Move practical functions into utilities folder

Separates out the useful/practical seasonal bot features from the
evergreen folder into a "utilities" folder.
Adjusts the paths to resources to reflect the folder move.

1 files changed, 368 insertions, 0 deletions

diff --git a/bot/exts/utilities/reddit.py b/bot/exts/utilities/reddit.py
new file mode 100644
index 00000000..e6cb5337
--- /dev/null
+++ b/bot/exts/utilities/reddit.py
@@ -0,0 +1,368 @@
+import asyncio
+import logging
+import random
+import textwrap
+from collections import namedtuple
+from datetime import datetime, timedelta
+from typing import Union
+
+from aiohttp import BasicAuth, ClientError
+from discord import Colour, Embed, TextChannel
+from discord.ext.commands import Cog, Context, group, has_any_role
+from discord.ext.tasks import loop
+from discord.utils import escape_markdown, sleep_until
+
+from bot.bot import Bot
+from bot.constants import Channels, ERROR_REPLIES, Emojis, Reddit as RedditConfig, STAFF_ROLES
+from bot.utils.converters import Subreddit
+from bot.utils.extensions import invoke_help_command
+from bot.utils.messages import sub_clyde
+from bot.utils.pagination import ImagePaginator, LinePaginator
+
+log = logging.getLogger(__name__)
+
+AccessToken = namedtuple("AccessToken", ["token", "expires_at"])
+
+
+class Reddit(Cog):
+    """Track subreddit posts and show detailed statistics about them."""
+
+    HEADERS = {"User-Agent": "python3:python-discord/bot:1.0.0 (by /u/PythonDiscord)"}
+    URL = "https://www.reddit.com"
+    OAUTH_URL = "https://oauth.reddit.com"
+    MAX_RETRIES = 3
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+        self.webhook = None
+        self.access_token = None
+        self.client_auth = BasicAuth(RedditConfig.client_id, RedditConfig.secret)
+
+        bot.loop.create_task(self.init_reddit_ready())
+        self.auto_poster_loop.start()
+
+    def cog_unload(self) -> None:
+        """Stop the loop task and revoke the access token when the cog is unloaded."""
+        self.auto_poster_loop.cancel()
+        if self.access_token and self.access_token.expires_at > datetime.utcnow():
+            asyncio.create_task(self.revoke_access_token())
+
+    async def init_reddit_ready(self) -> None:
+        """Sets the reddit webhook when the cog is loaded."""
+        await self.bot.wait_until_guild_available()
+        if not self.webhook:
+            self.webhook = await self.bot.fetch_webhook(RedditConfig.webhook)
+
+    @property
+    def channel(self) -> TextChannel:
+        """Get the #reddit channel object from the bot's cache."""
+        return self.bot.get_channel(Channels.reddit)
+
+    def build_pagination_pages(self, posts: list[dict], paginate: bool) -> Union[list[tuple], str]:
+        """Build embed pages required for Paginator."""
+        pages = []
+        first_page = ""
+        for post in posts:
+            post_page = ""
+            image_url = ""
+
+            data = post["data"]
+
+            title = textwrap.shorten(data["title"], width=50, placeholder="...")
+
+            # Normal brackets interfere with Markdown.
+            title = escape_markdown(title).replace("[", "⦋").replace("]", "⦌")
+            link = self.URL + data["permalink"]
+
+            first_page += f"**[{title.replace('*', '')}]({link})**\n"
+
+            text = data["selftext"]
+            if text:
+                text = escape_markdown(text).replace("[", "⦋").replace("]", "⦌")
+                first_page += textwrap.shorten(text, width=100, placeholder="...") + "\n"
+
+            ups = data["ups"]
+            comments = data["num_comments"]
+            author = data["author"]
+
+            content_type = Emojis.reddit_post_text
+            if data["is_video"] or {"youtube", "youtu.be"}.issubset(set(data["url"].split("."))):
+                # This means the content type in the post is a video.
+                content_type = f"{Emojis.reddit_post_video}"
+
+            elif data["url"].endswith(("jpg", "png", "gif")):
+                # This means the content type in the post is an image.
+                content_type = f"{Emojis.reddit_post_photo}"
+                image_url = data["url"]
+
+            first_page += (
+                f"{content_type}\u2003{Emojis.reddit_upvote}{ups}\u2003{Emojis.reddit_comments}"
+                f"\u2002{comments}\u2003{Emojis.reddit_users}{author}\n\n"
+            )
+
+            if paginate:
+                post_page += f"**[{title}]({link})**\n\n"
+                if text:
+                    post_page += textwrap.shorten(text, width=252, placeholder="...") + "\n\n"
+                post_page += (
+                    f"{content_type}\u2003{Emojis.reddit_upvote}{ups}\u2003{Emojis.reddit_comments}\u2002"
+                    f"{comments}\u2003{Emojis.reddit_users}{author}"
+                )
+
+                pages.append((post_page, image_url))
+
+        if not paginate:
+            # Return the first summery page if pagination is not required
+            return first_page
+
+        pages.insert(0, (first_page, ""))  # Using image paginator, hence settings image url to empty string
+        return pages
+
+    async def get_access_token(self) -> None:
+        """
+        Get a Reddit API OAuth2 access token and assign it to self.access_token.
+
+        A token is valid for 1 hour. There will be MAX_RETRIES to get a token, after which the cog
+        will be unloaded and a ClientError raised if retrieval was still unsuccessful.
+        """
+        for i in range(1, self.MAX_RETRIES + 1):
+            response = await self.bot.http_session.post(
+                url=f"{self.URL}/api/v1/access_token",
+                headers=self.HEADERS,
+                auth=self.client_auth,
+                data={
+                    "grant_type": "client_credentials",
+                    "duration": "temporary"
+                }
+            )
+
+            if response.status == 200 and response.content_type == "application/json":
+                content = await response.json()
+                expiration = int(content["expires_in"]) - 60  # Subtract 1 minute for leeway.
+                self.access_token = AccessToken(
+                    token=content["access_token"],
+                    expires_at=datetime.utcnow() + timedelta(seconds=expiration)
+                )
+
+                log.debug(f"New token acquired; expires on UTC {self.access_token.expires_at}")
+                return
+            else:
+                log.debug(
+                    f"Failed to get an access token: "
+                    f"status {response.status} & content type {response.content_type}; "
+                    f"retrying ({i}/{self.MAX_RETRIES})"
+                )
+
+            await asyncio.sleep(3)
+
+        self.bot.remove_cog(self.qualified_name)
+        raise ClientError("Authentication with the Reddit API failed. Unloading the cog.")
+
+    async def revoke_access_token(self) -> None:
+        """
+        Revoke the OAuth2 access token for the Reddit API.
+
+        For security reasons, it's good practice to revoke the token when it's no longer being used.
+        """
+        response = await self.bot.http_session.post(
+            url=f"{self.URL}/api/v1/revoke_token",
+            headers=self.HEADERS,
+            auth=self.client_auth,
+            data={
+                "token": self.access_token.token,
+                "token_type_hint": "access_token"
+            }
+        )
+
+        if response.status in [200, 204] and response.content_type == "application/json":
+            self.access_token = None
+        else:
+            log.warning(f"Unable to revoke access token: status {response.status}.")
+
+    async def fetch_posts(self, route: str, *, amount: int = 25, params: dict = None) -> list[dict]:
+        """A helper method to fetch a certain amount of Reddit posts at a given route."""
+        # Reddit's JSON responses only provide 25 posts at most.
+        if not 25 >= amount > 0:
+            raise ValueError("Invalid amount of subreddit posts requested.")
+
+        # Renew the token if necessary.
+        if not self.access_token or self.access_token.expires_at < datetime.utcnow():
+            await self.get_access_token()
+
+        url = f"{self.OAUTH_URL}/{route}"
+        for _ in range(self.MAX_RETRIES):
+            response = await self.bot.http_session.get(
+                url=url,
+                headers={**self.HEADERS, "Authorization": f"bearer {self.access_token.token}"},
+                params=params
+            )
+            if response.status == 200 and response.content_type == 'application/json':
+                # Got appropriate response - process and return.
+                content = await response.json()
+                posts = content["data"]["children"]
+
+                filtered_posts = [post for post in posts if not post["data"]["over_18"]]
+
+                return filtered_posts[:amount]
+
+            await asyncio.sleep(3)
+
+        log.debug(f"Invalid response from: {url} - status code {response.status}, mimetype {response.content_type}")
+        return list()  # Failed to get appropriate response within allowed number of retries.
+
+    async def get_top_posts(
+            self, subreddit: Subreddit, time: str = "all", amount: int = 5, paginate: bool = False
+    ) -> Union[Embed, list[tuple]]:
+        """
+        Get the top amount of posts for a given subreddit within a specified timeframe.
+
+        A time of "all" will get posts from all time, "day" will get top daily posts and "week" will get the top
+        weekly posts.
+
+        The amount should be between 0 and 25 as Reddit's JSON requests only provide 25 posts at most.
+        """
+        embed = Embed()
+
+        posts = await self.fetch_posts(
+            route=f"{subreddit}/top",
+            amount=amount,
+            params={"t": time}
+        )
+        if not posts:
+            embed.title = random.choice(ERROR_REPLIES)
+            embed.colour = Colour.red()
+            embed.description = (
+                "Sorry! We couldn't find any SFW posts from that subreddit. "
+                "If this problem persists, please let us know."
+            )
+
+            return embed
+
+        if paginate:
+            return self.build_pagination_pages(posts, paginate=True)
+
+        # Use only starting summary page for #reddit channel posts.
+        embed.description = self.build_pagination_pages(posts, paginate=False)
+        embed.colour = Colour.blurple()
+        return embed
+
+    @loop()
+    async def auto_poster_loop(self) -> None:
+        """Post the top 5 posts daily, and the top 5 posts weekly."""
+        # once d.py get support for `time` parameter in loop decorator,
+        # this can be removed and the loop can use the `time=datetime.time.min` parameter
+        now = datetime.utcnow()
+        tomorrow = now + timedelta(days=1)
+        midnight_tomorrow = tomorrow.replace(hour=0, minute=0, second=0)
+
+        await sleep_until(midnight_tomorrow)
+
+        await self.bot.wait_until_guild_available()
+        if not self.webhook:
+            await self.bot.fetch_webhook(RedditConfig.webhook)
+
+        if datetime.utcnow().weekday() == 0:
+            await self.top_weekly_posts()
+            # if it's a monday send the top weekly posts
+
+        for subreddit in RedditConfig.subreddits:
+            top_posts = await self.get_top_posts(subreddit=subreddit, time="day")
+            username = sub_clyde(f"{subreddit} Top Daily Posts")
+            message = await self.webhook.send(username=username, embed=top_posts, wait=True)
+
+            if message.channel.is_news():
+                await message.publish()
+
+    async def top_weekly_posts(self) -> None:
+        """Post a summary of the top posts."""
+        for subreddit in RedditConfig.subreddits:
+            # Send and pin the new weekly posts.
+            top_posts = await self.get_top_posts(subreddit=subreddit, time="week")
+            username = sub_clyde(f"{subreddit} Top Weekly Posts")
+            message = await self.webhook.send(wait=True, username=username, embed=top_posts)
+
+            if subreddit.lower() == "r/python":
+                if not self.channel:
+                    log.warning("Failed to get #reddit channel to remove pins in the weekly loop.")
+                    return
+
+                # Remove the oldest pins so that only 12 remain at most.
+                pins = await self.channel.pins()
+
+                while len(pins) >= 12:
+                    await pins[-1].unpin()
+                    del pins[-1]
+
+                await message.pin()
+
+                if message.channel.is_news():
+                    await message.publish()
+
+    @group(name="reddit", invoke_without_command=True)
+    async def reddit_group(self, ctx: Context) -> None:
+        """View the top posts from various subreddits."""
+        await invoke_help_command(ctx)
+
+    @reddit_group.command(name="top")
+    async def top_command(self, ctx: Context, subreddit: Subreddit = "r/Python") -> None:
+        """Send the top posts of all time from a given subreddit."""
+        async with ctx.typing():
+            pages = await self.get_top_posts(subreddit=subreddit, time="all", paginate=True)
+
+        await ctx.send(f"Here are the top {subreddit} posts of all time!")
+        embed = Embed(
+            color=Colour.blurple()
+        )
+
+        await ImagePaginator.paginate(pages, ctx, embed)
+
+    @reddit_group.command(name="daily")
+    async def daily_command(self, ctx: Context, subreddit: Subreddit = "r/Python") -> None:
+        """Send the top posts of today from a given subreddit."""
+        async with ctx.typing():
+            pages = await self.get_top_posts(subreddit=subreddit, time="day", paginate=True)
+
+        await ctx.send(f"Here are today's top {subreddit} posts!")
+        embed = Embed(
+            color=Colour.blurple()
+        )
+
+        await ImagePaginator.paginate(pages, ctx, embed)
+
+    @reddit_group.command(name="weekly")
+    async def weekly_command(self, ctx: Context, subreddit: Subreddit = "r/Python") -> None:
+        """Send the top posts of this week from a given subreddit."""
+        async with ctx.typing():
+            pages = await self.get_top_posts(subreddit=subreddit, time="week", paginate=True)
+
+        await ctx.send(f"Here are this week's top {subreddit} posts!")
+        embed = Embed(
+            color=Colour.blurple()
+        )
+
+        await ImagePaginator.paginate(pages, ctx, embed)
+
+    @has_any_role(*STAFF_ROLES)
+    @reddit_group.command(name="subreddits", aliases=("subs",))
+    async def subreddits_command(self, ctx: Context) -> None:
+        """Send a paginated embed of all the subreddits we're relaying."""
+        embed = Embed()
+        embed.title = "Relayed subreddits."
+        embed.colour = Colour.blurple()
+
+        await LinePaginator.paginate(
+            RedditConfig.subreddits,
+            ctx, embed,
+            footer_text="Use the reddit commands along with these to view their posts.",
+            empty=False,
+            max_lines=15
+        )
+
+
+def setup(bot: Bot) -> None:
+    """Load the Reddit cog."""
+    if not RedditConfig.secret or not RedditConfig.client_id:
+        log.error("Credentials not provided, cog not loaded.")
+        return
+    bot.add_cog(Reddit(bot))