"""Slack notifier for trade-executor.

Supports two transports, picked by what's configured:
  1. **Bot token + channel** (preferred) — uses chat.postMessage. Channel
     can be changed via env var without redeploying the Slack app or
     rotating webhook URLs.
  2. **Webhook URL** (legacy) — single-channel, pinned at webhook
     creation time.

If both are set, the bot-token path wins. If neither, the notifier
is a no-op.

Designed to fail-soft: a Slack outage MUST NOT bubble up and crash
the consumer loop. The trade has already happened on Alpaca — Slack
is a downstream observer, not a transactional dependency.
"""

from __future__ import annotations

import logging
from typing import Iterable

import httpx

from shared.constants.kevin import KEVIN_STRATEGY_UUID
from shared.schemas.trading import OrderResult, TradeSignal

logger = logging.getLogger(__name__)


# Reasons we DON'T want to spam Slack about. outside_market_hours fires
# every poll when a fresh signal lands after-hours — silencing it keeps
# Slack signal-to-noise high.
_DEFAULT_QUIET = frozenset({"outside_market_hours"})


class SlackNotifier:
    def __init__(
        self,
        webhook_url: str = "",
        bot_token: str = "",
        channel: str = "",
        quiet_rejections: Iterable[str] | None = None,
    ) -> None:
        self.webhook_url = webhook_url or ""
        self.bot_token = bot_token or ""
        self.channel = channel or ""
        self.quiet_rejections = frozenset(
            quiet_rejections if quiet_rejections is not None else _DEFAULT_QUIET
        )

    @property
    def enabled(self) -> bool:
        # Either transport must be fully configured.
        if self.bot_token and self.channel:
            return True
        if self.webhook_url:
            return True
        return False

    @property
    def uses_bot_token(self) -> bool:
        return bool(self.bot_token and self.channel)

    async def notify_trade(self, signal: TradeSignal, result: OrderResult) -> None:
        if not self.enabled:
            return
        text = self._format_trade(signal, result)
        await self._post(text)

    async def notify_rejection(self, signal: TradeSignal, reason: str) -> None:
        if not self.enabled:
            return
        if reason in self.quiet_rejections:
            return
        text = self._format_rejection(signal, reason)
        await self._post(text)

    # ------------------------------------------------------------------
    # Internal
    # ------------------------------------------------------------------

    def _strategy_tag(self, signal: TradeSignal) -> str:
        if signal.strategy_id == KEVIN_STRATEGY_UUID:
            return "Meet Kevin"
        return "trading-bot"

    def _format_trade(self, signal: TradeSignal, result: OrderResult) -> str:
        tag = self._strategy_tag(signal)
        price = (
            f"${result.filled_price:.2f}"
            if result.filled_price is not None
            else "—"
        )
        return (
            f":chart_with_upwards_trend: *{tag}*: "
            f"{result.side.value} {result.qty:g} {result.ticker} @ {price}  "
            f"(conviction {signal.strength:.2f}, status {result.status.value})"
        )

    def _format_rejection(self, signal: TradeSignal, reason: str) -> str:
        tag = self._strategy_tag(signal)
        return (
            f":no_entry: *{tag}*: REJECTED {signal.ticker} — {reason} "
            f"(conviction {signal.strength:.2f})"
        )

    async def _post(self, text: str) -> None:
        try:
            async with httpx.AsyncClient(timeout=5.0) as client:
                if self.uses_bot_token:
                    resp = await client.post(
                        "https://slack.com/api/chat.postMessage",
                        headers={
                            "Authorization": f"Bearer {self.bot_token}",
                            "Content-Type": "application/json; charset=utf-8",
                        },
                        json={"channel": self.channel, "text": text},
                    )
                    body = resp.json()
                    if not body.get("ok"):
                        logger.warning(
                            "Slack chat.postMessage refused: %s (channel=%s)",
                            body.get("error"),
                            self.channel,
                        )
                else:
                    await client.post(self.webhook_url, json={"text": text})
        except Exception as exc:
            logger.warning("Slack post failed (swallowed): %s", exc)