"""标准时间字段：Unix 秒级时间戳、默认值与 updated_at 自动维护。

业务表若包含 created_at / updated_at，在 CREATE TABLE 后调用
``init_updated_at_trigger(cursor, table_name)``。模板默认不建业务表。
"""

from __future__ import annotations

STANDARD_TIMESTAMP_COLUMNS = frozenset({"created_at", "updated_at"})
DATETIME_UNIX_SECONDS = "datetime_unix_seconds"


def updated_at_trigger_name(table_name: str) -> str:
    return f"{table_name}_set_updated_at"


def _quote_identifier(name: str) -> str:
    return '"' + name.replace('"', '""') + '"'


def init_updated_at_trigger(cursor, table_name: str) -> None:
    """幂等创建 {table}_set_updated_at：业务字段 UPDATE 后刷新 updated_at。"""
    trigger = updated_at_trigger_name(table_name)
    quoted = _quote_identifier(table_name)
    quoted_trigger = _quote_identifier(trigger)
    cursor.execute(
        f"""
CREATE TRIGGER IF NOT EXISTS {quoted_trigger}
AFTER UPDATE ON {quoted}
FOR EACH ROW
BEGIN
    UPDATE {quoted}
    SET updated_at = unixepoch()
    WHERE id = NEW.id AND updated_at = OLD.updated_at;
END
"""
    )


def has_updated_at_trigger(cursor, table_name: str) -> bool:
    trigger_name = updated_at_trigger_name(table_name)
    cursor.execute(
        """
        SELECT 1 FROM sqlite_master
        WHERE type = 'trigger' AND name = ? AND tbl_name = ?
        LIMIT 1
        """,
        (trigger_name, table_name),
    )
    return cursor.fetchone() is not None