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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sort_test

import (
        "fmt"
        "math"
        "math/rand"
        . "sort"
        "strconv"
        "testing"
)

var ints = [...]int{74, 59, 238, -784, 9845, 959, 905, 0, 0, 42, 7586, -5467984, 7586}
var float64s = [...]float64{74.3, 59.0, math.Inf(1), 238.2, -784.0, 2.3, math.NaN(), math.NaN(), math.Inf(-1), 9845.768, -959.7485, 905, 7.8, 7.8}
var strings = [...]string{"", "Hello", "foo", "bar", "foo", "f00", "%*&^*&^&", "***"}

func TestSortIntSlice(t *testing.T) {
        data := ints
        a := IntSlice(data[0:])
        Sort(a)
        if !IsSorted(a) {
                t.Errorf("sorted %v", ints)
                t.Errorf("   got %v", data)
        }
}

func TestSortFloat64Slice(t *testing.T) {
        data := float64s
        a := Float64Slice(data[0:])
        Sort(a)
        if !IsSorted(a) {
                t.Errorf("sorted %v", float64s)
                t.Errorf("   got %v", data)
        }
}

func TestSortStringSlice(t *testing.T) {
        data := strings
        a := StringSlice(data[0:])
        Sort(a)
        if !IsSorted(a) {
                t.Errorf("sorted %v", strings)
                t.Errorf("   got %v", data)
        }
}

func TestInts(t *testing.T) {
        data := ints
        Ints(data[0:])
        if !IntsAreSorted(data[0:]) {
                t.Errorf("sorted %v", ints)
                t.Errorf("   got %v", data)
        }
}

func TestFloat64s(t *testing.T) {
        data := float64s
        Float64s(data[0:])
        if !Float64sAreSorted(data[0:]) {
                t.Errorf("sorted %v", float64s)
                t.Errorf("   got %v", data)
        }
}

func TestStrings(t *testing.T) {
        data := strings
        Strings(data[0:])
        if !StringsAreSorted(data[0:]) {
                t.Errorf("sorted %v", strings)
                t.Errorf("   got %v", data)
        }
}

func TestSortLarge_Random(t *testing.T) {
        n := 1000000
        if testing.Short() {
                n /= 100
        }
        data := make([]int, n)
        for i := 0; i < len(data); i++ {
                data[i] = rand.Intn(100)
        }
        if IntsAreSorted(data) {
                t.Fatalf("terrible rand.rand")
        }
        Ints(data)
        if !IntsAreSorted(data) {
                t.Errorf("sort didn't sort - 1M ints")
        }
}

func BenchmarkSortString1K(b *testing.B) {
        b.StopTimer()
        for i := 0; i < b.N; i++ {
                data := make([]string, 1<<10)
                for i := 0; i < len(data); i++ {
                        data[i] = strconv.Itoa(i ^ 0x2cc)
                }
                b.StartTimer()
                Strings(data)
                b.StopTimer()
        }
}

func BenchmarkSortInt1K(b *testing.B) {
        b.StopTimer()
        for i := 0; i < b.N; i++ {
                data := make([]int, 1<<10)
                for i := 0; i < len(data); i++ {
                        data[i] = i ^ 0x2cc
                }
                b.StartTimer()
                Ints(data)
                b.StopTimer()
        }
}

func BenchmarkSortInt64K(b *testing.B) {
        b.StopTimer()
        for i := 0; i < b.N; i++ {
                data := make([]int, 1<<16)
                for i := 0; i < len(data); i++ {
                        data[i] = i ^ 0xcccc
                }
                b.StartTimer()
                Ints(data)
                b.StopTimer()
        }
}

const (
        _Sawtooth = iota
        _Rand
        _Stagger
        _Plateau
        _Shuffle
        _NDist
)

const (
        _Copy = iota
        _Reverse
        _ReverseFirstHalf
        _ReverseSecondHalf
        _Sorted
        _Dither
        _NMode
)

type testingData struct {
        desc    string
        t       *testing.T
        data    []int
        maxswap int // number of swaps allowed
        nswap   int
}

func (d *testingData) Len() int           { return len(d.data) }
func (d *testingData) Less(i, j int) bool { return d.data[i] < d.data[j] }
func (d *testingData) Swap(i, j int) {
        if d.nswap >= d.maxswap {
                d.t.Errorf("%s: used %d swaps sorting slice of %d", d.desc, d.nswap, len(d.data))
                d.t.FailNow()
        }
        d.nswap++
        d.data[i], d.data[j] = d.data[j], d.data[i]
}

func min(a, b int) int {
        if a < b {
                return a
        }
        return b
}

func lg(n int) int {
        i := 0
        for 1<<uint(i) < n {
                i++
        }
        return i
}

func testBentleyMcIlroy(t *testing.T, sort func(Interface)) {
        sizes := []int{100, 1023, 1024, 1025}
        if testing.Short() {
                sizes = []int{100, 127, 128, 129}
        }
        dists := []string{"sawtooth", "rand", "stagger", "plateau", "shuffle"}
        modes := []string{"copy", "reverse", "reverse1", "reverse2", "sort", "dither"}
        var tmp1, tmp2 [1025]int
        for ni := 0; ni < len(sizes); ni++ {
                n := sizes[ni]
                for m := 1; m < 2*n; m *= 2 {
                        for dist := 0; dist < _NDist; dist++ {
                                j := 0
                                k := 1
                                data := tmp1[0:n]
                                for i := 0; i < n; i++ {
                                        switch dist {
                                        case _Sawtooth:
                                                data[i] = i % m
                                        case _Rand:
                                                data[i] = rand.Intn(m)
                                        case _Stagger:
                                                data[i] = (i*m + i) % n
                                        case _Plateau:
                                                data[i] = min(i, m)
                                        case _Shuffle:
                                                if rand.Intn(m) != 0 {
                                                        j += 2
                                                        data[i] = j
                                                } else {
                                                        k += 2
                                                        data[i] = k
                                                }
                                        }
                                }

                                mdata := tmp2[0:n]
                                for mode := 0; mode < _NMode; mode++ {
                                        switch mode {
                                        case _Copy:
                                                for i := 0; i < n; i++ {
                                                        mdata[i] = data[i]
                                                }
                                        case _Reverse:
                                                for i := 0; i < n; i++ {
                                                        mdata[i] = data[n-i-1]
                                                }
                                        case _ReverseFirstHalf:
                                                for i := 0; i < n/2; i++ {
                                                        mdata[i] = data[n/2-i-1]
                                                }
                                                for i := n / 2; i < n; i++ {
                                                        mdata[i] = data[i]
                                                }
                                        case _ReverseSecondHalf:
                                                for i := 0; i < n/2; i++ {
                                                        mdata[i] = data[i]
                                                }
                                                for i := n / 2; i < n; i++ {
                                                        mdata[i] = data[n-(i-n/2)-1]
                                                }
                                        case _Sorted:
                                                for i := 0; i < n; i++ {
                                                        mdata[i] = data[i]
                                                }
                                                // Ints is known to be correct
                                                // because mode Sort runs after mode _Copy.
                                                Ints(mdata)
                                        case _Dither:
                                                for i := 0; i < n; i++ {
                                                        mdata[i] = data[i] + i%5
                                                }
                                        }

                                        desc := fmt.Sprintf("n=%d m=%d dist=%s mode=%s", n, m, dists[dist], modes[mode])
                                        d := &testingData{desc, t, mdata[0:n], n * lg(n) * 12 / 10, 0}
                                        sort(d)

                                        // If we were testing C qsort, we'd have to make a copy
                                        // of the slice and sort it ourselves and then compare
                                        // x against it, to ensure that qsort was only permuting
                                        // the data, not (for example) overwriting it with zeros.
                                        //
                                        // In go, we don't have to be so paranoid: since the only
                                        // mutating method Sort can call is TestingData.swap,
                                        // it suffices here just to check that the final slice is sorted.
                                        if !IntsAreSorted(mdata) {
                                                t.Errorf("%s: ints not sorted", desc)
                                                t.Errorf("\t%v", mdata)
                                                t.FailNow()
                                        }
                                }
                        }
                }
        }
}

func TestSortBM(t *testing.T) {
        testBentleyMcIlroy(t, Sort)
}

func TestHeapsortBM(t *testing.T) {
        testBentleyMcIlroy(t, Heapsort)
}

// This is based on the "antiquicksort" implementation by M. Douglas McIlroy.
// See http://www.cs.dartmouth.edu/~doug/mdmspe.pdf for more info.
type adversaryTestingData struct {
        data      []int
        keys      map[int]int
        candidate int
}

func (d *adversaryTestingData) Len() int { return len(d.data) }

func (d *adversaryTestingData) Less(i, j int) bool {
        if _, present := d.keys[i]; !present {
                if _, present := d.keys[j]; !present {
                        if i == d.candidate {
                                d.keys[i] = len(d.keys)
                        } else {
                                d.keys[j] = len(d.keys)
                        }
                }
        }

        if _, present := d.keys[i]; !present {
                d.candidate = i
                return false
        }
        if _, present := d.keys[j]; !present {
                d.candidate = j
                return true
        }

        return d.keys[i] >= d.keys[j]
}

func (d *adversaryTestingData) Swap(i, j int) {
        d.data[i], d.data[j] = d.data[j], d.data[i]
}

func TestAdversary(t *testing.T) {
        const size = 100
        data := make([]int, size)
        for i := 0; i < size; i++ {
                data[i] = i
        }

        d := &adversaryTestingData{data, make(map[int]int), 0}
        Sort(d) // This should degenerate to heapsort.
}