from __future__ import annotations

from dataclasses import dataclass, field
from typing import List, Dict, Optional
from datetime import datetime


@dataclass(frozen=True)
class Asset:
    symbol: str
    asset_type: str  # e.g., "equity", "option", "futures"
    venue: str

    def __post_init__(self):
        if self.asset_type not in {"equity", "option", "futures"}:
            raise ValueError("asset_type must be one of 'equity', 'option', or 'futures'")


@dataclass(frozen=True)
class MarketSignal:
    asset_symbol: str
    venue: str
    price: float
    delta: Optional[float] = None  # local delta proxy if available
    timestamp: datetime = field(default_factory=datetime.utcnow)
    meta: Dict[str, float] = field(default_factory=dict)


@dataclass
class StrategyDelta:
    asset: Asset
    target_delta: float  # desired delta exposure for this block
    risk_budget: float  # allowed risk budget for this block
    objective: str  # e.g., "delta-neutral", "calendar-spread"
    timestamp: datetime = field(default_factory=datetime.utcnow)


@dataclass
class PlanDelta:
    hedges: List[StrategyDelta] = field(default_factory=list)
    actions: List[Dict] = field(default_factory=list)  # provenance and trade actions
    total_cost: float = 0.0
    timestamp: datetime = field(default_factory=datetime.utcnow)