"""Blocking gateway approval wait for :mod:`tools.approval`.

Mirrors the CLI's synchronous ``input()`` flow: the agent thread enqueues a
pending approval, the gateway notifies the user, and the thread blocks until
``/approve`` / ``/deny`` resolves it or the approval timeout elapses. Multiple
threads (parallel subagents, execute_code RPC handlers) can block concurrently
— each gets its own ``threading.Event``; ``/approve`` resolves the oldest,
``/approve all`` every pending entry.

Queue state (``_gateway_queues``, ``_lock``) is owned by ``tools.approval`` and
reached through that module at call time so tests patching it keep working.
"""

import logging
import threading
import time
import uuid
from typing import Optional

from tools.interrupt import is_interrupted

logger = logging.getLogger("tools.approval")


class _ApprovalEntry:
    """One pending dangerous-command approval inside a gateway session."""
    __slots__ = ("event", "data", "result", "reason", "acknowledged")

    def __init__(self, data: dict):
        self.event = threading.Event()
        self.data = dict(data)
        self.data.setdefault("request_id", uuid.uuid4().hex)
        self.acknowledged = False
        self.result: Optional[str] = None  # "once"|"session"|"always"|"deny"
        # Free-text reason from ``/deny <reason>`` so the agent can adapt
        # instead of only hearing "denied".
        self.reason: Optional[str] = None


def _hook_payload(approval_data: dict, session_key: str, surface: str) -> dict:
    primary_key = approval_data.get("pattern_key", "")
    return {
        "command": approval_data.get("command", ""),
        "description": approval_data.get("description", ""),
        "pattern_key": primary_key,
        "pattern_keys": list(approval_data.get("pattern_keys", [primary_key])),
        "session_key": session_key,
        "surface": surface,
    }


def _hook_outcome(resolved: bool, choice: Optional[str]) -> str:
    """Unresolved (timeout) and a None choice both mean the user never answered."""
    return "timeout" if not resolved else (choice or "timeout")


def _poll_event(event: threading.Event, session_key: str, *, interrupt_log: str) -> str:
    """Wait on *event* until it fires, the turn is interrupted, or approvals.timeout elapses.

    Returns ``"set"`` | ``"interrupted"`` | ``"timeout"``. Polls in ~1s slices
    so activity heartbeats reach the agent's inactivity tracker every ~10s —
    otherwise the gateway watchdog kills the agent while the user is still
    responding (mirrors ``_wait_for_process()`` cadence). The loop is recorded
    as human-wait time so the concurrent batch deadline excludes it (#79719).

    ``is_interrupted()`` deliberately does NOT distinguish a deliberate /stop
    from a gateway inactivity timeout — both resolve as 'deny' (not
    outcome='timeout'). The per-thread interrupt flag carries no stable
    machine-checkable cause, so a fail-closed deny preserves #8697 semantics;
    changing this needs a dedicated interrupt-cause channel, not string
    matching (#85125).
    """
    from tools.approval import _get_approval_timeout, human_wait_window

    timeout = _get_approval_timeout()
    try:
        from tools.environments.base import touch_activity_if_due
    except Exception:  # pragma: no cover
        touch_activity_if_due = None
    now = time.monotonic()
    deadline = now + max(timeout, 0)
    activity_state = {"last_touch": now, "start": now}
    with human_wait_window(session_key):
        while True:
            if is_interrupted():
                logger.info(interrupt_log, session_key)
                return "interrupted"
            remaining = deadline - time.monotonic()
            if remaining <= 0:
                return "timeout"
            if event.wait(timeout=min(1.0, remaining)):
                return "set"
            if touch_activity_if_due is not None:
                touch_activity_if_due(activity_state, "waiting for user approval")


def _await_coalesced_leader(session_key: str, leader, approval_data: dict,
                            *, surface: str = "gateway"):
    """Wait on an already-pending identical approval instead of re-prompting.

    Adopts the leader's decision: ``session``/``always`` → approval (same dict
    shape as a direct resolution; persistence stays the caller's and is
    idempotent across leader and followers); ``deny`` → denial carrying the
    leader's reason; leader timeout / our own deadline → unresolved. ``once``
    returns ``None``: single-use consent covers only the leader's execution,
    so the caller must issue a fresh prompt. Hooks fire with ``coalesced=True``
    so observers see the follower's lifecycle without a duplicate prompt.
    """
    from tools.approval import _fire_approval_hook

    payload = _hook_payload(approval_data, session_key, surface)
    _fire_approval_hook("pre_approval_request", **payload, coalesced=True)

    state = _poll_event(
        leader.event, session_key,
        interrupt_log="Coalesced approval wait interrupted by user signal — "
                      "returning deny for session %s",
    )
    if state == "interrupted":
        # Deny only OUR follower; the leader thread handles its own signal.
        choice, resolved = "deny", True
    elif state == "timeout":
        choice, resolved = None, False
    else:
        choice = leader.result
        resolved = choice is not None

    if choice == "once":
        # The post hook fires for the fresh prompt's own lifecycle, not here.
        return None
    _fire_approval_hook(
        "post_approval_response", **payload,
        choice=_hook_outcome(resolved, choice), coalesced=True,
    )
    return {
        "resolved": resolved,
        "choice": choice,
        "reason": getattr(leader, "reason", None),
        "coalesced": True,
    }


def _await_gateway_decision(session_key: str, notify_cb, approval_data: dict,
                            *, surface: str = "gateway") -> dict:
    """Enqueue *approval_data*, notify the user, and block until resolved or timed out.

    Shared by the terminal command guard, the execute_code guard, the plugin
    escalation gate, and MCP elicitation. Returns ``{"resolved", "choice",
    "reason"}`` or ``{"resolved": False, "choice": None, "notify_failed": True}``
    when the notify callback raised. Persisting the choice and building the
    tool-facing result stay with the caller.

    Identical concurrent approvals (same command text + pattern-key set) are
    coalesced: parallel tool calls would otherwise fire N identical prompts
    the user must /approve N times while the agent sits wedged. Followers adopt
    the leader's ``session``/``always``/``deny``/timeout; a ``once`` covers only
    the leader, so the follower falls through to a fresh prompt.
    """
    from tools import approval as _approval

    payload = _hook_payload(approval_data, session_key, surface)

    leader = None
    with _approval._lock:
        for existing in _approval._gateway_queues.get(session_key, []):
            data = existing.data
            if (
                data.get("command") == approval_data.get("command")
                and list(data.get("pattern_keys") or [])
                == list(approval_data.get("pattern_keys") or [])
            ):
                leader = existing
                break
    if leader is not None:
        adopted = _await_coalesced_leader(
            session_key, leader, approval_data, surface=surface
        )
        if adopted is not None:
            return adopted

    entry = _ApprovalEntry(approval_data)
    with _approval._lock:
        _approval._gateway_queues.setdefault(session_key, []).append(entry)

    def _drop_entry() -> None:
        with _approval._lock:
            queue = _approval._gateway_queues.get(session_key, [])
            if entry in queue:
                queue.remove(entry)
            if not queue:
                _approval._gateway_queues.pop(session_key, None)

    # Plugins hear about the request before the gateway does (real-time observers).
    _approval._fire_approval_hook("pre_approval_request", **payload)

    # Bridges sync agent thread → async gateway.
    try:
        notify_cb(dict(entry.data))
    except Exception as exc:
        logger.warning("Gateway approval notify failed: %s", exc)
        _drop_entry()
        _approval._fire_approval_hook(
            "post_approval_response", **payload, choice="notify_failed"
        )
        return {"resolved": False, "choice": None, "notify_failed": True}

    state = _poll_event(
        entry.event, session_key,
        interrupt_log="Approval wait interrupted by user signal — "
                      "returning deny for session %s",
    )
    if state == "interrupted":
        entry.result = "deny"
        entry.event.set()
    resolved = state != "timeout"
    _drop_entry()

    choice = entry.result
    _approval._fire_approval_hook(
        "post_approval_response", **payload, choice=_hook_outcome(resolved, choice)
    )
    return {"resolved": resolved, "choice": choice, "reason": entry.reason}