from __future__ import annotations

import os
import resource
from io import StringIO
from typing import Dict

import weechat

from slack.log import LogLevel, log
from slack.task import FutureProcess, sleep, weechat_task_cb
from slack.util import get_callback_name


class HttpError(Exception):
    def __init__(self, url: str, return_code: int, http_status: int, error: str):
        super().__init__()
        self.url = url
        self.return_code = return_code
        self.http_status = http_status
        self.error = error


def available_file_descriptors():
    num_current_file_descriptors = len(os.listdir("/proc/self/fd/"))
    max_file_descriptors = min(resource.getrlimit(resource.RLIMIT_NOFILE))
    return max_file_descriptors - num_current_file_descriptors


async def hook_process_hashtable(command: str, options: Dict[str, str], timeout: int):
    future = FutureProcess()
    log(
        LogLevel.DEBUG,
        f"hook_process_hashtable calling ({future.id}): command: {command}",
    )
    while available_file_descriptors() < 10:
        await sleep(10)
    weechat.hook_process_hashtable(
        command, options, timeout, get_callback_name(weechat_task_cb), future.id
    )

    stdout = StringIO()
    stderr = StringIO()
    return_code = -1

    while return_code == -1:
        next_future = FutureProcess(future.id)
        _, return_code, out, err = await next_future
        log(
            LogLevel.TRACE,
            f"hook_process_hashtable intermediary response ({next_future.id}): command: {command}",
        )
        stdout.write(out)
        stderr.write(err)

    out = stdout.getvalue()
    err = stderr.getvalue()
    log(
        LogLevel.DEBUG,
        f"hook_process_hashtable response ({future.id}): command: {command}, "
        f"return_code: {return_code}, response length: {len(out)}"
        + (f", error: {err}" if err else ""),
    )

    return command, return_code, out, err


async def http_request(
    url: str, options: Dict[str, str], timeout: int, max_retries: int = 5
) -> str:
    options["header"] = "1"
    _, return_code, out, err = await hook_process_hashtable(
        f"url:{url}", options, timeout
    )

    if return_code != 0 or err:
        if max_retries > 0:
            log(
                LogLevel.INFO,
                f"HTTP error, retrying (max {max_retries} times): "
                f"return_code: {return_code}, error: {err}, url: {url}",
            )
            await sleep(1000)
            return await http_request(url, options, timeout, max_retries - 1)
        raise HttpError(url, return_code, 0, err)

    headers_end_index = out.index("\r\n\r\n")
    headers = out[:headers_end_index].split("\r\n")
    http_status = int(headers[0].split(" ")[1])

    if http_status == 429:
        for header in headers[1:]:
            name, value = header.split(":", 1)
            if name.lower() == "retry-after":
                retry_after = int(value.strip())
                log(
                    LogLevel.INFO,
                    f"HTTP ratelimit, retrying in {retry_after} seconds, url: {url}",
                )
                await sleep(retry_after * 1000)
                return await http_request(url, options, timeout)

    body = out[headers_end_index + 4 :]

    if http_status >= 400:
        raise HttpError(url, return_code, http_status, body)

    return body