Add currency converter cog and aliases

cogs/currency_converter.py

@@ -0,0 +1,83 @@
+import os
+import time
+import json
+import aiohttp
+import discord
+from discord.ext import commands
+
+# load aliases from json
+with open(os.path.join(os.path.dirname(__file__), 'currency_aliases.json'), 'r', encoding='utf-8') as f:
+    _ALIAS_MAP = json.load(f)
+
+# in‑memory cache for rates: {base: (timestamp, rates_dict)}
+_RATE_CACHE = {}
+_CACHE_TTL = 3600  # seconds
+
+class CurrencyConverter(commands.Cog):
+    def __init__(self, bot):
+        self.bot = bot
+
+    def _norm(self, cur: str) -> str:
+        """Normalize a currency string to its ISO code.
+        Returns upper‑case ISO code or raises ValueError if unknown.
+        """
+        cur = cur.strip().lower()
+        if cur in _ALIAS_MAP:
+            return _ALIAS_MAP[cur]
+        cur = cur.upper()
+        if len(cur) == 3 and cur.isalpha():
+            return cur
+        raise ValueError(f"unknown currency '{cur}'")
+
+    async def _get_rates(self, base: str) -> dict:
+        """Fetch rates for *base* from cache or the Frankfurter API.
+        Returns a dict mapping target ISO codes to float rates.
+        """
+        now = time.time()
+        cached = _RATE_CACHE.get(base)
+        if cached and now - cached[0] < _CACHE_TTL:
+            return cached[1]
+        url = f"https://frankfurter.app/latest?from={base}"
+        async with aiohttp.ClientSession() as session:
+            async with session.get(url) as resp:
+                if resp.status != 200:
+                    raise RuntimeError('currency API error')
+                data = await resp.json()
+        rates = data.get('rates', {})
+        _RATE_CACHE[base] = (now, rates)
+        return rates
+
+    @commands.command(name='currency')
+    async def currency(self, ctx, amount: float = 1, from_cur: str = None, to_cur: str = None):
+        """Convert *amount* from *from_cur* to *to_cur*.
+        If *amount* is omitted the command is parsed as ``!currency <from> <to>``.
+        """
+        # discord.py passes arguments left‑to‑right; we need to support two signatures.
+        # When the user supplies only two strings, *amount* will be parsed as the first string.
+        if from_cur is None and to_cur is None:
+            # only two arguments were given, treat them as from/to and default amount=1
+            to_cur = amount  # type: ignore
+            from_cur = str(amount)  # type: ignore
+            amount = 1.0
+        try:
+            from_code = self._norm(str(from_cur))
+            to_code = self._norm(str(to_cur))
+        except ValueError as e:
+            return await ctx.reply(f"❌ {e}")
+        try:
+            rates = await self._get_rates(from_code)
+        except Exception:
+            return await ctx.reply('❌ could not fetch conversion rates, try again later')
+        rate = rates.get(to_code)
+        if rate is None:
+            return await ctx.reply(f"❌ unsupported conversion: {from_code} → {to_code}")
+        result = amount * rate
+        embed = discord.Embed(title='Currency conversion', color=0x00ff00)
+        embed.add_field(name='From', value=f"{amount:g} {from_code}", inline=True)
+        embed.add_field(name='To', value=f"{result:g} {to_code}", inline=True)
+        embed.add_field(name='Rate', value=f"1 {from_code} = {rate:g} {to_code}", inline=False)
+        embed.set_footer(text='Data from frankfurter.app')
+        await ctx.reply(embed=embed)
+
+async def setup(bot):
+    await bot.add_cog(CurrencyConverter(bot))