from typing import List, Dict

class SACChunker:
    """
    Summary-Augmented Chunking (SAC).
    Prevents Document-Level Retrieval Mismatch (DRM) by injecting global context.
    Source: Reuter et al. (Reliable Retrieval in RAG)
    """
    def __init__(self, base_chunk_size: int = 500, summary_prefix: str = "DOCUMENT_CONTEXT: "):
        self.chunk_size = base_chunk_size
        self.prefix = summary_prefix

    def process_document(self, doc_text: str, doc_summary: str) -> List[str]:
        """
        Splits document and prepends summary to EVERY chunk.
        """
        # 1. Standard Recursive Split (Simplified for illustration)
        raw_chunks = self._split_text(doc_text)
        
        augmented_chunks = []
        
        # 2. Augmentation Step
        # Research shows generic summaries outperform expert-guided ones for retrieval.
        for chunk in raw_chunks:
            # The 'embedding' will now contain the global summary + local content
            # This ensures the chunk is 'stamped' with its parent identity
            augmented_content = f"{self.prefix}{doc_summary}\nCONTENT: {chunk}"
            augmented_chunks.append(augmented_content)
            
        return augmented_chunks

    def _split_text(self, text: str) -> List[str]:
        # Basic chunking logic (placeholder for recursive splitter)
        return [text[i:i+self.chunk_size] for i in range(0, len(text), self.chunk_size)]
