"""Docker host-side primitives used by DockerBottleBackend: probing
for docker on PATH, slugifying agent names, checking image/container
existence, and building images."""

from __future__ import annotations

import re
import shutil
import subprocess
from typing import Iterable, Iterator

from ...log import die, info


# Cap on the suffix the container-name conflict logic will try before
# giving up: base, base-2, ..., base-MAX_CONTAINER_SUFFIX.
MAX_CONTAINER_SUFFIX = 100


def container_name_candidates(base: str) -> Iterator[str]:
    """Yield `base`, then `base-2`, `base-3`, ... up to
    `base-MAX_CONTAINER_SUFFIX`. Both the prepare-time probe and the
    launch-time race retry walk this sequence."""
    yield base
    for suffix in range(2, MAX_CONTAINER_SUFFIX + 1):
        yield f"{base}-{suffix}"


def runsc_available() -> bool:
    """Return True if the Docker daemon has the gVisor (`runsc`) runtime
    registered. Called once per prepare; the result lives on the plan."""
    r = subprocess.run(
        ["docker", "info", "--format", "{{json .Runtimes}}"],
        capture_output=True,
        text=True,
        check=False,
    )
    return r.returncode == 0 and "runsc" in r.stdout


def require_docker() -> None:
    """Fail with an install pointer if `docker` is not on PATH."""
    if shutil.which("docker") is None:
        info("Docker is required but was not found on PATH.")
        info("macOS:  install Docker Desktop  https://docs.docker.com/desktop/install/mac-install/")
        info("Linux:  install Docker Engine   https://docs.docker.com/engine/install/")
        die("docker not found")


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


def container_exists(name: str) -> bool:
    """Returns True if a container (running or stopped) with the given
    name exists. Uses `docker ps -a -q -f name=^<name>$` so substring
    matches don't false-positive."""
    result = subprocess.run(
        ["docker", "ps", "-a", "-q", "-f", f"name=^{name}$"],
        capture_output=True,
        text=True,
        check=True,
    )
    return bool(result.stdout.strip())


def force_remove_container(name: str) -> None:
    """`docker rm -f` the named container if it exists. No-op if it
    doesn't — and the rm itself is best-effort (errors swallowed) so
    this is safe to register as a teardown callback."""
    if container_exists(name):
        subprocess.run(
            ["docker", "rm", "-f", name],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            check=False,
        )


def docker_exec_root(container: str, argv: list[str]) -> None:
    """Run `docker exec -u 0` in the named container, check=True. Used
    by SSH provisioning to chown/chmod files that need root."""
    subprocess.run(
        ["docker", "exec", "-u", "0", container, *argv],
        stdout=subprocess.DEVNULL,
        check=True,
    )


_SLUG_RE = re.compile(r"[^a-z0-9]+")


def slugify(name: str) -> str:
    """Lowercase, non-alnum runs → '-', trimmed. Dies on empty result."""
    if not name:
        die("slugify: missing name")
    slug = _SLUG_RE.sub("-", name.lower()).strip("-")
    if not slug:
        die(f"name '{name}' produced an empty slug; use alphanumeric characters")
    return slug


def build_image(ref: str, context: str, *, dockerfile: str = "") -> None:
    """Invokes `docker build` every call. Layer cache makes no-change
    rebuilds cheap; running every time means Dockerfile edits land
    without manual `docker rmi`.

    `dockerfile` is an optional path (relative to `context`, or
    absolute) for callers that need to build from a non-default
    Dockerfile in the same context — e.g. `Dockerfile.git-gate`."""
    info(f"building image {ref} from {context} (layer cache keeps repeat builds fast)")
    args = ["docker", "build", "-t", ref]
    if dockerfile:
        args.extend(["-f", dockerfile])
    args.append(context)
    subprocess.run(args, check=True)


_TRUST_DIALOG_NODE_SCRIPT = (
    'const fs=require("fs"),p=process.env.HOME+"/.claude.json",'
    'c=JSON.parse(fs.readFileSync(p,"utf8"));'
    'c.projects=c.projects||{};'
    'c.projects[process.env.HOME+"/workspace"]={hasTrustDialogAccepted:true};'
    'fs.writeFileSync(p,JSON.stringify(c,null,2));'
)


def build_image_with_cwd(derived: str, base: str, cwd: str) -> None:
    """Build a thin derived image that copies <cwd> into
    /home/node/workspace and adds a trust-dialog entry for it."""
    import os

    if not os.path.isdir(cwd):
        die(f"cwd not found at {cwd}")
    info(f"building image {derived} from {base} with {cwd} -> /home/node/workspace")
    dockerfile = (
        f"FROM {base}\n"
        f"COPY --chown=node:node . /home/node/workspace\n"
        f"RUN node -e '{_TRUST_DIALOG_NODE_SCRIPT}'\n"
        f"WORKDIR /home/node/workspace\n"
    )
    subprocess.run(
        ["docker", "build", "-t", derived, "-f", "-", cwd],
        input=dockerfile,
        text=True,
        check=True,
    )


def image_id(ref: str) -> str:
    """Return the content-addressed image ID (e.g.
    `sha256:abcd...`) for `ref`. The smolmachines backend keys its
    `.smolmachine` artifact cache on this, so a Dockerfile change
    that produces a new image automatically invalidates the cache."""
    r = subprocess.run(
        ["docker", "image", "inspect", "--format", "{{.Id}}", ref],
        capture_output=True,
        text=True,
        check=False,
    )
    if r.returncode != 0:
        die(
            f"docker image inspect for {ref!r} failed: "
            f"{(r.stderr or '').strip() or '<no stderr>'}"
        )
    return r.stdout.strip()


def save(ref: str, output: str) -> None:
    """`docker save REF -o OUTPUT`. Writes a tarball of the image
    layers + manifest to the host path. Used by smolmachines
    prepare to hand the agent image to a containerized crane that
    pushes it to the ephemeral registry — bypassing the docker
    daemon's `docker push` (which on Docker Desktop can't reach a
    host-loopback registry and refuses plain-HTTP pushes to
    non-loopback hosts)."""
    subprocess.run(["docker", "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