"""
三所共用：账户级方向 / 币种白名单（.env 开关，默认关闭=不限制）。
"""
from __future__ import annotations

import os
from dataclasses import dataclass
from typing import Callable, FrozenSet, Optional, Sequence, Tuple

DIR_BOTH = "both"
DIR_LONG_ONLY = "long_only"
DIR_SHORT_ONLY = "short_only"
VALID_DIRECTION_MODES = frozenset({DIR_BOTH, DIR_LONG_ONLY, DIR_SHORT_ONLY})

_DIR_ALIASES = {
    "both": DIR_BOTH,
    "双向": DIR_BOTH,
    "long": DIR_LONG_ONLY,
    "long_only": DIR_LONG_ONLY,
    "多": DIR_LONG_ONLY,
    "仅多": DIR_LONG_ONLY,
    "做多": DIR_LONG_ONLY,
    "short": DIR_SHORT_ONLY,
    "short_only": DIR_SHORT_ONLY,
    "空": DIR_SHORT_ONLY,
    "仅空": DIR_SHORT_ONLY,
    "做空": DIR_SHORT_ONLY,
}


def _env_bool(raw: Optional[str], default: bool = False) -> bool:
    if raw is None:
        return default
    return (raw or "").strip().lower() in ("1", "true", "yes", "on")


def normalize_direction_mode(raw: Optional[str]) -> str:
    v = (raw or DIR_BOTH).strip().lower()
    return _DIR_ALIASES.get(v, v if v in VALID_DIRECTION_MODES else DIR_BOTH)


def symbol_base_coin(symbol: str) -> str:
    """BTC/USDT:USDT、BTC/USDT、BTC、btc -> BTC"""
    s = (symbol or "").strip().upper()
    if not s:
        return ""
    if ":" in s:
        s = s.split(":", 1)[0]
    if "/" in s:
        return s.split("/", 1)[0].strip()
    if s.endswith("USDT") and len(s) > 4:
        return s[:-4]
    return s


def parse_symbol_whitelist(raw: Optional[str]) -> Tuple[str, ...]:
    if not raw or not str(raw).strip():
        return ()
    parts = []
    for piece in str(raw).replace(";", ",").split(","):
        base = symbol_base_coin(piece.strip())
        if base and base not in parts:
            parts.append(base)
    return tuple(parts)


@dataclass(frozen=True)
class TradePolicy:
    direction_restrict_enabled: bool
    direction_mode: str
    symbol_restrict_enabled: bool
    symbol_whitelist: Tuple[str, ...]

    @property
    def allows_long(self) -> bool:
        if not self.direction_restrict_enabled:
            return True
        return self.direction_mode in (DIR_BOTH, DIR_LONG_ONLY)

    @property
    def allows_short(self) -> bool:
        if not self.direction_restrict_enabled:
            return True
        return self.direction_mode in (DIR_BOTH, DIR_SHORT_ONLY)


def load_trade_policy(env: Optional[dict] = None) -> TradePolicy:
    e = env if env is not None else os.environ
    direction_restrict = _env_bool(e.get("TRADE_DIRECTION_RESTRICT_ENABLED"), False)
    symbol_restrict = _env_bool(e.get("TRADE_SYMBOL_RESTRICT_ENABLED"), False)
    direction_mode = normalize_direction_mode(e.get("TRADE_DIRECTION"))
    whitelist = parse_symbol_whitelist(e.get("TRADE_SYMBOL_WHITELIST"))
    if symbol_restrict and not whitelist:
        symbol_restrict = False
    return TradePolicy(
        direction_restrict_enabled=direction_restrict,
        direction_mode=direction_mode,
        symbol_restrict_enabled=symbol_restrict,
        symbol_whitelist=whitelist,
    )


def direction_mode_label_zh(mode: str) -> str:
    m = normalize_direction_mode(mode)
    if m == DIR_LONG_ONLY:
        return "仅多"
    if m == DIR_SHORT_ONLY:
        return "仅空"
    return "双向"


def trade_policy_badge_parts(policy: TradePolicy) -> Tuple[str, ...]:
    parts: list[str] = []
    if policy.direction_restrict_enabled:
        if policy.direction_mode == DIR_LONG_ONLY:
            parts.append("仅多")
        elif policy.direction_mode == DIR_SHORT_ONLY:
            parts.append("仅空")
    if policy.symbol_restrict_enabled and policy.symbol_whitelist:
        parts.append("/".join(policy.symbol_whitelist))
    return tuple(parts)


def trade_policy_to_dict(policy: TradePolicy) -> dict:
    badges = trade_policy_badge_parts(policy)
    return {
        "direction_restrict_enabled": policy.direction_restrict_enabled,
        "direction_mode": policy.direction_mode,
        "direction_label_zh": (
            direction_mode_label_zh(policy.direction_mode)
            if policy.direction_restrict_enabled
            else "双向"
        ),
        "allows_long": policy.allows_long,
        "allows_short": policy.allows_short,
        "symbol_restrict_enabled": policy.symbol_restrict_enabled,
        "symbol_whitelist": list(policy.symbol_whitelist),
        "badge_parts": list(badges),
        "badge_text": " · ".join(badges),
    }


def normalize_open_direction(policy: TradePolicy, direction: str) -> str:
    d = (direction or "long").strip().lower()
    if d not in ("long", "short"):
        d = "long"
    if policy.direction_restrict_enabled:
        if policy.direction_mode == DIR_LONG_ONLY:
            return "long"
        if policy.direction_mode == DIR_SHORT_ONLY:
            return "short"
    return d


def assert_direction_allowed(policy: TradePolicy, direction: str) -> Tuple[bool, str]:
    d = (direction or "").strip().lower()
    if d not in ("long", "short"):
        if d in ("watch", ""):
            return True, ""
        return False, "方向无效，请选择做多或做空"
    if d == "long" and not policy.allows_long:
        return False, "当前账户配置为仅做空，不允许做多"
    if d == "short" and not policy.allows_short:
        return False, "当前账户配置为仅做多，不允许做空"
    return True, ""


def assert_symbol_allowed(
    policy: TradePolicy,
    symbol: str,
    *,
    normalize_symbol_fn: Optional[Callable[[str], str]] = None,
) -> Tuple[bool, str]:
    if not policy.symbol_restrict_enabled:
        return True, ""
    sym = (symbol or "").strip()
    if not sym:
        return False, "请选择币种"
    if normalize_symbol_fn is not None:
        sym_norm = (normalize_symbol_fn(sym) or "").strip()
    else:
        sym_norm = sym
    base = symbol_base_coin(sym_norm or sym)
    allowed: FrozenSet[str] = frozenset(policy.symbol_whitelist)
    if base not in allowed:
        allowed_txt = "、".join(policy.symbol_whitelist)
        return False, f"当前账户仅允许 {allowed_txt}，不允许 {base or sym}"
    return True, ""


def assert_trade_policy_open(
    policy: TradePolicy,
    symbol: str,
    direction: str,
    normalize_symbol_fn: Optional[Callable[[str], str]] = None,
) -> Tuple[bool, str]:
    ok_sym, msg_sym = assert_symbol_allowed(
        policy, symbol, normalize_symbol_fn=normalize_symbol_fn
    )
    if not ok_sym:
        return False, msg_sym
    ok_dir, msg_dir = assert_direction_allowed(policy, direction)
    if not ok_dir:
        return False, msg_dir
    return True, ""