"""Ticker Registry service: add, delete, list, and retire tracked tickers."""

import logging
import re
from datetime import date

from sqlalchemy import select, update
from sqlalchemy.ext.asyncio import AsyncSession

from app.exceptions import DuplicateError, NotFoundError, ValidationError
from app.models.ticker import Ticker

logger = logging.getLogger(__name__)

# Reasons a symbol may be marked delisted, narrowest first.
REASON_FORM_25 = "form_25"   # SEC Form 25/25-NSE/15 confirmed the exchange exit
REASON_MANUAL = "manual"     # an operator decided

# How long a symbol must be without bars before we spend an SEC request asking
# whether it delisted. Guards against a market-data outage probing the whole
# universe at once; a real delisting is still stale days later.
MIN_STALE_DAYS_BEFORE_PROBE = 3


def _sec_client_factory():
    """Build the SEC client for a delisting probe (patched in tests).

    Imported lazily so the SEC/httpx stack stays off the import path of every
    module that only wants ``active_only``.
    """
    from app.services.sec_client import SecClient

    return SecClient()


def active_only(stmt):
    """Restrict a Ticker query to symbols that still trade.

    Opt-in on purpose rather than folded into a shared getter: list and admin
    views deliberately keep delisted rows so the delisting is *visible*, which a
    silent default would undo. Apply this on the live signal path — scanning,
    ranking, scoring, breadth, ingestion — and nowhere else.
    """
    return stmt.where(Ticker.delisted_on.is_(None))


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.

    Delisted symbols are included and carry ``delisted_on`` — the registry is
    where an operator needs to *see* that a symbol retired, not where it should
    quietly disappear.
    """
    result = await db.execute(select(Ticker).order_by(Ticker.symbol.asc()))
    return list(result.scalars().all())


async def mark_delisted(
    db: AsyncSession,
    symbol: str,
    *,
    delisted_on: date,
    reason: str = REASON_MANUAL,
) -> bool:
    """Record that a symbol stopped trading. True if this changed anything.

    Idempotent, so the staleness path can call it every run without churning the
    row: re-marking is a no-op. The one exception is an SEC confirmation landing
    on a row an operator marked by hand — Form 25 carries the real effective
    date, so it replaces the operator's estimate. Nothing downgrades a confirmed
    row back to a manual one.
    """
    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}")
    if ticker.delisted_on is not None:
        upgrading = (
            reason == REASON_FORM_25 and ticker.delisted_reason != REASON_FORM_25
        )
        if not upgrading:
            return False

    await db.execute(
        update(Ticker)
        .where(Ticker.id == ticker.id)
        .values(delisted_on=delisted_on, delisted_reason=reason)
    )
    await db.commit()
    logger.info(
        "ticker %s marked delisted on %s (%s)", normalised, delisted_on, reason
    )
    return True


async def confirm_delisting(
    db: AsyncSession,
    symbol: str,
    *,
    last_bar: date | None,
    today: date | None = None,
) -> date | None:
    """Ask SEC whether ``symbol`` actually delisted; mark it if so.

    Called when OHLCV goes stale, because "no new bars" alone cannot tell a
    delisting from a halt or a rename. Returns the effective date when this call
    marked the symbol, else ``None`` — already-marked and unconfirmed both return
    ``None``, so the caller keeps its existing alert for anything unproven.

    Deliberately driven by staleness rather than by the SEC fundamentals import:
    that importer stalls for days at a time on unrelated Company-Facts gaps, and
    detection wired into it would stall with it.

    The probe waits for ``MIN_STALE_DAYS_BEFORE_PROBE``. A delisted symbol stays
    stale forever, so the delay costs nothing, and it keeps a broad market-data
    outage — where every tracked symbol reports stale at once — from turning into
    one SEC request per symbol per run.
    """
    from app.services.sec_client import SecError

    normalised = symbol.strip().upper()
    result = await db.execute(select(Ticker).where(Ticker.symbol == normalised))
    ticker = result.scalar_one_or_none()
    if ticker is None or not ticker.cik:
        return None
    # Already confirmed by SEC — nothing left to learn. A row an operator marked
    # by hand is still worth probing: Form 25 upgrades the estimated date.
    if ticker.delisted_reason == REASON_FORM_25:
        return None
    # No bars at all is an ingestion problem, not evidence of a delisting.
    if last_bar is None:
        return None
    if ((today or date.today()) - last_bar).days < MIN_STALE_DAYS_BEFORE_PROBE:
        return None

    try:
        async with _sec_client_factory() as client:
            filing = await client.delisting_filing(ticker.cik)
    except SecError:
        # Never let a probe failure escalate a routine staleness warning.
        logger.warning("delisting probe failed for %s", normalised, exc_info=True)
        return None

    if filing is None:
        return None
    if await mark_delisted(
        db, normalised, delisted_on=filing["filing_date"], reason=REASON_FORM_25
    ):
        return filing["filing_date"]
    return None


async def clear_delisted(db: AsyncSession, symbol: str) -> bool:
    """Un-retire a symbol. True if it had been marked.

    The counterpart that makes automatic marking acceptable: a false positive
    costs one row update, where a delete would have cost the price history.
    """
    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}")
    if ticker.delisted_on is None:
        return False

    await db.execute(
        update(Ticker)
        .where(Ticker.id == ticker.id)
        .values(delisted_on=None, delisted_reason=None)
    )
    await db.commit()
    logger.info("ticker %s un-marked as delisted", normalised)
    return True