"""Boot-time verdict for ``gateway.multiplex_profiles`` (the default is on, and there is no opt-out).

``GatewayConfig.from_dict`` leaves the flag ``None`` when neither config.yaml nor
``GATEWAY_MULTIPLEX_PROFILES`` set it. Turning the default on must not make a default gateway
double-bind a fleet that still runs per-profile gateways (two pollers on one bot token, port
fights), so the implicit default is a *request*: the gateway runs the same preflight
``hermes gateway migrate --multiplex`` runs and multiplexes only when the fold would have been
safe. An explicit ``true`` is never second-guessed.

An explicit ``false`` is RETIRED (multiplex-only ruling): it parses, it is logged, and it is then
resolved exactly like an unset key. The key itself survives because it is still the RUNTIME
mode flag every scoped code path reads (``config.multiplex_profiles``) — what it can no longer do
is pin a second gateway process onto this host.

The refusal is logged, never fatal: the gateway comes up standalone exactly as before the
default flipped, and the log names the blocker plus ``hermes gateway migrate --multiplex``.
"""

from __future__ import annotations

import logging
from dataclasses import dataclass
from pathlib import Path
from typing import Optional

logger = logging.getLogger(__name__)

SINGLE_PROFILE_REASON = "only one profile exists (nothing to multiplex)"
STANDALONE_PROFILE_REASON = "this profile is standalone (gateway.standalone: true); it serves only itself"

#: ``gateway.standalone: true`` is a TEMPORARY backwards-compatibility shim, not a supported topology.
#: It exists so fleets that lost per-profile gateways in the multiplex-only switch keep working while
#: the remaining multiplexing gaps (per-profile stop/restart, WhatsApp bridge/relay on secondaries,
#: dashboard scoping) are closed; it is removed once they are. Every surface that names the key
#: prints this so nobody builds on it.
STANDALONE_DEPRECATION_NOTICE = (
    "gateway.standalone is a temporary compatibility shim while multiplexing gaps are fixed; "
    "it will be removed once they are — plan to fold this profile with `hermes gateway migrate --multiplex`."
)

#: ``gateway.multiplex_profiles: false`` is no longer an opt-out from the one-gateway-per-host
#: topology; it parses, it is reported, and it is ignored.
RETIRED_OPT_OUT_REASON = (
    "gateway.multiplex_profiles: false is retired and was rewritten to true; one gateway per host "
    "serves every profile. A per-profile gateway is `gateway.standalone: true` in that profile's "
    "config (temporary shim) or `--force`.")

#: One-time marker the gateway leaves after rewriting a retired ``false``; ``hermes update``'s summary
#: prints the notice from it and clears it, so the flip is never silent on either surface.
REWRITTEN_MARKER_NAME = ".multiplex_opt_out_rewritten"


def explicit_multiplex_flag(default_home: Path) -> Optional[bool]:
    """The operator's explicit choice for the DEFAULT profile's gateway: a recognized
    ``GATEWAY_MULTIPLEX_PROFILES``, else ``gateway.multiplex_profiles`` (or the top-level alias) as
    written in its config.yaml; ``None`` when neither is set. Raw read on purpose: the callers are
    other processes (``hermes -p X ...`` has X's config loaded) asking about the default's file."""
    from gateway.config import _bool_token, _env_multiplex_profiles_override
    env = _env_multiplex_profiles_override()
    if env is not None:
        return env
    cfg_path = Path(default_home) / "config.yaml"
    if not cfg_path.exists():
        return None
    from hermes_cli.config import read_user_config_raw
    cfg = read_user_config_raw(cfg_path) or {}
    gateway_section = cfg.get("gateway") if isinstance(cfg.get("gateway"), dict) else {}
    value = cfg.get("multiplex_profiles")
    if value is None:
        value = gateway_section.get("multiplex_profiles")
    if value is None:
        return None
    if isinstance(value, str):
        parsed = _bool_token(value)
        return True if parsed is None else parsed
    return bool(value)


def default_gateway_multiplexes(default_home: Optional[Path] = None) -> bool:
    """Does the default profile's gateway serve every profile? For CLI/dashboard processes: the LIVE
    gateway's ``served_profiles`` record when one runs (it settled the unset default itself), else
    the explicit flag, else False — an unset flag is decided by the gateway at boot, never guessed
    here.

    The one thing that can no longer report "standalone" is an explicit ``false``: it is RETIRED
    (warned about and ignored at boot, see :func:`resolve_multiplex_mode`), so answering False from
    it made every CLI surface contradict the gateway that was about to multiplex anyway.
    """
    from hermes_constants import get_default_hermes_root
    from hermes_cli.gateway_multiplex_served import recorded_served_profiles
    root = Path(default_home) if default_home is not None else get_default_hermes_root()
    recorded = recorded_served_profiles(root)
    if recorded is not None:
        return bool(recorded)
    flag = explicit_multiplex_flag(root)
    return False if flag is None else True


@dataclass(frozen=True)
class MultiplexDecision:
    enabled: bool
    # "config" (config.yaml / env override — explicit), "default" (implicit default applied),
    # "guard" (implicit default refused; ``reason`` names the blocker).
    source: str
    reason: str = ""


def _standalone_launcher() -> bool:
    from hermes_constants import get_hermes_home, profile_name_for_home
    from hermes_cli.profiles import profile_is_standalone

    home = get_hermes_home()
    return profile_name_for_home(home) not in (None, "default") and profile_is_standalone(home)


def standalone_launcher_decision(config) -> Optional[MultiplexDecision]:
    """The per-profile opt-out also binds callers supplying an explicit GatewayConfig."""
    if not _standalone_launcher():
        return None
    config.multiplex_profiles = False
    return MultiplexDecision(False, "guard", STANDALONE_PROFILE_REASON)


def implicit_multiplex_blocker() -> Optional[str]:
    """Why THIS process must not multiplex right now, or None when it may.

    Mirrors what makes ``hermes gateway migrate --multiplex`` refuse or leave a per-profile gateway
    in place: hosts whose per-profile gateways the preflight cannot see (s6 slots) stay standalone;
    a secondary that still runs its own gateway (live process or installed service) or a preflight
    blocker (duplicate bot credential, port binder without a ``/p/<profile>/`` ingress) keeps this
    gateway standalone.

    Every blocker here is a TRANSIENT, fixable condition, which is why this function is now also
    the whole answer for an explicit ``gateway.multiplex_profiles: false`` (see
    :func:`resolve_multiplex_mode`): the host converges the moment the blocker is gone.

    The launching profile's IDENTITY is deliberately not a blocker: multiplex-only means "the one
    host process", whichever profile started it. Gating on ``active == 'default'`` made a host
    whose only gateway runs under a named profile permanently standalone — and every lifecycle
    verb built on "the default's multiplexer" blind to the process actually serving the host.
    """
    from hermes_cli.profiles import profiles_to_serve
    if _standalone_launcher():
        return STANDALONE_PROFILE_REASON
    # Cheap and first: a single-profile install has nothing to multiplex, and the fail-closed secret
    # scope the multiplexer arms buys it nothing. (Also keeps every embedded/test runner off the
    # service-manager probes below.) Create a second profile and restart to start serving it.
    # Parking is reversible without a host restart, so keep the reconcile watcher alive.
    if len(profiles_to_serve(multiplex=True, include_parked=True)) < 2:
        return SINGLE_PROFILE_REASON
    from hermes_cli.gateway_migrate import MIGRATE_COMMAND, _host_supports_migration, build_migration_plan
    host_reason = _host_supports_migration()
    if host_reason:
        return host_reason
    plan = build_migration_plan()
    if plan.standalone_secondaries:
        owned = ", ".join(
            f"'{p.name}' ({'pid ' + str(p.pid) if p.pid else p.service_label()})"
            for p in plan.standalone_secondaries)
        return f"profile(s) {owned} still run their own gateway; fold them with `{MIGRATE_COMMAND}`"
    if plan.blocked:
        return "; ".join(plan.blockers)
    return None


def _default_profile_home() -> Path:
    from hermes_constants import get_default_hermes_root
    return get_default_hermes_root()


def persist_resolved_default(decision: MultiplexDecision, default_home: Optional[Path] = None) -> bool:
    """Write ``gateway.multiplex_profiles: true`` into the DEFAULT profile's config.yaml so the file
    reads as the gateway behaves. The key has ONE valid value right now (Teknium ruling): an unset key
    is made explicit ("left unset" was read as "off"), a retired ``false`` is rewritten in place and
    leaves a one-time marker for the boxed notice. Comment-preserving writer, once, and NEVER on a guard
    refusal (the file must not say true while the runtime is standalone). Returns True on a write."""
    if not decision.enabled or decision.source == "guard":
        return False
    default_home = Path(default_home) if default_home is not None else _default_profile_home()
    cfg_path = default_home / "config.yaml"
    try:
        from hermes_cli.config import read_user_config_raw
        cfg = read_user_config_raw(cfg_path) or {} if cfg_path.exists() else {}
        section = cfg.get("gateway") if isinstance(cfg.get("gateway"), dict) else {}
        in_file = cfg.get("multiplex_profiles", section.get("multiplex_profiles"))
        if in_file is True:
            return False
        from hermes_cli.gateway_migrate import _write_multiplex_flag
        _write_multiplex_flag(default_home, True)
        if decision.source == "retired-opt-out":
            (default_home / REWRITTEN_MARKER_NAME).write_text(RETIRED_OPT_OUT_REASON + "\n", encoding="utf-8")
    except Exception:
        logger.debug("could not persist gateway.multiplex_profiles: true", exc_info=True)
        return False
    logger.info("Wrote gateway.multiplex_profiles: true to %s (was %s).", cfg_path,
                "unset" if in_file is None else repr(in_file))
    return True


def retired_opt_out_notice_lines() -> list[str]:
    """The one-time boxed notice for a rewritten ``false`` (same box as the guard warning)."""
    return _box(["⚠ gateway.multiplex_profiles: false is retired and was rewritten to true;",
                 "one gateway per host serves every profile.",
                 "A per-profile gateway is `gateway.standalone: true` in that profile's config",
                 "(temporary shim) or `--force`."])


def consume_rewritten_notice(default_home: Optional[Path] = None) -> list[str]:
    """``hermes update``'s summary: print the rewrite notice ONCE more, then clear the marker."""
    default_home = Path(default_home) if default_home is not None else _default_profile_home()
    marker = default_home / REWRITTEN_MARKER_NAME
    if not marker.exists():
        return []
    try:
        marker.unlink()
    except OSError:
        return []
    return retired_opt_out_notice_lines()


def _box(body: list[str]) -> list[str]:
    width = max(len(line) for line in body) + 2
    return ["┌" + "─" * width + "┐",
            *[f"│ {line.ljust(width - 1)}│" for line in body],
            "└" + "─" * width + "┘"]


def resolve_multiplex_mode(config) -> MultiplexDecision:
    """Settle ``config.multiplex_profiles`` for one gateway boot; the config is updated in place.

    ``gateway.multiplex_profiles: false`` is RETIRED as a topology opt-out (multiplex-only ruling).
    The key still parses and still drives the runtime mode this function writes back, but an
    explicit ``false`` no longer pins a per-profile fleet: it is warned about and resolved exactly
    like an unset key. That is safe because the unset path is not optimistic — it refuses to
    multiplex while any real blocker holds (an s6 container, a secondary that still owns a gateway,
    a duplicate bot credential), so a host that genuinely cannot fold still comes up standalone and
    says why, and it converges by itself once ``hermes gateway migrate --multiplex`` has run.
    """
    current = getattr(config, "multiplex_profiles", None)
    standalone = standalone_launcher_decision(config)
    if standalone is not None:
        return standalone
    if current:
        return MultiplexDecision(True, "config")
    retired_opt_out = current is False
    try:
        blocker = implicit_multiplex_blocker()
    except Exception as exc:  # a broken preflight must not take the gateway down with it
        logger.warning("Multiplex preflight failed; starting standalone: %s", exc, exc_info=True)
        blocker = f"preflight failed ({exc})"
    if blocker:
        decision = MultiplexDecision(False, "guard", blocker)
    elif retired_opt_out:
        decision = MultiplexDecision(True, "retired-opt-out", RETIRED_OPT_OUT_REASON)
    else:
        decision = MultiplexDecision(True, "default", "gateway.multiplex_profiles unset; default applies")
    config.multiplex_profiles = decision.enabled
    return decision


def record_multiplex_decision(decision: MultiplexDecision) -> None:
    """Persist a guard refusal into ``gateway_state.json`` so `hermes gateway status` can show why this
    gateway serves one profile while the default says multiplex; any other verdict clears the field."""
    try:
        from gateway.status import write_runtime_status
        write_runtime_status(multiplex_standalone_reason=decision.reason if decision.source == "guard" else None)
    except Exception:
        logger.debug("could not record the multiplex decision", exc_info=True)


def log_multiplex_decision(decision: MultiplexDecision) -> None:
    record_multiplex_decision(decision)
    if decision.source == "retired-opt-out":
        logger.warning("%s", RETIRED_OPT_OUT_REASON)
        persist_resolved_default(decision)
        for line in retired_opt_out_notice_lines():
            print(line)
    elif decision.source == "guard" and decision.reason == SINGLE_PROFILE_REASON:
        logger.info("Single-profile install: gateway.multiplex_profiles unset, serving the default profile only.")
    elif decision.source == "guard":
        logger.warning(
            "This gateway stays standalone: %s. It serves only the launching profile.",
            decision.reason)
        for line in standalone_warning_lines(decision):
            print(line)
    elif decision.source == "default":
        logger.info("Serving every profile on this host (gateway.multiplex_profiles unset; default on).")
        persist_resolved_default(decision)


def unserved_profiles() -> list[str]:
    """Named profiles a standalone gateway leaves without a bot (the whole point of the warning)."""
    from hermes_constants import get_hermes_home, profile_name_for_home
    from hermes_cli.profiles import profiles_to_serve
    me = profile_name_for_home(get_hermes_home()) or "default"
    return [name for name, _home in profiles_to_serve(multiplex=True, include_parked=True) if name != me]


def standalone_warning_lines(decision: MultiplexDecision, unserved: Optional[list[str]] = None) -> list[str]:
    """The boxed warning a multi-profile host prints when a guard keeps its gateway standalone.

    Empty for anything but a guard refusal on a host with other profiles to serve: a single-profile
    install has nothing unserved, so there is nothing to shout about. The same box appears at
    gateway start, in the ``hermes update`` summary and (as text) in the dashboard banner.
    """
    if decision.source != "guard" or decision.reason == SINGLE_PROFILE_REASON:
        return []
    if unserved is None:
        try:
            unserved = unserved_profiles()
        except Exception:
            unserved = []
    if not unserved:
        return []
    from hermes_cli.gateway_migrate import MIGRATE_COMMAND
    body = [
        "⚠ This gateway is STANDALONE: it serves only its own profile.",
        "Profiles NOT served (their bots stay silent): " + ", ".join(unserved),
        f"Why: {decision.reason}",
        f"Fix: {MIGRATE_COMMAND}",
    ]
    return _box(body)


def recorded_standalone_warning_lines() -> list[str]:
    """Same box, rebuilt from the live gateway's ``gateway_state.json`` for processes that did not
    make the decision (``hermes update``'s summary, ``hermes gateway status``)."""
    try:
        from gateway.status import read_runtime_status, runtime_status_pid_is_live
        record = read_runtime_status() or {}
        if record.get("gateway_state") in (None, "stopped", "startup_failed"):
            return []
        # Liveness is the state + a live PID, never the heartbeat: a paused or wedged gateway is
        # still the standalone process the box warns about (#120991).
        if not runtime_status_pid_is_live(record):
            return []
        reason = record.get("multiplex_standalone_reason")
    except Exception:
        return []
    if not reason:
        return []
    return standalone_warning_lines(MultiplexDecision(False, "guard", str(reason)))