add METAR and TAF commands (#340)

fixes #171

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 ### Added
 - MUF and foF2 maps from [prop.kc2g.com](https://prop.kc2g.com/).
+- Commands to show METAR (`?metar`) and TAF (`?taf`) (aeronautical weather conditions).
 ### Changed
 - New colour theme for `?greyline`.
 - Moved great circle distance and bearing calculation from `?ungrid` to `?griddistance`.

exts/weather.py

@@ -9,7 +9,11 @@ the GNU General Public License, version 2.
 
 
 import re
+from typing import List
 
+import aiohttp
+
+from discord import Embed
 import discord.ext.commands as commands
 
 import common as cmn
@@ -20,8 +24,10 @@ class WeatherCog(commands.Cog):
 
     def __init__(self, bot: commands.Bot):
         self.bot = bot
+        self.session = aiohttp.ClientSession(connector=bot.qrm.connector)
 
-    @commands.command(aliases=["solar", "bandconditions", "cond", "condx", "conditions"], category=cmn.cat.weather)
+    @commands.command(name="solarweather", aliases=["solar", "bandconditions", "cond", "condx", "conditions"],
+                      category=cmn.cat.weather)
     async def solarweather(self, ctx: commands.Context):
         """Gets a solar weather report."""
         embed = cmn.embed_factory(ctx)
@@ -103,6 +109,73 @@ class WeatherCog(commands.Cog):
         embed.set_image(url=f"http://wttr.in/{loc}_0{units}pnFQ.png")
         await ctx.send(embed=embed)
 
+    @commands.command(name="metar", category=cmn.cat.weather)
+    async def metar(self, ctx: commands.Context, airport: str, hours: int = 0):
+        """Gets current raw METAR (Meteorological Terminal Aviation Routine Weather Report) for an airport. \
+        Optionally, a number of hours can be given to show a number of hours of historical METAR data.
+
+        Airports should be given as an \
+        [ICAO code](https://en.wikipedia.org/wiki/List_of_airports_by_IATA_and_ICAO_code)."""
+        await ctx.send(embed=await self.gen_metar_taf_embed(ctx, airport, hours, False))
+
+    @commands.command(name="taf", category=cmn.cat.weather)
+    async def taf(self, ctx: commands.Context, airport: str):
+        """Gets forecasted raw TAF (Terminal Aerodrome Forecast) data for an airport. Includes the latest METAR data.
+
+        Airports should be given as an \
+        [ICAO code](https://en.wikipedia.org/wiki/List_of_airports_by_IATA_and_ICAO_code)."""
+        await ctx.send(embed=await self.gen_metar_taf_embed(ctx, airport, 0, True))
+
+    async def gen_metar_taf_embed(self, ctx: commands.Context, airport: str, hours: int, taf: bool) -> Embed:
+        embed = cmn.embed_factory(ctx)
+        airport = airport.upper()
+
+        if re.fullmatch(r"\w(\w|\d){2,3}", airport):
+            metar = await self.get_metar_taf_data(airport, hours, taf)
+
+            if taf:
+                embed.title = f"Current TAF for {airport}"
+            elif hours > 0:
+                embed.title = f"METAR for {airport} for the last {hours} hour{'s' if hours > 1 else ''}"
+            else:
+                embed.title = f"Current METAR for {airport}"
+
+            embed.description = "Data from [aviationweather.gov](https://www.aviationweather.gov/metar/data)."
+            embed.colour = cmn.colours.good
+
+            data = "\n".join(metar)
+            embed.description += f"\n\n```\n{data}\n```"
+        else:
+            embed.title = "Invalid airport given!"
+            embed.colour = cmn.colours.bad
+        return embed
+
+    async def get_metar_taf_data(self, airport: str, hours: int, taf: bool) -> List[str]:
+        url = (f"https://www.aviationweather.gov/metar/data?ids={airport}&format=raw&hours={hours}"
+               f"&taf={'on' if taf else 'off'}&layout=off")
+        async with self.session.get(url) as r:
+            if r.status != 200:
+                raise cmn.BotHTTPError(r)
+            page = await r.text()
+
+        # pare down to just the data
+        page = page.split("<!-- Data starts here -->")[1].split("<!-- Data ends here -->")[0].strip()
+        # split at <hr>s
+        data = re.split(r"<hr.*>", page, maxsplit=len(airport))
+
+        parsed = []
+        for sec in data:
+            if sec.strip():
+                for line in sec.split("\n"):
+                    line = line.strip()
+                    # remove HTML stuff
+                    line = line.replace("<code>", "").replace("</code>", "")
+                    line = line.replace("<strong>", "").replace("</strong>", "")
+                    line = line.replace("<br/>", "\n").replace("&nbsp;", " ")
+                    line = line.strip("\n")
+                    parsed.append(line)
+        return parsed
+
 
 def setup(bot: commands.Bot):
     bot.add_cog(WeatherCog(bot))