// Copyright 2018 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package check

import (
	"strconv"

	"github.com/ngaut/log"
	"github.com/pingcap/parser/model"
)

// RowData is the struct of rows selected from mysql/tidb
type RowData struct {
	Data         map[string][]byte
	Null         map[string]bool
	OrderKeyCols []*model.ColumnInfo
}

// RowDatas is a heap of MergeItems.
type RowDatas []RowData

func (r RowDatas) Len() int { return len(r) }
func (r RowDatas) Less(i, j int) bool {
	var data1, data2 []byte

	for _, col := range r[i].OrderKeyCols {
		data1 = r[i].Data[col.Name.O]
		data2 = r[j].Data[col.Name.O]
		if needQuotes(col.FieldType) {
			if string(data1) > string(data2) {
				return false
			} else if string(data1) < string(data2) {
				return true
			} else {
				// `NULL` is less than ""
				if r[i].Null[col.Name.O] {
					return true
				}
				if r[j].Null[col.Name.O] {
					return false
				}
				continue
			}
		} else {
			num1, err1 := strconv.ParseFloat(string(data1), 64)
			num2, err2 := strconv.ParseFloat(string(data2), 64)
			if err1 != nil || err2 != nil {
				// it will never happened
				log.Errorf("convert %s, %s to float failed, err1: %v, err2: %v", string(data1), string(data2), err1, err2)
				return false
			}
			if num1 > num2 {
				return false
			} else if num1 < num2 {
				return true
			} else {
				continue
			}
		}
	}

	return true
}
func (r RowDatas) Swap(i, j int) { r[i], r[j] = r[j], r[i] }

// Push implements heap.Interface's Push function
func (r *RowDatas) Push(x interface{}) {
	*r = append(*r, x.(RowData))
}

// Pop implements heap.Interface's Pop function
func (r *RowDatas) Pop() interface{} {
	old := *r
	n := len(old)
	x := old[n-1]
	*r = old[0 : n-1]
	return x
}