"""Utility functions."""

from __future__ import annotations

from django.utils.translation import gettext_lazy as _

CASE_LOG_ALLOWED_EXTENSIONS = {
    ".pdf",
    ".doc",
    ".docx",
    ".xls",
    ".xlsx",
    ".ppt",
    ".pptx",
    ".jpg",
    ".jpeg",
    ".png",
}

CASE_LOG_MAX_FILE_SIZE = 50 * 1024 * 1024


def _basename(filename: str) -> str:
    name = str(filename or "")
    name = name.replace("\\", "/")
    return name.split("/")[-1]


def get_file_extension_lower(filename: str) -> str:
    base = _basename(filename).strip()
    if not base or base in {".", ".."}:
        return ""
    if "." not in base:
        return ""
    return "." + base.rsplit(".", 1)[-1].lower()


def validate_case_log_attachment(filename: str, size: int | None) -> tuple[bool, str | None]:
    ext = get_file_extension_lower(filename)
    if ext not in CASE_LOG_ALLOWED_EXTENSIONS:
        return False, _("不支持的文件类型")
    if size and size > CASE_LOG_MAX_FILE_SIZE:
        return False, _("文件大小超过50MB限制")
    return True, None


def fix_sqlite_orphan_contract_fk() -> None:
    """SQLite 不强制 FK 约束，删除案件前清理孤立的 contract_id 引用。"""
    from django.db import connection

    if connection.vendor == "sqlite":
        with connection.cursor() as cursor:
            cursor.execute(
                """
                UPDATE cases_case
                SET contract_id = NULL
                WHERE contract_id IS NOT NULL
                  AND contract_id NOT IN (SELECT id FROM contracts_contract)
                """
            )


def normalize_case_number(number: str, ensure_hao: bool = False) -> str:
    if not number:
        return ""

    result = str(number)
    result = result.replace("(", "（").replace(")", "）")
    result = result.replace("〔", "（").replace("〕", "）")
    result = result.replace("[", "（").replace("]", "）")
    result = result.replace(" ", "").replace("\u3000", "")

    if ensure_hao and result and not result.endswith("号"):
        result += "号"

    return result