#  Lines 72 through 90 are influenced heavily by cacobot's stats module:
#  https://github.com/Orangestar12/cacobot/blob/master/cacobot/stats.py
#  Big thanks to Redjumpman for changing the beta version from
#  Imagemagick/cairosvg to matplotlib.
#  Thanks to violetnyte for suggesting this cog.
import discord
import heapq
from io import BytesIO
from typing import Optional
import matplotlib

matplotlib.use("agg")
import matplotlib.pyplot as plt

plt.switch_backend("agg")
from redbot.core import commands


class Chatchart(commands.Cog):
    """Show activity."""

    async def red_delete_data_for_user(self, **kwargs):
        """ Nothing to delete """
        return

    def __init__(self, bot):
        self.bot = bot

    def create_chart(self, top, others, channel):
        plt.clf()
        sizes = [x[1] for x in top if x[1] > 0]
        labels = ["{} {:g}%".format(x[0], x[1]) for x in top if x[1] > 0]
        if len(top) >= 20:
            sizes = sizes + [others]
            labels = labels + ["Others {:g}%".format(others)]
        if len(channel.name) >= 19:
            channel_name = "{}...".format(channel.name[:19])
        else:
            channel_name = channel.name
        title = plt.title("Stats in #{}".format(channel_name), color="white")
        title.set_va("top")
        title.set_ha("center")
        plt.gca().axis("equal")
        colors = [
            "r",
            "darkorange",
            "gold",
            "y",
            "olivedrab",
            "green",
            "darkcyan",
            "mediumblue",
            "darkblue",
            "blueviolet",
            "indigo",
            "orchid",
            "mediumvioletred",
            "crimson",
            "chocolate",
            "yellow",
            "limegreen",
            "forestgreen",
            "dodgerblue",
            "slateblue",
            "gray",
        ]
        pie = plt.pie(sizes, colors=colors, startangle=0)
        plt.legend(
            pie[0],
            labels,
            bbox_to_anchor=(0.7, 0.5),
            loc="center",
            fontsize=10,
            bbox_transform=plt.gcf().transFigure,
            facecolor="#ffffff",
        )
        plt.subplots_adjust(left=0.0, bottom=0.1, right=0.45)
        image_object = BytesIO()
        plt.savefig(image_object, format="PNG", facecolor="#36393E")
        image_object.seek(0)
        return image_object

    @commands.guild_only()
    @commands.command()
    @commands.cooldown(1, 10, commands.BucketType.channel)
    @commands.max_concurrency(1, commands.BucketType.channel)
    async def chatchart(self, ctx, channel: Optional[discord.TextChannel] = None, messages=5000):
        """
        Generates a pie chart, representing the last 5000 messages in the specified channel.
        """
        e = discord.Embed(description="Loading...", colour=0x00CCFF)
        e.set_thumbnail(url="https://i.imgur.com/vSp4xRk.gif")
        em = await ctx.send(embed=e)

        if channel is None:
            channel = ctx.message.channel
        history = []
        if not channel.permissions_for(ctx.message.author).read_messages == True:
            await em.delete()
            return await ctx.send("You're not allowed to access that channel.")
        try:
            async for msg in channel.history(limit=messages):
                history.append(msg)
        except discord.errors.Forbidden:
            await em.delete()
            return await ctx.send("No permissions to read that channel.")
        msg_data = {"total count": 0, "users": {}}

        for msg in history:
            if len(msg.author.display_name) >= 20:
                short_name = "{}...".format(msg.author.display_name[:20]).replace("$", "\\$")
            else:
                short_name = msg.author.display_name.replace("$", "\\$")
            whole_name = "{}#{}".format(short_name, msg.author.discriminator)
            if msg.author.bot:
                pass
            elif whole_name in msg_data["users"]:
                msg_data["users"][whole_name]["msgcount"] += 1
                msg_data["total count"] += 1
            else:
                msg_data["users"][whole_name] = {}
                msg_data["users"][whole_name]["msgcount"] = 1
                msg_data["total count"] += 1

        if msg_data["users"] == {}:
            await em.delete()
            return await ctx.message.channel.send(f"Only bots have sent messages in {channel.mention}")

        for usr in msg_data["users"]:
            pd = float(msg_data["users"][usr]["msgcount"]) / float(msg_data["total count"])
            msg_data["users"][usr]["percent"] = round(pd * 100, 1)

        top_ten = heapq.nlargest(
            20,
            [(x, msg_data["users"][x][y]) for x in msg_data["users"] for y in msg_data["users"][x] if y == "percent"],
            key=lambda x: x[1],
        )
        others = 100 - sum(x[1] for x in top_ten)
        img = self.create_chart(top_ten, others, channel)
        await em.delete()
        await ctx.message.channel.send(file=discord.File(img, "chart.png"))