"""Single source of truth for the agent working directory.

`TERMINAL_CWD` is the runtime carrier for the configured working directory
(`terminal.cwd` is bridged to it once at gateway/cron startup; the local CLI
leaves it unset and relies on the launch dir). Reading it in one place keeps the
system prompt, tool surfaces, and context-file discovery agreeing on where the
agent lives. Multi-session gateways can pin a logical cwd via `_SESSION_CWD`.
"""

import logging
import os
from contextvars import ContextVar, Token
from pathlib import Path
from typing import Any

logger = logging.getLogger(__name__)

_UNSET: Any = object()

_SESSION_CWD: ContextVar = ContextVar("HERMES_SESSION_CWD", default=_UNSET)

# The package/source root (<root>/agent/runtime_cwd.py). A backend launched from
# or self-spawned into this tree (desktop default) must never let an os.getcwd()
# fallback inject this repo's contributor AGENTS.md as project context.
_PACKAGE_ROOT = Path(__file__).resolve().parent.parent


def _is_install_tree(p: Path) -> bool:
    """True only when ``p`` IS the package root or sits inside it — ancestors
    (a home dir containing the checkout) are legitimate workspaces."""
    try:
        p = p.resolve()
    except Exception:
        return False
    return p == _PACKAGE_ROOT or _PACKAGE_ROOT in p.parents


def set_session_cwd(cwd: str | None) -> Token:
    """Pin the logical cwd for the current context."""
    return _SESSION_CWD.set((cwd or "").strip())


def clear_session_cwd() -> None:
    _SESSION_CWD.set("")


def _session_cwd_override() -> str:
    value = _SESSION_CWD.get()
    if value is _UNSET:
        return ""
    return str(value).strip()


def _terminal_cwd_env() -> str:
    """Scope-aware TERMINAL_CWD read (tools.terminal_scope.terminal_env).

    Under gateway multiplexing the per-turn terminal scope carries the active
    profile's cwd; the process-global env var may hold another profile's. Only
    an ImportError falls back: an active refusal scope must raise, not silently
    resolve the launch profile's cwd.
    """
    try:
        from tools.terminal_scope import terminal_env
    except ImportError:
        return os.environ.get("TERMINAL_CWD", "")
    return terminal_env("TERMINAL_CWD", "")


def scope_terminal_cwd() -> str:
    """Public wrapper — the scope-aware TERMINAL_CWD value (may be empty).

    Shared by agent_init / skill_utils / code_execution_tool so every cwd consumer
    reads through the per-turn terminal scope under gateway multiplexing.
    """
    return _terminal_cwd_env()


def _resolve_configured_cwd(*, override_is_final: bool) -> Path | None:
    """Session override, then TERMINAL_CWD; each validated as a real directory.

    ``override_is_final``: a set-but-missing session override yields None
    instead of falling through to TERMINAL_CWD.
    """
    override = _session_cwd_override()
    if override:
        p = Path(override).expanduser()
        if p.is_dir():
            return p
        logger.warning("configured working directory does not exist: %s", override)
        if override_is_final:
            return None
    raw = _terminal_cwd_env().strip()
    if raw:
        p = Path(raw).expanduser()
        if p.is_dir():
            return p
        logger.warning("TERMINAL_CWD does not exist: %s", raw)
    return None


def resolve_agent_cwd() -> Path:
    """Configured cwd, else the launch dir (os.getcwd() — its OSError on a
    deleted cwd deliberately propagates; the caller owns that guard)."""
    p = _resolve_configured_cwd(override_is_final=False)
    return p if p is not None else Path(os.getcwd())


def resolve_context_cwd() -> Path | None:
    """Configured cwd for context-file discovery, or None for "no configured cwd".

    None makes build_context_files_prompt fall back to the launch dir (correct
    for a local CLI launched inside a real project). A configured path is
    validated here; an existing one is honored verbatim — including the Hermes
    source tree itself, a legitimate workspace when developing Hermes
    (fallback-directory policy lives in build_context_files_prompt).
    """
    return _resolve_configured_cwd(override_is_final=True)