Metadata-Version: 2.4
Name: h2hdb-downloader
Version: 0.6.0
Summary: Download gallery and insert into h2hdb
Project-URL: Homepage, https://github.com/Kuan-Lun/h2hdb-downloader
Project-URL: Source, https://github.com/Kuan-Lun/h2hdb-downloader
Project-URL: Tracker, https://github.com/Kuan-Lun/h2hdb-downloader/issues
Author: Kuan-Lun Wang
License: GNU Affero General Public License v3
License-File: LICENSE
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: GNU Affero General Public License v3 or later (AGPLv3+)
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 3.14
Requires-Python: <3.15,>=3.14
Requires-Dist: h2hdb<0.20,>=0.19.0.0
Requires-Dist: hbrowser<0.35,>=0.34.0
Provides-Extra: dev
Requires-Dist: black>=26.5.1; extra == 'dev'
Requires-Dist: mypy>=2.3.0; extra == 'dev'
Requires-Dist: pymarkdownlnt>=0.9.39; extra == 'dev'
Requires-Dist: pytest-asyncio>=1.4.0; extra == 'dev'
Requires-Dist: pytest>=9.1.1; extra == 'dev'
Requires-Dist: ruff>=0.16.0; extra == 'dev'
Description-Content-Type: text/markdown

# H2HDB Downloader (h2hdb-downloader)

Automates downloading galleries from exhentai/e-hentai (via `hbrowser`) and
recording their state in an `h2hdb` database. It has no CLI or standalone
runtime of its own — it's a library consumed by another project that owns
the browser session and the overall process lifecycle.

## Concepts

- **Gallery** — a single exhentai/e-hentai gallery, identified by a `gid`
  (numeric id) and represented as `h2h_galleryinfo_parser.GalleryURLParser`
  once its URL is known.
- **Dedup** — before issuing a real network download, the package reads live
  h2hdb state to see if the gid is already settled (downloaded, with no
  redownload flag or durable request). Settled gids are skipped — except
  periodically, at a random interval (1 to 19 attempts), when one is
  force-redownloaded as an integrity re-check.
- **Durable requests** — immediately before a real download starts, the
  package creates a tokenized request in h2hdb's `todownload_gids` table.
  It conditionally completes that exact token only after success. A `False`
  result, exception, cancellation, or process termination leaves resumable
  work behind, while a newer request for the same gid cannot be erased by
  an older attempt finishing late. h2hdb also uses this table to publish a
  redownload request after all active deletion-candidate folders for a gid
  have actually disappeared. For a deep root job, success means that the
  root gallery has resolved and its entire related-tag cascade has returned
  successfully; the root request remains queued throughout that traversal.
  A public single-root call performs exact-token deletion and the
  download-to-ingest handoff in one transaction. A `drain_queue()` batch
  instead checkpoints each returned root through its still-live turn, then
  performs one handoff at the batch boundary. A late worker that has lost its
  turn therefore cannot delete the recovered root request. If another caller
  has replaced the request token while the turn is still valid, that newer
  request remains queued. A GID is recorded as removed only from hbrowser's
  explicit `ConfirmedGalleryMissing` result, never by interpreting an empty or
  malformed page. Missing-marker writes and exact-token deletion are atomic;
  the single-root form includes the handoff in that transaction, while the
  batch form retains `DOWNLOADING` until the boundary. A newer request fences
  both missing mutations.
- **Database coordination** — every short h2hdb read/write section enters
  h2hdb's cross-process maintenance gate with a five-minute wait interval.
  Browser search, downloads, retry sleeps, and tag traversal stay outside the
  gate, so maintenance is never blocked by network work.
- **Ingest backpressure** — each public deep-download root still owns one h2hdb
  download turn, while `drain_queue()` groups up to
  `download_roots_per_ingest` complete queue roots into one turn and one ingest
  barrier. A heartbeat spans the entire root or batch. Between batch roots,
  successful and confirmed-missing dispositions are persisted through the live
  turn fence without releasing `DOWNLOADING`; unresolved roots stay queued. The
  batch hands off once at its configured root boundary or snapshot exhaustion.
  Failures and cancellation also attempt one immediate handoff without removing
  the interrupted root. If the process or container is killed before it can do
  so, lease expiry lets h2hdb recover and scan already published files. Each
  completed root is a durable checkpoint, so restarting resets only the
  process-local batch count, not correctness. Related downloads atomically reuse
  an existing request token instead of replacing a later snapshot root, and one
  drain snapshot remembers submitted GIDs so overlapping cascades do not submit
  them twice before ingest. This coordination uses only short database calls;
  browser work never holds a transaction or maintenance gate. SQLite may retry
  `BUSY` or `LOCKED` only at the ready-turn claim and completed-generation
  polling boundaries.
- **External submission semantics** — H@H is treated as an uncontrollable
  external downloader. If it accepts a submission and this process stops before
  the corresponding database checkpoint commits, the next run may submit that
  GID again. Queue and ingest state remain correct, but H@H submission is
  deliberately at-least-once rather than exactly-once.
- **Manual queue** — add a `(gid, url)` row to the CSV configured by
  `csv_path`. It is converted into the same durable request and picked up
  the next time the queue is drained. Before replay, the inbox is atomically
  rotated to a same-directory hidden claim file; interrupted claims are
  replayed automatically on the next run.
- **Deep download** — download a gallery, then look at its `artist`/`group`
  tags and download sibling galleries that match a set of search conditions
  (e.g. other-language releases of the same work).

## API

`Downloader` is the public service object. `TagCascadePolicy` and
`DownloadTurnLostError` are the other public exports. Every method either acts
on a target you explicitly pass in or, for the two queue-reading methods below,
hands back a plain value with no further bookkeeping required from you.
There is no "run the whole thing" method: deciding when to stop, what order
to process things in, and how to report progress is the calling
application's job, not the library's.

```python
Downloader(
    driver: ExHDriver,         # an un-entered driver; see below
    config_path: str,          # path to the h2hdb JSON config
    csv_path: str | None = None,  # path to the manual download-queue CSV
    *,
    wait4client: int,       # seconds to wait before retrying after ClientOfflineException
    retry2download: int,    # seconds to wait before retrying after InsufficientFundsException
    turn_poll_seconds: float = 5,       # wait interval for a turn / ingest completion
    turn_lease_seconds: int = 300,      # recoverable ownership lease
    turn_heartbeat_seconds: float = 60, # renewal interval; shorter than the lease
    download_roots_per_ingest: int = 10, # queue roots per drain_queue ingest
)
```

`csv_path` only enables the optional "queue a gid/url by editing a CSV file"
feature described above. Leave it as `None` if you don't need that; durable
database requests and live deduplication still work.

The turn timing defaults normally need no adjustment. All three timing values
must be positive and finite, `turn_lease_seconds` must be an integer, and the
heartbeat interval must be shorter than the lease.
`download_roots_per_ingest` must be a positive integer. It counts queue roots
whose traversal returned, regardless of whether the disposition was completed,
missing, or retained; it does not measure H@H processing time or materialized
gallery folders.

Coordinated methods raise `DownloadTurnLostError` if their lease can no longer
be renewed or the conditional handoff proves that another process owns the
turn. Callers may catch it separately from browser/download failures; the
durable root request for unfinished work remains available for a later retry.

`Downloader` is itself an async context manager that opens and closes the
browser session for you, so `driver` is expected un-entered:

```python
async with Downloader(ExHDriver(headless=False), ...) as downloader:
    ...
```

If you'd rather manage the driver's lifecycle yourself, pass an
already-entered driver and skip `async with downloader`.

Method names follow one rule throughout: no suffix means it operates
directly on a `GalleryURLParser` you already have; `_by_gid` means it
resolves a bare gid through hbrowser's exact typed lookup first, then does the same
thing.

- `await download_by_gallery(target)` — download one `GalleryURLParser`, or
  an iterable of them. Returns `{gid: downloaded}` for each. Retries
  automatically on `ClientOfflineException` (waits `wait4client` seconds)
  and `InsufficientFundsException` (waits `retry2download` seconds); a wait
  of `0` means "don't retry, raise immediately." This is a direct API and
  does not claim a download turn or wait for h2hdb ingest.
- `await download_by_gid(gid)` — resolve a bare gid through hbrowser's exact
  lookup, then download it. Only an explicit, independently confirmed missing
  result is recorded as removed in h2hdb; challenge, authentication, malformed,
  pagination, navigation, and bounded-search failures raise and leave the
  request retryable. A later successful lookup clears any stale removed
  marker. If the gid resolves to a *different* gid (the gallery was
  merged/redirected), the original gid is flagged for deletion after the
  replacement downloads successfully. This is also a direct, uncoordinated
  API.
- `await download_by_tag(tag, conditions)` — download every gallery under a
  `hbrowser` `Tag`, once per search condition in `conditions` (or
  unconditionally if `conditions` is empty). This is also a direct,
  uncoordinated API.
- `await deep_download_by_gallery(gallery, policy, skip_check=False)` —
  download `gallery`, then for each tag in `policy.filters` (e.g.
  `"artist"`, `"group"`) on that gallery, call `download_by_tag` with
  `policy.conditions`. The cascade only runs if the initial download
  actually happened, unless `skip_check=True` forces it to run regardless
  (useful when you already know the gallery is downloaded from a separate
  call and just want the cascade). `policy` is a
  `TagCascadePolicy(filters, conditions)` — both fields always travel
  together, so they're grouped into one frozen value object rather than two
  parallel parameters. The whole call is one coordinated root: it claims a
  turn, keeps its durable root request until the cascade finishes, atomically
  finishes the exact request while handing the turn to h2hdb, and waits for
  that generation to be ingested.
- `await deep_download_by_gid(gid, policy, skip_check=False)` — same
  gid-resolution as `download_by_gid`, but deep and coordinated as one root.
- `await drain_queue(policy, skip_check=True)` — absorb the manual CSV and
  process one live snapshot of durable database requests. A request is
  removed only after a successful root and complete related-tag cascade,
  confirmed removal, or successful redirect. Up to
  `download_roots_per_ingest` returned root traversals share one download turn,
  heartbeat, handoff, and h2hdb ingest wait. A URL-to-gid fallback remains part
  of its root traversal. Stale snapshot tokens are skipped without consuming
  the root limit, and the method does not loop for newly queued work after its
  snapshot.
- `pending_redownload_gids()` — a snapshot list of gids h2hdb currently
  flags as needing a periodic redownload. Every call reads live database
  state; read-only and safe to call repeatedly as you work through it.

## Example

The calling application owns the loop. A typical one drains the queue once,
then walks the pending-redownload list, deep-downloading anything that actually
got (re)downloaded. The queue drain applies bounded-batch backpressure; each
independent deep download in the pending loop retains its single-root barrier:

```python
import asyncio
from h2hdb_downloader import Downloader, TagCascadePolicy
from hbrowser import ExHDriver
from h2h_galleryinfo_parser import GalleryURLParser

policy = TagCascadePolicy(
    filters=("artist", "group"),
    conditions=("language:chinese$", "language:speechless$"),
)


async def main():
    async with Downloader(
        ExHDriver(headless=True),
        config_path="h2hdb-config.json",
        csv_path="todownload_gids.csv",
        wait4client=30 * 60,
        retry2download=4 * 60 * 60,
    ) as downloader:
        gallery = GalleryURLParser("https://exhentai.org/g/123/456/")
        await downloader.download_by_gallery(gallery)
        await downloader.download_by_gid(666)
        await downloader.deep_download_by_gallery(gallery, policy)

        await downloader.drain_queue(policy, skip_check=True)
        for gid in downloader.pending_redownload_gids():
            await downloader.deep_download_by_gid(gid, policy, skip_check=True)


asyncio.run(main())
```

## License

This project is distributed under the terms of the GNU General Public Licence
(GPL). For detailed licence terms, see the `LICENSE` file included in this
distribution.
