'''
In Windows, dependencies of a DLL can be obtained from its PE import table. 
A useful Python solution is to use the pefile package, which reads the DLL 
without loading or executing it. It gives only direct dependencies. The
pefile package does not guarantee the complete runtime dependency list.

Install pefile: pip install pefile

Run:
python getDependenciesDLL.py C:\Projects\dll_third_party.dll
'''
import sys
from pathlib import Path

import pefile


def get_dll_dependencies(dll_path):
    """
    Return the DLLs directly imported by a PE file (.dll/.exe).
    """
    pe = pefile.PE(dll_path)

    dependencies = []

    if hasattr(pe, "DIRECTORY_ENTRY_IMPORT"):
        for entry in pe.DIRECTORY_ENTRY_IMPORT:
            dll_name = entry.dll.decode(
                "utf-8",
                errors="replace"
            )
            dependencies.append(dll_name)

    pe.close()

    return sorted(set(dependencies))


def main():
    if len(sys.argv) != 2:
        print("Usage:")
        print("    python dll_dependencies.py <path_to_dll>")
        sys.exit(1)

    dll_path = Path(sys.argv[1])

    if not dll_path.exists():
        print(f"ERROR: File not found: {dll_path}")
        sys.exit(1)

    try:
        dependencies = get_dll_dependencies(dll_path)

        print(f"\nDLL: {dll_path}")
        print("\nDirect dependencies:")

        if not dependencies:
            print("  No imported DLLs found.")
        else:
            for dependency in dependencies:
                print(f"  {dependency}")

    except pefile.PEFormatError as e:
        print(f"ERROR: Not a valid PE/DLL file: {e}")
        sys.exit(1)

    except Exception as e:
        print(f"ERROR: {e}")
        sys.exit(1)


if __name__ == "__main__":
    main()