#!/usr/bin/env python3
"""IMMUTABLE_DECISION_LEDGER_V1 — spec/formulas/domains/governance.yaml.

Append-only decision log. Refuses to append a duplicate decision_id and never
mutates an existing record. governance/todo/v8_9_p2_adoption_plan.yaml P2-C.
"""
from __future__ import annotations

import argparse
import json
from datetime import datetime, timezone
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
DEFAULT_LEDGER = ROOT / "Temp" / "immutable_decision_ledger_v1.json"
DEFAULT_DECISION = ROOT / "Temp" / "portfolio_transition_optimizer_v1.json"

REQUIRED_FIELDS = [
    "decision_id",
    "engine_version",
    "input_hash_bundle",
    "execution_mode",
    "candidate_ids",
]


def _load_ledger(path: Path) -> dict:
    if not path.exists():
        return {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}
    try:
        data = json.loads(path.read_text(encoding="utf-8"))
        if isinstance(data, dict) and isinstance(data.get("records"), list):
            return data
        return {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}
    except Exception:
        return {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}


def append_decision(ledger: dict, decision: dict) -> tuple[dict, str]:
    missing = [f for f in REQUIRED_FIELDS if decision.get(f) is None]
    if missing:
        return ledger, "REJECTED_MISSING_FIELDS"

    decision_id = decision["decision_id"]
    existing_ids = {r["decision_id"] for r in ledger["records"]}
    if decision_id in existing_ids:
        return ledger, "DUPLICATE_DECISION_ID"

    record = {
        "decision_id": decision_id,
        "timestamp": decision.get("timestamp") or datetime.now(timezone.utc).isoformat(),
        "engine_version": decision["engine_version"],
        "input_hash_bundle": decision["input_hash_bundle"],
        "execution_mode": decision["execution_mode"],
        "candidate_ids": decision["candidate_ids"],
        "selected_transition_id": decision.get("selected_transition_id"),
        "hard_blocks": decision.get("hard_blocks", []),
        "transition_utility_krw": decision.get("transition_utility_krw"),
        "operator_override": decision.get("operator_override", False),
        "order_ids": decision.get("order_ids", []),
        "fill_prices": decision.get("fill_prices", []),
        "slippage": decision.get("slippage"),
        "T1_return": None,
        "T5_return": None,
        "T20_return": None,
        "MAE": None,
        "MFE": None,
    }
    new_ledger = {**ledger, "records": ledger["records"] + [record]}
    return new_ledger, "APPENDED"


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--ledger", default=str(DEFAULT_LEDGER))
    ap.add_argument("--decision", default=str(DEFAULT_DECISION))
    args = ap.parse_args()

    ledger = _load_ledger(Path(args.ledger))
    decision_doc = {}
    decision_path = Path(args.decision)
    if decision_path.exists():
        try:
            decision_doc = json.loads(decision_path.read_text(encoding="utf-8"))
        except Exception:
            decision_doc = {}

    decision = {
        "decision_id": decision_doc.get("packet_id") or decision_doc.get("formula_id"),
        "engine_version": "PORTFOLIO_TRANSITION_UTILITY_V1",
        "input_hash_bundle": decision_doc.get("input_hash") or "unknown",
        "execution_mode": decision_doc.get("execution_mode") or decision_doc.get("final_action"),
        "candidate_ids": [c.get("candidate_id") for c in decision_doc.get("candidate_actions", [])],
        "selected_transition_id": (decision_doc.get("selected_transition") or {}).get("candidate_id"),
        "hard_blocks": decision_doc.get("reason_codes", []),
        "transition_utility_krw": (decision_doc.get("selected_transition") or {}).get("transition_utility_krw"),
    }

    new_ledger, status = append_decision(ledger, decision)
    new_ledger["status"] = status
    out = Path(args.ledger)
    if status == "APPENDED":
        out.write_text(json.dumps(new_ledger, ensure_ascii=False, indent=2), encoding="utf-8")
    print(json.dumps({"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "ledger_append_status": status}, ensure_ascii=False, indent=2))
    return 0


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