"""File passthrough registry for remote terminal backends.

Remote backends (Docker, Modal, SSH) create sandboxes with no host files.
This module tells them which credential files (skill ``required_credential_files``
+ ``terminal.credential_files`` config), skill directories, and host-side cache
directories (documents, images, audio, screenshots, uploads) to mount or sync
in, at sandbox creation and before each command (resync on Modal).
"""

from __future__ import annotations

import logging
import os
import posixpath
from contextvars import ContextVar
from pathlib import Path
from typing import Dict, Iterator, List, Optional, Tuple

from hermes_cli.config import cfg_get
from hermes_constants import get_hermes_dir, get_hermes_home

from agent.skill_utils import EXCLUDED_SKILL_DIRS

try:  # pragma: no cover - exercised via the fail-closed test below
    from agent.file_safety import get_read_block_error
except ImportError:  # noqa: F401 - sentinel consumed in register_credential_file
    get_read_block_error = None  # type: ignore[assignment]

logger = logging.getLogger(__name__)

# Session-scoped registry; ContextVar prevents cross-session bleed in the gateway.
_registered_files_var: ContextVar[Dict[str, str]] = ContextVar("_registered_files")

# Cache for config-based file list (loaded once per process).
_config_files: List[Dict[str, str]] | None = None


def _get_registered() -> Dict[str, str]:
    try:
        return _registered_files_var.get()
    except LookupError:
        val: Dict[str, str] = {}
        _registered_files_var.set(val)
        return val


def _mount(host_path: Path | str, container_path: str) -> Dict[str, str]:
    return {"host_path": str(host_path), "container_path": container_path}


def _contained_host_path(
    rel: str, hermes_home: Path, abs_msg: str, traversal_msg: str
) -> Optional[Path]:
    """Resolve *rel* under HERMES_HOME, refusing absolute paths and escapes."""
    if os.path.isabs(rel):
        logger.warning(abs_msg, rel)
        return None
    host_path = hermes_home / rel
    # Resolve symlinks and ``..`` before the containment check.
    from tools.path_security import validate_within_dir

    containment_error = validate_within_dir(host_path, hermes_home)
    if containment_error:
        logger.warning(traversal_msg, rel, containment_error)
        return None
    return host_path.resolve()


def register_credential_file(
    relative_path: str,
    container_base: str = "/root/.hermes",
) -> bool:
    """Register a HERMES_HOME-relative credential file for mounting.

    Returns True if the file exists on the host and was registered. Rejects
    absolute paths and traversal out of HERMES_HOME. Containment alone is not
    enough because HERMES_HOME holds the MASTER stores (``.env``, ``auth.json``,
    ``mcp-tokens/``): those are refused via the canonical read deny-list
    (``agent.file_safety.get_read_block_error``), so the mount surface cannot
    hand a skill what the read surface denies it.
    """
    resolved = _contained_host_path(
        relative_path,
        get_hermes_home(),
        "credential_files: rejected absolute path %r (must be relative to HERMES_HOME)",
        "credential_files: rejected path traversal %r (%s)",
    )
    if resolved is None:
        return False
    if not resolved.is_file():
        logger.debug("credential_files: skipping %s (not found)", resolved)
        return False

    # Master stores pass the containment check above, so the deny-list is the
    # real gate. Fails CLOSED: if the guard can't be consulted, refuse rather
    # than risk bind-mounting auth.json into a sandbox; the import sentinel +
    # logger.exception keep guard failures debuggable, not silently swallowed.
    if get_read_block_error is None:
        logger.error(
            "credential_files: refusing %r — agent.file_safety could not be "
            "imported, so the master-store deny-list cannot be consulted",
            relative_path,
        )
        return False
    try:
        denied = get_read_block_error(str(resolved))
    except Exception:
        logger.exception(
            "credential_files: refusing %r — read guard raised", relative_path
        )
        return False
    if denied:
        logger.warning(
            "credential_files: refused %r — it is a credential store the agent "
            "is denied from reading; a skill may mount its own service token, "
            "not the master key files",
            relative_path,
        )
        return False

    container_path = f"{container_base.rstrip('/')}/{relative_path}"
    _get_registered()[container_path] = str(resolved)
    logger.debug("credential_files: registered %s -> %s", resolved, container_path)
    return True


def register_credential_files(
    entries: list,
    container_base: str = "/root/.hermes",
) -> List[str]:
    """Register skill-frontmatter entries (str or dict with ``path``); return missing paths."""
    missing = []
    for entry in entries:
        if isinstance(entry, str):
            rel_path = entry.strip()
        elif isinstance(entry, dict):
            rel_path = (entry.get("path") or entry.get("name") or "").strip()
        else:
            continue
        if rel_path and not register_credential_file(rel_path, container_base):
            missing.append(rel_path)
    return missing


def _load_config_files() -> List[Dict[str, str]]:
    """Load ``terminal.credential_files`` from config.yaml (cached)."""
    global _config_files
    if _config_files is not None:
        return _config_files

    result: List[Dict[str, str]] = []
    try:
        from hermes_cli.config import read_raw_config
        hermes_home = get_hermes_home()
        cred_files = cfg_get(read_raw_config(), "terminal", "credential_files")
        for item in cred_files if isinstance(cred_files, list) else []:
            if not (isinstance(item, str) and item.strip()):
                continue
            rel = item.strip()
            resolved_path = _contained_host_path(
                rel,
                hermes_home,
                "credential_files: rejected absolute config path %r",
                "credential_files: rejected config path traversal %r (%s)",
            )
            if resolved_path is not None and resolved_path.is_file():
                result.append(_mount(resolved_path, f"/root/.hermes/{rel}"))
    except Exception as e:
        logger.warning("Could not read terminal.credential_files from config: %s", e)

    _config_files = result
    return _config_files


def get_credential_file_mounts() -> List[Dict[str, str]]:
    """Skill-registered + config credential files as ``host_path``/``container_path`` dicts."""
    mounts: Dict[str, str] = {}

    # Re-check existence (file may have been deleted since registration).
    for container_path, host_path in _get_registered().items():
        if Path(host_path).is_file():
            mounts[container_path] = host_path

    for entry in _load_config_files():
        cp = entry["container_path"]
        if cp not in mounts and Path(entry["host_path"]).is_file():
            mounts[cp] = entry["host_path"]

    return [_mount(hp, cp) for cp, hp in mounts.items()]


# --- Skills directory mounts ---

def _skill_dir_roots(container_base: str) -> Iterator[Tuple[Path, str]]:
    """Yield ``(host_dir, container_root)`` for every existing skills directory.

    Local skills mount at ``<base>/skills``, external dirs at
    ``<base>/external_skills/<i>``, trusted project-local dirs at
    ``<base>/project_skills/<i>`` (separate namespace so container paths stay
    stable if external_dirs change).
    """
    base = container_base.rstrip("/")
    skills_dir = get_hermes_home() / "skills"
    if skills_dir.is_dir():
        yield skills_dir, f"{base}/skills"
    try:
        from agent.skill_utils import get_external_skills_dirs, get_project_skills_dirs
    except ImportError:
        return
    for label, dirs in (("external_skills", get_external_skills_dirs()),
                        ("project_skills", get_project_skills_dirs())):
        for idx, d in enumerate(dirs):
            if d.is_dir():
                yield d, f"{base}/{label}/{idx}"


def _iter_regular_files(host_dir: Path, container_root: str) -> Iterator[Dict[str, str]]:
    """Per-file mount entries under *host_dir*, skipping symlinks."""
    for item in host_dir.rglob("*"):
        if item.is_symlink() or not item.is_file():
            continue
        yield _mount(item, f"{container_root}/{item.relative_to(host_dir)}")


def get_skills_directory_mount(
    container_base: str = "/root/.hermes",
) -> list[Dict[str, str]]:
    """Directory mount entries for all skill dirs (local + external + project).

    Bind mounts follow symlinks, so a dir containing any symlink is replaced by
    a sanitized temp copy (regular files only); symlink-free dirs are returned
    directly with zero overhead.
    """
    return [
        _mount(_safe_skills_path(host_dir), container_path)
        for host_dir, container_path in _skill_dir_roots(container_base)
    ]


_safe_skills_tempdir: Path | None = None


def _safe_skills_path(skills_dir: Path) -> str:
    """Return *skills_dir* if symlink-free, else a sanitized temp copy."""
    global _safe_skills_tempdir

    symlinks = [p for p in skills_dir.rglob("*") if p.is_symlink()]
    if not symlinks:
        return str(skills_dir)

    for link in symlinks:
        logger.warning("credential_files: skipping symlink in skills dir: %s -> %s",
                       link, os.readlink(link))

    import atexit
    import shutil
    import tempfile

    # Reuse the same temp dir across calls to avoid accumulation.
    if _safe_skills_tempdir and _safe_skills_tempdir.is_dir():
        shutil.rmtree(_safe_skills_tempdir, ignore_errors=True)

    safe_dir = Path(tempfile.mkdtemp(prefix="hermes-skills-safe-"))
    _safe_skills_tempdir = safe_dir

    # Same exclusion rule as the per-file sync path (_iter_syncable_files):
    # the sanitized copy is what gets mounted, so it must not carry the
    # bookkeeping trees either. Prune before descending so a multi-GB
    # .curator_backups is never even walked.
    for dirpath, dirnames, filenames in os.walk(skills_dir):
        dirnames[:] = sorted(d for d in dirnames if d not in EXCLUDED_SKILL_DIRS)
        base = Path(dirpath)
        (safe_dir / base.relative_to(skills_dir)).mkdir(parents=True, exist_ok=True)
        for name in filenames:
            item = base / name
            if item.is_symlink() or not item.is_file():
                continue
            shutil.copy2(str(item), str(safe_dir / item.relative_to(skills_dir)))

    def _cleanup():
        if safe_dir.is_dir():
            shutil.rmtree(safe_dir, ignore_errors=True)

    atexit.register(_cleanup)
    logger.info("credential_files: created symlink-safe skills copy at %s", safe_dir)
    return str(safe_dir)


def _iter_syncable_files(root: Path):
    """Yield ``(path, rel)`` for every regular, non-symlink file under *root*
    that a sandbox should receive.

    Prunes ``agent.skill_utils.EXCLUDED_SKILL_DIRS`` *before* descending, so
    the walk never enters local bookkeeping and dependency trees (``.hub``
    download cache, ``.archive``, ``.curator_backups``, ``node_modules``,
    ``__pycache__``, ``.git``, ...) that the remote agent never reads — the
    sync path agrees with discovery on what counts as skill content.

    This deliberately does not use ``is_excluded_skill_path()``, which also
    prunes ``references/``, ``templates/``, ``assets/`` and ``scripts/``.
    Those hold progressive-disclosure support files and bundled scripts the
    sandbox does execute, so they must keep syncing.
    """
    for dirpath, dirnames, filenames in os.walk(root):
        dirnames[:] = sorted(d for d in dirnames if d not in EXCLUDED_SKILL_DIRS)
        base = Path(dirpath)
        for name in filenames:
            item = base / name
            if item.is_symlink() or not item.is_file():
                continue
            yield item, item.relative_to(root)


def iter_skills_files(
    container_base: str = "/root/.hermes",
) -> List[Dict[str, str]]:
    """Per-file entries for all skills files (for backends that upload individually).

    Skips symlinks and anything under EXCLUDED_SKILL_DIRS (see _iter_syncable_files).
    """
    return [
        _mount(item, f"{container_root}/{rel}")
        for host_dir, container_root in _skill_dir_roots(container_base)
        for item, rel in _iter_syncable_files(host_dir)
    ]


# --- Cache directory mounts (documents, images, audio, videos, screenshots) ---

# (new_subpath, old_name) pairs matching hermes_constants.get_hermes_dir().
_CACHE_DIRS: list[tuple[str, str]] = [
    ("cache/documents", "document_cache"),
    ("cache/images", "image_cache"),
    ("cache/audio", "audio_cache"),
    ("cache/videos", "video_cache"),
    ("cache/screenshots", "browser_screenshots"),
    ("cache/web", "web_cache"),
    ("cache/delegation", "delegation_cache"),
    # Oversized tool results (tools/tool_result_storage.py); host side is the
    # single canonical location.
    ("cache/spillover", "cache/spillover"),
    # Flat top-level desktop staging dirs (tui_gateway attach RPCs), not under
    # cache/; no legacy alias, so both slots match. Mounted so vision / file
    # tools inside sandbox containers can reach uploads and dropped files.
    ("images", "images"),
    ("attachments", "attachments"),
]


def _cache_dir_roots(container_base: str, *, create_missing: bool) -> Iterator[Tuple[Path, str]]:
    """Yield ``(host_dir, container_root)`` per cache dir; always maps to the *new* container layout."""
    base = container_base.rstrip("/")
    for new_subpath, old_name in _CACHE_DIRS:
        host_dir = get_hermes_dir(new_subpath, old_name)
        if not host_dir.is_dir():
            if not create_missing:
                continue
            # Docker snapshots this list at container CREATION, so a dir that
            # appears later would dangle for the container's life: create it
            # now; an empty bind mount costs nothing. get_hermes_dir already
            # picked new-vs-legacy, so creating its answer can't shadow a
            # populated legacy dir.
            try:
                host_dir.mkdir(parents=True, exist_ok=True)
            except OSError:
                continue  # unwritable home (tests, RO mounts) — skip as before
        yield host_dir, f"{base}/{new_subpath}"


def get_cache_directory_mounts(
    container_base: str = "/root/.hermes",
) -> List[Dict[str, str]]:
    """Bind-mount entries for each cache directory (host layout via ``get_hermes_dir``)."""
    return [_mount(h, c) for h, c in _cache_dir_roots(container_base, create_missing=True)]


def map_cache_path_to_container(
    host_path: str,
    container_base: str = "/root/.hermes",
) -> Optional[str]:
    """POSIX container path for a host path under an auto-mounted cache dir, else None."""
    path = Path(host_path)
    for mount in get_cache_directory_mounts(container_base=container_base):
        try:
            rel = path.relative_to(mount["host_path"])
        except ValueError:
            continue
        return posixpath.join(mount["container_path"], rel.as_posix())
    return None


def from_agent_visible_cache_path(
    container_path: str,
    container_base: str = "/root/.hermes",
) -> str:
    """Inverse of :func:`to_agent_visible_cache_path`; unchanged unless Docker + cache dir."""
    if os.environ.get("TERMINAL_ENV", "local") != "docker":
        return container_path

    path = Path(container_path)
    for mount in get_cache_directory_mounts(container_base=container_base):
        try:
            rel = path.relative_to(mount["container_path"])
        except ValueError:
            continue
        return str(Path(mount["host_path"]) / rel)
    return container_path


# Backends whose file-sync lands under the remote home: ``~/.hermes`` is
# expanded by the remote shell, so it resolves regardless of the actual home.
_HOME_RELATIVE_BACKENDS = frozenset({"ssh", "daytona", "vercel_sandbox"})


def to_agent_visible_cache_path(
    host_path: str,
    container_base: str = "/root/.hermes",
) -> str:
    """Translate a host cache path to where the active backend sees it.

    Per-backend base (mirrors ``_agent_cache_base_for_env`` in
    tools/image_generation_tool.py): docker/modal mount/sync at
    ``/root/.hermes``; ssh/daytona/vercel_sandbox under ``~/.hermes``; plugin
    backends declare ``cache_path_base`` (None = host paths remain correct);
    local/singularity/unknown stay unchanged (Apptainer auto-binds the host
    home, so translation would dangle). Backend comes from TERMINAL_ENV, as in
    terminal_tool._get_environment_config.
    """
    backend = (os.environ.get("TERMINAL_ENV") or "local").strip().lower()
    if backend in _HOME_RELATIVE_BACKENDS:
        container_base = "~/.hermes"
    elif backend not in ("docker", "modal"):
        try:
            from agent.terminal_env_registry import provider_flag
            plugin_base = provider_flag(backend, "cache_path_base", None)
        except Exception:
            plugin_base = None
        if not plugin_base:
            return host_path
        container_base = str(plugin_base)

    mapped = map_cache_path_to_container(host_path, container_base=container_base)
    return mapped if mapped is not None else host_path


def iter_cache_files(
    container_base: str = "/root/.hermes",
) -> List[Dict[str, str]]:
    """Per-file cache entries (Modal upload/resync); skips symlinks."""
    return [
        entry
        for host_dir, container_root in _cache_dir_roots(container_base, create_missing=False)
        for entry in _iter_regular_files(host_dir, container_root)
    ]


def clear_credential_files() -> None:
    """Reset the skill-scoped registry (e.g. on session reset)."""
    _get_registered().clear()