// Copyright 2020 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 aggfuncs_test

import (
	"fmt"
	"testing"
	"time"

	"github.com/pingcap/tidb/executor/aggfuncs"
	"github.com/pingcap/tidb/parser/ast"
	"github.com/pingcap/tidb/parser/mysql"
	"github.com/pingcap/tidb/types"
	"github.com/stretchr/testify/require"
)

type testSlice []int

func (a testSlice) Len() int           { return len(a) }
func (a testSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a testSlice) Less(i, j int) bool { return a[i] < a[j] }

func TestPercentile(t *testing.T) {
	tests := []aggTest{
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeLonglong, 5, nil, 2),
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeFloat, 5, nil, 2.0),
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeDouble, 5, nil, 2.0),
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeNewDecimal, 5, nil, types.NewDecFromFloatForTest(2.0)),
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeDate, 5, nil, types.TimeFromDays(367)),
		buildAggTester(ast.AggFuncApproxPercentile, mysql.TypeDuration, 5, nil, types.Duration{Duration: time.Duration(2)}),
	}
	for i, test := range tests {
		t.Run(fmt.Sprintf("%s_%d", test.funcName, i), func(t *testing.T) {
			testAggFunc(t, test)
		})
	}

	data := testSlice{}
	want := 28
	for i := 1; i <= want; i++ {
		data = append(data, i)
	}
	for i := 0; i < 10; i++ {
		index := aggfuncs.PercentileForTesting(data, 100)
		require.Equal(t, want, data[index])
	}
}