"""Runtime configuration, all from the environment."""

from __future__ import annotations

import os
from dataclasses import dataclass, field


def _int(name: str, default: int) -> int:
    try:
        return int(os.getenv(name, "") or default)
    except ValueError:
        return default


def _opt(name: str) -> str | None:
    # Compose passes unset optionals through as empty strings rather than
    # omitting them, so "" has to mean "absent" here.
    return (os.getenv(name) or "").strip() or None


@dataclass(frozen=True)
class Settings:
    auth_token: str = field(default_factory=lambda: os.environ["OWUITOOLS_AUTH_TOKEN"])
    egress_proxy: str = field(default_factory=lambda: os.getenv("OWUITOOLS_EGRESS_PROXY", "http://owuitools-egress:3128"))
    searxng_url: str = field(default_factory=lambda: os.getenv("OWUITOOLS_SEARXNG_URL", "http://owuitools-searxng:8080").rstrip("/"))
    valkey_url: str = field(default_factory=lambda: os.getenv("OWUITOOLS_VALKEY_URL", "redis://owuitools-valkey:6379/0"))
    contact: str = field(default_factory=lambda: os.getenv("OWUITOOLS_CONTACT", "owuitools@localhost"))
    # Optional. Goes in the User-Agent so a site that wants to know who is
    # fetching can look you up. Leave it unset if this is not reachable
    # from outside, which is the normal case.
    public_url: str | None = field(default_factory=lambda: _opt("OWUITOOLS_PUBLIC_URL"))

    max_response_chars: int = field(default_factory=lambda: _int("OWUITOOLS_MAX_RESPONSE_CHARS", 12000))
    probe_rate_per_hour: int = field(default_factory=lambda: _int("OWUITOOLS_PROBE_RATE_PER_HOUR", 30))
    log_level: str = field(default_factory=lambda: os.getenv("OWUITOOLS_LOG_LEVEL", "INFO").upper())

    github_token: str | None = field(default_factory=lambda: _opt("OWUITOOLS_GITHUB_TOKEN"))
    stackexchange_key: str | None = field(default_factory=lambda: _opt("OWUITOOLS_STACKEXCHANGE_KEY"))
    nvd_key: str | None = field(default_factory=lambda: _opt("OWUITOOLS_NVD_KEY"))

    @property
    def user_agent(self) -> str:
        # Wikimedia hard-blocks requests with no User-Agent (verified: 403)
        # and its policy explicitly disallows generic ones like "curl/8.5.0",
        # which pass today and may not tomorrow. OpenAlex and Crossref read
        # the same string to decide whether you get the polite pool.
        #
        # The URL is included only if there is one to give. It used to be
        # one deployment's address, hardcoded - which every other
        # deployment would then have been announcing as its own to every
        # site it fetched from.
        site = f"+{self.public_url}; " if self.public_url else ""
        return f"owuitools/1.0 ({site}{self.contact})"


settings = Settings()