"""Host-side primitives for Apple's `container` CLI."""

from __future__ import annotations

import platform
import shutil
import subprocess
from typing import Iterable

from ...log import die, info


_CONTAINER = "container"


def is_macos() -> bool:
    return platform.system() == "Darwin"


def is_available() -> bool:
    return is_macos() and shutil.which(_CONTAINER) is not None


def require_container() -> None:
    """Fail with an install pointer if Apple Container is unavailable."""
    if not is_macos():
        info("BOT_BOTTLE_BACKEND=macos-container requires macOS.")
        die("macos-container backend is only supported on macOS")
    if shutil.which(_CONTAINER) is None:
        info("Apple Container is required but was not found on PATH.")
        info("Install: https://github.com/apple/container/releases")
        die("container not found")


def build_image(ref: str, context: str, *, dockerfile: str = "") -> None:
    """Build an OCI image with Apple's BuildKit-backed `container build`."""
    info(
        f"building image {ref} from {context} with Apple Container "
        "(layer cache keeps repeat builds fast)"
    )
    args = [_CONTAINER, "build", "-t", ref]
    if dockerfile:
        args.extend(["-f", dockerfile])
    args.append(context)
    subprocess.run(args, check=True)


def image_exists(ref: str) -> bool:
    return _silent_run([_CONTAINER, "image", "inspect", ref]) == 0


def container_exists(name: str) -> bool:
    result = subprocess.run(
        [_CONTAINER, "list", "--all", "--quiet"],
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode != 0:
        return False
    return name in {line.strip() for line in result.stdout.splitlines()}


def force_remove_container(name: str) -> None:
    if container_exists(name):
        subprocess.run(
            [_CONTAINER, "delete", "--force", name],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            check=False,
        )


def image_id(ref: str) -> str:
    """Return the image digest/ID from `container image inspect`.

    The command returns JSON on current Apple Container releases. Keep
    parsing narrow and fatal so callers do not cache on an empty key.
    """
    import json

    result = subprocess.run(
        [_CONTAINER, "image", "inspect", ref],
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode != 0:
        die(
            f"container image inspect for {ref!r} failed: "
            f"{(result.stderr or '').strip() or '<no stderr>'}"
        )
    try:
        data = json.loads(result.stdout or "{}")
    except json.JSONDecodeError as exc:
        die(f"container image inspect for {ref!r} returned malformed JSON: {exc}")
    if isinstance(data, list) and data:
        data = data[0]
    if isinstance(data, dict):
        value = data.get("id") or data.get("digest") or data.get("ID")
        if value:
            return str(value)
    die(f"container image inspect for {ref!r} did not include an image id")
    raise AssertionError("unreachable")


def save(ref: str, output: str) -> None:
    subprocess.run([_CONTAINER, "image", "save", ref, "-o", output], check=True)


def _silent_run(cmd: Iterable[str]) -> int:
    return subprocess.run(
        list(cmd),
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
        check=False,
    ).returncode