// Copyright 2023 Greptime Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

mod build;
mod database;
mod pg_catalog;
mod procedure_state;
mod timezone;
mod version;

use build::BuildFunction;
use database::{
    ConnectionIdFunction, DatabaseFunction, PgBackendPidFunction, ReadPreferenceFunction,
};
use pg_catalog::PGCatalogFunction;
use procedure_state::ProcedureStateFunction;
use timezone::TimezoneFunction;
use version::VersionFunction;

use crate::function_registry::FunctionRegistry;

pub(crate) struct SystemFunction;

impl SystemFunction {
    pub fn register(registry: &FunctionRegistry) {
        registry.register_scalar(BuildFunction::default());
        registry.register_scalar(VersionFunction::default());
        registry.register_scalar(DatabaseFunction::default());
        registry.register_scalar(ReadPreferenceFunction::default());
        registry.register_scalar(PgBackendPidFunction::default());
        registry.register_scalar(ConnectionIdFunction::default());
        registry.register_scalar(TimezoneFunction::default());
        registry.register(ProcedureStateFunction::factory());
        PGCatalogFunction::register(registry);
    }
}

macro_rules! define_nullary_udf {
    ($(#[$attr:meta])* $name: ident) => {
        $(#[$attr])*
        #[derive(Clone, Debug, derive_more::Display)]
        #[display("{}", self.name())]
        pub(crate) struct $name {
            signature: datafusion_expr::Signature,
        }

        impl Default for $name {
            fn default() -> Self {
                Self {
                    signature: datafusion_expr::Signature::nullary(Volatility::Immutable),
                }
            }
        }
    };
}

pub(crate) use define_nullary_udf;
