import argparse
import json
import pathlib
import subprocess

GET_INPUTS_CMD = [
    "nix-instantiate",
    "--eval",
    "--json",  # This parser is stupid, better provide it with pre-eaten stuff
    "--expr",
    "builtins.fromJSON (builtins.toJSON (import ./flake.nix).inputs)",
]


def process_flake(flake_uri: pathlib.Path) -> None:
    # get full path
    flake_file = flake_uri / "flake.nix"
    if not flake_file.is_file():
        msg = f"Flake not found: {flake_uri}"
        raise FileNotFoundError(msg)
    # import dependencies
    p = subprocess.run(
        GET_INPUTS_CMD, cwd=flake_uri, stdout=subprocess.PIPE, check=True
    )
    deps = json.loads(p.stdout)
    # for each dependency
    for dep_name, dep in deps.items():
        dep_url = dep["url"]
        # if not local path, continue
        if not dep_url.startswith(("path:", "git+file:")):
            continue
        if dep.get("flake", True):
            #  get flake file corresponding
            dep_path = pathlib.Path(flake_uri, dep_url.split(":")[1])
            process_flake(dep_path)
        # update lockfile
        cmd = [
            "nix",
            "--extra-experimental-features",
            "nix-command",
            "--extra-experimental-features",
            "flakes",
            "flake",
            "update",
            dep_name,
        ]
        p = subprocess.run(cmd, cwd=flake_uri, check=True)


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Recursively update lockfiles "
        "of flakes located on the system"
    )
    parser.add_argument("flake", help="Starting flake", type=pathlib.Path)
    args = parser.parse_args()
    process_flake(args.flake)