import asyncio
import atexit

import httpx
import orjson
import uvloop
from environs import Env

env = Env()
env.read_env()

unit_status_url: str = env.str("UNIT_STATUS_URL")

uvloop.install()

client: httpx.AsyncClient = httpx.AsyncClient()


async def fetch_json_metrics() -> dict[str, str | int | float | dict]:
    response = await client.get(unit_status_url)
    response.raise_for_status()
    return orjson.loads(response.content)


def json_to_prometheus_metrics(data: dict[str, str | int | float | dict]) -> list[str]:
    lines: list[str] = []
    stack: list[tuple[str, dict[str, str | int | float | dict]]] = [("", data)]
    while stack:
        prefix, current_data = stack.pop()
        for key, value in current_data.items():
            metric_name = f"{prefix}_{key}" if prefix else key
            if isinstance(value, dict):
                stack.append((metric_name, value))
            elif isinstance(value, (int | float)):
                sanitized_name = metric_name.replace(".", "_").replace("-", "_")
                lines.append(f"{sanitized_name} {value}")
    return lines


async def app(scope: dict[str, str | dict], receive: callable, send: callable) -> None:
    if scope["type"] == "http":
        if scope["path"] == "/metrics":
            data = await fetch_json_metrics()
            metrics_lines = json_to_prometheus_metrics(data)
            metrics_text = "\n".join(metrics_lines) + "\n"

            headers = [(b"content-type", b"text/plain; version=0.0.4; charset=utf-8")]

            await send({"type": "http.response.start", "status": 200, "headers": headers})

            await send({"type": "http.response.body", "body": metrics_text.encode("utf-8")})
        else:
            await send(
                {
                    "type": "http.response.start",
                    "status": 404,
                    "headers": [(b"content-type", b"text/plain; charset=utf-8")],
                }
            )
            await send({"type": "http.response.body", "body": b"Not Found"})


@atexit.register
def close_client() -> None:
    asyncio.get_event_loop().run_until_complete(client.aclose())