# -*- coding: utf-8 -*-
"""
文本分块器 - 将长文本分割成小块
"""
import re
from config import CHUNK_SIZE, CHUNK_OVERLAP

def split_text(text, chunk_size=None, chunk_overlap=None):
    """
    将文本分割成小块
    
    Args:
        text: 要分割的文本
        chunk_size: 每块的最大字符数
        chunk_overlap: 块之间的重叠字符数
    
    Returns:
        文本块列表
    """
    if chunk_size is None:
        chunk_size = CHUNK_SIZE
    if chunk_overlap is None:
        chunk_overlap = CHUNK_OVERLAP
    
    if not text or not text.strip():
        return []
    
    # 清理文本
    text = text.strip()
    text = re.sub(r'\n{3,}', '\n\n', text)  # 多个换行合并
    text = re.sub(r' {2,}', ' ', text)  # 多个空格合并
    
    # 按段落分割
    paragraphs = re.split(r'\n\n+', text)
    
    chunks = []
    current_chunk = ""
    
    for para in paragraphs:
        para = para.strip()
        if not para:
            continue
        
        # 如果当前段落本身就超过chunk_size，需要进一步分割
        if len(para) > chunk_size:
            # 先保存当前chunk
            if current_chunk:
                chunks.append(current_chunk.strip())
                current_chunk = ""
            
            # 按句子分割长段落
            sentences = re.split(r'([。！？.!?])', para)
            temp_chunk = ""
            
            for i in range(0, len(sentences), 2):
                sentence = sentences[i]
                if i + 1 < len(sentences):
                    sentence += sentences[i + 1]
                
                if len(temp_chunk) + len(sentence) <= chunk_size:
                    temp_chunk += sentence
                else:
                    if temp_chunk:
                        chunks.append(temp_chunk.strip())
                    temp_chunk = sentence[-chunk_overlap:] + sentence if len(sentence) > chunk_overlap else sentence
            
            if temp_chunk:
                current_chunk = temp_chunk
        else:
            # 检查是否可以添加到当前chunk
            if len(current_chunk) + len(para) + 1 <= chunk_size:
                current_chunk += ("\n" if current_chunk else "") + para
            else:
                # 保存当前chunk，开始新的
                if current_chunk:
                    chunks.append(current_chunk.strip())
                # 保留重叠部分
                if len(current_chunk) > chunk_overlap:
                    current_chunk = current_chunk[-chunk_overlap:] + "\n" + para
                else:
                    current_chunk = para
    
    # 保存最后一个chunk
    if current_chunk.strip():
        chunks.append(current_chunk.strip())
    
    return chunks