"""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 fomc-events/1.0 algo@limex.com"
DEFAULT_HF_REPO = "ZipLime/fomc-events"

HOST = "https://www.federalreserve.gov"
# Everything the Committee publishes is embargoed in Washington time. The
# offset is never computed -- a March statement and a June statement 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 Summary of Economic Projections begins in 2007 and the dot plot in 2012.
# Statements reach back to 1994 and the historical pages to 1936; starting at
# the SEP keeps the subsets comparable, and metadata/coverage.parquet records
# what each one actually spans.
BACKFILL_FROM_YEAR = 2007


@dataclass(frozen=True, slots=True)
class Settings:
    data_dir: Path = Path("data")
    cache_dir: Path = Path(".cache/fomc")
    user_agent: str = DEFAULT_USER_AGENT
    requests_per_second: float = 3.0
    hf_repo: str = DEFAULT_HF_REPO
    backfill_from_year: int = BACKFILL_FROM_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("FOMC_CACHE_DIR", ".cache/fomc")
            ),
            user_agent=os.environ.get("FOMC_USER_AGENT", DEFAULT_USER_AGENT),
            requests_per_second=float(os.environ.get("FOMC_REQUESTS_PER_SECOND", "3")),
            hf_repo=overrides.get("hf_repo") or os.environ.get("HF_DATASET_REPO", DEFAULT_HF_REPO),
            backfill_from_year=int(
                overrides.get("backfill_from_year")
                or os.environ.get("FOMC_BACKFILL_FROM_YEAR", BACKFILL_FROM_YEAR)
            ),
        )


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