import hashlib
import json
import os
from itertools import chain
from os import path

import pandas as pd
from pdf2image import convert_from_path

from cv_analysis.config import get_config

settings = get_config()


def read_json(path):
    with open(path, encoding="utf-8") as file:
        data = json.load(file)
    return data


def collect_metadata(example_pages, save=False):
    metadata = []
    make_metadata_entry = make_metadata_entry_maker()
    for name, document_sections in example_pages.items():
        metadata.append(f(name, document_sections, make_metadata_entry))
    metadata = list(chain.from_iterable(metadata))
    if save:
        df = pd.DataFrame(data=metadata, columns=["image_name", "pdf_name", "page"])
        df.to_csv(path.join(settings.paths.dvc_data_dir, "metadata_testing_files.csv"))
    else:
        return pd.DataFrame(data=metadata, columns=["image_name", "pdf_name", "page"])


def f(name, document_sections, make_metadata_entry):
    for pages in document_sections:
        span = list(range(pages[0], pages[1] + 1))
        for page_nr in span:
            yield make_metadata_entry(name, page_nr)


def make_metadata_entry_maker():
    i = -1

    def make_metadata_entry(name, page_nr):
        nonlocal i
        i += 1
        return [f"fig_table{i:0>3}", name, page_nr]

    return make_metadata_entry


def split_pdf(example_pages):
    dir_path = settings.paths.pdf_for_testing
    i = 0
    for name, document_sections in example_pages.items():
        for pages in document_sections:
            images = convert_from_path(
                pdf_path=path.join(dir_path, name), dpi=300, first_page=pages[0], last_page=pages[1]
            )
            for image in images:
                fp = path.join(settings.paths.png_for_testing, f"fig_table{i:0>3}.png")
                image.save(fp=fp, dpi=(300, 300))
                i += 1


def find_hash(file_path):
    BLOCK_SIZE = 65536

    file_hash = hashlib.sha256()
    with open(file_path, "rb") as f:
        fb = f.read(BLOCK_SIZE)
        while len(fb) > 0:
            file_hash.update(fb)
            fb = f.read(BLOCK_SIZE)

    return file_hash.hexdigest()


def rename_files_with_hash(example_pages):
    files_to_rename = list(example_pages.keys())
    folder = settings.paths.hashed_pdfs_for_testing

    # Iterate through the folder
    for file in os.listdir(folder):
        # Checking if the file is present in the list
        if file in files_to_rename:
            # construct current name using file name and path
            old_name = path.join(folder, file)
            # get file name without extension
            only_name = path.splitext(file)[0]

            # Adding the new name with extension
            hash = find_hash(old_name)
            # construct full file path
            new_name = path.join(folder, hash + ".pdf")

            # Renaming the file
            os.rename(old_name, new_name)

    # verify the result
    res = os.listdir(folder)
    print(res)


def main():
    examples_pages = read_json(path.join(settings.paths.test_data_dir, "example_pages.json"))
    rename_files_with_hash(examples_pages)
    # collect_metadata(examples_pages, save=True)
    # split_pdf(examples_pages)


if __name__ == "__main__":
    main()