discord.User] = None):
+    if payload is not None:
+        # when on_raw_reaction_add event
+        if str(payload.emoji) != DELETE_REACTION_EMOJI:
+            return
+        if payload.user_id == bot.user.id:
+            return
+
+        channel = bot.get_channel(payload.channel_id)
+        message = await channel.fetch_message(payload.message_id)
+        await _delete_dispand(bot, message, payload.user_id)
+    elif reaction is not None:
+        # when on_reaction_add event
+        if str(reaction.emoji) != DELETE_REACTION_EMOJI:
+            return
+        if user.id == bot.user.id:
+            return
+        await _delete_dispand(bot, reaction.message, user.id)
+    else:
+        raise ValueError("payload or reaction must be setted")
+
+
+async def _delete_dispand(bot: discord.Client, message: discord.Message, operator_id: int):
+    if message.author.id != bot.user.id:
+        return
+    elif not message.embeds:
+        return
+
+    embed = message.embeds[0]
+    if getattr(embed.author, "url", None) is None:
+        return
+    data = from_jump_url(embed.author.url)
+    if not (data["base_author_id"] == operator_id or data["author_id"] == operator_id):
+        return
+    await message.delete()
+    for message_id in data["extra_messages"]:
+        extra_message = await message.channel.fetch_message(message_id)
+        if extra_message is not None:
+            await extra_message.delete()
+
 
 async def dispand(message):
     messages = await extract_message(message)
     for m in messages:
+        sent_messages = []
+
         if m.content or m.attachments:
-            await message.channel.send(embed=compose_embed(m))
+            sent_message = await message.channel.send(embed=compose_embed(m))
+            sent_messages.append(sent_message)
         # Send the second and subsequent attachments with embed (named 'embed') respectively:
         for attachment in m.attachments[1:]:
             embed = Embed()
             embed.set_image(
                 url=attachment.proxy_url
             )
-            await message.channel.send(embed=embed)
+            sent_attachment_message = await message.channel.send(embed=embed)
+            sent_messages.append(sent_attachment_message)
+
         for embed in m.embeds:
-            await message.channel.send(embed=embed)
+            sent_embed_message = await message.channel.send(embed=embed)
+            sent_messages.append(sent_embed_message)
+
+        # 一番先頭のメッセージにゴミ箱のリアクションをつける
+        main_message = sent_messages.pop(0)
+        await main_message.add_reaction(DELETE_REACTION_EMOJI)
+        main_embed = main_message.embeds[0]
+        main_embed.set_author(
+            name=getattr(main_embed.author, "name", EmptyEmbed),
+            icon_url=getattr(main_embed.author, "icon_url", EmptyEmbed),
+            url=make_jump_url(message, m, sent_messages)
+        )
+        await main_message.edit(embed=main_embed)
 
 
 async def extract_message(message):
@@ -55,6 +132,39 @@ async def fetch_message_from_id(guild, channel_id, message_id):
     return message
 
 
+def make_jump_url(base_message, dispand_message, extra_messages):
+    """
+    make jump url which include more information
+    :param base_message: メッセージリンクが貼られていたメッセージ
+    :param dispand_message: 展開中のメッセージ
+    :param extra_messages: 展開する際にでた二つ目以降のメッセージ(e.g. 画像やembed)
+    :return: 混入が完了したメッセージリンク
+    """
+    # base_aid: メッセージリンクで飛べる最初のメッセージの送信者のid
+    # aid: メッセージリンクを送信したユーザーのid
+    return "{0.jump_url}?base_aid={1.id}&aid={2.id}&extra={3}".format(
+        dispand_message,
+        dispand_message.author,
+        base_message.author,
+        ",".join([str(i.id) for i in extra_messages])
+    )
+
+
+def from_jump_url(url):
+    """
+    メッセージリンクから情報を取得します。
+    :param url: メッセージリンク
+    :return: dict
+    """
+    base_url_match = re.match(regex_discord_message_url + regex_extra_url, url)
+    data = base_url_match.groupdict()
+    return {
+        "base_author_id": int(data["base_author_id"]),
+        "author_id": int(data["author_id"]),
+        "extra_messages": [int(_id) for _id in data["extra_messages"].split(",")] if data["extra_messages"] else []
+    }
+
+
 def compose_embed(message):
     embed = Embed(
         description=message.content,
@@ -63,6 +173,7 @@ def compose_embed(message):
     embed.set_author(
         name=message.author.display_name,
         icon_url=message.author.avatar_url,
+        url=message.jump_url
     )
     embed.set_footer(
         text=message.channel.name,