refactor base ContestBot logic to use new sqlalchemy models, commit exceptions.py

bot/bot.py

@@ -1,44 +1,91 @@
 import logging
-from typing import Optional
+from contextlib import contextmanager
+from datetime import datetime
 
 import discord
 from discord.ext import commands
+from sqlalchemy.engine import Engine
+from sqlalchemy.orm import sessionmaker
 
 from bot import constants
-from bot.db import ContestDatabase
+from bot.models import Guild, Period
 
 logger = logging.getLogger(__file__)
 logger.setLevel(constants.LOGGING_LEVEL)
 
 
-async def fetch_prefix(bot: 'ContestBot', message: discord.Message):
-    """Fetches the prefix used by the relevant guild."""
-    user_id = bot.user.id
-    base = [f'<@!{user_id}> ', f'<@{user_id}> ']
-
-    if message.guild:
-        if bot.db is not None:
-            base.append(await bot.db.get_prefix(message.guild.id))
-    return base
-
-
 class ContestBot(commands.Bot):
-    def __init__(self, **options):
-        self.db: Optional[ContestDatabase] = None
-        super().__init__(fetch_prefix, **options)
+    def __init__(self, engine: Engine, **options):
+        super().__init__(self.fetch_prefix, **options)
+
+        self.engine = engine
+        self.Session = sessionmaker(bind=engine)
+
+    @contextmanager
+    def autocommit(self):
+        """Provides automatic commit and closing of Session with exception rollback."""
+        session = self.Session()
+        try:
+            yield session
+            session.commit()
+        except Exception:
+            session.rollback()
+            raise
+        finally:
+            session.close()
+
+    @contextmanager
+    def autoclose(self):
+        """Provides automatic closing of Session."""
+        session = self.Session()
+        try:
+            yield session
+        except Exception:
+            session.rollback()
+            raise
+        finally:
+            session.close()
+
+    async def fetch_prefix(self, bot: 'ContestBot', message: discord.Message):
+        """Fetches the prefix used by the relevant guild."""
+        user_id = bot.user.id
+        base = [f'<@!{user_id}> ', f'<@{user_id}> ']
+
+        if message.guild:
+            with self.autocommit() as session:
+                guild = session.query(Guild).filter_by(id=message.guild.id).first()
+                base.append(guild.prefix)
+        return base
 
     async def on_ready(self):
-        if self.db is None:
-            self.db = await ContestDatabase.create()
         logger.info('Bot is now ready and connected to Discord.')
         guild_count = len(self.guilds)
         logger.info(
             f'Connected as {self.user.name}#{self.user.discriminator} to {guild_count} guild{"s" if guild_count > 1 else ""}.')
 
     async def on_guild_join(self, guild: discord.Guild) -> None:
+        """Handles adding or reactivating a Guild in the database."""
         logger.info(f'Added to new guild: {guild.name} ({guild.id})')
-        await self.db.setup_guild(guild.id)
+
+        with self.autocommit() as session:
+            _guild: Guild = session.query(Guild).filter_by(active=False, id=guild.id).first()
+            if _guild is None:
+                session.add(Guild(id=guild.id))
+            else:
+                # Guild has been seen before. Update last_joined and set as active again.
+                _guild.active = True
+                _guild.last_joined = datetime.utcnow()
 
     async def on_guild_remove(self, guild: discord.Guild) -> None:
+        """Handles disabling the guild in the database, as well."""
         logger.info(f'Removed from guild: {guild.name} ({guild.id})')
-        await self.db.teardown_guild(guild.id)
+
+        with self.autocommit() as session:
+            # Get the associated Guild and mark it as disabled.
+            _guild = session.query(Guild).filter_by(active=True, id=guild.id).first()
+            _guild.active = False
+
+            # Shut down any current running Period objects if possible.
+            period: Period = _guild.current_period
+            if period is not None and period.active:
+                period.deactivate()

bot/exceptions.py

@@ -0,0 +1,3 @@
+class FinishedPeriod(Exception):
+    """A inactive period, or a period in it's final state cannot be advanced or further modified."""
+    pass