package util

import (
	"reflect"
	"testing"
)

func TestChunkStrings(t *testing.T) {
	tests := []struct {
		name     string
		input    []string
		size     int
		expected [][]string
	}{
		{"exact multiple", []string{"a", "b", "c", "d"}, 2, [][]string{{"a", "b"}, {"c", "d"}}},
		{"with a remainder", []string{"a", "b", "c"}, 2, [][]string{{"a", "b"}, {"c"}}},
		{"size larger than input", []string{"a", "b"}, 5, [][]string{{"a", "b"}}},
		{"size of one", []string{"a", "b"}, 1, [][]string{{"a"}, {"b"}}},
		{"size of zero", []string{"a", "b"}, 0, nil},
		{"negative size", []string{"a", "b"}, -1, nil},
		{"empty input", []string{}, 2, nil},
		{"nil input", nil, 2, nil},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			got := ChunkStrings(test.input, test.size)
			if !reflect.DeepEqual(got, test.expected) {
				t.Errorf("expected %#v got %#v", test.expected, got)
			}
		})
	}
}

func TestChunkStringsReturnsCopies(t *testing.T) {
	input := []string{"a", "b", "c", "d"}
	chunks := ChunkStrings(input, 2)
	chunks[0][0] = "changed"

	if input[0] != "a" {
		t.Errorf("expected the input to be unchanged, got %#v", input)
	}
}