import os

import chromadb
from dotenv import load_dotenv
from langchain_community.document_loaders import PyMuPDFLoader
from langchain_community.embeddings import DashScopeEmbeddings
from langchain_community.vectorstores import Chroma
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI
from langchain_classic.chains.combine_documents import create_stuff_documents_chain
from langchain_text_splitters import RecursiveCharacterTextSplitter

# ── 配置 ──────────────────────────────────────────────────────────
BASE_DIR = os.path.dirname(os.path.abspath(__file__))

PDF_PATH = os.path.join(BASE_DIR, "docs", "浦发上海浦东发展银行西安分行个金客户经理考核办法.pdf")
CHROMA_DB_PATH = os.path.join(BASE_DIR, "chroma")
COLLECTION_NAME = "shanghai_bank_policy"

PROMPT_TEMPLATE = """
你是一个专业的知识库助手。请根据以下上下文回答问题。

**规则：**
- 只基于提供的上下文回答，不要编造
- 如果上下文中没有相关信息，直接说「根据现有资料，我找不到这个问题的答案」
- 回答要简洁直接，引用原文时用引号

**上下文：**
{context}

**问题：**
{question}
"""


def load_config() -> dict:
    """加载 .env 中的配置项"""
    load_dotenv()
    config = {
        "api_key": os.getenv("ALIYUN_API_KEY"),
        "base_url": os.getenv("ALIYUN_BASE_URL"),
        "chat_model": os.getenv("ALIYUN_CHAT_MODEL"),
        "embedding_model": os.getenv("ALIYUN_EMBEDDING_MODEL", "text-embedding-v3"),
    }

    missing = [k for k, v in config.items() if not v and k != "embedding_model"]
    if missing:
        raise EnvironmentError(f"缺少环境变量: {missing}，请检查 .env 文件")

    return config


def init_llm(config: dict) -> ChatOpenAI:
    return ChatOpenAI(
        base_url=config["base_url"],
        api_key=config["api_key"],
        model=config["chat_model"],
        temperature=0,
        timeout=10,
        max_retries=1,
    )


def init_embeddings(config: dict) -> DashScopeEmbeddings:
    return DashScopeEmbeddings(
        model=config["embedding_model"],
        dashscope_api_key=config["api_key"],
    )


def clean_pdf_text(text: str) -> str:
    """清洗 PDF 解析出的文本，去除常见噪声"""
    import re

    # 删除非中文字符之间的换行符
    text = re.sub(r'[^一](\n)[^一]',
                  lambda m: m.group(0).replace('\n', ''), text)

    # 删除项目符号和多余空格
    text = text.replace('•', '').replace('  ', ' ')

    # 删除连续的换行符（保留一个）
    text = re.sub(r'\n{2,}', '\n', text)

    return text.strip()

def build_or_load_vectorstore(embeddings: DashScopeEmbeddings) -> Chroma:
    """如果 collection 已存在则直接加载，否则解析 PDF 并建库"""
    chroma_client = chromadb.PersistentClient(path=CHROMA_DB_PATH)
    existing_collections = [col.name for col in chroma_client.list_collections()]

    if COLLECTION_NAME in existing_collections:
        print(f"✅ 检测到已有 collection「{COLLECTION_NAME}」，直接加载")
        return Chroma(
            embedding_function=embeddings,
            collection_name=COLLECTION_NAME,
            client=chroma_client,
        )

    print(f"ℹ️  未检测到 collection「{COLLECTION_NAME}」，开始解析文档并建库")

    loader = PyMuPDFLoader(PDF_PATH)
    pages = loader.load()

    # ========== 第二步：清洗数据（可选，根据文档质量决定）==========
    clean_pages = [clean_pdf_text(page) for page in pages]


    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=500,
        chunk_overlap=50,
        separators=["\n\n", "\n", "。", "；", "，", " ", ""],
    )
    docs = text_splitter.split_documents(pages)

    vectorstore = Chroma.from_documents(
        embedding=embeddings,
        collection_name=COLLECTION_NAME,
        client=chroma_client,
        documents=docs,
    )
    print(f"✅ 建库完成，共 {len(docs)} 个分块")
    return vectorstore


def ask(query: str, retriever, llm) -> str:
    """检索 + 生成回答"""
    relevant_docs = retriever.invoke(query)
    context = "\n\n---\n\n".join(d.page_content for d in relevant_docs)

    prompt = ChatPromptTemplate.from_template(PROMPT_TEMPLATE)
    chain = prompt | llm | StrOutputParser()


    return chain.invoke({"context": context, "question": query})


def main():
    config = load_config()

    llm = init_llm(config)
    embeddings = init_embeddings(config)
    print("✅ 模型初始化完成")

    vectorstore = build_or_load_vectorstore(embeddings)
    retriever = vectorstore.as_retriever(search_kwargs={"k": 3})

    query = "什么是工作质量考核标准？"
    answer = ask(query, retriever, llm)

    print("\n" + "=" * 60)
    print(f"问题：{query}")
    print("=" * 60)
    print(answer)


if __name__ == "__main__":
    main()