from __future__ import annotations

import logging
from dataclasses import dataclass
from enum import Enum

from config import Config
from portfolio import Position

log = logging.getLogger(__name__)


class ExitReason(Enum):
    HARD_STOP = "hard_stop"          # Price dropped too far from entry
    TRAILING_STOP = "trailing_stop"  # Price dropped too far from peak
    TAKE_PROFIT = "take_profit"      # Price hit the profit target
    TIME_LIMIT = "time_limit"        # Position held too long


@dataclass
class ExitSignal:
    reason: ExitReason
    current_price: float
    pnl_pct: float


class RiskManager:
    def __init__(self, config: Config):
        self.config = config

    def check(self, position: Position, current_price: float) -> ExitSignal | None:
        """
        Evaluate a position against all exit rules. Returns an ExitSignal if any
        rule triggers, otherwise None. Also updates the position's peak price.

        Rules are checked in priority order:
          1. Hard stop  — worst-case absolute floor
          2. Trailing stop — peak-relative stop, protects accumulated gains
          3. Take profit — locks in the profit target
          4. Time limit — exits stagnant positions to free capital
        """
        position.update_peak(current_price)

        pnl_pct = position.pnl_pct(current_price)
        drop_from_peak = position.drop_from_peak_pct(current_price)
        hours_held = position.hours_held()

        # 1. Hard stop-loss
        if pnl_pct <= -self.config.hard_stop_pct:
            log.warning(
                "%s HARD STOP: pnl=%.2f%% (limit=%.2f%%)",
                position.pair, pnl_pct, -self.config.hard_stop_pct,
            )
            return ExitSignal(ExitReason.HARD_STOP, current_price, pnl_pct)

        # 2. Trailing stop
        if drop_from_peak >= self.config.trailing_stop_pct:
            log.warning(
                "%s TRAILING STOP: dropped %.2f%% from peak $%.6f (current $%.6f)  pnl=%.2f%%",
                position.pair, drop_from_peak, position.peak_price, current_price, pnl_pct,
            )
            return ExitSignal(ExitReason.TRAILING_STOP, current_price, pnl_pct)

        # 3. Take profit
        if pnl_pct >= self.config.take_profit_pct:
            log.info(
                "%s TAKE PROFIT: pnl=%.2f%% (target=%.2f%%)",
                position.pair, pnl_pct, self.config.take_profit_pct,
            )
            return ExitSignal(ExitReason.TAKE_PROFIT, current_price, pnl_pct)

        # 4. Time limit
        if hours_held >= self.config.max_hold_hours:
            log.info(
                "%s TIME LIMIT: held %.1fh / %dh  pnl=%.2f%%",
                position.pair, hours_held, self.config.max_hold_hours, pnl_pct,
            )
            return ExitSignal(ExitReason.TIME_LIMIT, current_price, pnl_pct)

        log.debug(
            "%s HOLD: pnl=%.2f%%  peak_drop=%.2f%%  held=%.1fh  peak=$%.6f",
            position.pair, pnl_pct, drop_from_peak, hours_held, position.peak_price,
        )
        return None