// Copyright 2023 Dolthub, Inc.
//
// 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.

package ast

import (
	vitess "github.com/dolthub/vitess/go/vt/sqlparser"

	"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
	"github.com/dolthub/doltgresql/utils"
)

// nodeSubquery handles *tree.Subquery nodes.
func nodeSubquery(ctx *Context, node *tree.Subquery) (*vitess.Subquery, error) {
	if node == nil {
		return nil, nil
	}
	selectStmt, err := nodeSelectStatement(ctx, node.Select)
	if err != nil {
		return nil, err
	}
	return &vitess.Subquery{
		Select: selectStmt,
	}, nil
}

// nodeSubquery handles *tree.Subquery nodes, returning a vitess.TableExpr.
func nodeSubqueryToTableExpr(ctx *Context, node *tree.Subquery) (vitess.TableExpr, error) {
	subquery, err := nodeSubquery(ctx, node)
	if err != nil {
		return nil, err
	}
	return &vitess.AliasedTableExpr{
		Expr: subquery,
		As:   vitess.NewTableIdent(utils.GenerateUniqueAlias()),
	}, nil
}

// nodeSubqueryOrExists handles *tree.Subquery nodes that may be an EXISTS subquery, returning a vitess.Expr.
func nodeSubqueryOrExists(ctx *Context, node *tree.Subquery) (vitess.Expr, error) {
	subquery, err := nodeSubquery(ctx, node)
	if err != nil {
		return nil, err
	}
	if !node.Exists {
		return subquery, nil
	}
	return &vitess.ExistsExpr{
		Subquery: subquery,
	}, nil
}