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FabledCurator/backend/app/services/post_feed_service.py
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refactor: four small cleanups from the review pass (#3072)
Items 2-5 of #3072. Item 1 (the per-row sweep inserts) is separate.

2. .fc-bad was not merely duplicated — it is .fc-weak under a second
   name. Both local definitions were `color: rgb(var(--v-theme-error))`,
   identical to the global .fc-weak, and GpuAgentCard was already using
   .fc-weak to colour exactly what GpuActivityPanel coloured .fc-bad (an
   errored count, red when non-zero). So rather than promoting a synonym
   to app.css, both call sites now use .fc-weak and the local defs are
   gone. app.css's status-colour comment records why there is no .fc-bad,
   next to the existing note on why .fc-ok is deliberately NOT global.

3. GalleryItem.vue's obsidian literals now use --v-theme-background,
   which IS obsidian (vuetify-theme.js maps background -> surfaces.
   obsidian). Preferred over --fc-chrome-rgb: same value, but that
   variable is named for the nav fade, not for the palette entry.

   The ticket said these were the only three real uses in the tree. They
   are not — GalleryItem itself had two more in the artist-label
   gradient (fixed here, so the file is now consistent), and ~13 more
   live in SeriesView, SeriesReaderView, ImageViewer, ArtistHeader,
   ExploreView and GalleryFilterBar. Those are a separate sweep, filed
   rather than folded in here.

4. The attachment download path had two hand-formatted copies. One
   definition now, `attachment_download_url`, next to the model both
   serializers already import. The test pins it by MATCHING the built
   path against the app's real URL map rather than comparing to a
   literal — a string-equality test would still pass after someone
   renamed the route, which is the drift the helper exists to prevent.

5. Extension API key now compares with hmac.compare_digest. Compared as
   BYTES, not str: compare_digest's str form raises TypeError on
   non-ASCII, and this value comes straight from an attacker-controlled
   header, so the str form would turn a junk key into a 500 instead of a
   403. Low stakes either way — the API is unauthenticated-by-design on
   a LAN — but it costs nothing.

Refs #3072
2026-08-27 07:48:18 -04:00

412 lines
17 KiB
Python

"""FC-3e: cursor-paginated read service for the Posts stream.
Uses the shared `pagination` cursor (base64 of "<iso8601_sort_key>|<id>") so
every feed paginates identically. Sort key here is COALESCE(Post.post_date,
Post.downloaded_at) so posts without a publish date sort by when we captured them.
Pure read-surface; no writes. The service composes the post dict
(thumbnails from every image linked to the post — its own primary images
plus cross-posted duplicates via image_provenance — and non-media
attachments from PostAttachment) so the API layer can jsonify directly.
"""
from __future__ import annotations
from html import unescape
from sqlalchemy import and_, func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession
from ..models import (
Artist,
ExternalLink,
ImageProvenance,
ImageRecord,
Post,
PostAttachment,
Source,
attachment_download_url,
)
from ..utils.html_sanitize import (
extract_img_srcs,
rewrite_img_srcs,
sanitize_post_html,
)
from ..utils.paths import filehash_from_url
from ..utils.text import html_to_plain, truncate_at_word
from .gallery_service import image_url, thumbnail_url
from .pagination import decode_cursor, encode_cursor
DESCRIPTION_LIMIT = 280
THUMBNAIL_LIMIT = 6
def _sort_key():
"""Postgres COALESCE expression used in ORDER BY and WHERE clauses."""
return func.coalesce(Post.post_date, Post.downloaded_at)
class PostFeedService:
def __init__(self, session: AsyncSession):
self.session = session
async def scroll(
self,
*,
cursor: str | None = None,
artist_id: int | None = None,
platform: str | None = None,
q: str | None = None,
limit: int = 24,
direction: str = "older",
) -> dict:
"""Paginate the feed from `cursor`. direction='older' walks back in
time (default, infinite-scroll down); direction='newer' walks forward
(scroll up in an anchored view). Items are always returned in feed
(descending) order; `next_cursor` points to the far edge in the
requested direction (null when exhausted).
`q` is a free-text filter (ILIKE substring over post_title OR
description) applied INSIDE the artist/platform scope, so a search
from the Browse bar stays within whatever artist is filtered in
view (operator-asked 2026-06-11)."""
if limit < 1 or limit > 100:
raise ValueError("limit must be between 1 and 100")
if direction not in ("older", "newer"):
raise ValueError("direction must be 'older' or 'newer'")
sort_key = _sort_key()
# Artist via the denormalized Post.artist_id (alembic 0030);
# Source via LEFT JOIN since post.source_id can now be NULL for
# filesystem-imported posts with no live subscription. A
# platform= filter implicitly excludes NULL-source posts (they
# have no platform); an artist_id= filter still surfaces them
# because Post.artist_id is always set.
stmt = (
select(Post, Artist, Source)
.join(Artist, Post.artist_id == Artist.id)
.outerjoin(Source, Post.source_id == Source.id)
)
if artist_id is not None:
stmt = stmt.where(Post.artist_id == artist_id)
if platform is not None:
stmt = stmt.where(Source.platform == platform)
if q:
like = f"%{q}%"
stmt = stmt.where(or_(
Post.post_title.ilike(like),
Post.description.ilike(like),
))
if cursor:
cur_ts, cur_id = decode_cursor(cursor)
if direction == "older":
stmt = stmt.where(or_(
sort_key < cur_ts,
and_(sort_key == cur_ts, Post.id < cur_id),
))
else:
stmt = stmt.where(or_(
sort_key > cur_ts,
and_(sort_key == cur_ts, Post.id > cur_id),
))
if direction == "older":
stmt = stmt.order_by(sort_key.desc(), Post.id.desc())
else:
stmt = stmt.order_by(sort_key.asc(), Post.id.asc())
stmt = stmt.limit(limit + 1)
rows = (await self.session.execute(stmt)).all()
has_more = len(rows) > limit
rows = rows[:limit]
if direction == "newer":
# Fetched ascending (closest-newer first); flip to feed order.
rows = list(reversed(rows))
next_cursor: str | None = None
if has_more and rows:
# Far edge in the travel direction: oldest row going older,
# newest row going newer (rows is descending for display).
edge_post = rows[-1][0] if direction == "older" else rows[0][0]
edge_key = edge_post.post_date or edge_post.downloaded_at
next_cursor = encode_cursor(edge_key, edge_post.id)
post_ids = [p.id for p, _, _ in rows]
thumbs_map = await self._thumbnails_for(post_ids)
atts_map = await self._attachments_for(post_ids)
items = [
self._to_dict(post, artist, source, thumbs_map, atts_map)
for post, artist, source in rows
]
return {"items": items, "next_cursor": next_cursor}
async def around(
self,
*,
post_id: int,
artist_id: int | None = None,
platform: str | None = None,
q: str | None = None,
limit: int = 12,
) -> dict | None:
"""A window centered on `post_id`: up to `limit` newer posts + the
post + up to `limit` older posts, in feed (descending) order, with a
cursor for each end. Returns None if the post doesn't exist."""
anchor = (await self.session.execute(
select(Post, Artist, Source)
.join(Artist, Post.artist_id == Artist.id)
.outerjoin(Source, Post.source_id == Source.id)
.where(Post.id == post_id)
)).one_or_none()
if anchor is None:
return None
anchor_post, anchor_artist, anchor_source = anchor
anchor_key = anchor_post.post_date or anchor_post.downloaded_at
anchor_cursor = encode_cursor(anchor_key, anchor_post.id)
older = await self.scroll(
cursor=anchor_cursor, artist_id=artist_id, platform=platform,
q=q, limit=limit, direction="older",
)
newer = await self.scroll(
cursor=anchor_cursor, artist_id=artist_id, platform=platform,
q=q, limit=limit, direction="newer",
)
thumbs_map = await self._thumbnails_for([anchor_post.id])
atts_map = await self._attachments_for([anchor_post.id])
anchor_item = self._to_dict(
anchor_post, anchor_artist, anchor_source, thumbs_map, atts_map,
)
return {
"items": newer["items"] + [anchor_item] + older["items"],
"cursor_older": older["next_cursor"],
"cursor_newer": newer["next_cursor"],
"anchor_id": anchor_post.id,
}
async def get_post(self, post_id: int) -> dict | None:
row = (await self.session.execute(
select(Post, Artist, Source)
.join(Artist, Post.artist_id == Artist.id)
.outerjoin(Source, Post.source_id == Source.id)
.where(Post.id == post_id)
)).one_or_none()
if row is None:
return None
post, artist, source = row
# Detail endpoint returns the FULL image list for PostModal's
# masonry grid — feed query still caps at THUMBNAIL_LIMIT via
# the default arg.
thumbs_map = await self._thumbnails_for([post.id], limit=None)
atts_map = await self._attachments_for([post.id])
item = self._to_dict(post, artist, source, thumbs_map, atts_map)
item["description_full"] = html_to_plain(post.description)
# Full (uncapped) translated description for the detail view (#143).
item["description_translated_full"] = post.description_translated
# Sanitized HTML body for faithful (semantic) rendering in the post view;
# detail-only (the feed list stays lightweight plain text). None when the
# post has no body. Inline `<img>` sources are remapped to locally-served
# copies (#830 Phase 2) so the body never hotlinks the public CDN.
item["description_html"] = await self._localize_inline_images(
sanitize_post_html(post.description), post.artist_id,
)
item["external_links"] = await self._external_links_for(post.id)
return item
async def _localize_inline_images(
self, html: str | None, artist_id: int | None,
) -> str | None:
"""Rewrite a post body's inline `<img src=CDN>` to locally-served copies.
The join key is the CDN filehash the downloader persisted on each
ImageRecord (source_filehash): for every body image whose filehash maps
to a stored image of THIS artist, swap the src to /images/<path>. Images
we never captured (or pre-Phase-2 rows with no filehash) are left as-is —
they keep hotlinking, which is the prior behavior. Scoped to the post's
artist so one creator's body never resolves to another's file."""
if not html or artist_id is None:
return html
srcs = extract_img_srcs(html)
if not srcs:
return html
# filehash -> the raw (as-in-HTML) src strings carrying it. A body can
# repeat the same image; keep every raw form so each is substituted.
by_hash: dict[str, list[str]] = {}
for raw in srcs:
fh = filehash_from_url(unescape(raw))
if fh:
by_hash.setdefault(fh, []).append(raw)
if not by_hash:
return html
rows = (await self.session.execute(
select(ImageRecord.source_filehash, ImageRecord.path)
.where(
ImageRecord.artist_id == artist_id,
ImageRecord.source_filehash.in_(list(by_hash)),
)
)).all()
replace: dict[str, str] = {}
for fh, path in rows:
for raw in by_hash.get(fh, ()):
replace[raw] = image_url(path)
return rewrite_img_srcs(html, replace)
async def _external_links_for(self, post_id: int) -> list[dict]:
"""Off-platform file-host links recorded for a post (detail-only). Each
carries its host, full url, label, and download status so the post view
can surface them (and, later, a retry/download affordance)."""
rows = (await self.session.execute(
select(ExternalLink)
.where(ExternalLink.post_id == post_id)
.order_by(ExternalLink.id.asc())
)).scalars().all()
return [
{
"id": e.id, "host": e.host, "url": e.url,
"label": e.label, "status": e.status,
}
for e in rows
]
# --- composition helpers ---------------------------------------------
async def _thumbnails_for(
self, post_ids: list[int], *, limit: int | None = THUMBNAIL_LIMIT,
) -> dict[int, dict]:
"""post_id -> {"thumbs": [...up to limit], "more": int}.
Selects up to `limit` images per post via window function so we
can detect overflow in a single query. Pass `limit=None` to
return ALL thumbnails per post (used by `get_post` for PostModal's
masonry grid; the feed pass keeps the default cap so payloads
stay small).
"""
if not post_ids:
return {}
# A post shows EVERY image linked to it — both its own primary images and
# cross-posted duplicates linked via image_provenance (a near-dup of an
# existing image gets a provenance row for the new post, not dropped; see
# image_provenance docstring + the importer enrich-on-duplicate path). The
# UNION dedups (image, post) pairs and also keeps any legacy image that has
# a primary_post_id but no provenance row. Partition the window on the
# link's post_id, not ImageRecord.primary_post_id, so a duplicate counts
# under each post it belongs to.
links = (
select(
ImageProvenance.image_record_id.label("image_id"),
ImageProvenance.post_id.label("post_id"),
)
.where(ImageProvenance.post_id.in_(post_ids))
.union(
select(
ImageRecord.id.label("image_id"),
ImageRecord.primary_post_id.label("post_id"),
).where(ImageRecord.primary_post_id.in_(post_ids))
)
.subquery()
)
# Rank images within each post; cap at `limit` rows per post when
# limit is set, return all when limit is None.
ranked = (
select(
ImageRecord.id,
links.c.post_id,
ImageRecord.sha256,
ImageRecord.mime,
ImageRecord.thumbnail_path,
func.row_number().over(
partition_by=links.c.post_id,
order_by=ImageRecord.id.asc(),
).label("rn"),
func.count(ImageRecord.id).over(
partition_by=links.c.post_id,
).label("total"),
)
.join(ImageRecord, ImageRecord.id == links.c.image_id)
.subquery()
)
stmt = select(
ranked.c.id, ranked.c.post_id,
ranked.c.sha256, ranked.c.mime, ranked.c.thumbnail_path, ranked.c.total,
)
if limit is not None:
stmt = stmt.where(ranked.c.rn <= limit)
rows = (await self.session.execute(stmt)).all()
out: dict[int, dict] = {pid: {"thumbs": [], "more": 0} for pid in post_ids}
for img_id, pid, sha, mime, tp, total in rows:
entry = out.setdefault(pid, {"thumbs": [], "more": 0})
entry["thumbs"].append({
"image_id": img_id,
"thumbnail_url": thumbnail_url(tp, sha, mime),
"mime": mime,
})
# `total` is constant per partition; overflow = total - THUMBNAIL_LIMIT.
entry["more"] = max(0, total - THUMBNAIL_LIMIT)
return out
async def _attachments_for(self, post_ids: list[int]) -> dict[int, list[dict]]:
if not post_ids:
return {}
rows = (await self.session.execute(
select(PostAttachment)
.where(PostAttachment.post_id.in_(post_ids))
.order_by(PostAttachment.id.asc())
)).scalars().all()
out: dict[int, list[dict]] = {pid: [] for pid in post_ids}
for att in rows:
out.setdefault(att.post_id, []).append({
"id": att.id,
"original_filename": att.original_filename,
"ext": att.ext,
"mime": att.mime,
"size_bytes": att.size_bytes,
"download_url": attachment_download_url(att.id),
})
return out
def _to_dict(
self, post: Post, artist: Artist, source: Source | None,
thumbs_map: dict, atts_map: dict,
) -> dict:
plain_full = html_to_plain(post.description) if post.description else None
if plain_full is None:
description_plain, truncated = None, False
else:
description_plain, truncated = truncate_at_word(plain_full, DESCRIPTION_LIMIT)
# Translation (#143): the stored translated description is already plain
# text; truncate it the same way for the card.
desc_trans = post.description_translated
desc_trans_short = (
truncate_at_word(desc_trans, DESCRIPTION_LIMIT)[0] if desc_trans else None
)
thumbs_entry = thumbs_map.get(post.id, {"thumbs": [], "more": 0})
# `source` is null for filesystem-imported posts with no live
# subscription (alembic 0030). Frontend renders that as a
# "filesystem import" affordance instead of a platform chip.
return {
"id": post.id,
"external_post_id": post.external_post_id,
"post_url": post.post_url,
"post_title": post.post_title,
"post_date": post.post_date.isoformat() if post.post_date else None,
"downloaded_at": post.downloaded_at.isoformat(),
"description_plain": description_plain,
"description_truncated": truncated,
# Translation-forward fields (#143): shown by default when present;
# UI toggles back to the originals above. Source lang labels the toggle.
"post_title_translated": post.post_title_translated,
"description_translated": desc_trans_short,
"translated_source_lang": post.translated_source_lang,
# Sticky per-post translation choice (auto/force/original, #155).
"translation_override": post.translation_override,
"artist": {"id": artist.id, "name": artist.name, "slug": artist.slug},
"source": (
{"id": source.id, "platform": source.platform}
if source is not None else None
),
"thumbnails": thumbs_entry["thumbs"],
"thumbnails_more": thumbs_entry["more"],
"attachments": atts_map.get(post.id, []),
}