from __future__ import annotations

import contextlib
import os
import sys
from typing import Generator
from typing import Sequence

from pre_commit import lang_base
from pre_commit.envcontext import envcontext
from pre_commit.envcontext import PatchesT
from pre_commit.envcontext import SubstitutionT
from pre_commit.envcontext import UNSET
from pre_commit.envcontext import Var
from pre_commit.prefix import Prefix
from pre_commit.util import cmd_output_b

ENVIRONMENT_DIR = "conda"
get_default_version = lang_base.basic_get_default_version
health_check = lang_base.basic_health_check
run_hook = lang_base.basic_run_hook


def get_env_patch(env: str) -> PatchesT:
    # On non-windows systems executable live in $CONDA_PREFIX/bin, on Windows
    # they can be in $CONDA_PREFIX/bin, $CONDA_PREFIX/Library/bin,
    # $CONDA_PREFIX/Scripts and $CONDA_PREFIX. Whereas the latter only
    # seems to be used for python.exe.
    path: SubstitutionT = (os.path.join(env, "bin"), os.pathsep, Var("PATH"))
    if sys.platform == "win32":  # pragma: win32 cover
        path = (env, os.pathsep, *path)
        path = (os.path.join(env, "Scripts"), os.pathsep, *path)
        path = (os.path.join(env, "Library", "bin"), os.pathsep, *path)

    return (
        ("PYTHONHOME", UNSET),
        ("VIRTUAL_ENV", UNSET),
        ("CONDA_PREFIX", env),
        ("PATH", path),
    )


@contextlib.contextmanager
def in_env(prefix: Prefix, version: str) -> Generator[None, None, None]:
    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
    with envcontext(get_env_patch(envdir)):
        yield


def _conda_exe() -> str:
    if os.environ.get("PRE_COMMIT_USE_MICROMAMBA"):
        return "micromamba"
    elif os.environ.get("PRE_COMMIT_USE_MAMBA"):
        return "mamba"
    else:
        return "conda"


def install_environment(
    prefix: Prefix,
    version: str,
    additional_dependencies: Sequence[str],
) -> None:
    lang_base.assert_version_default("conda", version)

    conda_exe = _conda_exe()

    env_dir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
    cmd_output_b(
        conda_exe,
        "env",
        "create",
        "-p",
        env_dir,
        "--file",
        "environment.yml",
        cwd=prefix.prefix_dir,
    )
    if additional_dependencies:
        cmd_output_b(
            conda_exe,
            "install",
            "-p",
            env_dir,
            *additional_dependencies,
            cwd=prefix.prefix_dir,
        )
