Implementace prevodu HTML na PDF

Sluzba prijme adresu HTML dokumentu nebo HTML v tele requestu a vrati PDF.
Navrzena pro dokumenty o stovkach az tisicich stranek.

Rendering:
- WeasyPrint jako vychozi engine, spravne CSS Paged Media, nizka pametova
  narocnost, bez JavaScriptu
- Chromium pres Playwright pro dokumenty dokreslovane skripty
- rezim auto s detekci skriptu a fallbackem pri selhani WeasyPrintu

Velke dokumenty:
- deleni na casti na strukturalnich hranicich, rez nikdy uvnitr tabulky
  nebo odstavce
- dvoupruchodovy render obsahu se skutecnymi cisly stranek, pozice nadpisu
  se ctou z kotev hlasenych u kazde stranky
- cislovani stranek bud pres CSS countery, nebo pres cislovaci vrstvu
  nastampovanou na hotove PDF, rozmer stranky se cte z vysledneho souboru
- Chromium se restartuje po N jobech, nikdy vsak behem beziciho renderu

API:
- POST /convert synchronne, POST /jobs asynchronne se sledovanim stavu,
  stahovanim vysledku, rusenim a volitelnym callbackem
- GET /health s overenim dostupnosti obou enginu a stavem fronty
- OpenAPI respektuje prefix reverse proxy pres root_path

Bezpecnost a provoz:
- SSRF kontrola po DNS resolvu, na kazdem presmerovani a u vsech pozadavku
  prohlizece
- nedostupne assety render nezastavi, ale hlasi se v odpovedi i v logu
- fronta s omezenym poctem workeru, rozpracovane joby se pri ukonceni
  oznaci jako failed, nezmizi potichu
- strukturovane JSON logovani s job_id
- vsechny limity vypnute ve vychozim stavu

Dockerfile je dvoufazovy, obsahuje zavislosti WeasyPrintu, Chromium
a fonty s ceskou diakritikou.

Autentizace zamerne neni implementovana, zpusob predavani neni domluveny.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/test_jobs.py

@@ -0,0 +1,133 @@
+"""Job queue behaviour."""
+
+from __future__ import annotations
+
+import asyncio
+from pathlib import Path
+
+import pytest
+
+from app.config import Settings
+from app.errors import LimitExceededError, QueueFullError
+from app.models import ConvertRequest, Source
+from app.services.jobs import JobManager
+from app.services.pipeline import ConversionResult
+from app.services.storage import Storage
+
+pytestmark = pytest.mark.asyncio
+
+
+class StubPipeline:
+    def __init__(self, behaviour="ok", delay=0.0) -> None:
+        self.behaviour = behaviour
+        self.delay = delay
+
+    async def run(self, request, workdir: Path, progress=None) -> ConversionResult:
+        if progress is not None:
+            progress(1, 1, 1, 1)
+        if self.delay:
+            await asyncio.sleep(self.delay)
+        if self.behaviour == "conversion_error":
+            raise LimitExceededError("Prekrocen limit stranek.", {"limit": 10})
+        if self.behaviour == "crash":
+            raise RuntimeError("necekana chyba enginu")
+
+        workdir.mkdir(parents=True, exist_ok=True)
+        produced = workdir / "out.pdf"
+        produced.write_bytes(b"%PDF-1.7\n%fake\n")
+        return ConversionResult(path=produced, page_count=1, engine_used="stub")
+
+
+def make_manager(tmp_path, behaviour="ok", delay=0.0, **overrides) -> JobManager:
+    settings = Settings()
+    for key, value in overrides.items():
+        object.__setattr__(settings, key, value)
+    object.__setattr__(settings, "storage_dir", str(tmp_path))
+
+    storage = Storage(str(tmp_path))
+    return JobManager(StubPipeline(behaviour, delay), storage, settings)
+
+
+def simple_request() -> ConvertRequest:
+    return ConvertRequest(source=Source(html="<html><body><p>ahoj</p></body></html>"))
+
+
+async def test_successful_job_publishes_a_result(tmp_path) -> None:
+    manager = make_manager(tmp_path)
+    await manager.start()
+    try:
+        job = manager.submit(simple_request())
+        await asyncio.wait_for(job.done.wait(), timeout=5)
+
+        assert job.state.status == "done"
+        assert job.state.page_count == 1
+        assert (Path(tmp_path) / job.id / "result.pdf").exists()
+    finally:
+        await manager.stop()
+
+
+async def test_conversion_error_keeps_its_code(tmp_path) -> None:
+    manager = make_manager(tmp_path, behaviour="conversion_error")
+    await manager.start()
+    try:
+        job = manager.submit(simple_request())
+        await asyncio.wait_for(job.done.wait(), timeout=5)
+
+        assert job.state.status == "failed"
+        assert job.state.error is not None
+        assert job.state.error.error_code == "limit_exceeded"
+    finally:
+        await manager.stop()
+
+
+async def test_unexpected_error_is_reported_not_swallowed(tmp_path) -> None:
+    manager = make_manager(tmp_path, behaviour="crash")
+    await manager.start()
+    try:
+        job = manager.submit(simple_request())
+        await asyncio.wait_for(job.done.wait(), timeout=5)
+
+        assert job.state.status == "failed"
+        assert job.state.error.error_code == "internal_error"
+    finally:
+        await manager.stop()
+
+
+async def test_running_job_can_be_cancelled(tmp_path) -> None:
+    manager = make_manager(tmp_path, delay=5.0)
+    await manager.start()
+    try:
+        job = manager.submit(simple_request())
+        await asyncio.sleep(0.2)
+        manager.cancel(job.id)
+        await asyncio.wait_for(job.done.wait(), timeout=5)
+
+        assert job.state.status == "cancelled"
+        assert not (Path(tmp_path) / job.id).exists()
+    finally:
+        await manager.stop()
+
+
+async def test_full_queue_is_rejected(tmp_path) -> None:
+    manager = make_manager(tmp_path, delay=5.0, queue_max_size=1, workers=1)
+    await manager.start()
+    try:
+        manager.submit(simple_request())
+        await asyncio.sleep(0.1)
+        manager.submit(simple_request())
+
+        with pytest.raises(QueueFullError):
+            manager.submit(simple_request())
+    finally:
+        await manager.stop()
+
+
+async def test_shutdown_marks_pending_jobs_as_failed(tmp_path) -> None:
+    manager = make_manager(tmp_path, delay=5.0, workers=1)
+    await manager.start()
+    job = manager.submit(simple_request())
+    await asyncio.sleep(0.1)
+    await manager.stop()
+
+    assert job.state.status == "failed"
+    assert job.state.error.error_code == "service_restarted"