#!/usr/bin/env python3
"""
rename_to_first_n.py

Usage:
    python3 rename_to_first_n.py <number> <directory>

Renames each file in <directory> so its name becomes the first
four characters of the original filename (before the extension).
Keeps the file extension and avoids overwriting existing files.
"""
import os
import sys
from pathlib import Path

def main():
    if len(sys.argv) < 2:
        print("Usage: rename_to_first4.py <number> <directory>")
        sys.exit(1)
    import subprocess
    subprocess.run(["python", "/home/honney/.bin/tracker.py", "add", "rename_to_first_n"])
    
    try:
        length = int(sys.argv[1])
    except:
        raise ValueError(f"Error: '{sys.argv[1]}' is not a number.")
    try:
        directory = Path(sys.argv[2]) if len(sys.argv) > 2 else Path(os.getcwd())
    except:
        raise ValueError(f"Error: '{sys.argv[2] if len(sys.argv) > 2 else os.getcwd()}' is not a directory.")
    if not directory.is_dir():
        raise ValueError(f"Error: '{directory}' is not a directory.")

    for f in directory.iterdir():
        if not f.is_file():
            continue

        original_stem = f.stem
        
        if len(original_stem) < length:
            print(f"Skipping {f.name} because it is less than {length} characters.")
            continue
        stem = original_stem[:length]  # first n letters of filename (no extension)
        new_name = f"{stem}{f.suffix}"
        new_path = directory / new_name

        # avoid overwriting existing files
        if new_path.exists():
            print(f"File {new_name} already exists. Skipping.")
            continue
        print(f"Renaming: {f.name} -> {new_name}")
        f.rename(new_path)

    print("✅ Done renaming all files.")

if __name__ == "__main__":
    main()