// Copyright 2020 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 gsort

import (
	"math"
	"sort"
	"testing"

	"constraints"
	"slices"
)

// Test data copied from the standard library sort package.

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 strs = []string{"", "Hello", "foo", "bar", "foo", "f00", "%*&^*&^&", "***"}

func TestSortOrderedInts(t *testing.T) {
	testOrdered(t, ints, sort.Ints)
}

func TestSortOrderedFloat64s(t *testing.T) {
	testOrdered(t, float64s, sort.Float64s)
}

func TestSortOrderedStrings(t *testing.T) {
	testOrdered(t, strs, sort.Strings)
}

func testOrdered[Elem constraints.Ordered](t *testing.T, s []Elem, sorter func([]Elem)) {
	s1 := make([]Elem, len(s))
	copy(s1, s)
	s2 := make([]Elem, len(s))
	copy(s2, s)
	OrderedSlice(s1)
	sorter(s2)
	if !slices.Equal(s1, s2) {
		t.Fatalf("got %v, want %v", s1, s2)
	}
	for i := len(s1) - 1; i > 0; i-- {
		if s1[i] < s1[i-1] {
			t.Fatalf("element %d (%v) < element %d (%v)", i, s1[i], i - 1, s1[i - 1])
		}
	}
}

var slicesToSort = [][]int {
	[]int{1, 2},
	[]int{3, 2, 1},
	[]int{1},
	[]int{1, 3},
	[]int{1, 2, 3},
}

var sortedSlices = [][]int {
	[]int{1},
	[]int{1, 2},
	[]int{1, 3},
	[]int{1, 2, 3},
	[]int{3, 2, 1},
}

func sorter(s1, s2 []int) bool {
	switch {
	case len(s1) < len(s2):
		return true
	case len(s1) > len(s2):
		return false
	}
	for i := range s1 {
		switch {
		case s1[i] < s2[i]:
			return true
		case s1[i] > s2[i]:
			return false
		}
	}
	return false
}

func TestSortSliceFn(t *testing.T) {
	c := make([][]int, len(slicesToSort))
	copy(c, slicesToSort)
	SliceFn(c, sorter)
	if !slices.EqualFn(c, sortedSlices, func(a, b []int) bool { return slices.Equal[int](a, b) }) {
		t.Errorf("got %v, want %v", c, sortedSlices)
	}
}