// Copyright 2022 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 (
	"encoding/binary"
	"fmt"
	"time"
	"unsafe"

	"github.com/pingcap/tidb/pkg/expression"
	"github.com/pingcap/tidb/pkg/parser/model"
	"github.com/pingcap/tidb/pkg/util/ranger"
)

// CloneExprs uses Expression.Clone to clone a slice of Expression.
func CloneExprs(exprs []expression.Expression) []expression.Expression {
	cloned := make([]expression.Expression, 0, len(exprs))
	for _, e := range exprs {
		cloned = append(cloned, e.Clone())
	}
	return cloned
}

// CloneCols uses (*Column).Clone to clone a slice of *Column.
func CloneCols(cols []*expression.Column) []*expression.Column {
	cloned := make([]*expression.Column, 0, len(cols))
	for _, c := range cols {
		if c == nil {
			cloned = append(cloned, nil)
			continue
		}
		cloned = append(cloned, c.Clone().(*expression.Column))
	}
	return cloned
}

// CloneColInfos uses (*ColumnInfo).Clone to clone a slice of *ColumnInfo.
func CloneColInfos(cols []*model.ColumnInfo) []*model.ColumnInfo {
	cloned := make([]*model.ColumnInfo, 0, len(cols))
	for _, c := range cols {
		cloned = append(cloned, c.Clone())
	}
	return cloned
}

// CloneRanges uses (*Range).Clone to clone a slice of *Range.
func CloneRanges(ranges []*ranger.Range) []*ranger.Range {
	cloned := make([]*ranger.Range, 0, len(ranges))
	for _, r := range ranges {
		cloned = append(cloned, r.Clone())
	}
	return cloned
}

// QueryTimeRange represents a time range specified by TIME_RANGE hint
type QueryTimeRange struct {
	From time.Time
	To   time.Time
}

// Condition returns a WHERE clause base on it's value
func (tr *QueryTimeRange) Condition() string {
	return fmt.Sprintf("where time>='%s' and time<='%s'",
		tr.From.Format(MetricTableTimeFormat), tr.To.Format(MetricTableTimeFormat))
}

// MetricTableTimeFormat is the time format for metric table explain and format.
const MetricTableTimeFormat = "2006-01-02 15:04:05.999"

const emptyQueryTimeRangeSize = int64(unsafe.Sizeof(QueryTimeRange{}))

// MemoryUsage return the memory usage of QueryTimeRange
func (tr *QueryTimeRange) MemoryUsage() (sum int64) {
	if tr == nil {
		return
	}
	return emptyQueryTimeRangeSize
}

// EncodeIntAsUint32 is used for LogicalPlan Interface
func EncodeIntAsUint32(result []byte, value int) []byte {
	var buf [4]byte
	binary.BigEndian.PutUint32(buf[:], uint32(value))
	return append(result, buf[:]...)
}