"""
Paper Trading Executor — simulates order execution without real money.

Simulates realistic slippage and fees to get accurate paper P&L.
All trades are logged to PostgreSQL for metrics analysis.
"""
import logging
import uuid
from dataclasses import dataclass, field
from datetime import datetime, UTC
from typing import Optional

from bot.risk.manager import Order, Portfolio
from bot.data.db import Database

log = logging.getLogger(__name__)

# Polymarket taker fee used for paper simulation.
# Also stored as commission in each Trade for audit purposes.
# NOTE: this is a heuristic — see COMMISSION_RATE in bayesian.py for context.
POLYMARKET_FEE = 0.02  # 2%


@dataclass
class Trade:
    id: str
    market_id: str
    question: str
    direction: str
    size_usdc: float
    entry_price: float
    shares: float          # How many YES/NO shares bought
    fee_usdc: float
    net_cost: float
    timestamp: datetime
    reasoning: str
    paper: bool = True
    # ── Phase 1: edge neto audit fields ──────────────────────────────────────
    # edge_gross: raw model edge before any cost deductions
    # edge_net:   edge_gross - spread_estimate - commission/size_usdc
    # Both are heuristic estimates — see schema.sql comment for details.
    edge_gross: float = 0.0
    edge_net: float = 0.0
    prior_prob: float = 0.0      # market.yes_price clamped, before Bayesian update
    final_prob: float = 0.0      # estimated probability after all signals
    # mid_price: order-book midpoint when available; falls back to market.yes_price
    mid_price: float = 0.0
    spread_estimate: float = 0.02
    commission: float = 0.0      # = POLYMARKET_FEE * size_usdc
    # ── Phase 2: market family ────────────────────────────────────────────────
    family_key: str = ""

    def __str__(self) -> str:
        return (
            f"[PAPER] {self.direction} {self.shares:.1f} shares @ {self.entry_price:.3f} "
            f"= ${self.net_cost:.2f} (fee ${self.fee_usdc:.2f}) "
            f"edge_net={self.edge_net:+.3f} family={self.family_key} "
            f"| {self.question[:40]}"
        )


class PaperExecutor:
    """Executes trades on paper — no real money, realistic simulation."""

    def __init__(self, db: Database, bankroll: float) -> None:
        self._db = db
        self._portfolio = Portfolio(
            cash=bankroll,
            positions={},
        )
        log.info("Paper executor initialized with $%.2f bankroll", bankroll)

    async def initialize(self) -> None:
        """Reconcile in-memory portfolio with DB state.

        Called once after __init__ so the executor reflects any trades that
        survived a pod restart.  After a TRUNCATE the DB is empty and the
        portfolio resets to a full bankroll automatically.
        """
        positions = await self._db.get_open_positions()
        if not positions:
            log.info("No open positions in DB — starting with full bankroll")
            return

        total_deployed = sum(positions.values())
        self._portfolio.positions = positions
        self._portfolio.cash = max(0.0, self._portfolio.cash - total_deployed)
        log.info(
            "Restored %d open position(s) from DB — deployed $%.2f, cash $%.2f",
            len(positions),
            total_deployed,
            self._portfolio.cash,
        )

    def get_portfolio(self) -> Portfolio:
        return self._portfolio

    async def execute(self, order: Order) -> Optional[Trade]:
        """Simulate order execution with fees and slippage."""
        if order.size_usdc > self._portfolio.cash:
            log.warning(
                "Insufficient paper cash: need $%.2f have $%.2f",
                order.size_usdc,
                self._portfolio.cash,
            )
            return None

        # Simulate small slippage (0.1-0.3% depending on order size)
        slippage = min(0.003, order.size_usdc / 100000)

        # Determine entry price based on direction.
        # We fill at the current Polymarket mid price + slippage (buying at ask).
        # BUY_YES  → paying the YES price (order.market_price)
        # BUY_NO   → paying the NO price (1 - order.market_price)
        if order.direction == "BUY_YES":
            entry_price = min(0.99, order.market_price + slippage)
        else:
            entry_price = min(0.99, (1 - order.market_price) + slippage)

        fee = order.size_usdc * POLYMARKET_FEE
        net_cost = order.size_usdc + fee
        shares = order.size_usdc / entry_price

        # commission mirrors the heuristic COMMISSION_RATE applied in bayesian.py
        # when computing edge_net.  Stored for audit: confirms cost assumption held.
        commission = order.size_usdc * POLYMARKET_FEE  # = fee_usdc at current rate

        trade = Trade(
            id=str(uuid.uuid4()),
            market_id=order.market_id,
            question=order.question,
            direction=order.direction,
            size_usdc=order.size_usdc,
            entry_price=entry_price,
            shares=shares,
            fee_usdc=fee,
            net_cost=net_cost,
            timestamp=datetime.now(UTC),
            reasoning=order.reasoning,
            paper=True,
            # Phase 1 audit fields
            edge_gross=order.edge_gross,
            edge_net=order.edge_net,
            prior_prob=order.prior_prob,
            final_prob=order.final_prob,
            mid_price=order.mid_price,
            spread_estimate=order.spread_estimate,
            commission=commission,
            # Phase 2 family
            family_key=order.family_key,
        )

        # Update paper portfolio
        self._portfolio.cash -= net_cost
        self._portfolio.positions[order.market_id] = order.size_usdc

        # Persist to DB
        await self._db.save_trade(trade)

        return trade

    async def close_legacy_position(self, market_id: str, reason: str) -> float:
        """
        Close a paper position flagged by the legacy scan.

        Returns the capital recovered to cash (cost basis, assuming break-even
        exit — exact P&L would require the live exit price which isn't available
        at scan time).
        """
        cost = self._portfolio.positions.pop(market_id, 0.0)
        self._portfolio.cash += cost  # return capital at break-even
        await self._db.close_paper_position(market_id, reason)
        log.warning(
            "LEGACY_CLOSE market=%s | returned $%.2f to cash | %s",
            market_id, cost, reason[:80],
        )
        return cost

    async def close_position(self, market_id: str, resolution: float) -> Optional[float]:
        """Close a paper position after market resolution.

        resolution: 1.0 if YES won, 0.0 if NO won.
        Persists resolution and close_pnl to DB (computed via SQL from stored
        entry_price and shares). Returns approximate P&L for logging.
        """
        if market_id not in self._portfolio.positions:
            return None

        position_cost = self._portfolio.positions.pop(market_id)
        self._portfolio.cash += position_cost * resolution  # pay out winnings

        await self._db.close_paper_position(
            market_id,
            reason=f"market_resolved resolution={resolution:.1f}",
            resolution=resolution,
        )
        log.info("Closed position in %s, resolution=%.1f", market_id, resolution)
        # Approximate PnL: settlement value minus cost. Exact value is in close_pnl.
        return position_cost * resolution - position_cost