from __future__ import annotations

import re
from pathlib import Path
from urllib.parse import unquote, urlparse

import httpx

from app.config import settings
from app.storage.repository import Repository
from app.utils.validators import validate_url_host


SAFE_FILE_RE = re.compile(r"[^a-zA-Z0-9._+-]+")


def _safe_file_name(url: str) -> str:
    parsed = urlparse(url)
    name = Path(unquote(parsed.path)).name or "package.deb"
    return SAFE_FILE_RE.sub("-", name).strip("-") or "package.deb"


class Downloader:
    def __init__(self, repository: Repository, task_id: str) -> None:
        self.repository = repository
        self.task_id = task_id

    def download(self, url: str) -> Path:
        validate_url_host(url, settings.allowed_download_hosts)
        settings.cache_dir.mkdir(parents=True, exist_ok=True)
        destination = settings.cache_dir / _safe_file_name(url)

        self.repository.add_log(self.task_id, "info", f"Downloading {url}")
        with httpx.stream("GET", url, follow_redirects=True, timeout=120) as response:
            response.raise_for_status()
            self._validate_response(url, response)
            with destination.open("wb") as handle:
                for chunk in response.iter_bytes():
                    handle.write(chunk)

        self.repository.add_log(self.task_id, "info", f"Downloaded to {destination}")
        return destination

    def _validate_response(self, requested_url: str, response: httpx.Response) -> None:
        final_url = str(response.url)
        validate_url_host(final_url, settings.allowed_download_hosts)

        content_type = response.headers.get("content-type", "").split(";", 1)[0].strip().lower()
        if content_type in {"text/html", "text/plain"}:
            raise ValueError(
                "download did not return a package file "
                f"(requested {requested_url}, final {final_url}, content-type {content_type or 'unknown'})"
            )