import re
from functools import reduce
from typing import List, Iterator
from xml.etree.ElementTree import ElementTree, fromstring, tostring, register_namespace

import httpx
from fastapi import FastAPI
from starlette.responses import Response, PlainTextResponse

app = FastAPI()

URL = "https://jovemnerd.com.br/feed-nerdcast/"

RegexCollection = {
    "nerdcast": "NerdCast [0-9]+[a-c]* -",
    "empreendedor": "Empreendedor [0-9]+ -",
    "mamicas": "Caneca de Mamicas [0-9]+ -",
    "english": "Speak English [0-9]+ -",
    "nerdcash": "NerdCash [0-9]+ -",
    "bunker": "Lá do Bunker  [0-9]+ -",
}

register_namespace("googleplay", "http://www.google.com/schemas/play-podcasts/1.0")
register_namespace("itunes", "http://www.itunes.com/dtds/podcast-1.0.dtd")
register_namespace("atom", "http://www.w3.org/2005/Atom")


class XMLResponse(Response):
    media_type = "application/xml"


def match(title: str, series: List[str]) -> bool:
    def _match(s):
        return re.match(RegexCollection[s], title) is not None

    return reduce(lambda x, y: x or _match(y), series, False)


def filter_xml(xml_str: str, series: List[str]) -> str:
    tree = ElementTree(fromstring(xml_str))
    tree_root = tree.getroot()
    for channel in tree_root.findall("./channel"):
        for item in channel.findall("item"):
            title = item.find("title").text
            if not match(title, series):
                channel.remove(item)

    return tostring(tree_root, encoding='utf8', method='xml')


def filter_titles_xml(xml_str) -> Iterator[str]:
    tree = ElementTree(fromstring(xml_str))
    tree_root = tree.getroot()
    for item in tree_root.findall("./channel/item"):
        yield item.find("title").text


async def load_and_filter(series: str) -> str:
    series = series or 'nerdcast'
    series = series.split(',')
    async with httpx.AsyncClient() as client:
        response = await client.get(URL)
        xml_str = response.content
        return filter_xml(xml_str, series)


async def load_titles() -> Iterator[str]:
    async with httpx.AsyncClient() as client:
        response = await client.get(URL)
        xml_str = response.content
        return filter_titles_xml(xml_str)

@app.head("/")
@app.get("/", response_class=XMLResponse)
async def root(q: str = ''):
    return await load_and_filter(q)


@app.get("/titles", response_class=PlainTextResponse)
async def titles():
    titles = await load_titles()
    return "\n".join(titles)


@app.get("/series")
async def titles():
    return [i[0] for i in RegexCollection.items()]