from __future__ import annotations

from contextlib import asynccontextmanager
from pathlib import Path
from typing import Any

from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse, HTMLResponse
from fastapi.staticfiles import StaticFiles
from pydantic import BaseModel

from app.service import KvmSwitcherService


PROJECT_ROOT = Path(__file__).resolve().parent.parent
STATIC_DIR = PROJECT_ROOT / "static"
INDEX_PATH = STATIC_DIR / "index.html"


class SettingsPayload(BaseModel):
    device_port: str


def create_app(
    service: KvmSwitcherService | None = None,
    manage_lifecycle: bool = True,
) -> FastAPI:
    active_service = service or KvmSwitcherService()

    lifespan = None
    if manage_lifecycle:
        @asynccontextmanager
        async def lifespan(app_instance: FastAPI):
            del app_instance
            active_service.start()
            try:
                yield
            finally:
                active_service.stop()

    app = FastAPI(title="Internal KVM Switch", version="0.1.0", lifespan=lifespan)
    app.state.kvm_service = active_service

    if STATIC_DIR.exists():
        app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")

    @app.get("/")
    async def root() -> Any:
        if INDEX_PATH.exists():
            return FileResponse(INDEX_PATH)
        return HTMLResponse("<h1>Internal KVM Switch</h1><p>Dashboard file not found.</p>")

    @app.get("/api/status")
    async def get_status() -> dict[str, Any]:
        return active_service.get_status()

    @app.post("/api/settings")
    async def post_settings(payload: SettingsPayload) -> dict[str, Any]:
        try:
            return active_service.save_settings(
                device_port=payload.device_port,
            )
        except ValueError as exc:
            raise HTTPException(status_code=400, detail=str(exc)) from exc

    return app


app = create_app()