// Copyright 2023 RisingWave Labs
//
// 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.

use std::hash::Hash;

use pretty_xmlish::{Str, XmlNode};
use risingwave_common::catalog::Schema;

use super::{DistillUnit, GenericPlanNode, GenericPlanRef};
use crate::OptimizerContextRef;
use crate::optimizer::plan_node::utils::childless_record;
use crate::optimizer::property::FunctionalDependencySet;

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct MaxOneRow<PlanRef> {
    pub input: PlanRef,
}

impl<PlanRef: GenericPlanRef> GenericPlanNode for MaxOneRow<PlanRef> {
    fn ctx(&self) -> OptimizerContextRef {
        self.input.ctx()
    }

    fn schema(&self) -> Schema {
        self.input.schema().clone()
    }

    fn functional_dependency(&self) -> FunctionalDependencySet {
        self.input.functional_dependency().clone()
    }

    fn stream_key(&self) -> Option<Vec<usize>> {
        self.input.stream_key().map(|s| s.to_vec())
    }
}

impl<PlanRef> MaxOneRow<PlanRef> {
    pub fn new(input: PlanRef) -> Self {
        MaxOneRow { input }
    }
}

impl<PlanRef> DistillUnit for MaxOneRow<PlanRef> {
    fn distill_with_name<'a>(&self, name: impl Into<Str<'a>>) -> XmlNode<'a> {
        childless_record(name, vec![])
    }
}
