// Copyright 2024 PingCAP, 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 util

import (
	"github.com/pingcap/tidb/pkg/expression"
)

// ResolveExprAndReplace replaces columns fields of expressions by children logical plans.
func ResolveExprAndReplace(origin expression.Expression, replace map[string]*expression.Column) {
	switch expr := origin.(type) {
	case *expression.Column:
		ResolveColumnAndReplace(expr, replace)
	case *expression.CorrelatedColumn:
		ResolveColumnAndReplace(&expr.Column, replace)
	case *expression.ScalarFunction:
		for _, arg := range expr.GetArgs() {
			ResolveExprAndReplace(arg, replace)
		}
	}
}

// ResolveColumnAndReplace replaces columns fields of expressions by children logical plans.
func ResolveColumnAndReplace(origin *expression.Column, replace map[string]*expression.Column) {
	dst := replace[string(origin.HashCode())]
	if dst != nil {
		retType, inOperand := origin.RetType, origin.InOperand
		*origin = *dst
		origin.RetType, origin.InOperand = retType, inOperand
	}
}

// SetPredicatePushDownFlag is a hook for other packages to set rule flag.
var SetPredicatePushDownFlag func(uint64) uint64