cleveragents-core/tools/_status_comments.py

"""Shared per-fingerprint operator-status comment substrate.

Houses the dedup substrate every dispatcher uses to post operator-
visibility comments on PR / issue timelines without re-implementing
the fingerprinting logic in two places. The reviewer dispatcher
(:mod:`_review_post`) and the implementer dispatcher
(``tools/dispatch_implementer.py`` via :mod:`_review_post`) both
key off this module; their public posters (``post_operator_status_comment``,
``post_implementer_status_comment``) are thin per-pipeline wrappers
that supply the marker family + body template.

Public surface:

- ``_sanitize_status_detail`` — normalise + cap free-form reason
  strings before they enter the fingerprint or the body.
- ``_compute_status_fingerprint`` — sha256-derived 12-hex-char
  identifier for ``(action, sanitised(reason))``.
- ``_has_existing_operator_status`` — generic "marker prefix +
  fingerprint already on this PR" predicate (parameterised on the
  pipeline's marker prefix).
- ``OPERATOR_STATUS_MARKER_PREFIX`` /
  ``IMPLEMENTER_STATUS_MARKER_PREFIX`` (and their suffix
  counterparts) — the on-wire marker namespaces. Two-key namespacing
  protects each pipeline's idempotency from cross-talk if a future
  audit enumerates "every status comment one dispatcher kind posted
  on a given PR".
- ``operator_status_marker`` / ``implementer_status_marker`` —
  public marker constructors so external callers don't have to
  string-concat the prefix + fingerprint themselves.

The module is import-safe and self-contained; no cycle risk against
:mod:`_review_post` or any dispatcher driver. Extracting it here
prevents :mod:`_review_post` from drifting into a junk drawer of
"reviewer-specific posters AND a shared dedup substrate AND the
implementer's marker family" — the previous shape paid the cohesion
price for backwards compatibility.
"""

from __future__ import annotations

import hashlib
import re
from typing import Any

# ─── Reviewer-side marker family ────────────────────────────────────────────
#
# Format: ``<!-- pr-review-dispatcher:operator-status:fp=ABCDEF123456 -->``
#
# Stable wire string: lands in PR comment bodies; mutating it would
# break fingerprint compatibility with previously-posted comments.
_OPERATOR_STATUS_MARKER_PREFIX = "<!-- pr-review-dispatcher:operator-status:fp="
_OPERATOR_STATUS_MARKER_SUFFIX = " -->"
OPERATOR_STATUS_MARKER_PREFIX = _OPERATOR_STATUS_MARKER_PREFIX
OPERATOR_STATUS_MARKER_SUFFIX = _OPERATOR_STATUS_MARKER_SUFFIX


def _operator_status_marker(fingerprint: str) -> str:
    """Build the full HTML-comment marker for ``fingerprint``."""
    return (
        f"{_OPERATOR_STATUS_MARKER_PREFIX}{fingerprint}{_OPERATOR_STATUS_MARKER_SUFFIX}"
    )


def operator_status_marker(fingerprint: str) -> str:
    """Public form of :func:`_operator_status_marker`. Tests and any
    external caller that needs to construct or recognise a marker
    should import this rather than the underscore-prefixed helper.
    """
    return _operator_status_marker(fingerprint)


# ─── Implementer-side marker family (Phase 5b) ──────────────────────────────
#
# Distinct prefix from the reviewer namespace so the dedup logic
# keyed off either prefix cannot mis-match a comment from the other
# pipeline.
_IMPLEMENTER_STATUS_MARKER_PREFIX = "<!-- pr-implementer-dispatcher:operator-status:fp="
_IMPLEMENTER_STATUS_MARKER_SUFFIX = " -->"
IMPLEMENTER_STATUS_MARKER_PREFIX = _IMPLEMENTER_STATUS_MARKER_PREFIX
IMPLEMENTER_STATUS_MARKER_SUFFIX = _IMPLEMENTER_STATUS_MARKER_SUFFIX


def implementer_status_marker(fingerprint: str) -> str:
    """Public form of the implementer-side fingerprint marker. Mirrors
    :func:`operator_status_marker` on the reviewer side.
    """
    return (
        f"{_IMPLEMENTER_STATUS_MARKER_PREFIX}"
        f"{fingerprint}"
        f"{_IMPLEMENTER_STATUS_MARKER_SUFFIX}"
    )


# ─── Detail sanitisation + fingerprinting ───────────────────────────────────


# Cap on the action_reason / detail string we surface in the
# operator-status body. Large reasons (a verbose Forgejo error blob,
# a 5 KB Python traceback excerpt) hurt readability and inflate the
# fingerprint surface area.
_STATUS_DETAIL_MAX_CHARS = 600


def _sanitize_status_detail(detail: str) -> str:
    """Normalise + cap the action_reason string for operator display.

    - Collapse runs of whitespace (newlines, tabs) into single spaces
      so a multi-line traceback doesn't span the operator comment.
    - Strip control characters (other than tab/newline) for log
      hygiene.
    - Cap at :data:`_STATUS_DETAIL_MAX_CHARS` characters with an
      ellipsis. Without the cap a runaway worker error message
      could blow past the comment-body limit.

    Used both for fingerprint computation (so stylistic whitespace
    differences don't fork a new fingerprint) and for the rendered
    body. Returns the empty string when ``detail`` is empty.
    """
    if not detail:
        return ""
    cleaned = "".join(
        ch
        for ch in detail
        if ch == "\n" or ch == "\t" or (0x20 <= ord(ch) < 0x7F) or ord(ch) >= 0xA0
    )
    cleaned = re.sub(r"\s+", " ", cleaned).strip()
    if len(cleaned) > _STATUS_DETAIL_MAX_CHARS:
        cleaned = cleaned[: _STATUS_DETAIL_MAX_CHARS - 1] + "\u2026"
    return cleaned


def _compute_status_fingerprint(action: str, detail: str) -> str:
    """Compute the 12-hex-char idempotency fingerprint for a status
    comment.

    Built from ``sha256(f"{action}|{sanitised_detail}")[:12]`` so two
    cycles producing the same outcome surface the same fingerprint
    and skip the duplicate post; distinct outcomes get distinct
    fingerprints and distinct posts. The ``action`` argument is the
    pipeline-specific verb (``failed`` / ``stale`` / ``rebase-failed``
    / ``timeout`` / etc.); the ``detail`` argument is whatever
    free-form reason string the dispatcher captured.
    """
    canonical = f"{action}|{_sanitize_status_detail(detail)}"
    return hashlib.sha256(canonical.encode("utf-8", errors="replace")).hexdigest()[:12]


def _has_existing_operator_status(
    pr_comments: list[dict[str, Any]] | None,
    fingerprint: str,
    *,
    marker_prefix: str,
) -> bool:
    """Return True iff any prefetched PR comment carries the marker
    for ``fingerprint``. Used to short-circuit the operator-status
    POST so identical-outcome cycles don't double-post.

    ``marker_prefix`` is required (no default) so that a third
    pipeline cannot accidentally key against the reviewer's namespace.
    Reviewer callers pass :data:`_OPERATOR_STATUS_MARKER_PREFIX`;
    implementer callers pass :data:`_IMPLEMENTER_STATUS_MARKER_PREFIX`;
    each pipeline's idempotency stays scoped to its own namespace.

    Tolerates malformed entries: any comment whose ``body`` is not a
    string is skipped silently.
    """
    if not pr_comments:
        return False
    needle = f"{marker_prefix}{fingerprint}"
    for comment in pr_comments:
        if not isinstance(comment, dict):
            continue
        body = comment.get("body")
        if isinstance(body, str) and needle in body:
            return True
    return False


__all__ = (
    "IMPLEMENTER_STATUS_MARKER_PREFIX",
    "IMPLEMENTER_STATUS_MARKER_SUFFIX",
    "OPERATOR_STATUS_MARKER_PREFIX",
    "OPERATOR_STATUS_MARKER_SUFFIX",
    "_compute_status_fingerprint",
    "_has_existing_operator_status",
    "_operator_status_marker",
    "_sanitize_status_detail",
    "implementer_status_marker",
    "operator_status_marker",
)