"""
Funding Rate Arbitrage strategy.

Hyperliquid pays funding every 8 hours. When the rate is positive,
longs pay shorts. This strategy:

1. Goes LONG spot (no funding payments)
2. Goes SHORT perp (collects funding)
3. Maintains delta neutrality

The profit comes from funding, not price direction.
"""
from nautilus_trader.trading.strategy import Strategy
from nautilus_trader.config import StrategyConfig


class FundingRateArbConfig(StrategyConfig, frozen=True):
    spot_instrument: str
    perp_instrument: str
    min_funding_rate: float = 0.0001
    rebalance_threshold: float = 0.05
    position_size: float = 0.01


class FundingRateArb(Strategy):
    """
    Delta-neutral funding rate carry trade.

    Key idea: funding rate IS the edge. Stay neutral, collect
    the payments.
    """

    def __init__(self, config: FundingRateArbConfig) -> None:
        super().__init__(config)
        self.config = config
        self.position_open = False

    def on_start(self) -> None:
        bar_type = f"{self.config.perp_instrument}-1-MINUTE-LAST-INTERNAL"
        self.subscribe_bars(bar_type)
        self.log.info(
            f"Funding arb: {self.config.spot_instrument} / {self.config.perp_instrument}"
        )

    def on_bar(self, bar) -> None:
        funding_rate = self._get_funding_rate()
        if funding_rate is None:
            return

        spot_pos = self.portfolio.net_position(self.config.spot_instrument)

        if funding_rate > self.config.min_funding_rate and spot_pos == 0:
            self._open()
            self.position_open = True
        elif funding_rate < self.config.min_funding_rate / 2 and self.position_open:
            self._close()
            self.position_open = False

    def _get_funding_rate(self) -> float | None:
        # TODO: fetch from Hyperliquid API
        return 0.0001

    def _open(self) -> None:
        self.submit_order(self.order_factory.market(
            instrument_id=self.config.spot_instrument,
            order_side="BUY",
            quantity=self.config.position_size,
        ))
        self.submit_order(self.order_factory.market(
            instrument_id=self.config.perp_instrument,
            order_side="SELL",
            quantity=self.config.position_size,
        ))

    def _close(self) -> None:
        self.close_all_positions(self.config.spot_instrument)
        self.close_all_positions(self.config.perp_instrument)