import sys

import dataclasses
from urllib import request
from urllib.error import HTTPError

import requests
import xmltodict
from packaging import version

from jetbrains_nix_updater.config import SUPPORTED_SYSTEMS
from jetbrains_nix_updater.ides import Ide
from jetbrains_nix_updater.util import one_or_more

UPDATES_URL = "https://www.jetbrains.com/updates/updates.xml"


@dataclasses.dataclass(slots=True)
class VersionInfo:
    version: str
    build_number: str
    urls: dict[str, str | None]

    def download_sha256(self, system: str) -> str:
        if self.urls[system] is None:
            raise Exception("No URL available")
        print(f"[.] Downloading sha256 for {self.urls[system]}")
        url = f"{self.urls[system]}.sha256"
        download_response = requests.get(url)
        download_response.raise_for_status()
        return download_response.content.decode("UTF-8").split(" ")[0]


class VersionFetcher:
    # Cached updates.xml content
    _channels: dict | None = None

    @property
    def channels(self) -> dict:
        if self._channels is None:
            self._channels = self.download_channels()
        return self._channels

    def latest_version_info(
        self, ide: Ide, ignore_no_url_error=False
    ) -> VersionInfo | None:
        if ide.update_info is None:
            print(
                f"[!] no update info for {ide.name} in `updateInfo.json` - skipping!",
                file=sys.stderr,
            )
            return None
        channel_name = ide.update_info["channel"]
        channel = self.channels.get(channel_name)
        if channel is None:
            print(
                f"[!] failed to find IDE channel {channel_name} - skipping! check {ide.name}'s `channel`!",
                file=sys.stderr,
            )
            return None
        try:
            build = self.latest_build(channel)
            new_version = build["@version"]
            if "@fullNumber" not in build:
                new_build_number = build["@number"]
            else:
                new_build_number = build["@fullNumber"]
            if "EAP" not in channel["@name"]:
                version_or_build_number = new_version
            else:
                version_or_build_number = new_build_number
            version_number = new_version.split(" ")[0]
            download_urls = {}
            for system in SUPPORTED_SYSTEMS:
                download_url = self.make_url(
                    ide.update_info["urls"].get(system, None),
                    version_or_build_number,
                    version_number,
                )
                if not download_url and not ignore_no_url_error:
                    print(
                        f"[!] no valid URL found for '{ide.name}' for '{system}'! make sure `updater/updateInfo.json` contains an entry and is correct.",
                        file=sys.stderr,
                    )
                    download_urls[system] = None
                else:
                    download_urls[system] = download_url
            return VersionInfo(
                version=new_version,
                build_number=new_build_number,
                urls=download_urls,
            )
        except Exception as e:
            print(
                f"[!] exception while trying to fetch version: {e} - skipping!",
                file=sys.stderr,
            )
            return None

    @classmethod
    def latest_build(cls, channel: dict) -> dict:
        builds = one_or_more(channel["build"])
        latest = max(builds, key=cls.build_version)
        return latest

    @staticmethod
    def download_channels():
        print(f"[-] Checking for updates from {UPDATES_URL}")
        updates_response = requests.get(UPDATES_URL)
        updates_response.raise_for_status()
        root = xmltodict.parse(updates_response.text)
        products = root["products"]["product"]
        return {
            channel["@name"]: channel
            for product in products
            if "channel" in product
            for channel in one_or_more(product["channel"])
        }

    @staticmethod
    def build_version(build):
        build_number = (
            build["@fullNumber"] if "@fullNumber" in build else build["@number"]
        )
        return version.parse(build_number)

    @staticmethod
    def make_url(
        template: str | None, version_or_build_number: str, version_number: str
    ) -> str | None:
        if template is None:
            return None
        release = [str(n) for n in version.parse(version_number).release]
        for k in range(len(release), 0, -1):
            s = ".".join(release[0:k])
            url = template.format(version=version_or_build_number, versionMajorMinor=s)
            try:
                if request.urlopen(url).getcode() == 200:
                    return url
            except HTTPError:
                pass
        return None
