"""FastAPI app factory — lifespan, CORS, health, routers."""

from contextlib import asynccontextmanager

import httpx
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

from .agents.registry import AgentRegistry, register_builtin_agents
from .agents.session import InMemorySessionStore
from .api import (
    assessment_router,
    chat_router,
    lab_router,
    mentor_router,
    proctor_router,
)
from .config import Settings
from .llm import create_provider


def create_app(settings: Settings | None = None) -> FastAPI:
    settings = settings or Settings()

    @asynccontextmanager
    async def lifespan(app: FastAPI):
        # Shared HTTP client pool (D-017): 10s connect / 300s read for cloud TTFT
        timeout = httpx.Timeout(connect=10.0, read=300.0, write=30.0, pool=10.0)
        app.state.http_client = httpx.AsyncClient(timeout=timeout)
        app.state.settings = settings
        app.state.provider = create_provider(settings, app.state.http_client)
        app.state.session_store = InMemorySessionStore()
        app.state.agent_registry = AgentRegistry()
        register_builtin_agents(app.state.agent_registry)
        yield
        await app.state.http_client.aclose()

    app = FastAPI(title="Nextcraft AI Service", version="0.2.0", lifespan=lifespan)

    # A-008: localhost-only CORS, no credentials
    app.add_middleware(
        CORSMiddleware,
        allow_origins=["http://localhost:3000", "http://127.0.0.1:3000"],
        allow_methods=["GET", "POST", "OPTIONS"],
        allow_headers=["Content-Type"],
        allow_credentials=False,
    )

    @app.get("/health")
    async def health() -> dict:
        return {
            "status": "ok",
            "provider": settings.provider,
            "model": settings.model,
        }

    app.include_router(chat_router)
    app.include_router(lab_router)
    app.include_router(assessment_router)
    app.include_router(mentor_router)
    app.include_router(proctor_router)
    return app


app = create_app()