# -*- coding: utf-8 -*-
"""检索结果候选规范化与去重。"""

from __future__ import annotations

from hashlib import md5
import re
from typing import Any, Dict, List, Sequence

import yaml

from core.document_chat.retrieval.config import RetrievalConfig
from core.document_chat.retrieval.utils import to_float


DEFAULT_OUTPUT_FIELDS = (
    "pk",
    "text",
    "document_id",
    "parent_id",
    "index",
    "tag_list",
    "metadata",
    "file_name",
    "chapter_title",
    "chapter_level_1",
    "chapter_level_2",
    "chapter_level_3",
)


def normalize_row_metadata(
    row_or_metadata: Any,
    output_fields: Sequence[str] = DEFAULT_OUTPUT_FIELDS,
) -> Dict[str, Any]:
    """规范化行数据为统一的 metadata 字典。处理嵌套 metadata 和 YAML 字符串。"""
    metadata = normalize_metadata(row_or_metadata)
    inner = normalize_metadata(metadata.get("metadata")) if metadata.get("metadata") else {}
    for key, value in inner.items():
        metadata.setdefault(key, value)
    for key in output_fields:
        if isinstance(row_or_metadata, dict) and row_or_metadata.get(key) not in (None, ""):
            metadata[key] = row_or_metadata.get(key)
    return metadata


def normalize_metadata(metadata: Any) -> Dict[str, Any]:
    """将 metadata 转为字典，支持 YAML 字符串解析。"""
    if isinstance(metadata, dict):
        return dict(metadata)
    if isinstance(metadata, str) and metadata.strip():
        try:
            loaded = yaml.safe_load(metadata)
            return dict(loaded) if isinstance(loaded, dict) else {}
        except Exception:
            return {}
    return {}


def metadata_value(metadata: Dict[str, Any], key: str) -> Any:
    """安全获取 metadata 值，支持嵌套 metadata.metadata 和 YAML 字符串。"""
    if key in metadata:
        return metadata.get(key)
    nested = metadata.get("metadata")
    if isinstance(nested, dict):
        return nested.get(key)
    if isinstance(nested, str) and nested.strip():
        try:
            parsed = yaml.safe_load(nested)
            if isinstance(parsed, dict):
                return parsed.get(key)
        except Exception:
            return None
    return None


def build_candidate_key(
    metadata: Dict[str, Any],
    text: Any = "",
    output_fields: Sequence[str] = DEFAULT_OUTPUT_FIELDS,
) -> str:
    """构建候选唯一标识键，按优先级尝试不同字段组合。"""
    metadata = normalize_row_metadata(metadata, output_fields)
    document_id = str(metadata_value(metadata, "document_id") or "").strip()
    parent_id = str(metadata_value(metadata, "parent_id") or "").strip()
    chunk_id = str(metadata_value(metadata, "chunk_id") or "").strip()
    chapter_title = str(metadata_value(metadata, "chapter_title") or "").strip()
    index = metadata_value(metadata, "index")
    pk = str(metadata_value(metadata, "pk") or "").strip()

    if document_id and parent_id and chunk_id:
        return f"{document_id}::{parent_id}::{chunk_id}"
    if document_id and parent_id and chapter_title and index not in (None, ""):
        return f"{document_id}::{parent_id}::{chapter_title}::{index}"
    if pk:
        return pk
    if parent_id and chapter_title and index not in (None, ""):
        return f"{parent_id}::{chapter_title}::{index}"
    return str(text or "")[:300]


def merge_metadata(current: Dict[str, Any], incoming: Dict[str, Any]) -> None:
    """合并两条候选的 metadata，不覆盖已有非空值。"""
    current_meta = current.setdefault("metadata", {})
    incoming_meta = incoming.get("metadata") if isinstance(incoming.get("metadata"), dict) else {}
    for key, value in incoming_meta.items():
        if key not in current_meta or current_meta.get(key) in (None, "", []):
            current_meta[key] = value
    if incoming.get("source") and not current.get("source"):
        current["source"] = incoming.get("source")


def clean_candidates(candidates: List[Dict[str, Any]], config: RetrievalConfig) -> List[Dict[str, Any]]:
    """清理候选：过滤过短文本、双重去重（candidate_key + 内容哈希）。"""
    cleaned = []
    seen_keys = set()
    seen_hashes = set()
    for item in candidates:
        text = str(item.get("text") or "").strip()
        if len(text) < 20:
            continue
        metadata = item.get("metadata") if isinstance(item.get("metadata"), dict) else {}
        dedupe_key = str(item.get("candidate_key") or text[:300])
        content_hash = _content_hash(text[:300])
        file_name = str(metadata.get("file_name") or "")
        hash_key = f"{file_name}::{content_hash}"
        if dedupe_key in seen_keys or hash_key in seen_hashes:
            continue
        seen_keys.add(dedupe_key)
        seen_hashes.add(hash_key)
        metadata["candidate_key"] = dedupe_key
        cleaned.append(
            {
                "candidate_key": dedupe_key,
                "text": text[: config.max_single_reference_chars],
                "source": str(item.get("source") or metadata.get("file_name") or "向量知识库"),
                "vector_similarity": to_float(item.get("vector_similarity"), 0.0),
                "fusion_score": to_float(item.get("fusion_score"), 0.0),
                "source_hits": item.get("source_hits") if isinstance(item.get("source_hits"), dict) else {},
                "metadata": metadata,
            }
        )
    cleaned.sort(key=lambda item: (item.get("fusion_score", 0.0), item.get("vector_similarity", 0.0)), reverse=True)
    return cleaned[: config.recall_top_k]


def _content_hash(text: str) -> str:
    """基于归一化文本的短 MD5 哈希，用于内容去重。"""
    normalized = re.sub(r"\s+", " ", text.strip().lower())
    return md5(normalized.encode("utf-8")).hexdigest()[:12]