"""Official optional-skill provenance: hub-lock backfill and restore. Profile-scoped paths and
patchable helpers resolve through ``_ss()`` at call time so ``tools.skills_sync`` patches work."""

import json
import logging
from contextlib import suppress
from datetime import datetime, timezone
from pathlib import Path, PurePosixPath
from typing import Dict, Iterator, List, Optional, Set, Tuple

from agent.skill_utils import is_excluded_skill_path
from utils import atomic_write_text

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


def _ss():
    """Live ``tools.skills_sync`` module (imported lazily: it imports helpers from this module)."""
    from tools import skills_sync
    return skills_sync


def _content_hash(directory: Path) -> str:
    """Hub-lock hash style; provenance metadata only, so fall back to local MD5 sans guard deps."""
    try:
        from tools.skills_guard import content_hash
        return content_hash(directory)
    except Exception:
        return _ss()._dir_hash(directory)


def _safe_rel_install_path(path: Path, base: Path) -> str:
    """Normalized relative POSIX path; rejects traversal/absolute paths."""
    pure = PurePosixPath(posix := path.relative_to(base).as_posix())
    parts = [part for part in pure.parts if part not in {"", "."}]
    if pure.is_absolute() or not parts or ".." in parts:
        raise ValueError(f"Unsafe optional skill path: {posix}")
    return "/".join(parts)


# Only generated runtime state, never generic cache/ or arbitrary dotfiles. This
# is updater ownership, not the security scanner's content-integrity policy.
_RUNTIME_CACHE_DIRS = frozenset({"__pycache__", ".pytest_cache", ".mypy_cache", ".ruff_cache"})


def _is_runtime_cache(path: Path, skill_dir: Path) -> bool:
    """Whether a skill-relative path is disposable Python/tool runtime state.

    Install prefixes may themselves contain a cache directory name. Legacy
    sibling bytecode is ignored only alongside its source; source-less .pyc
    files can be deliberately shipped or user-owned content.
    """
    relative = path.relative_to(skill_dir)
    if any(part in _RUNTIME_CACHE_DIRS for part in relative.parts[:-1]):
        return True
    if path.name in _RUNTIME_CACHE_DIRS and path.is_dir():
        return True
    return path.suffix in {".pyc", ".pyo"} and path.with_suffix(".py").is_file()


def _ignore_runtime_cache(directory: str, names: List[str]) -> List[str]:
    """copytree callback: don't seed generated caches into managed packages."""
    root = Path(directory)
    return [name for name in names if _is_runtime_cache(root / name, root)]


def _skill_file_list(skill_dir: Path) -> List[str]:
    """List package files for provenance/diff, excluding generated runtime caches."""
    return [f.relative_to(skill_dir).as_posix() for f in sorted(skill_dir.rglob("*"))
            if not _is_runtime_cache(f, skill_dir) and f.is_file()]


def _load_hub_lock() -> Optional[dict]:
    """Parse the skills-hub lock; None when missing or unreadable."""
    try:
        return json.loads((_ss()._skills_dir() / ".hub" / "lock.json").read_text(encoding="utf-8-sig"))
    except (FileNotFoundError, json.JSONDecodeError, OSError):
        return None


def _hub_lock_entries(data: Optional[dict]) -> List[dict]:
    return [e for e in ((data or {}).get("installed") or {}).values() if isinstance(e, dict)]


def _read_hub_install_paths() -> Set[str]:
    """Hub-lock install paths as POSIX strings. Hub-installed skills are owned by the hub: rename
    recovery must not move them even when content matches a bundled origin hash (dangling lock)."""
    return {str(e["install_path"]).strip("/") for e in _hub_lock_entries(_load_hub_lock()) if e.get("install_path")}


def _iter_optional_skills(optional_dir: Path, *, root_relative: bool) -> Iterator[Tuple[Path, Path, str]]:
    """Yield ``(skill_md, src, install_path)`` for every safe official optional skill."""
    for skill_md in sorted(optional_dir.rglob("SKILL.md")):
        if (is_excluded_skill_path(skill_md.relative_to(optional_dir), root=optional_dir)
                if root_relative else is_excluded_skill_path(skill_md)):
            continue
        try:
            yield skill_md, skill_md.parent, _safe_rel_install_path(skill_md.parent, optional_dir)
        except ValueError as e:
            logger.debug("Skipping optional skill with unsafe path %s: %s", skill_md.parent, e)


def _optional_skill_index() -> Dict[str, Tuple[str, str, Path]]:
    """Official optional skills keyed by BOTH folder name and frontmatter name (hub-lock slug or
    user-facing name). Values are ``(folder_name, install_path, source_dir)``."""
    ss = _ss()
    optional_dir = ss._get_optional_dir()
    index: Dict[str, Tuple[str, str, Path]] = {}
    if optional_dir.exists():
        for skill_md, src, install_path in _iter_optional_skills(optional_dir, root_relative=True):
            value = (src.name, install_path, src)
            index[src.name] = index[ss._read_skill_name(skill_md, src.name)] = value
    return index


def _move_to_restore_backup(path: Path, backup_root: Path) -> str:
    """Move an existing skill directory into a restore backup, preserving rel path."""
    ss = _ss()
    rel = path.relative_to(ss._skills_dir())
    target, suffix = backup_root / rel, 0
    while target.exists():
        suffix += 1
        target = (backup_root / rel).with_name(f"{rel.name}-{suffix}")
    ss._move_dir(path, target)
    return rel.as_posix()


def restore_official_optional_skill(name: str, *, restore: bool = False) -> dict:
    """Restore one or all official optional skills from repo source. ``restore=False`` only
    backfills exact-match provenance; ``restore=True`` also backs up matching active copies
    and copies the official source into its canonical path."""
    ss = _ss()
    index = _optional_skill_index()
    if index and name in {"all", "*"}:
        targets = sorted(set(index.values()), key=lambda item: item[1])
    elif name in index:
        targets = [index[name]]
    else:
        message = f"Official optional skill not found: {name}" if index else "No official optional skills directory found."
        return {"ok": False, "message": message, "restored": [], "backfilled": [], "backed_up": []}
    restored: List[str] = []
    backed_up: List[str] = []
    timestamp = datetime.now(timezone.utc).strftime("%Y%m%d-%H%M%S")
    backup_root = ss._skills_dir() / ".restore-backups" / f"official-optional-{timestamp}"
    for folder_name, install_path, src in targets if restore else []:
        dest = ss._skills_dir() / Path(*install_path.split("/"))
        canonical_ok = dest.exists() and ss._dir_hash(dest) == ss._dir_hash(src)
        # Active copies by frontmatter name or folder slug (the curator may have moved the skill
        # into another category); ``dest`` itself is handled below.
        names = {folder_name, ss._read_skill_name(src / "SKILL.md", folder_name)}
        for md in ss._iter_active_skill_mds(sort=True):
            match = md.parent
            if match != dest and match.exists() and (
                    match.name == folder_name or ss._read_skill_name(md, match.name) in names):
                backed_up.append(_move_to_restore_backup(match, backup_root))
        if dest.exists() and not canonical_ok:
            backed_up.append(_move_to_restore_backup(dest, backup_root))
        if not dest.exists():
            ss._copy_dir(src, dest)
            restored.append(folder_name)
    return {
        "ok": True, "message": "Official optional skill repair complete.", "restored": restored,
        "backfilled": _backfill_optional_provenance(quiet=True), "backed_up": backed_up,
        "backup_dir": str(backup_root) if backed_up else ""}


def _index_installed_skill_dirs_by_name() -> Dict[str, List[Path]]:
    """Installed skills by directory name in one active-tree scan, skipping anything that
    resolves outside the skills tree (symlinks/external)."""
    ss = _ss()
    index: Dict[str, List[Path]] = {}
    root = ss._skills_dir().resolve()
    for skill_md in ss._iter_active_skill_mds():
        with suppress(OSError, ValueError):
            skill_md.parent.resolve().relative_to(root)
            index.setdefault(skill_md.parent.name, []).append(skill_md.parent)
    return index


def _relocated_dest(src_name: str, index: Dict[str, List[Path]]) -> Optional[Tuple[Path, str]]:
    """``(dest, install_path)`` of a UNIQUE same-directory-name match, else None: the active
    tree may hold a skill under a DIFFERENT category than the repo (upstream reorganized,
    installed copy kept its place); ambiguity gives no basis to pick."""
    if len(candidates := index.get(src_name, [])) != 1:
        return None
    try:
        return candidates[0], _safe_rel_install_path(candidates[0], _ss()._skills_dir())
    except ValueError as e:
        logger.debug("Skipping relocated optional skill %s: %s", candidates[0], e)
        return None


def _backfill_optional_provenance(quiet: bool = False) -> List[str]:
    """Mark already-present official optional skills as hub-installed: formerly bundled (or
    hand-copied) skills now under optional-skills/ get official provenance when byte-identical
    to the source; modified/local skills are left alone."""
    ss = _ss()
    optional_dir = ss._get_optional_dir()
    if not optional_dir.exists():
        return []
    data = _load_hub_lock()
    if data is None:
        data = {"version": 1, "installed": {}}
    installed = data.setdefault("installed", {})
    existing_paths = {entry.get("install_path") for entry in _hub_lock_entries(data)}
    backfilled: List[str] = []
    installed_dir_index: Optional[Dict[str, List[Path]]] = None
    for _skill_md, src, install_path in _iter_optional_skills(optional_dir, root_relative=False):
        lock_name = src.name
        if lock_name in installed or install_path in existing_paths:
            continue
        dest = ss._skills_dir() / Path(*install_path.split("/"))
        if not dest.is_dir():
            if installed_dir_index is None:
                installed_dir_index = _index_installed_skill_dirs_by_name()
            if (found := _relocated_dest(src.name, installed_dir_index)) is None:
                continue
            dest, install_path = found  # still requires a byte-identical hash below
        if install_path in existing_paths or ss._dir_hash(dest) != ss._dir_hash(src):
            continue
        timestamp = datetime.now(timezone.utc).isoformat()
        installed[lock_name] = {
            "source": "official", "identifier": f"official/{install_path}",
            "trust_level": "builtin", "scan_verdict": "backfilled",
            "content_hash": _content_hash(dest), "install_path": install_path,
            "files": _skill_file_list(dest), "metadata": {"backfilled_from": "optional-skills"},
            "installed_at": timestamp, "updated_at": timestamp}
        existing_paths.add(install_path)
        backfilled.append(lock_name)
        if not quiet:
            print(f"  = {lock_name} (official optional provenance backfilled)")
    if backfilled:  # atomic: a mid-write crash must not wipe provenance (reader resets bad JSON)
        atomic_write_text(ss._skills_dir() / ".hub" / "lock.json", tmp_prefix=".lock_",
                          content=json.dumps(data, indent=2, ensure_ascii=False) + "\n")
    return backfilled