"""Bundled-skill maintenance ops: reset, diff, list-modified, opt-out, remove-pristine.
Profile-scoped paths and patchable helpers resolve through ``_ss()`` at call time."""

import os
import shutil
from pathlib import Path
from typing import List, Optional, Tuple

from tools.skills_sync_optional import _ignore_runtime_cache, _skill_file_list, _ss


def _bundled_state():
    """``(skills_sync, manifest, bundled_dir, {skill_name: bundled_src})`` — shared op preamble."""
    ss = _ss()
    bundled_dir = ss._get_bundled_dir()
    return ss, ss._read_manifest(), bundled_dir, dict(ss._discover_bundled_skills(bundled_dir))


def reset_bundled_skill(name: str, restore: bool = False) -> dict:
    """Reset a bundled skill's manifest tracking so future syncs work normally. An edited bundled
    skill stays ``user_modified`` forever because the manifest holds the OLD origin hash; clearing
    the entry breaks that loop. ``restore`` also deletes the user's copy so the next sync re-copies
    bundled. Returns ``{ok, action, message, synced}``; action is manifest_cleared / restored /
    not_in_manifest / bundled_missing / not_reset."""
    ss, manifest, bundled_dir, bundled_by_name = _bundled_state()
    in_manifest = name in manifest
    is_bundled = name in bundled_by_name

    def _fail(action: str, message: str) -> dict:
        return {"ok": False, "action": action, "message": message, "synced": None}

    if not in_manifest and not is_bundled:
        return _fail("not_in_manifest", f"'{name}' is not a tracked bundled skill. Nothing to reset. "
                     f"(Hub-installed skills use `hermes skills uninstall`.)")
    # Step 1 (optional): delete the user's copy so next sync re-copies bundled. Must happen BEFORE manifest
    # deletion so that a failed rmtree does not leave the skill in a manifest-less limbo state (see #34972).
    deleted_user_copy = False
    if restore:  # delete the user's copy BEFORE the manifest so a failed rmtree can't strand it
        if not is_bundled:
            return _fail("bundled_missing", f"'{name}' has no bundled source — manifest entry preserved "
                         f"but cannot restore from bundled (skill was removed upstream).")
        dest = ss._compute_relative_dest(bundled_by_name[name], bundled_dir)
        if deleted_user_copy := dest.exists():
            try:
                ss._rmtree_writable(dest)
            except OSError as e:
                return _fail("not_reset", f"Could not delete user copy at {dest}: {e}. "
                             f"Manifest entry preserved — nothing was changed.")
    if in_manifest:
        del manifest[name]
        ss._write_manifest(manifest)
    synced = ss.sync_skills(quiet=True)
    if not restore:
        action, message = "manifest_cleared", (f"Cleared manifest entry for '{name}'. Future `hermes update` runs "
                                               f"will re-baseline against your current copy and accept upstream changes.")
    else:
        action = "restored"
        message = (f"Restored '{name}' from bundled source." if deleted_user_copy
                   else f"Restored '{name}' (no prior user copy, re-copied from bundled).")
    return {"ok": True, "action": action, "message": message, "synced": synced}


_OWN_REPO_PREFIXES = ("nousresearch/hermes-agent/skills/", "skills-sh/nousresearch/hermes-agent/")


def bundled_skill_for_install(identifier: str) -> Optional[str]:
    """Bundled skill name an install identifier means, else None: a bare bundled name, or this
    repo's own copy of one (``NousResearch/hermes-agent/skills/<cat>/<name>``, which the Skills Hub
    site hands out for built-ins, or its ``skills-sh/nousresearch/hermes-agent/<name>`` mirror).
    Fetched from GitHub, that copy is scanned as a community skill and refused — every time."""
    ident = identifier.strip().strip("/")
    lowered = ident.lower()
    if "/" in ident and not lowered.startswith(_OWN_REPO_PREFIXES):
        return None
    name = ident.rsplit("/", 1)[-1]
    return name if name in _bundled_state()[3] else None


def ensure_bundled_skill(name: str) -> dict:
    """Make bundled ``name`` active: ``{ok, action, path, message}``, action ``present`` (any active
    copy, user edits included, is left alone), ``restored`` (copied from the bundled source and
    re-tracked, so an opt-out, curator prune or manual delete no longer hides it), or
    ``hub_shadowed`` (a hub install owns the name; it is the user's to remove, never overwritten).
    A restore into a leftover dir only adds the missing files (a user file is never overwritten) and
    the manifest records the bundled hash, so a dest that kept user files reads as user-modified and
    ``hermes update`` leaves it alone: intended, the user's data wins."""
    from tools import skill_usage
    ss, manifest, bundled_dir, bundled_by_name = _bundled_state()
    src = bundled_by_name[name]
    dest = ss._compute_relative_dest(src, bundled_dir)
    if skill_usage.is_hub_installed(name):
        return {"ok": True, "action": "hub_shadowed", "path": None, "message": (
            f"'{name}' is a built-in skill, but a skill installed from the hub uses the same name and "
            f"shadows it. To get the built-in back: `hermes skills uninstall {name}`, then "
            f"`hermes skills install {name}`.")}
    # The rglob walk does not descend a symlinked category the loader follows, so the canonical
    # SKILL.md counts as present too.
    skill_md = dest / "SKILL.md"
    active = next((md.parent for md in ss._iter_active_skill_mds()
                   if ss.read_skill_name(md, md.parent.name) == name), None) or (
        dest if skill_md.is_file() and ss.read_skill_name(skill_md, name) == name else None)
    if active is not None or name in ss._build_external_skill_index():
        return {"ok": True, "action": "present", "path": active, "message": ""}
    try:  # the hub's containment check: a symlinked category must not carry the copy out of skills/
        from pm.filesystem import is_junction
        from tools.skills_hub_install import _resolve_lock_install_path
        rel = dest.relative_to(ss._skills_dir()).as_posix()
        _resolve_lock_install_path(rel, dest.name)
        # A dir with no SKILL.md (a delete or earlier copy that died partway) is no skill; filling in
        # its missing files beats failing with EEXIST on every retry. A link inside it would carry the
        # copy out of skills/, and a SKILL.md there is another skill: refuse both.
        if os.path.lexists(skill_md):
            raise ValueError("the directory holds a different skill's SKILL.md")
        if dest.exists() and any(p.is_symlink() or is_junction(p) for p in dest.rglob("*")):
            raise ValueError("the leftover directory contains a symlink or junction")
        dest.parent.mkdir(parents=True, exist_ok=True)
        shutil.copytree(src, dest, ignore=_ignore_runtime_cache, dirs_exist_ok=True,
                        copy_function=lambda s, d: d if os.path.lexists(d) else shutil.copy2(s, d))
    except (OSError, ValueError) as e:
        return {"ok": False, "action": "not_restored", "path": dest,
                "message": f"Could not copy the built-in skill '{name}' to {dest}: {e}"}
    manifest[name] = ss.dir_hash(src)
    ss._write_manifest(manifest)
    skill_usage._toggle_suppressed_name(name, add=False)  # lift a curator prune the way restore_skill does
    skill_usage.set_state(name, skill_usage.STATE_ACTIVE)
    return {"ok": True, "action": "restored", "path": dest, "message": ""}


def list_user_modified_bundled_skills() -> list[dict]:
    """Bundled skills ``hermes update`` keeps because the user edited them (same test the sync
    loop uses). Name-sorted ``{"name", "dest", "bundled_src"}`` dicts."""
    ss = _ss()
    if not (manifest := ss._read_manifest()):
        return []
    bundled_dir = ss._get_bundled_dir()
    modified: list[dict] = []
    for skill_name, skill_dir in ss._discover_bundled_skills(bundled_dir):
        origin_hash = manifest.get(skill_name, "")  # empty = untracked/un-baselined v1: next sync handles it
        dest = ss._compute_relative_dest(skill_dir, bundled_dir)
        if origin_hash and dest.exists() and not ss._matches_origin_hash(dest, origin_hash):
            modified.append({"name": skill_name, "dest": dest, "bundled_src": skill_dir})
    return sorted(modified, key=lambda e: e["name"])


def _read_for_diff(path: Path) -> tuple[Optional[bytes], Optional[str]]:
    """``(raw_bytes, text)`` for diffing; ``text=None`` for binary, ``(None, None)`` if unreadable."""
    try:
        data = path.read_bytes()
    except OSError:
        return None, None
    try:
        return data, (None if b"\x00" in data else data.decode("utf-8"))
    except UnicodeDecodeError:
        return data, None


def diff_bundled_skill(name: str) -> dict:
    """Diff a user's copy of a bundled skill against stock. Returns ``{ok, name, found, modified,
    message, diffs}``; each diff is ``{"path", "status", "diff"}`` with status modified / added
    (only in user copy) / removed (only in bundled) / binary."""
    import difflib
    ss, _, bundled_dir, bundled_by_name = _bundled_state()

    def _fail(found: bool, message: str) -> dict:
        return {"ok": False, "name": name, "found": found, "modified": False, "diffs": [], "message": message}

    if (bundled_src := bundled_by_name.get(name)) is None:
        return _fail(False, f"'{name}' is not a tracked bundled skill (no stock version to "
                     f"diff against). Hub-installed skills use `hermes skills inspect`.")
    dest = ss._compute_relative_dest(bundled_src, bundled_dir)
    if not dest.exists():
        return _fail(True, f"No local copy of '{name}' found at {dest}.")
    user_files = set(_skill_file_list(dest))
    stock_files = set(_skill_file_list(bundled_src))
    diffs: list[dict] = []
    for rel in sorted(user_files | stock_files):
        if rel not in stock_files:
            diffs.append({"path": rel, "status": "added", "diff": f"+ only in your copy: {rel}"})
            continue
        if rel not in user_files:
            diffs.append({"path": rel, "status": "removed", "diff": f"- only in stock: {rel}"})
            continue
        user_bytes, user_text = _read_for_diff(dest / rel)
        stock_bytes, stock_text = _read_for_diff(bundled_src / rel)
        if user_text is None or stock_text is None:  # a binary side: report only if bytes differ
            if user_bytes != stock_bytes:
                diffs.append({"path": rel, "status": "binary", "diff": "<binary file differs>"})
        elif user_text != stock_text:
            text = "".join(difflib.unified_diff(
                stock_text.splitlines(keepends=True), user_text.splitlines(keepends=True),
                fromfile=f"stock/{rel}", tofile=f"yours/{rel}"))
            diffs.append({"path": rel, "status": "modified", "diff": text})
    message = (f"'{name}' differs from the stock version in {len(diffs)} file(s)." if diffs
               else f"'{name}' matches the stock version.")
    return {"ok": True, "name": name, "found": True, "modified": bool(diffs), "diffs": diffs, "message": message}


_OPT_OUT_MESSAGES = {  # (enabled, changed) -> message
    (True, True): "Opted out of bundled skills. Future install / update / sync runs will not seed bundled skills into this profile.",
    (True, False): "Already opted out — marker was already present.",
    (False, True): "Opted back in. The next `hermes update` (or `hermes skills opt-in --sync`) will re-seed bundled skills.",
    (False, False): "Not opted out — no marker to remove."}


def set_bundled_skills_opt_out(enabled: bool) -> dict:
    """Toggle the .no-bundled-skills marker (on-disk half of ``hermes skills opt-out`` / ``opt-in``;
    removing present skills is ``remove_pristine_bundled_skills``)."""
    ss = _ss()
    marker = ss._hermes_home() / ss.NO_BUNDLED_SKILLS_MARKER
    existed = marker.exists()
    try:
        if enabled:
            ss._hermes_home().mkdir(parents=True, exist_ok=True)
            marker.write_text(
                "This profile opted out of bundled-skill seeding (`hermes skills opt-out`).\n"
                "Delete this file to re-enable sync on the next `hermes update`.\n",
                encoding="utf-8")
        elif existed:
            marker.unlink()
    except OSError as e:
        return {"ok": False, "changed": False, "marker": str(marker),
                "message": f"Could not update opt-out marker at {marker}: {e}"}
    changed = enabled != existed
    return {"ok": True, "changed": changed, "marker": str(marker), "message": _OPT_OUT_MESSAGES[(enabled, changed)]}


def remove_pristine_bundled_skills(dry_run: bool = False) -> dict:
    """Delete bundled skills that are manifest-tracked, still in the bundled source AND
    byte-identical to the origin hash; everything else lands in ``skipped``. Removed skills lose
    their manifest entry so a later opt-in re-seed treats them as new.
    Returns ``{ok, removed, skipped: [{name, reason}], dry_run, message}``."""
    ss, manifest, bundled_dir, bundled_by_name = _bundled_state()
    removed: list[str] = []
    skipped: list[dict] = []
    for name, origin_hash in sorted(manifest.items()):
        src = bundled_by_name.get(name)
        if src is None:
            skipped.append({"name": name, "reason": "no bundled source (removed upstream)"})
            continue
        dest = ss._compute_relative_dest(src, bundled_dir)
        if not dest.exists():
            if not dry_run:  # already gone from disk; forget the stale manifest entry
                manifest.pop(name, None)
            continue
        if not ss._matches_origin_hash(dest, origin_hash):
            skipped.append({"name": name, "reason": "user-modified (kept)"})
            continue
        if not dry_run:
            try:
                ss._rmtree_writable(dest)
            except OSError as e:
                skipped.append({"name": name, "reason": f"delete failed: {e}"})
                continue
            manifest.pop(name, None)
        removed.append(name)
    if not dry_run and removed:
        ss._write_manifest(manifest)
    verb = "Would remove" if dry_run else "Removed"
    return {"ok": True, "removed": removed, "skipped": skipped, "dry_run": dry_run,
            "message": f"{verb} {len(removed)} pristine bundled skill(s); kept {len(skipped)}."}