from __future__ import annotations

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


@dataclass(frozen=True)
class SignalNode:
    asset: str
    venue: str
    signal_type: str
    timestamp: int
    quality: float = 1.0
    id: Optional[str] = None

    def __post_init__(self):
        if self.timestamp < 0:
            raise ValueError("timestamp must be non-negative")


@dataclass(frozen=True)
class Edge:
    from_node: SignalNode
    to_node: SignalNode
    relation: str  # e.g., "causal", "derived_from", etc.
    delta_hash: str


@dataclass
class Scenario:
    id: str
    nodes: List[SignalNode] = field(default_factory=list)
    edges: List[Edge] = field(default_factory=list)
    description: str = ""


@dataclass
class HedgePlan:
    id: str
    delta: dict
    version: int = 1
    approvals: List[str] = field(default_factory=list)


@dataclass
class AuditLog:
    entries: List[str] = field(default_factory=list)
    signer: str | None = None
    timestamp: int | None = None
    contract_id: str | None = None
    # Optional provenance fields for verifiable provenance and chaining
    parent_hash: str | None = None
    signature: str | None = None


@dataclass
class PrivacyBudget:
    per_signal_budget: dict[str, float] = field(default_factory=dict)
    global_budget: float = 0.0