first commit

app/services/ticker_service.py

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+"""Ticker Registry service: add, delete, and list tracked tickers."""
+
+import re
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.exceptions import DuplicateError, NotFoundError, ValidationError
+from app.models.ticker import Ticker
+
+
+async def add_ticker(db: AsyncSession, symbol: str) -> Ticker:
+    """Add a new ticker after validation.
+
+    Validates: non-empty, uppercase alphanumeric. Auto-uppercases input.
+    Raises DuplicateError if symbol already tracked.
+    """
+    stripped = symbol.strip()
+    if not stripped:
+        raise ValidationError("Ticker symbol must not be empty or whitespace-only")
+
+    normalised = stripped.upper()
+    if not re.fullmatch(r"[A-Z0-9]+", normalised):
+        raise ValidationError(
+            f"Ticker symbol must be alphanumeric: {normalised}"
+        )
+
+    result = await db.execute(select(Ticker).where(Ticker.symbol == normalised))
+    if result.scalar_one_or_none() is not None:
+        raise DuplicateError(f"Ticker already exists: {normalised}")
+
+    ticker = Ticker(symbol=normalised)
+    db.add(ticker)
+    await db.commit()
+    await db.refresh(ticker)
+    return ticker
+
+
+async def delete_ticker(db: AsyncSession, symbol: str) -> None:
+    """Delete a ticker and cascade all associated data.
+
+    Raises NotFoundError if the symbol is not tracked.
+    """
+    normalised = symbol.strip().upper()
+    result = await db.execute(select(Ticker).where(Ticker.symbol == normalised))
+    ticker = result.scalar_one_or_none()
+    if ticker is None:
+        raise NotFoundError(f"Ticker not found: {normalised}")
+
+    await db.delete(ticker)
+    await db.commit()
+
+
+async def list_tickers(db: AsyncSession) -> list[Ticker]:
+    """Return all tracked tickers sorted alphabetically by symbol."""
+    result = await db.execute(select(Ticker).order_by(Ticker.symbol.asc()))
+    return list(result.scalars().all())