from typing import Optional
from docx import Document
try:
    import fitz  # PyMuPDF
except Exception:
    # fall back to pymupdf module name if present
    import pymupdf as fitz

def load_pdf_text(file_path: str) -> str:
    try:
        doc = fitz.open(file_path)
        text = ""
        # iterate directly over pages
        for page in doc:
            # use standard PyMuPDF API
            try:
                page_text = page.get_text()
            except Exception:
                # try alternate name for older versions
                page_text = page.getText() if hasattr(page, 'getText') else ''
            if page_text:
                text += page_text + "\n"
        try:
            doc.close()
        except Exception:
            pass
        return text.strip()
    except Exception as e:
        print(f"Error reading PDF {file_path}: {e}")
        return ""


def load_docx_text(file_path: str) -> str:
    try:
        doc = Document(file_path)
        paragraphs = [p.text for p in doc.paragraphs if p.text]
        return "\n".join(paragraphs).strip()
    except Exception as e:
        print(f"Error reading DOCX {file_path}: {e}")
        return ""


def load_txt_text(file_path: str) -> str:
    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            return f.read()
    except Exception as e:
        print(f"Error reading TXT {file_path}: {e}")
        return ""


def extract_text_from_path(path: str) -> Optional[str]:
    if path.lower().endswith('.pdf'):
        return load_pdf_text(path)
    if path.lower().endswith('.docx'):
        return load_docx_text(path)
    if path.lower().endswith('.txt'):
        return load_txt_text(path)
    return None


def chunk_text(text: str, chunk_size: int = 500, overlap: int = 100) -> list:
    chunks = []
    start = 0
    text_length = len(text)
    while start < text_length:
        end = min(start + chunk_size, text_length)
        chunk = text[start:end]
        chunks.append(chunk)
        start += chunk_size - overlap
    return chunks


if __name__ == '__main__':
    import sys

    def usage():
        print('Usage: python src/index_docs.py <path-to-file-or-folder> [chunk_size]')

    if len(sys.argv) < 2:
        usage()
        sys.exit(1)

    path = sys.argv[1]
    chunk_size = int(sys.argv[2]) if len(sys.argv) > 2 else 500

    print(f'Testing extraction for: {path}')
    text = extract_text_from_path(path)
    if not text:
        print('No text extracted or unsupported file type.')
        sys.exit(1)

    print('Characters extracted:', len(text))
    chunks = chunk_text(text, chunk_size=chunk_size)
    print('Chunks produced:', len(chunks))
    if chunks:
        preview = 300
        print('\n--- First chunk preview ---')
        print(chunks[0][:preview])
        print('\n--- Second chunk preview ---')
        print(chunks[1][:preview] if len(chunks) > 1 else '<none>')