package pwgen

import (
	"math/rand"
	"reflect"
	"testing"
	"unsafe"
)

func Test_alphabet(t *testing.T) {
	type args struct {
		start rune
		end   rune
	}
	tests := []struct {
		name       string
		args       args
		wantResult []rune
	}{
		{
			name: "Lowercase runes",
			args: args{
				start: 'a',
				end:   'z',
			},
			//lowercase runes a to z
			wantResult: []rune{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'},
		},
		{
			name: "Uppercase runes",
			args: args{
				start: 'A',
				end:   'Z',
			},
			wantResult: []rune("ABCDEFGHIJKLMNOPQRSTUVWXYZ"),
		},
		{
			name: "Digit runes",
			args: args{
				start: '0',
				end:   '9',
			},
			wantResult: []rune("0123456789"),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if gotResult := alphabet(tt.args.start, tt.args.end); !reflect.DeepEqual(gotResult, tt.wantResult) {
				t.Errorf("alphabet() = %v, want %v", gotResult, tt.wantResult)
			}
		})
	}
}

func Fuzz_shuffle(f *testing.F) {
	defaultPrng := rand.New(rand.NewSource(1))

	f.Add("hello, world")
	f.Add("a")
	f.Add("aa")
	f.Add("abcdef")
	f.Add("01234")

	f.Fuzz(func(t *testing.T, input string) {
		in := []rune(input)
		out := shuffle(in, defaultPrng)

		if sliceReferenceEqual(in, out) {
			t.Logf("returned the same input")
			return
		}

		if len(input) > 1 && string(out) == input {
			t.Errorf("shuffle() = %s, input %s", string(out), input)
		}
	})
}

func sliceReferenceEqual[T any](a, b []T) bool {
	ah := (*reflect.SliceHeader)(unsafe.Pointer(&a))
	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))

	return ah.Data == bh.Data
}