"""Разделы экспорта analytics: итоги, сравнение, отчёты."""

from __future__ import annotations

VALID_EXPORT_SECTIONS = frozenset({"summary", "comparison", "reports"})

_SECTION_FILENAMES = {
    "summary": "itogi",
    "comparison": "sravnenie",
    "reports": "podrobno",
}


def parse_export_sections(section: str | None = None) -> frozenset[str]:
    if not section or not str(section).strip() or str(section).strip().lower() == "all":
        return VALID_EXPORT_SECTIONS
    parts = {p.strip().lower() for p in str(section).split(",") if p.strip()}
    filtered = parts & VALID_EXPORT_SECTIONS
    return filtered if filtered else VALID_EXPORT_SECTIONS


def export_filename_base(*, date_from: str, date_to: str, sections: frozenset[str]) -> str:
    if sections == VALID_EXPORT_SECTIONS:
        return f"otchety_{date_from}_{date_to}"
    if len(sections) == 1:
        key = next(iter(sections))
        return f"{_SECTION_FILENAMES[key]}_{date_from}_{date_to}"
    joined = "_".join(sorted(_SECTION_FILENAMES[s] for s in sections))
    return f"{joined}_{date_from}_{date_to}"