calc_crc32

#!/usr/bin/env python3

import os
import binascii
import csv
import sys


def calculate_crc32(file_path):
    """
    Calculate the CRC32 of a file.
    """
    prev_crc = 0
    with open(file_path, "rb") as f:
        while True:
            chunk = f.read(8192)  # Read in 8k chunks
            if not chunk:
                break
            prev_crc = binascii.crc32(chunk, prev_crc)
    return prev_crc & 0xFFFFFFFF  # Ensure it's a 32-bit value


def check_and_update_crc32(image_path, csv_file="images_crc32.csv"):
    """
    Check if the CRC32 of an image exists in the CSV file. If not, add it.
    Returns the name of the existing image if found, otherwise an empty string.
    """
    image_crc32 = calculate_crc32(image_path)
    image_crc32_hex = f"{image_crc32:08X}"
    existing_image_name = ""

    # Read the existing entries in the CSV file
    entries = []
    if os.path.exists(csv_file):
        with open(csv_file, "r", newline="") as f:
            reader = csv.reader(f, delimiter=";", quoting=csv.QUOTE_ALL)
            for row in reader:
                if len(row) >= 2:
                    entries.append(row)
                    if row[1] == image_crc32_hex:
                        existing_image_name = row[0]

    # If an existing entry is found, return the image name
    if existing_image_name:
        return existing_image_name

    # Otherwise, add the new entry
    entries.append([image_path, image_crc32_hex])
    with open(csv_file, "w", newline="") as f:
        writer = csv.writer(f, delimiter=";", quoting=csv.QUOTE_ALL)
        writer.writerows(entries)

    # Return empty string if no match was found
    return ""


if __name__ == "__main__":
    # Check if the image path is provided
    if len(sys.argv) < 2:
        print("Usage: python calc_crc32.py <image_path>")
        sys.exit(1)

    # Get the image path from arguments
    image_path = sys.argv[1]

    # Check if the file exists
    if not os.path.isfile(image_path):
        print(f"Error: File not found: {image_path}")
        sys.exit(1)

    # Check the CRC32 and update the CSV
    result = check_and_update_crc32(image_path)
    if result:
        print(result)
    else:
        print(image_path)