"""pipelock_apply — host-side helper to apply an api_allowlist
change to a running pipelock sidecar (PRD 0015).

Used by the supervise dashboard when the operator approves a
pipelock-block proposal (or runs the operator-initiated `pipelock
edit <bottle>` verb). Fetches the current pipelock.yaml via `docker
exec`, parses it, swaps the api_allowlist with the proposed hosts,
re-renders, writes back via the bind-mount path, then signals the
bundle supervisor to restart the pipelock daemon (`docker kill
--signal USR1`) so
pipelock picks up the new config.

v1 uses restart, not SIGHUP — pipelock has no in-process reload
hook and adding one is the "SIGHUP reload for pipelock" open
question in PRD 0015. Restart drops in-flight outbound calls; the
agent's HTTP client retries pick up against the restarted proxy.
"""

from __future__ import annotations

import os
import re
import subprocess
import tempfile
from pathlib import Path

from ...pipelock import pipelock_render_yaml
from ...yaml_subset import YamlSubsetError, parse_yaml_subset
from .bottle_state import pipelock_state_dir
from .sidecar_bundle import sidecar_bundle_container_name


def _pipelock_yaml_host_path(slug: str) -> Path:
    """The bind-mount source for the pipelock sidecar's
    pipelock.yaml — matches what pipelock.prepare wrote at chunk-2
    paths."""
    return pipelock_state_dir(slug) / "pipelock.yaml"


PIPELOCK_YAML_IN_CONTAINER = "/etc/pipelock.yaml"

# Allowlist proposals are one-hostname-per-line. Blank lines and
# `#`-prefixed comments are ignored. The character set matches the
# supervise sidecar's syntactic check on the agent's pipelock-block
# proposal (alphanumerics + dot/dash/underscore).
_HOST_OK = re.compile(r"^[A-Za-z0-9_.-]+$")


class PipelockApplyError(RuntimeError):
    """Raised when fetch / parse / apply fails. The dashboard renders
    the message and keeps the proposal pending — never crashes."""


def parse_allowlist_content(content: str) -> list[str]:
    """One hostname per line. Blanks and `#` comments are ignored.
    Raises PipelockApplyError if a line has a disallowed character."""
    hosts: list[str] = []
    for i, raw_line in enumerate(content.splitlines(), start=1):
        line = raw_line.strip()
        if not line or line.startswith("#"):
            continue
        if not _HOST_OK.match(line):
            raise PipelockApplyError(
                f"allowlist line {i}: {line!r} has disallowed characters"
            )
        hosts.append(line)
    return hosts


def render_allowlist_content(hosts: list[str]) -> str:
    """Hosts → one-per-line string (the operator-facing format)."""
    if not hosts:
        return ""
    return "\n".join(hosts) + "\n"


def fetch_current_yaml(slug: str) -> str:
    """Read the live /etc/pipelock.yaml from the sidecar bundle.

    Uses `docker cp` because pipelock inside the bundle is the
    distroless pipelock binary with no shell, and `docker cp` is a
    daemon-API tarball copy that works regardless of what's
    available inside the container.

    Raises PipelockApplyError if the read fails."""
    container = sidecar_bundle_container_name(slug)
    fd, tmp_path = tempfile.mkstemp(prefix="cb-pipelock-fetch.", suffix=".yaml")
    os.close(fd)
    try:
        r = subprocess.run(
            [
                "docker", "cp",
                f"{container}:{PIPELOCK_YAML_IN_CONTAINER}", tmp_path,
            ],
            capture_output=True, text=True, check=False,
        )
        if r.returncode != 0:
            raise PipelockApplyError(
                f"could not fetch pipelock.yaml from {container}: "
                f"{(r.stderr or '').strip() or 'container not running?'}"
            )
        return Path(tmp_path).read_text()
    finally:
        try:
            Path(tmp_path).unlink()
        except OSError:
            pass


def fetch_current_allowlist(slug: str) -> str:
    """Fetch the live yaml, extract api_allowlist, render as one-per-
    line — the operator-facing format for the TUI / agent's
    current-config mount."""
    yaml = fetch_current_yaml(slug)
    try:
        cfg = parse_yaml_subset(yaml)
    except YamlSubsetError as e:
        raise PipelockApplyError(f"running pipelock yaml: {e}") from e
    hosts = cfg.get("api_allowlist", [])
    if not isinstance(hosts, list):
        raise PipelockApplyError(
            "running pipelock yaml: api_allowlist is not a list"
        )
    return render_allowlist_content([str(h) for h in hosts])


def apply_allowlist_change(
    slug: str, new_allowlist_content: str,
) -> tuple[str, str]:
    """Apply `new_allowlist_content` to the sidecar bundle:
      1. Parse the proposed hosts (one per line).
      2. Fetch + parse current pipelock.yaml.
      3. Replace api_allowlist with the proposed hosts; re-render.
      4. Write the new yaml to the bind-mount source.
      5. `docker kill --signal USR1 <bundle>` so the supervisor
         restarts the pipelock daemon in place (leaving egress,
         git-gate, and supervise running). Pipelock has no
         in-process reload; the supervisor's per-daemon restart
         keeps the agent's MCP socket alive — a whole-bundle
         `docker restart` would bounce supervise too.

    Returns (before, after) where both are one-per-line allowlist
    strings (operator-facing format). Raises PipelockApplyError on
    any failure; the sidecar's existing config stays in place until
    the host write succeeds, and the SIGUSR1 is what makes it
    live."""
    new_hosts = parse_allowlist_content(new_allowlist_content)
    container = sidecar_bundle_container_name(slug)
    current_yaml = fetch_current_yaml(slug)
    try:
        cfg = parse_yaml_subset(current_yaml)
    except YamlSubsetError as e:
        raise PipelockApplyError(f"running pipelock yaml: {e}") from e
    current_hosts = cfg.get("api_allowlist", [])
    if not isinstance(current_hosts, list):
        raise PipelockApplyError(
            "running pipelock yaml: api_allowlist is not a list"
        )

    before = render_allowlist_content([str(h) for h in current_hosts])
    after = render_allowlist_content(new_hosts)

    cfg["api_allowlist"] = new_hosts
    rendered = pipelock_render_yaml(cfg)

    # pipelock.yaml is bind-mounted into the container as a SINGLE
    # FILE — same Docker single-file inode issue as egress_apply:
    # write-temp-then-rename swaps the host inode and leaves the
    # container's mount pointing at the orphaned old one. Write
    # in-place. The SIGUSR1 below makes the new content live
    # (pipelock has no in-process reload, so the supervisor
    # restarts the pipelock daemon in response).
    target = _pipelock_yaml_host_path(slug)
    target.parent.mkdir(parents=True, exist_ok=True)
    target.write_text(rendered)
    # pipelock runs as root in its distroless image — any mode is
    # fine — but 0o600 matches what prepare wrote.
    target.chmod(0o600)
    restart = subprocess.run(
        ["docker", "kill", "--signal", "USR1", container],
        capture_output=True, text=True, check=False,
    )
    if restart.returncode != 0:
        raise PipelockApplyError(
            f"failed to signal {container} for pipelock restart: "
            f"{(restart.stderr or '').strip()}"
        )

    return before, after


__all__ = [
    "PIPELOCK_YAML_IN_CONTAINER",
    "PipelockApplyError",
    "apply_allowlist_change",
    "fetch_current_allowlist",
    "fetch_current_yaml",
    "parse_allowlist_content",
    "render_allowlist_content",
]