"""Fail-closed parser for the official Receita Federal TIPI workbook."""
from dataclasses import dataclass
from io import BytesIO
import hashlib
import unicodedata

import openpyxl


@dataclass(frozen=True)
class TipiEntry:
    ncm: str
    ex: str | None
    description: str
    rate: str


@dataclass(frozen=True)
class TipiPayload:
    sha256: str
    entries: tuple[TipiEntry, ...]
    parser_version: str = "tipi-xlsx-v1"


def parse_tipi_xlsx(raw: bytes) -> TipiPayload:
    workbook = openpyxl.load_workbook(BytesIO(raw), read_only=True, data_only=True)
    sheet = workbook.active
    normalize = lambda value: "".join(char for char in unicodedata.normalize("NFKD", str(value or "")).encode("ascii", "ignore").decode().upper() if char.isalnum())
    header_row = next((row for row in sheet.iter_rows(values_only=True) if {"NCM", "DESCRICAO", "ALIQUOTA"} <= {normalize(cell) for cell in row}), None)
    if header_row is None:
        raise ValueError("TIPI workbook has no recognized official header")
    headers = [normalize(cell) for cell in header_row]
    ncm_index = headers.index("NCM")
    ex_index = headers.index("EX")
    description_index = next(index for index, value in enumerate(headers) if value == "DESCRICAO")
    rate_index = next(index for index, value in enumerate(headers) if value.startswith("ALIQUOTA"))
    entries = []
    started = False
    for row in sheet.iter_rows(values_only=True):
        if tuple(row) == tuple(header_row):
            started = True; continue
        if not started or ncm_index >= len(row):
            continue
        ncm = "".join(char for char in str(row[ncm_index] or "") if char.isdigit())
        if len(ncm) != 8:
            continue
        description = str(row[description_index] or "").strip()
        if not description:
            raise ValueError("TIPI NCM row has no description")
        ex = str(row[ex_index] or "").strip() or None
        entries.append(TipiEntry(ncm, ex, description, str(row[rate_index] or "").strip()))
    if not entries:
        raise ValueError("TIPI workbook has no 8-digit NCM rows")
    return TipiPayload(hashlib.sha256(raw).hexdigest(), tuple(entries))