Phillip Tarrant
9a8506970c
Head Hen CMS end-to-end: dashboard lists all posts (drafts + published), Markdown editor with live preview + drag-drop image upload, Pillow media pipeline re-encoding every upload to JPEG, post CRUD + publish toggle + hard delete, About page edit, and double-submit CSRF cookie enforced on every admin mutating endpoint (Phase 3's TODO markers resolved). Slug auto-generated on create and server-locked once a post has been published. Unpublish preserves `published_at` so re-publish keeps original date ordering. Every admin write invalidates the read-side Post/Page TTL caches and records an `auth_events` audit row. CSRF middleware is narrow by design — issues/refreshes the `cb_csrf` cookie only on `GET /admin*`, and mutating endpoints opt in via `require_csrf_form` or `require_csrf_header` Depends. Public routes, healthz, and pre-auth login stay untouched. 64 new tests cover slugs, CSRF, media, admin posts/pages services, and end-to-end CMS routes. Tests never mock the DB — real temp SQLite files per the CLAUDE.md mandate. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
107 lines
3.4 KiB
Python
107 lines
3.4 KiB
Python
"""Slug helpers for posts (and, eventually, any other slug-keyed row).
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A slug is the URL-safe identifier used in public post URLs. Keeping the
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algorithm tiny, dependency-free, and in its own module makes it easy to
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test in isolation and to reuse for the Phase 4 admin create/update
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flow.
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Rules applied by :func:`slugify`:
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- lowercase the input
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- replace every run of non-alphanumeric characters with a single ``-``
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- collapse consecutive ``-`` runs
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- strip leading and trailing ``-``
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- never return an empty string — callers that pass empty / all-punctuation
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input get a deterministic fallback (``"post"``) so they can still
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build a valid URL.
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:func:`ensure_unique` suffixes ``-2``, ``-3`` ... on collision, checking
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the database row presence via a callable the caller supplies. Keeping
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the DB access injectable keeps this module trivially testable.
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"""
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from __future__ import annotations
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import re
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from typing import Callable
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# Single-pass regex collapses any run of non-alphanumeric characters
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# into a single hyphen. Unicode letters are NOT preserved — the URL
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# column is ASCII-safe by design, so exotic characters collapse away.
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_NON_ALNUM_RE: re.Pattern[str] = re.compile(r"[^a-z0-9]+")
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# Fallback slug when the user submits a title that slugifies to the
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# empty string (e.g. only punctuation). Keeps write paths from crashing
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# on pathological input while remaining human-readable in the URL.
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_FALLBACK_SLUG: str = "post"
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def slugify(title: str) -> str:
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"""Return a URL-safe slug derived from ``title``.
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Parameters
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----------
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title:
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Human-authored title, typically from an admin form. Treated as
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untrusted — no assumption about length or character set.
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Returns
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-------
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str
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A lowercased, hyphen-separated string containing only
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``[a-z0-9-]`` with no leading or trailing hyphens. Never
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empty; returns :data:`_FALLBACK_SLUG` if the input produced
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an empty result after normalization.
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"""
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lowered = (title or "").lower()
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collapsed = _NON_ALNUM_RE.sub("-", lowered).strip("-")
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if not collapsed:
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return _FALLBACK_SLUG
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return collapsed
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def ensure_unique(
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base: str,
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exists: Callable[[str], bool],
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*,
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max_attempts: int = 1000,
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) -> str:
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"""Return a slug not currently in use, suffixing ``-2`` / ``-3`` as needed.
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Parameters
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----------
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base:
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Starting slug — typically the output of :func:`slugify`.
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exists:
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Callable that returns ``True`` if the candidate slug is already
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taken. The admin service passes a closure that hits the DB.
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max_attempts:
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Defensive bound on suffix-iteration so a degenerate ``exists``
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callable can never spin forever. 1000 is wildly more than any
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realistic collision rate.
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Returns
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-------
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str
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A slug ``exists`` returned ``False`` for. Raises
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:class:`RuntimeError` in the pathological case where every
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suffix is taken up to ``max_attempts``.
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"""
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if not exists(base):
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return base
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# Start at -2 because the bare slug is already taken. -1 would be
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# reserved for the same row we're competing with, which is confusing
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# in the DB.
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for n in range(2, max_attempts + 1):
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candidate = f"{base}-{n}"
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if not exists(candidate):
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return candidate
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raise RuntimeError(
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f"could not allocate a unique slug after {max_attempts} attempts"
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f" (base={base!r})"
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)
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