local-translator/local_translator/api.py

from contextlib import asynccontextmanager
import asyncio
import logging

from fastapi import FastAPI, HTTPException, Query
from fastapi.middleware.cors import CORSMiddleware

from .config import Settings, load_settings
from .engine import Engine
from .models import Project, TranslationRequest
from .protection import BUILTIN_RULES
from .provider import Provider, ProviderError, autostart
from .storage import Storage


API_VERSION = 2


def create_app(settings: Settings | None = None, provider_factory=Provider):
    settings = settings or load_settings()
    storage = Storage(settings.database)
    engine = Engine(storage, provider_factory)
    startup_errors = {}

    @asynccontextmanager
    async def lifespan(app):
        with storage.exclusive_worker():
            for name, config in settings.providers.items():
                if config.autostart:
                    try:
                        await autostart(config)
                    except ProviderError as exc:
                        startup_errors[name] = str(exc)
                        logging.getLogger(__name__).warning("%s: %s", name, exc)
            engine.start()
            try:
                yield
            finally:
                await engine.stop()

    app = FastAPI(title="Local Translator", version="0.1.0", lifespan=lifespan,
                  description="Local translation projects, glossary, durable jobs and protected placeholders.")
    if settings.allowed_origins:
        # allow_private_network answers Chrome's preflight for https page -> localhost.
        app.add_middleware(CORSMiddleware, allow_origins=settings.allowed_origins, allow_methods=["GET", "POST", "PUT"],
                           allow_headers=["Content-Type"], expose_headers=["Location"], allow_private_network=True, max_age=600)
    app.state.storage = storage
    app.state.engine = engine

    def project_or_404(identity):
        project = storage.get_project(identity)
        if not project:
            raise HTTPException(404, "Project not found")
        return project

    def job_or_404(identity):
        job = storage.get_job(identity)
        if not job:
            raise HTTPException(404, "Job not found")
        return job

    def validate_provider(project):
        if project.provider not in settings.providers:
            raise HTTPException(422, "Provider is not configured")

    def enqueue(project_id, request):
        project = project_or_404(project_id)
        config = settings.providers.get(project["provider"])
        if config is None:
            raise HTTPException(422, "Provider is not configured")
        result = storage.create_job(project, config.model_dump(), request.model_dump())
        engine.wakeup.set()
        return result

    @app.get("/health")
    async def health():
        return {"status": "ok", "api_version": API_VERSION, "worker_running": engine.task is not None and not engine.task.done(), "startup_errors": startup_errors}

    @app.get("/providers")
    async def providers():
        return {name: {"base_url": config.base_url, "model": config.model} for name, config in settings.providers.items()}

    @app.get("/providers/{name}/models")
    async def models(name: str):
        config = settings.providers.get(name)
        if config is None:
            raise HTTPException(404, "Provider not found")
        provider = provider_factory(config)
        try:
            return await provider.request("GET", "models")
        except ProviderError as exc:
            raise HTTPException(502, str(exc)) from exc
        finally:
            await provider.close()

    @app.get("/protection-rules")
    async def protection_rules():
        return BUILTIN_RULES

    @app.post("/projects", status_code=201)
    async def create_project(project: Project):
        validate_provider(project)
        return storage.create_project(project.model_dump())

    @app.get("/projects")
    async def projects():
        return storage.projects()

    @app.get("/projects/{project_id}")
    async def get_project(project_id: str):
        return project_or_404(project_id)

    @app.put("/projects/{project_id}")
    async def replace_project(project_id: str, project: Project):
        project_or_404(project_id)
        validate_provider(project)
        return storage.update_project(project_id, project.model_dump())

    @app.post("/projects/{project_id}/jobs", status_code=202)
    async def create_job(project_id: str, request: TranslationRequest):
        return enqueue(project_id, request)

    @app.post("/projects/{project_id}/translate")
    async def translate(project_id: str, request: TranslationRequest):
        job = enqueue(project_id, request)
        # Bounded HTTP wait; the durable job continues after timeout/disconnect.
        deadline = asyncio.get_running_loop().time() + 30
        while asyncio.get_running_loop().time() < deadline:
            job = storage.get_job(job["id"])
            if job["status"] not in {"queued", "running"}:
                return job
            await asyncio.sleep(0.1)
        from fastapi.responses import JSONResponse
        return JSONResponse(status_code=202, content=job, headers={"Location": f"/jobs/{job['id']}"})

    @app.get("/projects/{project_id}/jobs")
    async def list_jobs(project_id: str, limit: int = Query(50, ge=1, le=200), offset: int = Query(0, ge=0)):
        project_or_404(project_id)
        return storage.list_jobs(project_id, limit, offset)

    @app.get("/jobs/{job_id}")
    async def get_job(job_id: str):
        return job_or_404(job_id)

    @app.post("/jobs/{job_id}/retry", status_code=202)
    async def retry_job(job_id: str):
        job = job_or_404(job_id)
        if job["status"] in {"queued", "running"}:
            raise HTTPException(409, "Job is already queued or running")
        if job["status"] == "completed":
            raise HTTPException(409, "All items are already completed")
        storage.retry(job_id)
        engine.wakeup.set()
        return storage.get_job(job_id)

    @app.post("/jobs/{job_id}/cancel")
    async def cancel_job(job_id: str):
        job = job_or_404(job_id)
        if job["status"] in {"queued", "running"}:
            storage.cancel(job_id)
            return storage.get_job(job_id)
        return job

    return app