"""Stable macOS TCC anchor for the uv-managed Python interpreter.

macOS TCC grants are keyed to the interpreter binary's path; a venv ``bin/python`` that symlinks
into uv's store changes identity on every interpreter upgrade. The anchor replaces it with a
signed real-file copy, gated on a real boot, with uv's alias names (``python3``,
``python3.N``) materialized as real-file copies too (never symlinks — the #95541 crash shape)
and the store's ``libpython*`` hardlinked into ``venv/lib/`` (existing ``LC_RPATH`` already points
at ``@executable_path/../lib``). All functions are no-ops off macOS and for non-uv interpreters,
and never raise to callers.
"""

from __future__ import annotations

import contextlib
import errno
import logging
import os
import platform
import re
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path

from pm.environments import venv_python
from utils import atomic_write_text

logger = logging.getLogger(__name__)

_MARKER_NAME = ".tcc-anchor-source"

_STORE_COMMON_MARKERS = ("cpython-", "-macos-")
# Recognize both historical interpreter locations during upgrades.
_STORE_ROOT_MARKERS = ("/uv/python/", "/.hermes-runtime/python/")

_ALIAS_NAMES = ("python3", f"python3.{sys.version_info.minor}")
_STORE_BIN_NAMES = (f"python3.{sys.version_info.minor}", "python3", "python")


class _BootGateFailed(Exception):
    """Staged copy refused to boot; the live venv must stay untouched."""


def _marker_value(source_file: Path) -> str:
    """Fully resolved so symlinked spellings of the same store binary compare equal."""
    return os.path.realpath(str(source_file))


def is_macos() -> bool:
    return platform.system() == "Darwin"


def _is_uv_macos_store(path: str) -> bool:
    normalized = path.replace("\\", "/")
    if not all(marker in normalized for marker in _STORE_COMMON_MARKERS):
        return False
    return any(marker in normalized for marker in _STORE_ROOT_MARKERS)


def _venv_dir(project_root: Path | None = None) -> Path | None:
    root = Path(project_root) if project_root is not None else Path(__file__).resolve().parents[1]
    return next((root / n for n in ("venv", ".venv") if _present(venv_python(root / n))), None)


def _present(path: Path) -> bool:
    return path.is_file() or path.is_symlink()


def _interpreter_file(src: str | Path) -> Path | None:
    """Return the interpreter binary file at/inside *src*."""
    p = Path(src)
    if p.is_file():
        return p
    if not p.is_dir():
        return None
    try:
        candidates = [p / n for n in _STORE_BIN_NAMES] + sorted(
            c for c in p.glob("python3.*") if not c.name.endswith((".dSYM", ".txt"))
        )
        return next((c for c in candidates if c.is_file()), None)
    except OSError:
        return None


def _interpreter_source(venv_dir: Path) -> str | None:
    """Return the interpreter file the venv currently resolves to (symlink target or pyvenv.cfg home)."""
    venv_py = venv_python(venv_dir)
    if venv_py.is_symlink():
        try:
            return str(venv_py.resolve(strict=False))
        except OSError:
            return None
    cfg = venv_dir / "pyvenv.cfg"
    if not cfg.is_file():
        return None
    try:
        lines = cfg.read_text(encoding="utf-8-sig").splitlines()
    except OSError:
        return None
    home = next((l.partition("=")[2].strip() for l in lines if l.lower().startswith("home")), "")
    interp = _interpreter_file(home) if home else None
    return str(interp) if interp is not None else None


def _managed_venv(project_root: Path | None) -> tuple[Path, Path, str] | str:
    """``(venv_dir, venv_py, source)`` for a uv-managed macOS venv, else the skip reason."""
    if not is_macos():
        return "not macOS"
    venv_dir = _venv_dir(project_root)
    if venv_dir is None:
        return "no venv interpreter"
    source = _interpreter_source(venv_dir)
    if source is None or not _is_uv_macos_store(source):
        return "interpreter not uv-managed (stable path)"
    return venv_dir, venv_python(venv_dir), source


def _anchor_marker(venv_bin: Path) -> Path:
    return venv_bin / _MARKER_NAME


def _marker_matches(venv_bin: Path, expected: str) -> bool:
    marker = _anchor_marker(venv_bin)
    try:
        return marker.is_file() and marker.read_text(encoding="utf-8-sig").strip() == expected
    except OSError:
        return False


def _write_marker(venv_bin: Path, source_file: Path) -> None:
    """Atomic: a concurrent ensure (update + doctor --fix) must never read a torn marker, which
    would compare unequal and trigger a spurious reinstall."""
    atomic_write_text(
        _anchor_marker(venv_bin),
        _marker_value(source_file),
        tmp_prefix=f"{_MARKER_NAME}.",
    )


def _store_root(source_file: Path) -> Path:
    # .../cpython-<ver>-macos-*/bin/python3.N → store root
    return source_file.resolve(strict=False).parent.parent


def _provision_libpython(venv_dir: Path, source_file: Path, *, refresh: bool = False) -> None:
    """Hardlink (else copy) store ``libpython*`` into ``venv/lib/``.

    Provision-if-present: a surplus hardlink on a statically-linked build is free; a missed
    detection is the only way the dylib-not-found crash returns.

    See #95425.
    """
    src_lib = _store_root(source_file) / "lib"
    if not src_lib.is_dir():
        return
    dst_lib = venv_dir / "lib"
    try:
        dst_lib.mkdir(parents=True, exist_ok=True)
        for src in src_lib.glob("libpython*"):
            if not src.is_file():
                continue
            dst = dst_lib / src.name
            if dst.exists() or dst.is_symlink():
                if not refresh:
                    continue
                try:
                    dst.unlink()
                except OSError:
                    continue
            try:
                os.link(src, dst)
            except OSError:
                try:
                    shutil.copy2(src, dst)
                except OSError:
                    logger.debug("libpython provision failed for %s", src, exc_info=True)
    except OSError:
        logger.debug("libpython provision skipped", exc_info=True)


def _stage_copy(venv_bin: Path, prefix: str, source: Path) -> Path:
    """Copy *source* to a unique (mkstemp) executable staging file in *venv_bin*.

    Unique names mean a concurrent ensure cannot promote another run's truncated interim copy.
    """
    fd, tmp_name = tempfile.mkstemp(prefix=prefix, dir=str(venv_bin))
    os.close(fd)
    tmp_path = Path(tmp_name)
    try:
        shutil.copy2(source, tmp_path)
        os.chmod(tmp_path, source.stat().st_mode | 0o111)
    except BaseException:
        _discard(tmp_path)
        raise
    return tmp_path


def _discard(tmp_path: Path | None) -> None:
    if tmp_path is not None:
        with contextlib.suppress(OSError):
            tmp_path.unlink(missing_ok=True)


def _copy_alias(venv_bin: Path, name: str, anchor: Path) -> bool:
    """Materialize *name* as a real-file copy of *anchor* (atomic rename).

    Returns False (and warns) on failure: a leftover alias *symlink* to the anchor is the exact
    crash shape, so callers must know when the alias set is incomplete.
    """
    tmp_path: Path | None = None
    try:
        tmp_path = _stage_copy(venv_bin, f".{name}.tcc-", anchor)
        os.replace(tmp_path, venv_bin / name)
        return True
    except OSError as exc:
        logger.warning("TCC anchor alias %s not materialized: %s", name, exc)
        _discard(tmp_path)
        return False


def _materialize_aliases(venv_bin: Path, anchor: Path, *, refresh: bool = False) -> bool:
    """Materialize uv alias names as real-file copies; True only if every needed one succeeded."""
    names = set(_ALIAS_NAMES)
    try:
        names.update(
            p.name for p in venv_bin.glob("python3*") if re.fullmatch(r"python3(\.\d+)?", p.name)
        )
    except OSError:
        pass
    ok = True
    for name in sorted(names):
        alias = venv_bin / name
        try:
            if refresh or alias.is_symlink() or not alias.exists():
                ok = _copy_alias(venv_bin, name, anchor) and ok
        except OSError:
            ok = False
    return ok


def _passes_boot_gate(staged: Path, venv_dir: Path) -> bool:
    """Launch *staged* and demand encodings + the venv prefix.

    Runs with ``PYTHONHOME``/``PYTHONPATH`` scrubbed: an inherited PYTHONHOME papers over the very
    prefix failure this gate exists to catch. ``ENOENT``/``ENOEXEC`` (fixture binaries, foreign
    arch) mean the binary can't run here at all, so the symlinked venv was equally dead: skip.
    Anything else (notably ``EACCES`` after our own chmod) is a broken install going live: refuse.
    """
    env = {
        k: v
        for k, v in os.environ.items()
        if k not in ("PYTHONHOME", "PYTHONPATH", "PYTHONSTARTUP", "__PYVENV_LAUNCHER__")
    }
    try:
        proc = subprocess.run(
            [str(staged), "-c", "import encodings, sys; print(sys.prefix)"],
            capture_output=True,
            text=True, encoding="utf-8", errors="replace",
            timeout=30,
            env=env,
        )
    except OSError as exc:
        if exc.errno in (errno.ENOENT, errno.ENOEXEC):
            logger.debug("boot gate skipped: cannot execute %s (%s)", staged, exc)
            return True
        logger.warning("boot gate: staged copy not executable: %s", exc)
        return False
    except subprocess.TimeoutExpired:
        return False
    if proc.returncode != 0:
        return False
    printed = (proc.stdout or "").strip().splitlines()
    if not printed:
        return False
    try:
        return Path(printed[-1]).resolve() == venv_dir.resolve()
    except OSError:
        return str(venv_dir) in printed[-1]


def _install_anchor(venv_dir: Path, source_file: Path) -> None:
    """Replace ``bin/python`` with a signed copy, gated on a real boot."""
    from hermes_cli.macos_signing import sign_managed_python

    venv_py = venv_python(venv_dir)
    venv_bin = venv_py.parent
    venv_bin.mkdir(parents=True, exist_ok=True)

    _provision_libpython(venv_dir, source_file, refresh=True)

    tmp_path = _stage_copy(venv_bin, ".python-tcc-", source_file)
    try:
        try:
            sign_managed_python(tmp_path)
        except Exception:  # pragma: no cover - never block the anchor
            logger.debug("anchor copy signing skipped", exc_info=True)
        if not _passes_boot_gate(tmp_path, venv_dir):
            raise _BootGateFailed(f"staged copy at {tmp_path} failed encodings/prefix probe")
        os.replace(tmp_path, venv_py)
        if _materialize_aliases(venv_bin, venv_py, refresh=True):
            # Marker last, atomically: it asserts the WHOLE layout (anchor + aliases) is complete.
            # A partial alias set must not read "active" in doctor; an absent marker makes the
            # next ensure retry the install.
            _write_marker(venv_bin, source_file)
        else:
            logger.warning(
                "TCC anchor installed but alias materialization was "
                "incomplete; leaving anchor unmarked so the next run retries"
            )
    except Exception:
        _discard(tmp_path)
        raise


def ensure_tcc_anchor(project_root: Path | None = None) -> Path | None:
    """Pin a dylib-complete interpreter anchor for macOS TCC.

    No-op (None) on non-macOS, without a venv interpreter, or when the interpreter is not
    uv-managed. Idempotent. Best-effort — None (and logs) if the copy or boot-gate fails; callers
    must never depend on success.

    See #95596.
    """
    found = _managed_venv(project_root)
    if isinstance(found, str):
        return None
    venv_dir, venv_py, source = found
    source_file = _interpreter_file(source)
    if source_file is None:
        return None
    if not venv_py.is_symlink() and _marker_matches(venv_py.parent, _marker_value(source_file)):
        try:
            _provision_libpython(venv_dir, source_file, refresh=False)
            if _passes_boot_gate(venv_py, venv_dir):
                _materialize_aliases(venv_py.parent, venv_py)
                return venv_py
        except OSError:
            pass
    try:
        _install_anchor(venv_dir, source_file)
    except _BootGateFailed as exc:
        logger.warning("macOS TCC anchor boot-gate refused install: %s", exc)
        return None
    except Exception as exc:  # best-effort: never break update/doctor
        logger.warning("macOS TCC anchor install failed: %s", exc)
        return None
    return venv_py


def tcc_anchor_state(project_root: Path | None = None) -> tuple[str, str]:
    """Report the anchor state for ``hermes doctor`` as ``(status, detail)``.

    ``skip`` = not applicable; ``active`` = pinned at a stable real-file anchor; ``stale`` = pinned
    but the interpreter changed since the last copy; ``missing`` = uv-managed with no anchor.
    """
    found = _managed_venv(project_root)
    if isinstance(found, str):
        return "skip", found
    _venv, venv_py, source = found
    if venv_py.is_symlink():
        return "missing", str(venv_py)
    source_file = _interpreter_file(source)
    expected = _marker_value(source_file) if source_file is not None else source
    status = "active" if _marker_matches(venv_py.parent, expected) else "stale"
    return status, str(venv_py)