"""资金占用成本（borrow cost）归因测试（spec §195）。

每策略占用资金按无风险利率日扣，归因到 per_strategy_pnl；不影响账户总账净值。
"""
import json
from types import SimpleNamespace

import pytest

from sanguo_trader.account import Account
from sanguo_trader.cta_adapter import PaperCtaEngine
from sanguo_trader.engine import PaperEngine
from sanguo_trader.models import AccountConfig, MatchSession
from sanguo_trader.persistence import init_db, list_daily_balance, save_account
from sanguo_trader.position_ledger import PositionLedger
from sanguo_trader.strategy_runner import StrategyRunner


def _bar(date, o, h, l, c):
    return SimpleNamespace(open_price=o, high_price=h, low_price=l,
                           close_price=c, datetime=date)


class _FakeDataSource:
    def __init__(self, sections):
        self.sections = sections

    def iter_bars(self, symbols, start, end, interval, adjust="qfq", cfg=None):
        del symbols, start, end, interval, adjust, cfg
        for date, bars in self.sections:
            yield date, bars


class _NoOrderStrategy:
    """空策略：on_bar 不下单（仅驱动 step 走完盯市/归因路径）。"""

    def __init__(self, engine, vt_symbol):
        self.cta_engine = engine
        self.vt_symbol = vt_symbol

    def on_bar(self, bar):
        pass


def _make_position(symbol, volume, avg_price):
    pos = PositionLedger(symbol)
    pos.volume = volume
    pos.avg_price = avg_price
    return pos


def test_daily_borrow_cost_calculation():
    # Arrange：200 股 @10 → 占用 2000，rate=0.02 → 日成本 2000*0.02/365
    runner = StrategyRunner("s1", symbol="600000")
    runner.positions["600000"] = _make_position("600000", 200, 10.0)
    closes = {"600000": 10.0}

    # Act
    cost = runner.daily_borrow_cost(closes, risk_free_rate=0.02)

    # Assert
    assert cost == pytest.approx(2000 * 0.02 / 365)


def test_holding_cost_greater_than_empty():
    # Arrange：持仓 runner vs 空仓 runner
    runner_holding = StrategyRunner("s1", symbol="600000")
    runner_holding.positions["600000"] = _make_position("600000", 200, 10.0)
    runner_empty = StrategyRunner("s2", symbol="600000")
    closes = {"600000": 10.0}

    # Act
    cost_holding = runner_holding.daily_borrow_cost(closes, 0.02)
    cost_empty = runner_empty.daily_borrow_cost(closes, 0.02)

    # Assert
    assert cost_empty == 0.0
    assert cost_holding > 0
    assert cost_holding > cost_empty


def test_borrow_cost_attributed_not_affecting_account(tmp_path):
    # Arrange：预置持仓 200 股 @10（占用 2000），空策略不下单，rate=0.03
    db = str(tmp_path / "borrow.db")
    init_db(db)
    aid = save_account(db, {"name": "t", "initial_capital": 1_000_000})
    cfg = AccountConfig(initial_capital=1_000_000)
    account = Account(1_000_000)
    account.cash = 998000              # 已花 2000 买入
    account.positions["600000"] = _make_position("600000", 200, 10.0)
    cta = PaperCtaEngine("s1", match_session=MatchSession.CURRENT_CLOSE)
    strat = _NoOrderStrategy(cta, "600000.SSE")
    cta.set_strategy(strat)
    runner = StrategyRunner("s1", strategy=strat, paper_cta_engine=cta,
                            symbol="600000")
    runner.positions["600000"] = _make_position("600000", 200, 10.0)
    sections = [("2024-01-01", {"600000": _bar("2024-01-01", 10.0, 10.5, 9.5, 10.0)})]
    pe = PaperEngine(account, [runner], _FakeDataSource(sections), cfg, db, aid,
                     symbols=["600000"], start="2024-01-01", end="2024-01-31",
                     risk_free_rate=0.03)
    cash_before = account.cash

    # Act
    pe.run()

    # Assert：账户总账不受占用成本影响（仅归因记账）
    assert account.cash == cash_before
    balances = list_daily_balance(db, aid)
    assert len(balances) == 1
    psp = json.loads(balances[0]["per_strategy_pnl"])
    assert "s1" in psp
    assert psp["s1"]["borrow_cost"] == pytest.approx(2000 * 0.03 / 365)