"""周易六爻起卦算法。

每爻由三枚铜钱决定:
  正面 (字, face=3) — 两正一反为多,视为阳
  反面 (背, face=2) — 两反一正为多,视为阴
  三枚之和:  6(老阴·三背·动) | 7(少阴·两背一字) | 8(少阳·两字一背) | 9(老阳·三字·动)

爻的阴阳:
  8(少阳), 9(老阳) → 阳爻
  6(老阴), 7(少阴) → 阴爻

动爻 (变爻):
  6(老阴) → 变阳,  9(老阳) → 变阴
"""
from __future__ import annotations

import random
from typing import List, Tuple

from .constants import HEXAGRAMS


# ---------------------------------------------------------------------------
# 基础枚举
# ---------------------------------------------------------------------------
LAO_YIN = 6    # 老阴 ━ ━ 动 (三背, 全反面)
SHAO_YANG = 8  # 少阳 ━━━ (两正一反 = 二字一背 = face3+face3+face2)
SHAO_YIN = 7   # 少阴 ━ ━ (两反一正 = 二背一字 = face2+face2+face3)
LAO_YANG = 9   # 老阳 ━━━ 动 (三字, 全正面)

YANG_LINES = (SHAO_YANG, LAO_YANG)
YIN_LINES = (LAO_YIN, SHAO_YIN)
MOVING_LINES = (LAO_YIN, LAO_YANG)


def cast_one_line() -> Tuple[int, Tuple[int, int, int]]:
    """起一爻: 随机三枚铜钱,返回 (爻值, (c1, c2, c3))。

    钱币值: 字=2, 背=3
    """
    coins = (random.randint(2, 3), random.randint(2, 3), random.randint(2, 3))
    return sum(coins), coins


def cast_six_lines(seed: int | None = None) -> List[int]:
    """连起六爻,自下而上(返回顺序即 [初爻, 二爻, ..., 上爻])。"""
    rng = random.Random(seed)
    out: List[int] = []
    for _ in range(6):
        coins = (rng.randint(2, 3), rng.randint(2, 3), rng.randint(2, 3))
        out.append(sum(coins))
    return out


def is_yang(line: int) -> bool:
    return line in YANG_LINES


def is_moving(line: int) -> bool:
    return line in MOVING_LINES


# ---------------------------------------------------------------------------
# 卦象查表
# ---------------------------------------------------------------------------
def _to_key(lines: List[int]) -> str:
    """六爻 (自下而上) → '111000' 形式的二进制 key (1=阳 0=阴)。"""
    return "".join("1" if is_yang(v) else "0" for v in lines)


def lines_to_hex(lines: List[int]) -> dict:
    """根据六爻查主卦信息。"""
    key = _to_key(lines)
    return HEXAGRAMS[key]


def get_changed_hex(lines: List[int]) -> dict | None:
    """动爻变卦: 老阳 9→阴, 老阴 6→阳; 无动爻返回 None。"""
    has_moving = any(is_moving(v) for v in lines)
    if not has_moving:
        return None
    new_lines = [
        (SHAO_YANG if v == LAO_YIN else SHAO_YIN if v == LAO_YANG else v)
        for v in lines
    ]
    return lines_to_hex(new_lines)


def moving_indices(lines: List[int]) -> List[int]:
    """返回动爻位置 (1-indexed, 自下而上)。"""
    return [i + 1 for i, v in enumerate(lines) if is_moving(v)]


# ---------------------------------------------------------------------------
# 爻画 (前端直接渲染的字符串)
# ---------------------------------------------------------------------------
def line_glyph(line: int) -> dict:
    """返回单爻的可视化信息。"""
    yang = is_yang(line)
    moving = is_moving(line)
    return {
        "value": line,
        "yang": yang,
        "moving": moving,
        "mark": "○" if line == LAO_YANG else "×" if line == LAO_YIN else "",
        "label": (
            "老阳动爻" if line == LAO_YANG
            else "老阴动爻" if line == LAO_YIN
            else "少阳" if line == SHAO_YANG
            else "少阴"
        ),
    }


def all_lines_glyph(lines: List[int]) -> List[dict]:
    """自下而上,前端按数组顺序自上而下渲染。"""
    return [line_glyph(v) for v in lines]


# ---------------------------------------------------------------------------
# 凶吉 (7 档详细等级 → 收束为 3 档大分类)
# ---------------------------------------------------------------------------
LEVEL_TO_CATEGORY = {
    "大吉":     "吉",
    "吉":       "吉",
    "中平偏吉": "吉",
    "中平":     "平",
    "中平偏凶": "凶",
    "凶":       "凶",
    "大凶":     "凶",
}


def hex_auspicious_level(hex_info: dict) -> str:
    """从卦名反查 7 档吉凶等级(来自 constants.HEX_LEVELS)。

    找不到时,按卦象初判给一个 3 档粗结果再退回 `中平`。
    """
    from .constants import HEX_LEVELS
    name = hex_info["name"]
    info = HEX_LEVELS.get(name)
    if info:
        return info["level"]
    # 兜底:用经典 3 档集合粗分
    return LEVEL_TO_CATEGORY.get(hex_auspicious(hex_info), "中平")


def hex_auspicious(hex_info: dict) -> str:
    """根据卦名给出一个粗略的吉凶倾向(3 档:吉/平/凶)。"""
    name = hex_info["name"]
    bad = {"讼", "否", "剥", "坎", "困", "明夷", "蹇", "小过", "大过", "夬"}
    good = {"乾", "泰", "谦", "大有", "随", "晋", "复", "临", "升", "家人",
            "益", "鼎", "震", "渐", "中孚", "既济", "需", "同人"}
    if name in bad:
        return "凶"
    if name in good:
        return "吉"
    return "平"