import asyncio
import contextlib
import os

import aiofiles
import orjson
from environs import Env

env = Env()
env.read_env()

unit_log_file: str = env.str("UNIT_LOG_FILE")


async def process_log_entry(log_entry):
    with contextlib.suppress(Exception):
        log_data = orjson.loads(log_entry)
        request_time = float(log_data["request_time"])
        url = log_data["url"]
        http_method = log_data["http_method"]
        key = (url, http_method)
        return key, {"count": 1, "sum": request_time}
    return None


async def read_and_process_logs():
    metrics_data = {}

    if os.path.exists(unit_log_file):
        async with aiofiles.open(unit_log_file, mode="r+") as f:
            lines = await f.readlines()
            await f.truncate(0)

        tasks = [process_log_entry(line) for line in lines]
        results = await asyncio.gather(*tasks)

        for result in results:
            if not result:
                continue
            key, data = result
            if key in metrics_data:
                metrics_data[key]["count"] += data["count"]
                metrics_data[key]["sum"] += data["sum"]
            else:
                metrics_data[key] = data

    return metrics_data


async def generate_metrics_text():
    lines = [
        "# HELP request_duration_seconds_total Request duration in seconds",
        "# TYPE request_duration_seconds_total counter",
        "# HELP request_duration_seconds_count Number of requests",
        "# TYPE request_duration_seconds_count counter",
    ]

    metrics_data = await read_and_process_logs()

    for key, data in metrics_data.items():
        url, http_method = key
        count = data["count"]
        sum_values = data["sum"]

        labels = f'url="{url}",http_method="{http_method}"'

        lines.append(f"request_duration_seconds_count{{{labels}}} {count}")
        lines.append(f"request_duration_seconds_total{{{labels}}} {sum_values}")

    return "\n".join(lines) + "\n"


async def app(scope, receive, send):
    if scope["type"] == "http":
        if scope["path"] == "/metrics":
            headers = [(b"content-type", b"text/plain; charset=utf-8")]
            metrics_text = await generate_metrics_text()
            body = metrics_text.encode("utf-8")

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