"""Runtime configuration, and the constants the whole recipe agrees on."""

from __future__ import annotations

import os
from dataclasses import dataclass
from pathlib import Path
from zoneinfo import ZoneInfo

DEFAULT_USER_AGENT = "ZipLime us-treasury-events/1.0 algo@limex.com"
DEFAULT_HF_REPO = "ZipLime/us-treasury-events"

TREASURY_DIRECT = "https://www.treasurydirect.gov"
HOME_TREASURY = "https://home.treasury.gov"

# Auctions close and curves are struck in New York. The offset is never
# computed: a February auction and a July auction are on opposite sides of
# daylight saving, and which is which is a question for the timezone database.
RELEASE_TIMEZONE = "America/New_York"
EASTERN = ZoneInfo(RELEASE_TIMEZONE)

COUNTRY = "US"

# The auction query reaches back to 1979 and the rate feeds to 1990. Both are
# taken whole; `metadata/coverage.parquet` records what each subset spans and
# from when each field is populated.
FIRST_CURVE_YEAR = 1990


@dataclass(frozen=True, slots=True)
class Settings:
    data_dir: Path = Path("data")
    cache_dir: Path = Path(".cache/treasury")
    user_agent: str = DEFAULT_USER_AGENT
    requests_per_second: float = 4.0
    hf_repo: str = DEFAULT_HF_REPO
    first_curve_year: int = FIRST_CURVE_YEAR

    @classmethod
    def from_env(cls, **overrides) -> Settings:
        return cls(
            data_dir=Path(overrides.get("data_dir") or os.environ.get("DATA_DIR", "data")),
            cache_dir=Path(
                overrides.get("cache_dir")
                or os.environ.get("TREASURY_CACHE_DIR", ".cache/treasury")
            ),
            user_agent=os.environ.get("TREASURY_USER_AGENT", DEFAULT_USER_AGENT),
            requests_per_second=float(os.environ.get("TREASURY_REQUESTS_PER_SECOND", "4")),
            hf_repo=overrides.get("hf_repo") or os.environ.get("HF_DATASET_REPO", DEFAULT_HF_REPO),
            first_curve_year=int(
                overrides.get("first_curve_year")
                or os.environ.get("TREASURY_FIRST_CURVE_YEAR", FIRST_CURVE_YEAR)
            ),
        )


def validate_user_agent(value: str) -> str:
    cleaned = (value or "").strip()
    if "@" not in cleaned or len(cleaned) < 12:
        raise ValueError(
            f"the Treasury expects a User-Agent carrying a contact address, got {value!r}"
        )
    return cleaned


__all__ = [
    "COUNTRY",
    "DEFAULT_HF_REPO",
    "DEFAULT_USER_AGENT",
    "EASTERN",
    "FIRST_CURVE_YEAR",
    "HOME_TREASURY",
    "RELEASE_TIMEZONE",
    "TREASURY_DIRECT",
    "Settings",
    "validate_user_agent",
]