import io
import pandas as pd
from PyPDF2 import PdfReader

def read_pdf(file_bytes):
    reader = PdfReader(io.BytesIO(file_bytes))
    return "\n".join(page.extract_text() for page in reader.pages if page.extract_text())

def read_csv(file_bytes):
    df = pd.read_csv(io.BytesIO(file_bytes))
    return df.to_string()

def read_txt(file_bytes):
    return file_bytes.decode("utf-8")