"""Maintenance tasks run in isolated environments."""

import collections
import pathlib
import re
import tempfile
from collections.abc import Mapping
from typing import Any

import nox
from packaging import version as pkg_version


try:
    from nox_poetry import session as nox_session
except ImportError:
    nox_session = nox.session
    nox_poetry_available = False
else:
    nox_poetry_available = True


def nested_defaultdict() -> collections.defaultdict[str, Any]:
    """Create a multi-level `defaultdict` with variable depth.

    The returned `dict`ionary never raises a `KeyError`
    but always returns an empty `dict`ionary instead.
    This behavior is occurs recursively.

    Adjusted from: https://stackoverflow.com/a/8702435
    """
    return collections.defaultdict(nested_defaultdict)


def defaultify(obj: Any) -> Any:
    """Turn nested `dict`s into nested `defaultdict`s."""
    if isinstance(obj, Mapping):
        return collections.defaultdict(
            nested_defaultdict,
            {key: defaultify(val) for key, val in obj.items()},
        )
    return obj


def load_pyproject_toml() -> collections.defaultdict[str, Any]:
    """Load the contents of the pyproject.toml file.

    The contents are represented as a `nested_defaultdict`;
    so, missing keys and tables (i.e., "sections" in the .ini format)
    do not result in `KeyError`s but return empty `nested_defaultdict`s.
    """
    return defaultify(nox.project.load_toml("pyproject.toml"))


def load_supported_python_versions(*, reverse: bool = False) -> list[str]:
    """Parse the Python versions from the pyproject.toml file."""
    pyproject = load_pyproject_toml()
    version_names = {
        classifier.rsplit(" ")[-1]
        for classifier in pyproject["tool"]["poetry"]["classifiers"]
        if classifier.startswith("Programming Language :: Python :: ")
    }
    return sorted(version_names, key=pkg_version.Version, reverse=reverse)


SUPPORTED_PYTHONS = load_supported_python_versions(reverse=True)
MAIN_PYTHON = "3.12"

SRC_LOCATIONS = ("./noxfile.py", "src/")


nox.options.envdir = ".cache/nox"
nox.options.error_on_external_run = True  # only `git` and `poetry` are external
nox.options.reuse_venv = "no"
nox.options.sessions = (  # run by default when invoking `nox` on the CLI
    "format",
    "lint",
)
nox.options.stop_on_first_error = True


@nox_session(name="format", python=MAIN_PYTHON)
def format_(session: nox.Session) -> None:
    """Format source files with `autoflake`, `black`, and `isort`."""
    start(session)

    install_pinned(session, "autoflake", "black", "isort", "ruff")

    locations = session.posargs or SRC_LOCATIONS

    session.run("autoflake", "--version")
    session.run("autoflake", *locations)

    session.run("black", "--version")
    session.run("black", *locations)

    session.run("isort", "--version-number")
    session.run("isort", *locations)

    session.run("ruff", "--version")
    session.run("ruff", "check", "--fix-only", *locations)


@nox_session(python=MAIN_PYTHON)
def lint(session: nox.Session) -> None:
    """Lint source files with `flake8`, `mypy`, and `ruff`."""
    start(session)

    install_pinned(
        session,
        "flake8",
        "flake8-annotations",
        "flake8-bandit",
        "flake8-black",
        "flake8-broken-line",
        "flake8-bugbear",
        "flake8-commas",
        "flake8-comprehensions",
        "flake8-debugger",
        "flake8-docstrings",
        "flake8-eradicate",
        "flake8-isort",
        "flake8-quotes",
        "flake8-string-format",
        "flake8-pyproject",
        "mypy",
        "pep8-naming",  # flake8 plug-in
        "pydoclint[flake8]",
        "ruff",
    )

    locations = session.posargs or SRC_LOCATIONS

    session.run("flake8", "--version")
    session.run("flake8", *locations)

    session.run("mypy", "--version")
    session.run("mypy", *locations)

    session.run("ruff", "--version")
    session.run("ruff", "check", *locations)


def start(session: nox.Session) -> None:
    """Show generic info about a session."""
    if session.posargs:
        session.debug(f"Received extra arguments: {session.posargs}")

    session.debug("Some generic information about the environment")
    session.run("python", "--version")
    session.run("python", "-c", "import sys; print(sys.executable)")
    session.run("python", "-c", "import sys; print(sys.path)")
    session.run("python", "-c", "import os; print(os.getcwd())")
    session.run("python", "-c", 'import os; print(os.environ["PATH"])')

    session.env["BLACK_CACHE_DIR"] = ".cache/black"
    session.env["PIP_CACHE_DIR"] = ".cache/pip"
    session.env["PIP_DISABLE_PIP_VERSION_CHECK"] = "true"


def install_pinned(
    session: nox.Session,
    *packages_or_pip_args: str,
    **kwargs: Any,
) -> None:
    """Install packages respecting the "poetry.lock" file.

    Wraps `nox.sessions.Session.install()` such that it installs
    packages respecting the pinned versions specified in poetry's
    lock file. This makes nox sessions more deterministic.
    """
    session.debug("Install packages respecting the poetry.lock file")

    session.run(  # temporary fix to avoid poetry's future warning
        "poetry",
        "config",
        "--local",
        "warnings.export",
        "false",
        external=True,
        log=False,  # because it's just a fix
    )

    if nox_poetry_available:
        session.install(*packages_or_pip_args, **kwargs)
        return

    with tempfile.NamedTemporaryFile() as requirements_txt:
        session.run(
            "poetry",
            "export",
            "--format=requirements.txt",
            f"--output={requirements_txt.name}",
            "--with=dev",
            "--without-hashes",
            external=True,
        )

        # `pip install --constraint ...` raises an error if the
        # dependencies in requirements.txt contain "extras"
        # => Strip "package[extras]==1.2.3" into "package==1.2.3"
        dependencies = pathlib.Path(requirements_txt.name).read_text().split("\n")
        dependencies = [re.sub(r"\[.*\]==", "==", dep) for dep in dependencies]
        pathlib.Path(requirements_txt.name).write_text("\n".join(dependencies))

        session.install(
            f"--constraint={requirements_txt.name}",
            *packages_or_pip_args,
            **kwargs,
        )


if MAIN_PYTHON not in SUPPORTED_PYTHONS:
    msg = f"MAIN_PYTHON version, v{MAIN_PYTHON}, is not in SUPPORTED_PYTHONS"
    raise RuntimeError(msg)