"""Pydantic schemas for the Kevin strategy.

Used by KevinStrategy.evaluate_mention as input/output contracts and by
the live signal bridge + backtest engine to talk to the strategy.
"""

from __future__ import annotations

from decimal import Decimal
from enum import Enum

from pydantic import BaseModel, ConfigDict, Field, model_validator


class KevinDecisionType(str, Enum):
    OPEN_LONG = "open_long"  # new position or top-up
    CLOSE_LONG = "close_long"  # exit existing long
    NO_OP = "no_op"  # filter says skip


class KevinDecision(BaseModel):
    """A single trade decision emitted by KevinStrategy.evaluate_mention."""

    model_config = ConfigDict(frozen=True)

    decision: KevinDecisionType
    symbol: str = Field(min_length=1, max_length=16)
    target_dollars: Decimal | None = None  # required for OPEN_LONG
    holding_days: int | None = None  # required for OPEN_LONG
    effective_conviction: Decimal | None = None  # post-aggregation, 0-1
    rationale: str  # one-line audit string

    @model_validator(mode="after")
    def _open_long_requires_target_dollars(self) -> "KevinDecision":
        if self.decision == KevinDecisionType.OPEN_LONG:
            if self.target_dollars is None:
                raise ValueError("OPEN_LONG requires target_dollars")
            if self.holding_days is None:
                raise ValueError("OPEN_LONG requires holding_days")
            if self.target_dollars <= 0:
                raise ValueError("target_dollars must be positive")
        return self


class KevinAccountState(BaseModel):
    """Snapshot of the account passed to KevinStrategy.evaluate_mention.

    The bridge populates this from live Alpaca account + Redis counters; the
    backtest populates it from the simulated portfolio state. Same shape.
    """

    model_config = ConfigDict(frozen=True)

    equity_usd: Decimal
    cash_usd: Decimal
    held_positions: dict[str, Decimal]  # symbol -> cost-basis $
    blocklisted_symbols: frozenset[str] | set[str]
    daily_trade_count: int
    daily_alloc_usd: Decimal
    paused: bool

    def is_held(self, symbol: str) -> bool:
        return symbol in self.held_positions and self.held_positions[symbol] > 0

    def is_blocklisted(self, symbol: str) -> bool:
        return symbol in self.blocklisted_symbols