import csv
import io
from pathlib import Path

from docx import Document
from pypdf import PdfReader

SUPPORTED_EXTENSIONS = {".txt", ".md", ".json", ".yaml", ".yml", ".csv", ".pdf", ".docx"}


def extract_text(filename: str, content: bytes, max_chars: int = 60_000) -> str:
    suffix = Path(filename).suffix.lower()
    if suffix not in SUPPORTED_EXTENSIONS:
        raise ValueError("Этот тип файла пока не поддерживается")
    if suffix in {".txt", ".md", ".json", ".yaml", ".yml"}:
        text = content.decode("utf-8", errors="replace")
    elif suffix == ".csv":
        rows = csv.reader(io.StringIO(content.decode("utf-8", errors="replace")))
        text = "\n".join(" | ".join(row) for row in rows)
    elif suffix == ".pdf":
        text = "\n".join(page.extract_text() or "" for page in PdfReader(io.BytesIO(content)).pages)
    else:
        text = "\n".join(p.text for p in Document(io.BytesIO(content)).paragraphs)
    return text[:max_chars]