import inspect
from pathlib import Path
from typing import Optional, Tuple

from discord import Embed
from discord.ext import commands

from bot.bot import Bot
from bot.constants import Source
from bot.utils.converters import SourceConverter, SourceType


class BotSource(commands.Cog):
    """Displays information about the bot's source code."""

    @commands.command(name="source", aliases=("src",))
    async def source_command(self, ctx: commands.Context, *, source_item: SourceConverter = None) -> None:
        """Display information and a GitHub link to the source code of a command, tag, or cog."""
        if not source_item:
            embed = Embed(title="Sir Lancebot's GitHub Repository")
            embed.add_field(name="Repository", value=f"[Go to GitHub]({Source.github})")
            embed.set_thumbnail(url=Source.github_avatar_url)
            await ctx.send(embed=embed)
            return

        embed = await self.build_embed(source_item)
        await ctx.send(embed=embed)

    def get_source_link(self, source_item: SourceType) -> Tuple[str, str, Optional[int]]:
        """
        Build GitHub link of source item, return this link, file location and first line number.

        Raise BadArgument if `source_item` is a dynamically-created object (e.g. via internal eval).
        """
        if isinstance(source_item, commands.Command):
            src = source_item.callback.__code__
            filename = src.co_filename
        else:
            src = type(source_item)
            try:
                filename = inspect.getsourcefile(src)
            except TypeError:
                raise commands.BadArgument("Cannot get source for a dynamically-created object.")

        if not isinstance(source_item, str):
            try:
                lines, first_line_no = inspect.getsourcelines(src)
            except OSError:
                raise commands.BadArgument("Cannot get source for a dynamically-created object.")

            lines_extension = f"#L{first_line_no}-L{first_line_no+len(lines)-1}"
        else:
            first_line_no = None
            lines_extension = ""

        file_location = Path(filename).relative_to(Path.cwd()).as_posix()

        url = f"{Source.github}/blob/main/{file_location}{lines_extension}"

        return url, file_location, first_line_no or None

    async def build_embed(self, source_object: SourceType) -> Optional[Embed]:
        """Build embed based on source object."""
        url, location, first_line = self.get_source_link(source_object)

        if isinstance(source_object, commands.Command):
            if source_object.cog_name == "Help":
                title = "Help Command"
                description = source_object.__doc__.splitlines()[1]
            else:
                description = source_object.short_doc
                title = f"Command: {source_object.qualified_name}"
        else:
            title = f"Cog: {source_object.qualified_name}"
            description = source_object.description.splitlines()[0]

        embed = Embed(title=title, description=description)
        embed.set_thumbnail(url=Source.github_avatar_url)
        embed.add_field(name="Source Code", value=f"[Go to GitHub]({url})")
        line_text = f":{first_line}" if first_line else ""
        embed.set_footer(text=f"{location}{line_text}")

        return embed


def setup(bot: Bot) -> None:
    """Load the BotSource cog."""
    bot.add_cog(BotSource())