"""Resource bounds shared by every XLSX importer.

Lived in ``app/domains/auditor/`` until 2026-08-30, when the support domain
needed the same archive-amplification guards for the Feishu-helpdesk FAQ
import. Domain modules do not import each other, so the guards moved here.
"""

from __future__ import annotations

import io
import zipfile

from app.core.exceptions import ValidationError

MAX_XLSX_MEMBERS = 1_000
MAX_XLSX_UNCOMPRESSED_BYTES = 64 * 1024 * 1024
MAX_XLSX_MEMBER_BYTES = 32 * 1024 * 1024
MAX_XLSX_COMPRESSION_RATIO = 200.0
MAX_XLSX_COLUMNS = 100
MAX_XLSX_CELL_CHARS = 32_767


def preflight_xlsx(payload: bytes) -> None:
    """Reject archive amplification before openpyxl reads workbook XML."""

    try:
        with zipfile.ZipFile(io.BytesIO(payload)) as archive:
            members = [item for item in archive.infolist() if not item.is_dir()]
    except (zipfile.BadZipFile, OSError) as exc:
        raise ValidationError("could not read xlsx: not a valid workbook") from exc

    if len(members) > MAX_XLSX_MEMBERS:
        raise ValidationError("workbook archive contains too many members")

    total = 0
    for member in members:
        if member.flag_bits & 0x1:
            raise ValidationError("encrypted workbooks are not supported")
        if member.file_size > MAX_XLSX_MEMBER_BYTES:
            raise ValidationError("workbook archive member is too large")
        total += member.file_size
        if total > MAX_XLSX_UNCOMPRESSED_BYTES:
            raise ValidationError("workbook contents exceed the 64 MB inflated limit")
        if member.file_size / max(member.compress_size, 1) > MAX_XLSX_COMPRESSION_RATIO:
            raise ValidationError("workbook compression ratio is suspiciously high")


def bounded_row(row: tuple[object, ...]) -> tuple[object, ...]:
    """Validate the sentinel column and cell sizes, then trim empty tail cells."""

    if len(row) > MAX_XLSX_COLUMNS and row[MAX_XLSX_COLUMNS] is not None:
        raise ValidationError(f"workbook exceeds {MAX_XLSX_COLUMNS} columns")
    values = row[:MAX_XLSX_COLUMNS]
    for value in values:
        if isinstance(value, str) and len(value) > MAX_XLSX_CELL_CHARS:
            raise ValidationError("workbook cell text is too long")
    last = len(values)
    while last and values[last - 1] is None:
        last -= 1
    return values[:last]