"""
重排客户端：调用外部 BGE 重排服务，并对 ES 分数与重排分数进行融合。

流程：
1. 从 ES hits 构造用于重排的文档文本列表
2. POST 请求到重排服务 /rerank，获取每条文档的 relevance 分数
3. 提取 ES 文本/向量子句分数，与重排分数做乘法融合并重排序
"""

from typing import Dict, Any, List, Optional, Tuple
import logging

from providers import create_rerank_provider

logger = logging.getLogger(__name__)

# 历史配置项，保留签名兼容；当前乘法融合公式不再使用线性权重。
DEFAULT_WEIGHT_ES = 0.4
DEFAULT_WEIGHT_AI = 0.6
# 重排服务默认超时（文档较多时需更大，建议 config 中 timeout_sec 调大）
DEFAULT_TIMEOUT_SEC = 15.0


def build_docs_from_hits(
    es_hits: List[Dict[str, Any]],
    language: str = "zh",
    doc_template: str = "{title}",
) -> List[str]:
    """
    从 ES 命中结果构造重排服务所需的文档文本列表（与 hits 一一对应）。

    使用 doc_template 将文档字段组装为重排服务输入。
    支持占位符：{title} {brief} {vendor} {description} {category_path}

    Args:
        es_hits: ES 返回的 hits 列表，每项含 _source
        language: 语言代码，如 "zh"、"en"

    Returns:
        与 es_hits 等长的字符串列表，用于 POST /rerank 的 docs
    """
    lang = (language or "zh").strip().lower()
    if lang not in ("zh", "en"):
        lang = "zh"

    def pick_lang_text(obj: Any) -> str:
        if obj is None:
            return ""
        if isinstance(obj, dict):
            return str(obj.get(lang) or obj.get("zh") or obj.get("en") or "").strip()
        return str(obj).strip()

    class _SafeDict(dict):
        def __missing__(self, key: str) -> str:
            return ""

    docs: List[str] = []
    only_title = "{title}" == doc_template
    need_brief = "{brief}" in doc_template
    need_vendor = "{vendor}" in doc_template
    need_description = "{description}" in doc_template
    need_category_path = "{category_path}" in doc_template
    for hit in es_hits:
        src = hit.get("_source") or {}
        title_suffix = str(hit.get("_style_rerank_suffix") or "").strip()
        if only_title:
            title = pick_lang_text(src.get("title"))
            if title_suffix:
                title = f"{title} {title_suffix}".strip()
            docs.append(title)
        else:
            values = _SafeDict(
                title=(
                    f"{pick_lang_text(src.get('title'))} {title_suffix}".strip()
                    if title_suffix
                    else pick_lang_text(src.get("title"))
                ),
                brief=pick_lang_text(src.get("brief")) if need_brief else "",
                vendor=pick_lang_text(src.get("vendor")) if need_vendor else "",
                description=pick_lang_text(src.get("description")) if need_description else "",
                category_path=pick_lang_text(src.get("category_path")) if need_category_path else "",
            )
            docs.append(str(doc_template).format_map(values))
    return docs


def call_rerank_service(
    query: str,
    docs: List[str],
    timeout_sec: float = DEFAULT_TIMEOUT_SEC,
    top_n: Optional[int] = None,
) -> Tuple[Optional[List[float]], Optional[Dict[str, Any]]]:
    """
    调用重排服务 POST /rerank，返回分数列表与 meta。
    Provider 和 URL 从 services_config 读取。
    """
    if not docs:
        return [], {}
    try:
        client = create_rerank_provider()
        return client.rerank(query=query, docs=docs, timeout_sec=timeout_sec, top_n=top_n)
    except Exception as e:
        logger.warning("Rerank request failed: %s", e, exc_info=True)
        return None, None


def _to_score(value: Any) -> float:
    try:
        if value is None:
            return 0.0
        return float(value)
    except (TypeError, ValueError):
        return 0.0


def _extract_named_query_score(matched_queries: Any, name: str) -> float:
    if isinstance(matched_queries, dict):
        return _to_score(matched_queries.get(name))
    if isinstance(matched_queries, list):
        return 1.0 if name in matched_queries else 0.0
    return 0.0


def _collect_text_score_components(matched_queries: Any, fallback_es_score: float) -> Dict[str, float]:
    source_score = _extract_named_query_score(matched_queries, "base_query")
    translation_score = 0.0

    if isinstance(matched_queries, dict):
        for query_name, score in matched_queries.items():
            if not isinstance(query_name, str):
                continue
            numeric_score = _to_score(score)
            if query_name.startswith("base_query_trans_"):
                translation_score = max(translation_score, numeric_score)
    elif isinstance(matched_queries, list):
        for query_name in matched_queries:
            if not isinstance(query_name, str):
                continue
            if query_name.startswith("base_query_trans_"):
                translation_score = 1.0

    weighted_source = source_score
    weighted_translation = 0.8 * translation_score
    weighted_components = [weighted_source, weighted_translation]
    primary_text_score = max(weighted_components)
    support_text_score = sum(weighted_components) - primary_text_score
    text_score = primary_text_score + 0.25 * support_text_score

    if text_score <= 0.0:
        text_score = fallback_es_score
        weighted_source = fallback_es_score
        primary_text_score = fallback_es_score
        support_text_score = 0.0

    return {
        "source_score": source_score,
        "translation_score": translation_score,
        "weighted_source_score": weighted_source,
        "weighted_translation_score": weighted_translation,
        "primary_text_score": primary_text_score,
        "support_text_score": support_text_score,
        "text_score": text_score,
    }


def _fuse_score(rerank_score: float, text_score: float, knn_score: float) -> float:
    rerank_factor = max(rerank_score, 0.0) + 0.00001
    text_factor = (max(text_score, 0.0) + 0.1) ** 0.35
    knn_factor = (max(knn_score, 0.0) + 0.6) ** 0.2
    return rerank_factor * text_factor * knn_factor


def fuse_scores_and_resort(
    es_hits: List[Dict[str, Any]],
    rerank_scores: List[float],
    weight_es: float = DEFAULT_WEIGHT_ES,
    weight_ai: float = DEFAULT_WEIGHT_AI,
) -> List[Dict[str, Any]]:
    """
    将 ES 分数与重排分数按乘法公式融合（不修改原始 _score），并按融合分数降序重排。

    对每条 hit 会写入：
    - _original_score: 原始 ES 分数
    - _rerank_score: 重排服务返回的分数
    - _fused_score: 融合分数
    - _text_score: 文本相关性分数（优先取 named queries 的 base_query 分数）
    - _knn_score: KNN 分数（优先取 named queries 的 knn_query 分数）

    Args:
        es_hits: ES hits 列表（会被原地修改）
        rerank_scores: 与 es_hits 等长的重排分数列表
        weight_es: 兼容保留，当前未使用
        weight_ai: 兼容保留，当前未使用

    Returns:
        每条文档的融合调试信息列表，用于 debug_info
    """
    n = len(es_hits)
    if n == 0 or len(rerank_scores) != n:
        return []

    fused_debug: List[Dict[str, Any]] = []

    for idx, hit in enumerate(es_hits):
        es_score = _to_score(hit.get("_score"))

        ai_score_raw = rerank_scores[idx]
        rerank_score = _to_score(ai_score_raw)

        matched_queries = hit.get("matched_queries")
        knn_score = _extract_named_query_score(matched_queries, "knn_query")
        text_components = _collect_text_score_components(matched_queries, es_score)
        text_score = text_components["text_score"]
        fused = _fuse_score(rerank_score, text_score, knn_score)

        hit["_original_score"] = hit.get("_score")
        hit["_rerank_score"] = rerank_score
        hit["_text_score"] = text_score
        hit["_knn_score"] = knn_score
        hit["_text_source_score"] = text_components["source_score"]
        hit["_text_translation_score"] = text_components["translation_score"]
        hit["_text_primary_score"] = text_components["primary_text_score"]
        hit["_text_support_score"] = text_components["support_text_score"]
        hit["_fused_score"] = fused

        fused_debug.append({
            "doc_id": hit.get("_id"),
            "es_score": es_score,
            "rerank_score": rerank_score,
            "text_score": text_score,
            "text_source_score": text_components["source_score"],
            "text_translation_score": text_components["translation_score"],
            "text_primary_score": text_components["primary_text_score"],
            "text_support_score": text_components["support_text_score"],
            "knn_score": knn_score,
            "matched_queries": matched_queries,
            "fused_score": fused,
        })

    # 按融合分数降序重排
    es_hits.sort(
        key=lambda h: h.get("_fused_score", h.get("_score", 0.0)),
        reverse=True,
    )
    return fused_debug


def run_rerank(
    query: str,
    es_response: Dict[str, Any],
    language: str = "zh",
    timeout_sec: float = DEFAULT_TIMEOUT_SEC,
    weight_es: float = DEFAULT_WEIGHT_ES,
    weight_ai: float = DEFAULT_WEIGHT_AI,
    rerank_query_template: str = "{query}",
    rerank_doc_template: str = "{title}",
    top_n: Optional[int] = None,
) -> Tuple[Dict[str, Any], Optional[Dict[str, Any]], List[Dict[str, Any]]]:
    """
    完整重排流程：从 es_response 取 hits -> 构造 docs -> 调服务 -> 融合分数并重排 -> 更新 max_score。
    Provider 和 URL 从 services_config 读取。
    top_n 可选；若传入，会透传给 /rerank（供云后端按 page+size 做部分重排）。
    """
    hits = es_response.get("hits", {}).get("hits") or []
    if not hits:
        return es_response, None, []

    query_text = str(rerank_query_template).format_map({"query": query})
    docs = build_docs_from_hits(hits, language=language, doc_template=rerank_doc_template)
    scores, meta = call_rerank_service(
        query_text,
        docs,
        timeout_sec=timeout_sec,
        top_n=top_n,
    )

    if scores is None or len(scores) != len(hits):
        return es_response, None, []

    fused_debug = fuse_scores_and_resort(
        hits,
        scores,
        weight_es=weight_es,
        weight_ai=weight_ai,
    )

    # 更新 max_score 为融合后的最高分
    if hits:
        top = hits[0].get("_fused_score", hits[0].get("_score", 0.0)) or 0.0
        if "hits" in es_response:
            es_response["hits"]["max_score"] = top

    return es_response, meta, fused_debug