// Copyright 2022 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 pgwire::pg_response::{PgResponse, StatementType};
use risingwave_sqlparser::ast::ObjectName;

use super::RwPgResponse;
use crate::binder::Binder;
use crate::catalog::root_catalog::SchemaPath;
use crate::error::Result;
use crate::handler::HandlerArgs;

pub async fn handle_drop_view(
    handler_args: HandlerArgs,
    table_name: ObjectName,
    if_exists: bool,
    cascade: bool,
) -> Result<RwPgResponse> {
    let session = handler_args.session;
    let db_name = &session.database();
    let (schema_name, table_name) = Binder::resolve_schema_qualified_name(db_name, &table_name)?;
    let search_path = session.config().search_path();
    let user_name = &session.user_name();

    let schema_path = SchemaPath::new(schema_name.as_deref(), &search_path, user_name);

    let view_id = {
        let reader = session.env().catalog_reader().read_guard();
        let (view, schema_name) =
            match reader.get_view_by_name(&session.database(), schema_path, &table_name) {
                Ok((t, s)) => (t, s),
                Err(e) => {
                    return if if_exists {
                        Ok(RwPgResponse::builder(StatementType::DROP_VIEW)
                            .notice(format!("view \"{}\" does not exist, skipping", table_name))
                            .into())
                    } else {
                        Err(e.into())
                    };
                }
            };

        session.check_privilege_for_drop_alter(schema_name, &**view)?;

        view.id
    };

    let catalog_writer = session.catalog_writer()?;
    catalog_writer.drop_view(view_id, cascade).await?;

    Ok(PgResponse::empty_result(StatementType::DROP_VIEW))
}
