from itertools import chain, starmap
from operator import itemgetter

import fitz
from funcy import rcompose

from image_prediction.image_extractor.extractor import ImageExtractor, ImageMetadataPair


class ParsablePDFImageExtractor(ImageExtractor):
    def __init__(self):
        self.doc: fitz.fitz.Document = None

    def __process_images_on_page(self, page: fitz.fitz.Page):
        def load_image_from_xref(xref):
            return self.doc.extract_image(xref)["image"]

        def format_metadata(image_info):
            x1, y1, x2, y2 = map(rounder, image_info["bbox"])
            width, height = itemgetter("width", "height")(image_info)
            return {
                "page_width": page_width,
                "page_height": page_height,
                "page_idx": page.number,
                "width": width,
                "height": height,
                "x1": x1,
                "x2": x2,
                "y1": y1,
                "y2": y2
            }

        rounder = rcompose(round, int)

        page_width, page_height = map(rounder, page.mediabox_size)

        image_handles = page.get_images(full=True)
        xrefs = map(itemgetter(0), image_handles)
        images = map(load_image_from_xref, xrefs)
        image_infos = page.get_image_info()
        metadata = map(format_metadata, image_infos)

        return starmap(ImageMetadataPair, zip(images, metadata))

    def extract(self, pdf: bytes):
        self.doc = fitz.Document(stream=pdf)
        image_metadata_pairs = chain(*map(self.__process_images_on_page, self.doc))
        return image_metadata_pairs