FabledCurator/backend/app/services/extension_service.py

"""FC-3g: backend support for the Firefox extension.

`ExtensionService.quick_add_source(url)` derives platform + artist
slug from a URL using regex patterns mirrored from
extension/lib/platforms.js, then find-or-creates Artist + Source rows
and returns a JSON-shaped dict for the API layer.
"""

from __future__ import annotations

import logging
import re

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from ..models import Artist, Source
from ..utils.slug import slugify
from .db_helpers import get_or_create
from .source_service import BACKFILL_MAX_CHUNKS

log = logging.getLogger(__name__)

# The probe runs while the chip is drawing; names that take longer are skipped.
_NAME_LOOKUP_SECONDS = 6.0


class UnknownPlatformError(Exception):
    """URL didn't match any platform pattern."""


class InvalidUrlError(Exception):
    """URL was empty or missing a scheme."""


class UnknownArtistError(Exception):
    """quick-add named an `artist_id` that does not exist."""


# Mirrored byte-for-byte from extension/lib/platforms.js
# PLATFORM_ARTIST_PATTERNS. Keep these two copies in sync by hand —
# reviewers catch drift.
_PLATFORM_PATTERNS: list[tuple[str, re.Pattern[str]]] = [
    ("patreon", re.compile(
        # Three creator URL shapes — bare (patreon.com/Atole), `c/`, and `cw/`
        # (the "creator workspace" URL served once subscribed, see
        # patreon_resolver._VANITY_RE). A trailing sub-path is allowed so a
        # creator's inner page still derives the slug. Nav pages stay excluded.
        r"^https?://(?:www\.)?patreon\.com/"
        r"(?:cw/|c/)?"
        r"(?!(?:home|search|messages|notifications|library|settings|posts)(?:[/?#]|$))"
        r"(?P<slug>[^/?#]+)",
        re.IGNORECASE,
    )),
    ("subscribestar", re.compile(
        r"^https?://(?:www\.)?subscribestar\.(?:com|adult)/"
        r"(?!feed$|messages$|library$)"
        r"(?P<slug>[^/?#]+)/?$",
        re.IGNORECASE,
    )),
    ("hentaifoundry", re.compile(
        r"^https?://(?:www\.)?hentai-foundry\.com/user/(?P<slug>[^/?#]+)",
        re.IGNORECASE,
    )),
    # A Discord URL names a server or a channel, never a creator, so the slug is
    # `<server>` or `<server>/<channel>` and the artist is chosen, not derived.
    # A trailing message id (a jump link) still names its channel. DMs (`@me`)
    # are not sources; thread links (`/threads/`) are left to the manual form.
    ("discord", re.compile(
        r"^https?://(?:www\.|ptb\.|canary\.)?discord\.com/channels/"
        r"(?P<slug>\d+(?:/\d+)?)(?:/\d+)?/?(?:[?#].*)?$",
        re.IGNORECASE,
    )),
]

DISCORD = "discord"


def canonical_source_url(platform: str, url: str, slug: str) -> str:
    """The URL a new source is stored under. Discord's is rebuilt from the ids
    — the form the manual Add form and the ingester use — so a jump link, a
    ptb/canary host or a trailing slash never makes a second source for the
    same channel. Every other platform keeps the URL as given."""
    if platform == DISCORD:
        return f"https://discord.com/channels/{slug}"
    return url


def _discord_ids(url: str) -> tuple[str | None, str | None] | None:
    """`(server_id, channel_id)` of a stored Discord source URL, None if it
    does not parse (a DM or thread link, or an old malformed row)."""
    from .discord_client import DiscordAPIError, parse_source_url
    try:
        return parse_source_url(url)
    except DiscordAPIError:
        return None


class ExtensionService:
    def __init__(self, session: AsyncSession, crypto=None) -> None:
        self.session = session
        # Optional decryptor for resolving a platform's display name at
        # add-time. None → skip resolution, fall back to the handle.
        self._crypto = crypto

    async def quick_add_source(
        self,
        url: str,
        *,
        artist_id: int | None = None,
        artist_name: str | None = None,
    ) -> dict:
        """Add `url` as a source. `artist_id` connects it to an existing
        artist, `artist_name` to that artist (created if new); with neither,
        the artist is resolved from the platform as before."""
        platform, raw_slug = self._derive(url)
        url = canonical_source_url(platform, url, raw_slug)
        # Identity by SOURCE handle (#130): an existing (platform, url) source
        # keeps its artist on re-add — even if that artist was since renamed (its
        # frozen slug no longer matches the current name), and even when the
        # add named a different artist. Only a genuinely new source
        # resolves/creates an artist.
        existing = await self._existing_source(platform, url)
        if existing is not None:
            artist = (await self.session.execute(
                select(Artist).where(Artist.id == existing.artist_id)
            )).scalar_one()
            return self._shape(existing, artist, created_source=False, created_artist=False)

        if artist_id is not None:
            artist = (await self.session.execute(
                select(Artist).where(Artist.id == artist_id)
            )).scalar_one_or_none()
            if artist is None:
                raise UnknownArtistError(f"no artist with id {artist_id}")
            created_artist = False
        else:
            name = (artist_name or "").strip()
            if not name:
                # Name the artist properly by resolving the real display name
                # from the platform (falls back to the URL handle).
                name = await self._resolve_artist_name(platform, raw_slug, url)
            artist, created_artist = await self._find_or_create_artist(name)
        source, created_source = await self._find_or_create_source(
            artist_id=artist.id, platform=platform, url=url,
        )
        return self._shape(source, artist, created_source, created_artist)

    async def _existing_source(self, platform: str, url: str) -> Source | None:
        """The source this URL already is, whichever artist owns it. Discord
        compares ids, not strings, so a row stored before canonicalisation (a
        ptb host, a trailing slash) is still found."""
        if platform != DISCORD:
            return (await self.session.execute(
                select(Source).where(Source.platform == platform, Source.url == url)
            )).scalars().first()
        want = _discord_ids(url)
        rows = (await self.session.execute(
            select(Source).where(Source.platform == DISCORD).order_by(Source.id)
        )).scalars().all()
        return next((s for s in rows if _discord_ids(s.url) == want), None)

    @staticmethod
    def _shape(source, artist, created_source: bool, created_artist: bool) -> dict:
        return {
            "source": {
                "id": source.id,
                "artist_id": source.artist_id,
                "platform": source.platform,
                "url": source.url,
                "enabled": source.enabled,
            },
            "artist": {
                "id": artist.id,
                "name": artist.name,
                "slug": artist.slug,
            },
            "created_source": created_source,
            "created_artist": created_artist,
        }

    async def _resolve_artist_name(
        self, platform: str, raw_slug: str, url: str
    ) -> str:
        """The real display name for a new artist, resolved from the platform at
        add-time (#130). Our native platforms each have a name source — patreon
        the campaigns API, subscribestar the profile page (both cookies). Other
        platforms (and any failure — no credential, network error) fall back to
        the URL handle, which is already readable.
        The resolvers are sync, so they run in an executor."""
        if platform == DISCORD:
            # The server's name: what the operator knows the community as.
            server_id = raw_slug.split("/", 1)[0]
            names = await self._discord_names(server_id, None)
            return names.get("server") or f"Discord {server_id}"
        if self._crypto is None or platform not in ("patreon", "subscribestar"):
            return raw_slug
        import asyncio

        from .credential_service import CredentialService
        cred = CredentialService(self.session, self._crypto)
        loop = asyncio.get_running_loop()
        try:
            if platform == "patreon":
                cookies = await cred.get_cookies_path("patreon")
                from .patreon_resolver import resolve_display_name
                name = await loop.run_in_executor(
                    None, resolve_display_name, raw_slug,
                    str(cookies) if cookies else None,
                )
            else:  # subscribestar
                cookies = await cred.get_cookies_path("subscribestar")
                from .subscribestar_client import SubscribeStarClient
                client = SubscribeStarClient(str(cookies) if cookies else None)
                name = await loop.run_in_executor(
                    None, client.resolve_display_name, url
                )
        except Exception as exc:      # resolution is best-effort — never block the add
            log.warning("artist display-name resolution failed (%s): %s", platform, exc)
            return raw_slug
        return name or raw_slug

    async def probe(self, url: str) -> dict:
        """Read-only resolution of a creator-page URL against the FC DB.
        Returns one of:
          - {state: 'unknown_platform'}            — URL didn't match any
            platform's strict artist-page pattern
          - {state: 'new',          platform, slug} — would create both
            artist and source on quick-add
          - {state: 'artist_match', platform, slug, artist}
                                                   — artist exists, this
            exact URL isn't a Source yet (collapses the sidecar-synthetic
            case too — the synthetic anchor counts as an existing artist
            row but not as a pollable Source for this URL)
          - {state: 'source_match', platform, slug, artist, source}
                                                   — exact (artist, platform,
            url) Source already exists

        Side-effect-free: two SELECTs at most.
        """
        try:
            platform, raw_slug = self._derive(url)
        except (UnknownPlatformError, InvalidUrlError):
            return {"state": "unknown_platform"}
        if platform == DISCORD:
            return await self._probe_discord(raw_slug)

        slug = slugify(raw_slug)
        artist = (await self.session.execute(
            select(Artist).where(Artist.slug == slug)
        )).scalar_one_or_none()
        if artist is None:
            return {"state": "new", "platform": platform, "slug": slug}

        artist_payload = {"id": artist.id, "name": artist.name, "slug": artist.slug}

        source = (await self.session.execute(
            select(Source).where(
                Source.artist_id == artist.id,
                Source.platform == platform,
                Source.url == url,
            )
        )).scalar_one_or_none()
        if source is None:
            return {
                "state": "artist_match",
                "platform": platform,
                "slug": slug,
                "artist": artist_payload,
            }

        return {
            "state": "source_match",
            "platform": platform,
            "slug": slug,
            "artist": artist_payload,
            "source": {
                "id": source.id,
                "artist_id": source.artist_id,
                "platform": source.platform,
                "url": source.url,
                "enabled": source.enabled,
            },
        }

    async def _probe_discord(self, raw_slug: str) -> dict:
        """probe for a Discord server or channel. The states mean what they
        mean elsewhere, but the artist is never read off the URL:

          - source_match: this channel is a source — or the whole server is
            (`covered_by_server`), which already walks every channel;
          - artist_match: another source on this server belongs to an artist,
            the one this channel most likely belongs to too (a suggestion the
            Add panel preselects, not a decision);
          - new: nothing on this server yet.

        `discord` carries the ids, both canonical URLs and the display names,
        read with the stored token; a name that can't be read is None."""
        server_id, _, channel_id = raw_slug.partition("/")
        channel_id = channel_id or None
        rows = (await self.session.execute(
            select(Source, Artist)
            .join(Artist, Artist.id == Source.artist_id)
            .where(Source.platform == DISCORD)
            .order_by(Source.id)
        )).all()
        exact = server_whole = on_server = None
        for source, artist in rows:
            ids = _discord_ids(source.url)
            if ids is None or ids[0] != server_id:
                continue
            if ids[1] == channel_id and exact is None:
                exact = (source, artist)
            elif ids[1] is None and server_whole is None:
                server_whole = (source, artist)
            if on_server is None:
                on_server = (source, artist)

        names = await self._discord_names(server_id, channel_id)
        base = f"https://discord.com/channels/{server_id}"
        result: dict = {
            "platform": DISCORD,
            "slug": raw_slug,
            "discord": {
                "server_id": server_id,
                "channel_id": channel_id,
                "server_name": names.get("server"),
                "channel_name": names.get("channel"),
                "server_url": base,
                "channel_url": f"{base}/{channel_id}" if channel_id else None,
            },
        }
        hit = exact or server_whole
        if hit is not None:
            source, artist = hit
            result.update(
                state="source_match",
                artist=self._artist_payload(artist),
                source=self._source_payload(source),
                covered_by_server=exact is None,
            )
        elif on_server is not None:
            result.update(state="artist_match", artist=self._artist_payload(on_server[1]))
        else:
            result["state"] = "new"
        return result

    async def _discord_names(self, server_id: str | None, channel_id: str | None) -> dict:
        """Server/channel display names via the stored Discord token. Never
        raises and never waits out a rate limit: it runs while the operator
        looks at a page, so a slow or missing answer just means no names."""
        if self._crypto is None:
            return {}
        import asyncio

        from .credential_service import CredentialService
        from .discord_client import DiscordClient
        try:
            token = await CredentialService(self.session, self._crypto).get_token(DISCORD)
            if not token:
                return {}
            client = DiscordClient(token, max_retries=0)
            loop = asyncio.get_running_loop()
            return await asyncio.wait_for(
                loop.run_in_executor(None, client.describe, server_id, channel_id),
                timeout=_NAME_LOOKUP_SECONDS,
            )
        except Exception as exc:      # names are decoration — never fail the call
            log.info("Discord name lookup failed: %s", exc)
            return {}

    @staticmethod
    def _artist_payload(artist) -> dict:
        return {"id": artist.id, "name": artist.name, "slug": artist.slug}

    @staticmethod
    def _source_payload(source) -> dict:
        return {
            "id": source.id,
            "artist_id": source.artist_id,
            "platform": source.platform,
            "url": source.url,
            "enabled": source.enabled,
        }

    def _derive(self, url: str) -> tuple[str, str]:
        if not isinstance(url, str) or not url.strip():
            raise InvalidUrlError("url is empty")
        if not url.startswith(("http://", "https://")):
            raise InvalidUrlError(f"url must include http:// or https:// scheme: {url!r}")
        for platform, pattern in _PLATFORM_PATTERNS:
            m = pattern.match(url)
            if m:
                return platform, m.group("slug")
        raise UnknownPlatformError(f"no platform pattern matched {url!r}")

    async def _find_or_create_artist(self, raw_name: str) -> tuple[Artist, bool]:
        """Race-safe find-or-create on Artist by slug. Mirrors the
        savepoint + IntegrityError recovery pattern used in
        Importer._find_or_create_source/post (see
        reference_scalar_one_or_none_duplicates memory). Without this,
        two concurrent quick-add-source calls hitting the same artist
        would both miss the existence check and the second INSERT would
        500 against uq_artist_slug.
        """
        slug = slugify(raw_name)

        async def _create() -> Artist:
            artist = Artist(name=raw_name, slug=slug, is_subscription=True)
            self.session.add(artist)
            await self.session.flush()
            return artist

        return await get_or_create(
            self.session, select(Artist).where(Artist.slug == slug), _create
        )

    async def _find_or_create_source(
        self, *, artist_id: int, platform: str, url: str,
    ) -> tuple[Source, bool]:
        """Race-safe — same pattern as _find_or_create_artist above. The
        uq_source_artist_platform_url constraint catches the duplicate
        insert; we roll the savepoint back and re-select."""
        select_existing = select(Source).where(
            Source.artist_id == artist_id,
            Source.platform == platform,
            Source.url == url,
        )

        async def _create() -> Source:
            # New subscription sources arm run-until-done backfill (plan #693)
            # so the first ticks walk the full history (otherwise gallery-dl's
            # exit:20 short-circuits before the archive is built). Mirrors
            # SourceService.create — without it, Firefox quick-add on a creator
            # with >20 unsynced posts would surface as "check failed" with no
            # diagnosis. Audit 2026-06-02.
            src = Source(
                artist_id=artist_id, platform=platform,
                url=url, enabled=True,
                config_overrides={"_backfill_state": "running"},
                backfill_runs_remaining=BACKFILL_MAX_CHUNKS,
            )
            self.session.add(src)
            await self.session.flush()
            return src

        src, created = await get_or_create(
            self.session, select_existing, _create
        )
        if created:
            await self.session.commit()
        return src, created