"""
参考玩法检索注入（RAG-lite）

目标：
- 用本地示例玩法库（.md 主真理 + _mGDL_v1.3.txt 辅语法翻译）为当前用户需求挑选少量最相关参考
- 避免把所有示例全量注入导致注意力稀释
"""

import os
import re
from typing import Dict, List, Optional, Tuple

from cache_manager import file_cache


_MGDL_SUFFIX_RE = re.compile(r"^(?P<name>.+?)_mGDL_v1\.3\.txt$")
_CJK_RUN_RE = re.compile(r"[\u4e00-\u9fff]+")

# 非严格停用词：用于降低“通用词”对关键词召回的干扰（可按需要继续补充）
_STOP_TERMS = {
    "麻将", "玩法", "规则", "玩家", "游戏", "进行", "阶段", "流程", "说明", "机制",
    "可以", "允许", "是否", "如果", "那么", "以及", "但是", "因为", "所以", "同时",
    "庄家", "闲家", "手牌", "摸牌", "打牌", "出牌", "胡牌", "自摸", "点炮", "一炮",
    "结算", "得分", "倍数", "番型", "番数", "牌墙", "弃牌", "顺序", "回合", "开始", "结束",
    "默认", "配置", "支持", "包含", "采用", "需要", "必须", "不得",
    # 更偏“功能词/口水词”的补充（避免成为锚点）
    "一个", "做一", "做个", "加入", "增加", "带有", "希望", "想要", "想做", "更快", "更刺激",
}

# 锚点词的“领域提示字”：让锚点更偏向机制/规则名词，而不是偶然出现的通用短语
# 说明：这是启发式，但比“硬编码某个玩法/某个术语”更普适。
_ANCHOR_HINT_CHARS = set("鸟马赖鬼杠胡听鸡豆缺换海捞承包庄风中发白炮分番倍封顶")


def _cjk_ngrams(text: str, min_n: int = 2, max_n: int = 4) -> List[str]:
    """
    从文本中提取 CJK n-gram（用于关键词召回；无外部依赖，适合小规模本地样例库）。
    """
    s = (text or "").strip()
    if not s:
        return []

    grams = []
    for run in _CJK_RUN_RE.findall(s):
        if not run:
            continue
        # 对超长段落，限制采样长度，避免构造过多 n-gram
        run = run[:2000]
        L = len(run)
        for i in range(L):
            for n in range(min_n, max_n + 1):
                j = i + n
                if j > L:
                    continue
                g = run[i:j]
                if g in _STOP_TERMS:
                    continue
                grams.append(g)

    # 去重保持顺序（小规模即可）
    seen = set()
    uniq = []
    for g in grams:
        if g not in seen:
            seen.add(g)
            uniq.append(g)
    return uniq


def _base_dir() -> str:
    return os.path.dirname(__file__)


def _read_text(path: str) -> str:
    cached = file_cache.get(path)
    if cached is not None:
        return cached
    try:
        with open(path, "r", encoding="utf-8", errors="ignore") as f:
            txt = f.read()
        file_cache.set(path, txt)
        return txt
    except Exception:
        return ""


def _build_variant_index() -> Dict[str, Dict[str, str]]:
    """
    返回：
      {
        "疯狂血战": {"md": "...", "mgdl": "..."},
        ...
      }
    """
    base = _base_dir()
    index: Dict[str, Dict[str, str]] = {}

    try:
        for filename in os.listdir(base):
            if filename.endswith(".md") and filename != "README.md":
                name = filename[:-3]
                index.setdefault(name, {})["md_path"] = os.path.join(base, filename)
            elif filename.endswith("_mGDL_v1.3.txt"):
                m = _MGDL_SUFFIX_RE.match(filename)
                if not m:
                    continue
                name = m.group("name")
                index.setdefault(name, {})["mgdl_path"] = os.path.join(base, filename)
    except Exception:
        return {}

    # 只保留至少有 md 或 mgdl 的条目
    cleaned: Dict[str, Dict[str, str]] = {}
    for name, entry in index.items():
        md_path = entry.get("md_path")
        mgdl_path = entry.get("mgdl_path")
        if not md_path and not mgdl_path:
            continue
        cleaned[name] = {}
        if md_path:
            cleaned[name]["md_path"] = md_path
        if mgdl_path:
            cleaned[name]["mgdl_path"] = mgdl_path
    return cleaned


def list_variant_names() -> List[str]:
    """
    返回本地玩法库中可用的玩法名列表（含“麻将机制说明”）。
    """
    index = _build_variant_index()
    names = sorted(index.keys(), key=lambda x: len(x), reverse=True)
    return names


def match_variants_in_text(text: str) -> List[str]:
    """
    从用户文本中匹配玩法名（优先更长的名称）。
    """
    candidates = list_variant_names()
    return _find_mentions(text, candidates)


def load_variant_md(name: str) -> str:
    """
    读取指定玩法的 .md 内容（若不存在则返回空字符串）。
    """
    index = _build_variant_index()
    entry = index.get(name) or {}
    md_path = entry.get("md_path")
    if not md_path or not os.path.exists(md_path):
        return ""
    return _read_text(md_path) or ""


def _find_mentions(text: str, candidates: List[str]) -> List[str]:
    """
    朴素子串匹配（中文玩法名通常稳定），返回按“更长优先”的去重命中列表。
    """
    s = (text or "").strip()
    if not s:
        return []

    hits: List[str] = []
    # 长词优先，避免“血战”误命中“疯狂血战”
    for name in sorted(candidates, key=lambda x: len(x), reverse=True):
        if name and name in s:
            hits.append(name)

    # 去重保持顺序
    seen = set()
    uniq: List[str] = []
    for h in hits:
        if h not in seen:
            seen.add(h)
            uniq.append(h)
    return uniq


_TERM_CACHE: Optional[Dict[str, set]] = None
_TERM_DF: Optional[Dict[str, int]] = None
_TERM_POSTINGS: Optional[Dict[str, List[str]]] = None
_DOMAIN_TERMS: Optional[set] = None


def _build_domain_terms() -> set:
    """
    构建“领域词表”用于过滤用户 n-gram（降低把通用词当成锚点的概率）。

    策略：
    - 不引入外部依赖（如 jieba）
    - 直接从“所有玩法 .md 的关键词集合并集”构建 domain_terms（足够泛化）
    """
    global _DOMAIN_TERMS
    if _DOMAIN_TERMS is not None:
        return _DOMAIN_TERMS

    index = _build_variant_index()
    domain = set()
    for name, entry in index.items():
        if name == "麻将机制说明":
            continue
        md_path = entry.get("md_path")
        if not md_path or not os.path.exists(md_path):
            continue
        md_txt = _read_text(md_path)
        if not md_txt.strip():
            continue
        domain.update(_cjk_ngrams(md_txt, min_n=2, max_n=4))

    _DOMAIN_TERMS = domain
    return domain


def _build_variant_term_cache() -> Dict[str, set]:
    """
    为每个玩法构建关键词特征（来自 .md，必要时可扩展到 mgdl）。
    返回：{variant_name: {term1, term2, ...}}
    """
    global _TERM_CACHE, _TERM_DF, _TERM_POSTINGS
    if _TERM_CACHE is not None and _TERM_DF is not None:
        return _TERM_CACHE

    index = _build_variant_index()
    cache: Dict[str, set] = {}
    for name, entry in index.items():
        # 机制词典单独注入，不把它当“参考玩法”候选
        if name == "麻将机制说明":
            continue
        md_path = entry.get("md_path")
        if not md_path or not os.path.exists(md_path):
            continue

        md_txt = _read_text(md_path)
        if not md_txt.strip():
            continue

        # 只从 md 抽关键词：它是“内容真理”，且比 mGDL 更接近用户描述的术语
        cache[name] = set(_cjk_ngrams(md_txt, min_n=2, max_n=4))

    # 计算 df（每个 term 在多少个玩法中出现），用于稀有词加权（IDF-lite）
    df: Dict[str, int] = {}
    postings: Dict[str, List[str]] = {}
    for _, terms in cache.items():
        for t in terms:
            df[t] = df.get(t, 0) + 1
    for variant, terms in cache.items():
        for t in terms:
            postings.setdefault(t, []).append(variant)

    _TERM_CACHE = cache
    _TERM_DF = df
    _TERM_POSTINGS = postings
    return cache


def _score_by_terms(message: str, term_cache: Dict[str, set]) -> List[Tuple[str, int]]:
    """
    基于关键词重叠给玩法打分（分数越高越相关）。
    """
    global _TERM_DF
    domain = _build_domain_terms()
    user_terms = set(_cjk_ngrams(message, min_n=2, max_n=4))
    # 仅保留“在领域词表中出现过”的词（否则很多通用 n-gram 会干扰）
    user_terms = {t for t in user_terms if t in domain}
    if not user_terms:
        return []

    scored: List[Tuple[str, int]] = []
    for variant, terms in term_cache.items():
        if not terms:
            continue
        inter = user_terms.intersection(terms)
        if not inter:
            continue
        # 稀有词（df低）更有区分度：用 IDF-lite 加权，避免“通用词重叠”淹没关键术语（如“扎鸟”）
        score = 0
        for t in inter:
            df = (_TERM_DF or {}).get(t, 9999)
            # df=1 → 权重最高；df越大权重越低
            score += int((len(t) * 100) / max(1, df))
        scored.append((variant, score))

    scored.sort(key=lambda x: x[1], reverse=True)
    return scored


def _pick_anchor_terms(message: str, max_terms: int = 3) -> List[str]:
    """
    从用户输入中挑选“高区分度锚点词”（通用、可解释、无需硬编码具体玩法/术语）。

    规则：
    - 仅使用领域词表命中的词
    - 优先 df 小（更稀有）+ 词更长（更具体）
    """
    global _TERM_DF, _TERM_POSTINGS
    _build_variant_term_cache()
    domain = _build_domain_terms()
    terms = set(_cjk_ngrams(message, min_n=2, max_n=4))
    terms = {t for t in terms if t in domain and t not in _STOP_TERMS}
    if not terms:
        return []

    def _is_informative_anchor(term: str) -> bool:
        if not term or term in _STOP_TERMS:
            return False
        return any(ch in _ANCHOR_HINT_CHARS for ch in term)

    ranked = []
    for t in terms:
        df = (_TERM_DF or {}).get(t)
        if not df:
            continue
        # df=1 最佳；长度越长越好
        if not _is_informative_anchor(t):
            continue
        ranked.append((t, df, len(t)))
    ranked.sort(key=lambda x: (x[1], -x[2], x[0]))  # df asc, len desc
    return [t for t, _, _ in ranked[: max(1, max_terms)]]


def pick_reference_variants(
    message: str,
    max_variants: int = 3,
    fallback: Optional[List[str]] = None,
) -> List[str]:
    """
    依据用户输入挑选参考玩法名（仅返回玩法名，不读文件）。
    """
    index = _build_variant_index()
    names = list(index.keys())

    mentions = _find_mentions(message, names)
    if mentions:
        return mentions[: max(1, max_variants)]

    # 用户未显式说玩法名：走关键词召回（例如提到“扎鸟/买马/承包”等术语）
    term_cache = _build_variant_term_cache()
    scored = _score_by_terms(message, term_cache)
    anchor_terms = _pick_anchor_terms(message, max_terms=3)
    postings = _TERM_POSTINGS or {}

    # 将“锚点命中”作为加权 boost，而不是简单强制放前面截断
    base_scores = {name: score for name, score in scored}
    boost_scores: Dict[str, int] = {}
    for t in anchor_terms:
        df = (_TERM_DF or {}).get(t, 9999)
        w = int((len(t) * 100) / max(1, df))
        for v in postings.get(t, []):
            boost_scores[v] = boost_scores.get(v, 0) + w

    if scored or boost_scores:
        candidates = set(base_scores.keys()) | set(boost_scores.keys())
        ranked = []
        for v in candidates:
            base = base_scores.get(v, 0)
            boost = boost_scores.get(v, 0)
            ranked.append((v, base + boost))
        ranked.sort(key=lambda x: x[1], reverse=True)
        return [v for v, _ in ranked[: max(1, max_variants)]]

    if fallback:
        return fallback[: max(1, max_variants)]

    # 默认兜底：覆盖不同体系，给模型“底座参考面”
    default_pool = [
        "疯狂血战",
        "疯狂血流",
        "广东100张",
        "贵州捉鸡麻将",
        "妙手七星",
    ]
    return [n for n in default_pool if n in names][: max(1, max_variants)]


def build_reference_pack(
    message: str,
    max_variants: int = 3,
    include_mechanism_library: bool = True,
    include_mgdl: bool = False,
) -> Dict[str, str]:
    """
    返回可注入到 system message 的多段文本。
    """
    index = _build_variant_index()
    picked = pick_reference_variants(message, max_variants=max_variants)

    parts: Dict[str, str] = {}

    if include_mechanism_library:
        mech_path = os.path.join(_base_dir(), "麻将机制说明.md")
        if os.path.exists(mech_path):
            mech_txt = _read_text(mech_path).strip()
            if mech_txt:
                parts["mechanism_library"] = mech_txt

    md_chunks: List[str] = []
    mgdl_chunks: List[str] = []
    for name in picked:
        entry = index.get(name) or {}
        md_path = entry.get("md_path")
        mgdl_path = entry.get("mgdl_path")

        if md_path and os.path.exists(md_path):
            txt = _read_text(md_path).strip()
            if txt:
                md_chunks.append("\n# FILE: {0}\n{1}\n".format(os.path.basename(md_path), txt))

        if include_mgdl and mgdl_path and os.path.exists(mgdl_path):
            txt = _read_text(mgdl_path).strip()
            if txt:
                mgdl_chunks.append("\n# FILE: {0}\n{1}\n".format(os.path.basename(mgdl_path), txt))

    if md_chunks:
        parts["reference_md"] = "\n".join(md_chunks).strip()
    if mgdl_chunks:
        parts["reference_mgdl"] = "\n".join(mgdl_chunks).strip()

    # 透传“本轮选了哪些参考”，便于模型更聚焦
    parts["picked_names"] = ", ".join(picked)
    return parts