import os
from tkinter import Tk, filedialog
import re

def get_directory():
    """Displays a dialog to select directory with part files."""
    root = Tk()
    root.withdraw()
    directory = filedialog.askdirectory(
        title="Select Directory with Part Files"
    )
    return directory

def merge_files(directory):
    try:
        # Get all files in directory
        all_files = os.listdir(directory)
        
        # Filter files ending with 'partX' where X is a number
        part_files = [f for f in all_files if re.match(r'.+_part\d+\.txt$', f)]
        
        if not part_files:
            print("No part files found in the selected directory.")
            return
        
        # Sort files by part number
        part_files.sort(key=lambda x: int(re.search(r'_part(\d+)\.txt$', x).group(1)))
        
        # Get base name from first file (remove _partX.txt)
        base_name = re.sub(r'_part\d+\.txt$', '.txt', part_files[0])
        
        # Create output file path
        output_path = os.path.join(directory, base_name)
        
        # Merge all parts
        with open(output_path, 'w', encoding='utf-8') as outfile:
            for part_file in part_files:
                file_path = os.path.join(directory, part_file)
                with open(file_path, 'r', encoding='utf-8') as infile:
                    content = infile.read()
                    outfile.write(content)
        
        print(f"Files successfully merged into: {base_name}")
        print(f"Merged {len(part_files)} parts.")
        
    except Exception as e:
        print(f"An error occurred: {e}")

if __name__ == "__main__":
    directory = get_directory()
    if directory:
        merge_files(directory)
    else:
        print("No directory selected. Exiting.")