package eval

import (
	"math/rand"
	"testing"
	"unicode/utf8"
)

// TestMoveTypeFront guards against the slice-aliasing regression that made the
// type word disappear.
func TestMoveTypeFront(t *testing.T) {
	got := moveTypeFront("станционная улица 1/1")
	if got != "улица станционная 1/1" {
		t.Fatalf("moveTypeFront = %q", got)
	}
	got = moveTypeFront("2-я станционная улица 1/1")
	if got != "улица 2-я станционная 1/1" {
		t.Fatalf("moveTypeFront with ordinal = %q", got)
	}
}

// TestAddYoKeepsValidUTF8 guards against the byte-index regression.
func TestAddYoKeepsValidUTF8(t *testing.T) {
	cases := []string{"переулок 5", "Северный проезд 7", "Зеленхозовская улица 48", "дом 1"}
	for _, in := range cases {
		out := addYo(in)
		if out != "" && !utf8.ValidString(out) {
			t.Fatalf("addYo(%q) produced invalid UTF-8: %q", in, out)
		}
	}
	if got := addYo("переулок 5"); got != "пёреулок 5" {
		t.Fatalf("addYo = %q", got)
	}
}

// TestMutateOnlyNameTokens verifies typos never target the street type word,
// which would turn into a bogus name token.
func TestMutateOnlyNameTokens(t *testing.T) {
	rng := rand.New(rand.NewSource(7))
	for i := 0; i < 200; i++ {
		got := mutateLongestToken("Станционная улица 1/1", rng)
		if got == "" {
			continue
		}
		if got == "Станционная улицб 1/1" || got == "Станционная улиц 1/1" {
			t.Fatalf("type word was mutated: %q", got)
		}
	}
}