import re
from typing import List
from pydantic import BaseModel, Field
from typing_extensions import Literal

from configs.kb_config import CHUNK_SIZE, OVERLAP_SIZE


class Document(BaseModel):
    page_content: str
    metadata: dict = Field(default_factory=dict)
    type: Literal["Document"] = "Document"


class MarkdownTextSplitter:
    def __init__(self, headers_to_split_on: List[str] = None, **kwargs):
        self.chunk_size = CHUNK_SIZE
        self.overlap_size = OVERLAP_SIZE
        self.headers_to_split_on = headers_to_split_on or ["#", "##", "###", "####"]

    def clean_text(self, text: str) -> str:
        """
        清理文本中的特殊符号，如 \n、\t、\\n 等，及图片格式链接，如 ![](image_path)
        """
        # 去除 \n、\t、\\n 等多余的特殊符号
        text = text.replace("\n", " ").replace("\t", " ").replace("\\n", " ").strip()

        # 正则匹配 Markdown 图片格式并清除，例如 ![](image_path)
        text = re.sub(r'!\[.*?\]\(.*?\)', '', text)

        return text
    def split_text_by_headers(self, markdown_document: str):
        """
        使用正则表达式将 Markdown 文档根据标题分段
        """
        header_pattern = r"^(#{1,6})\s+(.*)$"  # 捕获所有级别的标题（从 # 到 ######）
        sections = []
        current_header = None
        current_content = []
        current_header_level = 0

        # 按行处理 markdown 文档
        for line in markdown_document.split("\n"):
            match = re.match(header_pattern, line)
            if match:
                # 如果找到标题，处理之前的部分
                if current_header:
                    sections.append((current_header, current_header_level, "\n".join(current_content)))
                # 更新标题和内容
                current_header = match.group(2).strip()  # 标题内容
                current_header_level = len(match.group(1))  # 标题级别，# 代表 h1, ## 代表 h2 等
                current_content = []
            else:
                # 否则将该行加入当前内容
                current_content.append(self.clean_text(line))

        # 添加最后一个部分
        if current_header:
            sections.append((current_header, current_header_level, "\n".join(current_content)))
        
        return sections

    def split_paragraphs(self, content: str) -> List[str]:
        """
        按照 chunk_size 将文本分段，保持语句完整，尽量在句子结束处分段。
        分段规则：按句号、换行符分割，且每段字数不超过 chunk_size。若没有合适的标点符号，则强制截断。
        """
        paragraphs = []
        current_paragraph = ""

        # 用正则按句子结束符（句号、问号、感叹号等）分割文本
        sentences = re.split(r'([。！？])', content)  # 捕获句子结尾符

        # 将分割后的句子和句末标点符号重新拼接成完整的句子
        sentences = [s.strip() + (sentences[i + 1] if i + 1 < len(sentences) else '')
                     for i, s in enumerate(sentences) if i % 2 == 0]

        # 遍历所有句子
        for sentence in sentences:
            sentence = self.clean_text(sentence)
            
            # 判断当前句子是否加入到当前段落
            if len(current_paragraph) + len(sentence) + 1 <= self.chunk_size:
                # 如果加入后不超过最大字数，继续添加到当前段落
                current_paragraph += (" " + sentence) if current_paragraph else sentence
            else:
                # 如果当前段落已超过字数限制，则检查是否能在当前句子末尾进行分割
                if len(current_paragraph) > self.chunk_size:
                    paragraphs.append(current_paragraph[:self.chunk_size])  # 强制截断
                    current_paragraph = current_paragraph[self.chunk_size:]  # 剩余部分移到下一个段落
                
                # 处理当前句子
                if len(sentence) > self.chunk_size:
                    # 如果单个句子超过 chunk_size，则强制截断
                    while len(sentence) > self.chunk_size:
                        paragraphs.append(sentence[:self.chunk_size])
                        sentence = sentence[self.chunk_size:]
                
                # 最后将剩余的句子添加到当前段落
                current_paragraph = sentence

        # 添加最后一个段落（如果有的话）
        if current_paragraph:
            paragraphs.append(current_paragraph)

        return paragraphs
    def split_documents(self, sections: List[str], doc_source) -> List[Document]:
        """
        递归分段，根据每个 Markdown 文档部分生成对应的内容
        """
        final_splits = []

        for header, header_level, content in sections:
            # 递归分段每个部分
            paragraphs = self.split_paragraphs(content)

            # 根据标题级别，将标题存入对应的 h1, h2, h3 等字段
            metadata = {"source": doc_source, "header": header}
            if header_level == 1:
                metadata["h1"] = header
            elif header_level == 2:
                metadata["h2"] = header
            elif header_level == 3:
                metadata["h3"] = header
            elif header_level == 4:
                metadata["h4"] = header
            elif header_level == 5:
                metadata["h5"] = header
            elif header_level == 6:
                metadata["h6"] = header

            # 对每个段落创建 Document 对象
            for paragraph in paragraphs:
                doc = Document(
                    page_content=paragraph,
                    metadata=metadata
                )
                final_splits.append(doc)

        return final_splits

    def split_markdown_text(self, markdown_document: str, doc_source: str) -> List[Document]:

        # 首先根据标题分段
        sections = self.split_text_by_headers(markdown_document)
        
        # 进一步分段并创建 Document 对象
        final_splits = self.split_documents(sections, doc_source)
        
        # 返回最终的文档段落列表
        return final_splits


# 示例使用
if __name__ == "__main__":
    doc_source = ""
    markdown_text = """
    # 标题 1
    QQQ
    
    ## 标题 2
    WWW
    
    ### 标题 3
    EEE
    """
    splitter = MarkdownTextSplitter()
    splits = splitter.split_markdown_text(markdown_text, doc_source)
    
    for split in splits:
        print(f"Header: {split.metadata}, Content: {split.page_content}")