"""Plugin update checks — the standard, read-only 'is it outdated?' verb.

Address resolution per plugin, in order, no derivation ever (settled
2026-09-03, plugin-auto-update plan):
  1. saved sidecar tag + matching manifest update_url → fetch the feed yml
  2. manifest update_url differs from the saved tag (or appeared where
     none was saved) → NEEDS-FIXING: fetch refused, tag untouched
  3. no update_url anywhere + git row → git ls-remote vs revision
  4. neither → manual/unupdatable
Plus the pip world, stateless: entry-point discovery → installed version
vs PyPI latest. NEVER mutates anything — no pulls, no row writes, no
saved-tag changes.
"""

from __future__ import annotations

import importlib.metadata
import json
import re
import subprocess
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Callable, Optional

from packaging.version import InvalidVersion, Version

from hermes_cli.plugins_provenance import (
    Provenance,
    ProvenanceClass,
    plugins_provenance,
)

_FETCH_TIMEOUT = 10.0
_MAX_FEED_BYTES = 1 * 1024 * 1024
_FULL_GIT_SHA_RE = re.compile(r"[0-9a-fA-F]{40}")


def _version_is_newer(latest: str, current: str) -> Optional[bool]:
    """Invalid versions are unknown, not evidence of an update."""
    try:
        return Version(latest) > Version(current)
    except InvalidVersion:
        return None


@dataclass
class CheckResult:
    name: str
    klass: str                      # provenance class value ('git', ...)
    current: Optional[str] = None
    latest: Optional[str] = None
    update_available: Optional[bool] = None   # None = unknown/uncheckable
    needs_fixing: Optional[str] = None        # mismatch reason when set
    min_hermes: Optional[str] = None          # feed's version floor, if any
    reason: str = ""

    def to_json(self) -> dict:
        return {
            "name": self.name,
            "class": self.klass,
            "current": self.current,
            "latest": self.latest,
            "update_available": self.update_available,
            "needs_fixing": self.needs_fixing,
            "min_hermes": self.min_hermes,
            "reason": self.reason,
        }


def _read_manifest_field(plugin_dir: Path, key: str) -> Optional[str]:
    """One field from the installed plugin.yaml (claims, not provenance)."""
    import hermes_yaml as yaml

    manifest = plugin_dir / "plugin.yaml"
    if not manifest.is_file():
        return None
    try:
        with manifest.open(encoding="utf-8-sig") as f:
            data = yaml.safe_load(f) or {}
    except Exception:
        return None
    if not isinstance(data, dict):
        return None
    value = data.get(key)
    return value.strip() if isinstance(value, str) and value.strip() else None


def check_local_provenance(prov: Provenance) -> CheckResult:
    """Check installed provenance without fetching remote metadata."""
    result = CheckResult(name=prov.name, klass=prov.klass.value)

    if prov.klass is ProvenanceClass.MANUAL:
        result.reason = "no provenance; not auto-updatable"
        return result
    if prov.klass is ProvenanceClass.DRIFT:
        result.reason = (
            f"provenance drift — sidecar records {prov.row.get('source')!r} "
            "but the dir has no .git; reinstall from the recorded source"
        )
        return result
    if prov.klass is ProvenanceClass.SELF_CLONED:
        result.reason = "self-cloned; run `hermes plugins adopt` first"
        return result

    row = prov.row or {}
    result.current = row.get("revision") or None
    if row.get("pinned") is True:
        result.update_available = False
        result.reason = f"pinned @ {(result.current or '')[:12] or 'sha'}"
        return result

    # ── the saved-tag comparison (the security heart) ──────────────
    saved = row.get("update_url") or None
    claimed = _read_manifest_field(prov.path, "update_url")
    if saved is None and claimed is not None:
        # a pulled commit introduced a url where none was saved — same
        # threat class as a swap; never adopt silently
        result.needs_fixing = (
            f"manifest declares update_url {claimed!r} but no url was saved "
            "at install; run `hermes plugins trust-update-url` after review"
        )
        return result
    if saved is not None and claimed != saved:
        result.needs_fixing = (
            f"update_url mismatch: saved {saved!r}, manifest declares "
            f"{claimed!r}; run `hermes plugins trust-update-url` after review"
        )
        return result

    return result


def check_provenanced(
    prov: Provenance,
    *,
    fetch: Callable[[str], str],
    ls_remote: Callable[[str], str],
) -> CheckResult:
    """Check local provenance before contacting its approved update source."""
    row = prov.row or {}
    catalog_value = row.get("catalog")
    catalog: dict = catalog_value if isinstance(catalog_value, dict) else {}
    catalog_name = catalog.get("name") or row.get("catalog_name")
    if catalog_name:
        from hermes_cli.plugin_catalog import find_removed, get_live_catalog_entry

        result = CheckResult(name=prov.name, klass="catalog", current=row.get("revision"))
        removed = None if row.get("allow_removed") is True else (
            find_removed(str(catalog_name))
            or find_removed(str(catalog.get("repo") or row.get("source", "")).split("#", 1)[0])
        )
        if removed:
            result.reason = f"removed from catalog: {removed.reason}"
            return result
        entry = get_live_catalog_entry(str(catalog_name))
        if entry is None:
            result.reason = "catalog entry is unavailable; installed pin retained"
            return result
        result.latest = entry.sha
        result.update_available = result.current != entry.sha
        return result
    result = check_local_provenance(prov)
    if result.reason or result.needs_fixing:
        return result
    row = prov.row or {}
    saved = row.get("update_url") or None

    # ── 1. matching saved tag → fetch the feed ─────────────────────
    if saved is not None:
        try:
            feed_text = fetch(saved)
        except Exception as exc:
            result.reason = f"feed fetch failed: {exc}"
            return result
        try:
            feed = parse_feed_yml(feed_text)
        except ValueError as exc:
            result.reason = f"feed unparseable: {exc}"
            return result
        result.latest = feed.get("version")
        result.min_hermes = feed.get("min_hermes")
        # Like-for-like identity only (audit C17): a feed that ships a full
        # git SHA compares SHA vs recorded revision; otherwise the feed's
        # semantic version compares against the installed manifest's
        # version. A SHA is never compared to a semantic version, and an
        # uncomparable pair reads as unknown — not as an update.
        feed_git = (feed.get("artifacts") or {}).get("git")
        if feed_git and _FULL_GIT_SHA_RE.fullmatch(feed_git):
            if not result.current or not _FULL_GIT_SHA_RE.fullmatch(
                str(result.current)
            ):
                result.update_available = None
                result.reason = (
                    "feed declares a git sha but the install records no "
                    "full revision sha to compare"
                )
                return result
            # Case-equivalent hex only after format validation.
            result.latest = feed_git.lower()
            result.update_available = feed_git.lower() != result.current.lower()
            return result
        installed_version = _read_manifest_field(prov.path, "version")
        if installed_version is None:
            result.update_available = None
            result.reason = (
                f"feed declares version {result.latest!r} but the installed "
                "plugin.yaml records no version to compare"
            )
            return result
        # Like-for-like fields: the semantic branch compares version vs
        # version, so `current` reports the installed version, not the
        # recorded revision sha.
        result.current = installed_version
        result.update_available = _version_is_newer(result.latest, installed_version)
        if result.update_available is None:
            result.reason = (
                f"cannot compare feed version {result.latest!r} with "
                f"installed version {installed_version!r}"
            )
        return result

    # ── 3. no update_url anywhere + git row → ls-remote ────────────
    source = row.get("source") or ""
    if not source:
        result.reason = "no recorded source"
        return result
    try:
        head = ls_remote(source)
    except Exception as exc:
        result.reason = f"ls-remote failed: {exc}"
        return result
    result.latest = head
    result.update_available = bool(head) and head != result.current
    return result


def parse_feed_yml(text: str) -> dict:
    """The electron-updater-derived feed shape: version, released,
    min_hermes, artifacts{git,bundle,bundle_sha256}, notes_url."""
    import hermes_yaml as yaml

    try:
        data = yaml.safe_load(text)
    except yaml.YAMLError as exc:
        raise ValueError(f"invalid feed YAML: {exc}") from exc
    if not isinstance(data, dict):
        raise ValueError("feed must be a YAML mapping")
    version = data.get("version")
    if not isinstance(version, str) or not version.strip():
        raise ValueError("feed missing 'version'")
    out: dict[str, Any] = {"version": version.strip()}
    for key in ("min_hermes", "notes_url"):
        value = data.get(key)
        if isinstance(value, str) and value.strip():
            out[key] = value.strip()
    artifacts = data.get("artifacts")
    if isinstance(artifacts, dict):
        git = artifacts.get("git")
        if git is not None and not isinstance(git, str):
            raise ValueError("feed artifacts.git must be a string")
        out["artifacts"] = {
            k: v for k, v in artifacts.items() if isinstance(v, str)
        }
    return out


def _owning_distribution(ep) -> Optional[str]:
    """The name of the distribution the entry point belongs to — metadata,
    never a guess derived from the import module (audit C17)."""
    dist = getattr(ep, "dist", None)
    if dist is None:
        return None
    try:
        return dist.metadata.get("Name") or None
    except Exception:
        return None


def check_pip_plugins(
    *,
    installed_version: Callable[[str], str],   # dist name -> version
    pypi_latest: Callable[[str], Optional[str]],  # dist name -> latest
    entry_points: Optional[list] = None,       # injectable for tests
) -> list[CheckResult]:
    """The pip world, stateless: entry-point dists vs PyPI. Nothing
    recorded, nothing to drift."""
    if entry_points is None:
        entry_points = list(
            importlib.metadata.entry_points().select(group="hermes_agent.plugins")
        )
    results: list[CheckResult] = []
    for ep in entry_points:
        dist_name = getattr(ep, "dist_name", None) or _owning_distribution(ep)
        if not dist_name:
            results.append(
                CheckResult(
                    name=ep.name,
                    klass="pip",
                    reason=(
                        "entry point has no owning distribution metadata; "
                        "cannot determine what to check"
                    ),
                )
            )
            continue
        try:
            current = installed_version(dist_name)
        except importlib.metadata.PackageNotFoundError:
            results.append(
                CheckResult(
                    name=ep.name,
                    klass="pip",
                    reason=f"distribution {dist_name!r} not importable",
                )
            )
            continue
        latest = pypi_latest(dist_name)
        # None (unknown / not on PyPI) must read as unknown — not False
        if latest is None:
            results.append(
                CheckResult(
                    name=ep.name,
                    klass="pip",
                    current=current,
                    latest=None,
                    update_available=None,
                    reason="unknown (not on PyPI)",
                )
            )
            continue
        update_available = _version_is_newer(latest, current)
        results.append(
            CheckResult(
                name=ep.name,
                klass="pip",
                current=current,
                latest=latest,
                update_available=update_available,
                reason=(
                    f"cannot compare PyPI version {latest!r} with installed {current!r}"
                    if update_available is None else ""
                ),
            )
        )
    return results


def https_update_url(url: object) -> str:
    """Normalize a manifest ``update_url``; raises ValueError unless it is ``https://``.

    The feed picks which commit of the trusted origin gets installed and the gateway fetches
    it unattended every check interval, so a plaintext ``http://`` (MITM → an old vulnerable
    commit), ``file://`` or ``ftp://`` feed is refused at install, at trust-update-url AND at
    the fetch itself (rows saved before this rule existed).
    """
    text = str(url or "").strip()
    if not text.lower().startswith("https://"):
        raise ValueError(f"update_url must be an https:// URL, got {text!r}")
    return text


def default_fetch(url: str) -> str:
    """The real feed fetcher: url -> text (raises on failure).

    ONE implementation shared by the manual ``hermes plugins
    check-updates`` and the cadence tick — callers never re-derive it.
    """
    import urllib.request

    class HTTPSFeedRedirectHandler(urllib.request.HTTPRedirectHandler):
        def redirect_request(self, req, fp, code, msg, headers, newurl):
            redirected = super().redirect_request(req, fp, code, msg, headers, newurl)
            if redirected is not None and not redirected.full_url.lower().startswith("https://"):
                fp.close()
                raise ValueError("update_url redirect must use https://")
            return redirected

    opener = urllib.request.build_opener(HTTPSFeedRedirectHandler())
    with opener.open(https_update_url(url), timeout=_FETCH_TIMEOUT) as resp:
        data = resp.read(_MAX_FEED_BYTES)
    return data.decode("utf-8", errors="replace")


def default_ls_remote(source: str) -> str:
    """The real git probe: source -> HEAD sha (raises on failure).

    Uses the same resolved git executable the CLI path resolves. Lazily
    imports plugins_cmd (which lazily imports this module) — no import
    cycle at module load.
    """
    from hermes_cli.plugins_cmd import _resolve_git_executable

    proc = subprocess.run(
        [_resolve_git_executable() or "git", "ls-remote", source, "HEAD"],
        capture_output=True,
        text=True, encoding="utf-8", errors="replace",
        timeout=30,
    )
    if proc.returncode != 0:
        raise RuntimeError((proc.stderr or "ls-remote failed").strip()[:200])
    # 'sha\trefs/heads/...' or empty
    out = (proc.stdout or "").strip()
    return out.split("\t")[0] if out else ""


def run_checks(
    plugins_dir: Path,
    *,
    fetch: Optional[Callable[[str], str]] = None,
    ls_remote: Optional[Callable[[str], str]] = None,
    include_pip: bool = True,
    pip_installed_version: Callable[[str], str] = importlib.metadata.version,
    pip_pypi_latest: Optional[Callable[[str], Optional[str]]] = None,
    pip_entry_points: Optional[list] = None,
) -> list[CheckResult]:
    """All checks for one plugins dir. NEVER mutates anything.

    ``fetch``/``ls_remote`` default to :func:`default_fetch` /
    :func:`default_ls_remote` — the single shared network implementation
    the manual command and the cadence tick both ride.
    """
    if fetch is None:
        fetch = default_fetch
    if ls_remote is None:
        ls_remote = default_ls_remote
    results = [
        check_provenanced(p, fetch=fetch, ls_remote=ls_remote)
        for p in plugins_provenance(plugins_dir)
    ]
    if include_pip:
        if pip_pypi_latest is None:
            pip_pypi_latest = _default_pypi_latest
        results.extend(
            check_pip_plugins(
                installed_version=pip_installed_version,
                pypi_latest=pip_pypi_latest,
                entry_points=pip_entry_points,
            )
        )
    return results


def _default_pypi_latest(dist: str) -> Optional[str]:
    """PyPI JSON API — the real fetcher (injectable in tests)."""
    import urllib.request

    url = f"https://pypi.org/pypi/{dist}/json"
    try:
        with urllib.request.urlopen(url, timeout=_FETCH_TIMEOUT) as resp:
            data = json.loads(resp.read(_MAX_FEED_BYTES))
        return (data.get("info") or {}).get("version")
    except Exception:
        return None