from numpy import array, ndarray
import pdf2image
from PIL import Image

from cv_analysis.utils.preprocessing import preprocess_page_array


def open_analysis_input_file(path_or_bytes, first_page=1, last_page=None):

    assert first_page > 0, "Page numbers are 1-based."
    assert last_page is None or last_page >= first_page, "last_page must be greater than or equal to first_page."

    last_page = last_page or first_page

    if type(path_or_bytes) == str:
        if path_or_bytes.lower().endswith((".png", ".jpg", ".jpeg")):
            pages = [Image.open(path_or_bytes)]
        elif path_or_bytes.lower().endswith(".pdf"):
            pages = pdf2image.convert_from_path(path_or_bytes, first_page=first_page, last_page=last_page)
        else:
            raise IOError("Invalid file extension. Accepted filetypes: .png, .jpg, .jpeg, .pdf")
    elif type(path_or_bytes) == bytes:
        pages = pdf2image.convert_from_bytes(path_or_bytes, first_page=first_page, last_page=last_page)
    elif type(path_or_bytes) in {list, ndarray}:
        return path_or_bytes

    pages = [preprocess_page_array(array(p)) for p in pages]

    return pages