"""DDInter 2.0 source URLs and per-ATC-category CSV file list.

Kept as a plain data module so build script logic is testable without
network access.
"""

from __future__ import annotations

DDINTER_BASE_URL = "https://ddinter2.scbdd.com/static/media/download/"

# DDInter publishes one CSV per ATC top-level category.
# Per the DDInter 2.0 release page, categories C/G/J/M/N/S are not available.
ATC_CATEGORIES: tuple[str, ...] = ("A", "B", "D", "H", "L", "P", "R", "V")

CSV_FILENAMES: tuple[str, ...] = tuple(
    f"ddinter_downloads_code_{c}.csv" for c in ATC_CATEGORIES
)


def csv_url(filename: str) -> str:
    """Return the absolute URL for a DDInter CSV asset."""
    return f"{DDINTER_BASE_URL}{filename}"


def atc_category(filename: str) -> str:
    """Extract the ATC category letter from a DDInter CSV filename.

    Raises ValueError if the filename does not match the expected pattern.
    """
    prefix = "ddinter_downloads_code_"
    suffix = ".csv"
    if not filename.startswith(prefix) or not filename.endswith(suffix):
        raise ValueError(f"Not a DDInter CSV filename: {filename!r}")
    code = filename[len(prefix):-len(suffix)]
    if code not in ATC_CATEGORIES:
        raise ValueError(f"Unknown ATC category: {code!r}")
    return code