#!/usr/bin/env python3
"""TRANSITION_SET_ENUMERATOR_V1 — spec/formulas/domains/portfolio.yaml.

Evaluates combinations of already-vetoed candidates as a portfolio-level set,
so individually-passing candidates that jointly breach cash floor or
concentration caps are rejected. governance/todo/v8_9_p2_adoption_plan.yaml P2-B.
"""
from __future__ import annotations

import argparse
import itertools
import json
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
DEFAULT_TRANSITION_OPTIMIZER = ROOT / "Temp" / "portfolio_transition_optimizer_v1.json"
DEFAULT_OUT = ROOT / "Temp" / "transition_set_enumerator_v1.json"

COMPLEXITY_PENALTY_RATE_KRW = 5000.0


def _load(path: Path) -> dict:
    if not path.exists():
        return {}
    try:
        data = json.loads(path.read_text(encoding="utf-8"))
        return data if isinstance(data, dict) else {}
    except Exception:
        return {}


def post_trade_mrc(transition_set: tuple[dict, ...], portfolio_total_risk_budget: float) -> float | None:
    if not portfolio_total_risk_budget:
        return None
    total = sum(c.get("marginal_risk_contribution", 0.0) for c in transition_set)
    return total / portfolio_total_risk_budget


def post_trade_cvar95_krw(transition_set: tuple[dict, ...]) -> float | None:
    values = [c.get("cvar95_loss_krw") for c in transition_set]
    if any(v is None for v in values):
        return None
    return sum(values)


def set_hard_constraint_pass(
    transition_set: tuple[dict, ...],
    portfolio_total_risk_budget: float = 0.0,
    mrc_cap: float = 1.0,
    cvar95_budget_krw: float | None = None,
) -> bool:
    post_trade_cash_floor_pct = sum(c.get("post_trade_cash_floor_delta_pct", 0.0) for c in transition_set)
    post_trade_concentration_pct = sum(c.get("post_trade_concentration_delta_pct", 0.0) for c in transition_set)
    if post_trade_cash_floor_pct < 0 or post_trade_concentration_pct > 0:
        return False

    mrc = post_trade_mrc(transition_set, portfolio_total_risk_budget)
    if mrc is not None and mrc > mrc_cap:
        return False

    cvar95 = post_trade_cvar95_krw(transition_set)
    if cvar95 is not None and cvar95_budget_krw is not None and cvar95 < -abs(cvar95_budget_krw):
        return False

    return True


def set_transition_utility_krw(transition_set: tuple[dict, ...]) -> float:
    total = sum(c.get("transition_utility_krw") or 0.0 for c in transition_set)
    combination_penalty = COMPLEXITY_PENALTY_RATE_KRW * (len(transition_set) - 1)
    return total - combination_penalty


def enumerate_transition_sets(
    candidates: list[dict],
    max_set_size: int = 3,
    portfolio_total_risk_budget: float = 0.0,
    mrc_cap: float = 1.0,
    cvar95_budget_krw: float | None = None,
) -> list[dict]:
    passing = [c for c in candidates if c.get("hard_constraint_pass") is True]
    evaluated_sets = []
    for size in range(1, min(max_set_size, len(passing)) + 1):
        for combo in itertools.combinations(passing, size):
            evaluated_sets.append(
                {
                    "candidate_ids": [c.get("candidate_id") for c in combo],
                    "set_hard_constraint_pass": set_hard_constraint_pass(
                        combo, portfolio_total_risk_budget, mrc_cap, cvar95_budget_krw
                    ),
                    "set_transition_utility_krw": set_transition_utility_krw(combo),
                    "post_trade_mrc": post_trade_mrc(combo, portfolio_total_risk_budget),
                    "post_trade_cvar95_krw": post_trade_cvar95_krw(combo),
                }
            )
    return evaluated_sets


def select_best_set(evaluated_sets: list[dict]) -> dict | None:
    passing_sets = [s for s in evaluated_sets if s["set_hard_constraint_pass"]]
    if not passing_sets:
        return None
    return max(
        passing_sets,
        key=lambda s: (s["set_transition_utility_krw"], -len(s["candidate_ids"])),
    )


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--transition-optimizer", default=str(DEFAULT_TRANSITION_OPTIMIZER))
    ap.add_argument("--max-set-size", type=int, default=3)
    ap.add_argument("--out", default=str(DEFAULT_OUT))
    args = ap.parse_args()

    doc = _load(Path(args.transition_optimizer))
    candidates = doc.get("candidate_actions") if isinstance(doc.get("candidate_actions"), list) else []

    if not candidates:
        result = {
            "formula_id": "TRANSITION_SET_ENUMERATOR_V1",
            "gate": "NO_TRADE",
            "selected_transition_set": [],
            "rejected_sets_count": 0,
            "source_paths": [str(Path(args.transition_optimizer))],
        }
        out = Path(args.out)
        out.write_text(json.dumps(result, ensure_ascii=False, indent=2), encoding="utf-8")
        print(json.dumps(result, ensure_ascii=False, indent=2))
        return 0

    evaluated_sets = enumerate_transition_sets(candidates, args.max_set_size)
    best = select_best_set(evaluated_sets)
    rejected_count = len(evaluated_sets) - (1 if best else 0)

    result = {
        "formula_id": "TRANSITION_SET_ENUMERATOR_V1",
        "gate": "PASS" if best else "NO_TRADE",
        "selected_transition_set": best["candidate_ids"] if best else [],
        "set_transition_utility_krw": best["set_transition_utility_krw"] if best else None,
        "post_trade_mrc": best["post_trade_mrc"] if best else None,
        "post_trade_cvar95_krw": best["post_trade_cvar95_krw"] if best else None,
        "rejected_sets_count": rejected_count,
        "source_paths": [str(Path(args.transition_optimizer))],
    }
    out = Path(args.out)
    out.write_text(json.dumps(result, ensure_ascii=False, indent=2), encoding="utf-8")
    print(json.dumps(result, ensure_ascii=False, indent=2))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())