'''
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.

This code generates dependency tree by recursively inspecting each DLL.

Install pefile: pip install pefile

Run:
python getDependenciesTreeDLL.py C:\Projects\dll_third_party.dll dir_1/ dir_2/
'''

from pathlib import Path
import pefile


def get_dependencies(path):
    """Get direct DLL dependencies of a PE file."""
    try:
        pe = pefile.PE(str(path), fast_load=True)
        pe.parse_data_directories(
            directories=[
                pefile.DIRECTORY_ENTRY["IMAGE_DIRECTORY_ENTRY_IMPORT"]
            ]
        )

        dependencies = []

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

        pe.close()

        return sorted(set(dependencies))

    except Exception:
        return []


def find_dll(name, search_dirs):
    """
    Find a DLL in the supplied directories.
    """
    for directory in search_dirs:
        candidate = directory / name

        if candidate.exists():
            return candidate

    return None


def print_dependency_tree(
    dll_path,
    search_dirs,
    prefix="",
    visited=None
):
    if visited is None:
        visited = set()

    dll_path = Path(dll_path).resolve()

    # Prevent circular dependencies
    if dll_path in visited:
        return

    visited.add(dll_path)

    print(f"{prefix}{dll_path.name}")

    dependencies = get_dependencies(dll_path)

    for i, dependency in enumerate(dependencies):
        is_last = i == len(dependencies) - 1

        branch = "└── " if is_last else "├── "
        child_prefix = "    " if is_last else "│   "

        dependency_path = find_dll(
            dependency,
            search_dirs
        )

        if dependency_path:
            print_dependency_tree(
                dependency_path,
                search_dirs,
                prefix + branch[:-4] + child_prefix,
                visited
            )
        else:
            print(
                f"{prefix}{branch}"
                f"{dependency} [not found]"
            )


if __name__ == "__main__":
    import sys

    if len(sys.argv) < 2:
        print(
            "Usage: python dll_tree.py "
            "<dll> [search_directory ...]"
        )
        sys.exit(1)

    dll = Path(sys.argv[1]).resolve()

    # Search the DLL's directory plus directories supplied
    # on the command line.
    search_dirs = [
        dll.parent
    ]

    for directory in sys.argv[2:]:
        search_dirs.append(
            Path(directory).resolve()
        )

    print_dependency_tree(
        dll,
        search_dirs
    )