#!/usr/bin/env python3

"""Download flags of countries (with error handling).

asyncio async/await version

"""
# tag::FLAGS2_ASYNCIO_TOP[]
import asyncio
from collections import Counter
from http import HTTPStatus
from pathlib import Path

import httpx
import tqdm  # type: ignore

from flags2_common import main, DownloadStatus, save_flag

# default set low to avoid errors from remote site, such as
# 503 - Service Temporarily Unavailable
DEFAULT_CONCUR_REQ = 5
MAX_CONCUR_REQ = 1000


async def get_flag(session: httpx.AsyncClient,  # <2>
                   base_url: str,
                   cc: str) -> bytes:
    url = f'{base_url}/{cc}/{cc}.gif'.lower()
    resp = await session.get(url, timeout=3.1, follow_redirects=True)   # <3>
    resp.raise_for_status()
    return resp.content


async def download_one(session: httpx.AsyncClient,
                       cc: str,
                       base_url: str,
                       semaphore: asyncio.Semaphore,
                       verbose: bool) -> DownloadStatus:
    try:
        async with semaphore:
            image = await get_flag(session, base_url, cc)
    except httpx.HTTPStatusError as exc:
        res = exc.response
        if res.status_code == HTTPStatus.NOT_FOUND:
            status = DownloadStatus.NOT_FOUND
            msg = f'not found: {res.url}'
        else:
            raise
    else:
# tag::FLAGS2_ASYNCIO_EXECUTOR[]
        loop = asyncio.get_running_loop()         # <1>
        loop.run_in_executor(None, save_flag,     # <2>
                             image, f'{cc}.gif')  # <3>
# end::FLAGS2_ASYNCIO_EXECUTOR[]
        status = DownloadStatus.OK
        msg = 'OK'
    if verbose and msg:
        print(cc, msg)
    return status

async def supervisor(cc_list: list[str],
                     base_url: str,
                     verbose: bool,
                     concur_req: int) -> Counter[DownloadStatus]:  # <1>
    counter: Counter[DownloadStatus] = Counter()
    semaphore = asyncio.Semaphore(concur_req)  # <2>
    async with httpx.AsyncClient() as session:
        to_do = [download_one(session, cc, base_url, semaphore, verbose)
                 for cc in sorted(cc_list)]  # <3>
        to_do_iter = asyncio.as_completed(to_do)  # <4>
        if not verbose:
            to_do_iter = tqdm.tqdm(to_do_iter, total=len(cc_list))  # <5>
        error: httpx.HTTPError | None = None
        for coro in to_do_iter:  # <6>
            try:
                status = await coro  # <7>
            except httpx.HTTPStatusError as exc:  # <13>
                error_msg = 'HTTP error {resp.status_code} - {resp.reason_phrase}'
                error_msg = error_msg.format(resp=exc.response)
                error = exc
            except httpx.RequestError as exc:  # <15>
                error_msg = f'{exc} {type(exc)}'.strip()
                error = exc
            except KeyboardInterrupt:  # <7>
                break
            else:  # <8>
                error = None

            if error:
                status = DownloadStatus.ERROR  # <9>
                if verbose:      # <11>
                    cc = Path(str(error.request.url)).stem.upper()
                    print(f'{cc} error: {error_msg}')
            counter[status] += 1           # <10>

    return counter  # <12>

def download_many(cc_list: list[str],
                  base_url: str,
                  verbose: bool,
                  concur_req: int) -> Counter[DownloadStatus]:
    coro = supervisor(cc_list, base_url, verbose, concur_req)
    counts = asyncio.run(coro)  # <14>

    return counts

if __name__ == '__main__':
    main(download_many, DEFAULT_CONCUR_REQ, MAX_CONCUR_REQ)
# end::FLAGS2_ASYNCIO_START[]
