// 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.

use std::sync::Arc;

use common_error::ext::BoxedError;
use common_recordbatch::{EmptyRecordBatchStream, SendableRecordBatchStream};
use datatypes::schema::SchemaRef;
use store_api::data_source::DataSource;
use store_api::storage::ScanRequest;

use crate::metadata::{FilterPushDownType, TableInfo};
use crate::{Table, TableRef};

pub struct EmptyTable;

impl EmptyTable {
    pub fn from_table_info(info: &TableInfo) -> TableRef {
        let data_source = Arc::new(EmptyDataSource {
            schema: info.meta.schema.clone(),
        });
        let table = Table::new(
            Arc::new(info.clone()),
            FilterPushDownType::Unsupported,
            data_source,
        );
        Arc::new(table)
    }
}

struct EmptyDataSource {
    schema: SchemaRef,
}

impl DataSource for EmptyDataSource {
    fn get_stream(
        &self,
        _request: ScanRequest,
    ) -> std::result::Result<SendableRecordBatchStream, BoxedError> {
        Ok(Box::pin(EmptyRecordBatchStream::new(self.schema.clone())))
    }
}
