"""
Database secondary indexes helper.

Creates small B-tree indexes for common equality filters to speed up searches.
Uses CREATE INDEX IF NOT EXISTS so it is safe to call repeatedly at startup
and works for existing databases without running a migration.
"""
from sqlalchemy.engine import Engine
from sqlalchemy import text


def ensure_secondary_indexes(engine: Engine) -> None:
    statements = [
        # Files
        "CREATE INDEX IF NOT EXISTS idx_files_status ON files(status)",
        "CREATE INDEX IF NOT EXISTS idx_files_file_type ON files(file_type)",
        "CREATE INDEX IF NOT EXISTS idx_files_empl_num ON files(empl_num)",
        # Ledger
        "CREATE INDEX IF NOT EXISTS idx_ledger_t_type ON ledger(t_type)",
        "CREATE INDEX IF NOT EXISTS idx_ledger_empl_num ON ledger(empl_num)",
    ]
    with engine.begin() as conn:
        for stmt in statements:
            try:
                conn.execute(text(stmt))
            except Exception:
                # Ignore failures (e.g., non-SQLite engines that still support IF NOT EXISTS;
                # if not supported, users should manage indexes via migrations)
                pass