package bot

import (
	"strings"
	"testing"
)

func TestStartTextLocalizesByLanguage(t *testing.T) {
	cases := []struct {
		name       string
		lang       string
		wantButton string
		wantSubstr string // a phrase unique to the chosen language body
	}{
		{"russian", "ru", "Открыть «Эрудит»", "Привет!"},
		{"russian region tag", "ru-RU", "Открыть «Эрудит»", "Первая партия"},
		{"english", "en", "Open “Erudite”", "Hi!"},
		{"other language falls back to english", "de", "Open “Erudite”", "Hi!"},
		{"absent language falls back to english", "", "Open “Erudite”", "no more talking"},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			text, button := startText(tc.lang, "erudit", "erudite_chat")
			if button != tc.wantButton {
				t.Errorf("button = %q, want %q", button, tc.wantButton)
			}
			if !strings.Contains(text, tc.wantSubstr) {
				t.Errorf("text %q does not contain %q", text, tc.wantSubstr)
			}
		})
	}
}

func TestStartTextEmbedsFollowHandles(t *testing.T) {
	for _, lang := range []string{"ru", "en"} {
		text, _ := startText(lang, "erudit", "erudite_chat")
		if !strings.Contains(text, "@erudit") || !strings.Contains(text, "@erudite_chat") {
			t.Errorf("lang %q: follow paragraph missing the handles: %q", lang, text)
		}
	}
}

func TestStartTextFallsBackToGenericWhenHandleMissing(t *testing.T) {
	// An unresolved handle degrades to a generic noun rather than a dangling "@" — and
	// only that slot degrades; a resolved sibling still shows its "@username".
	t.Run("both missing leaves no @", func(t *testing.T) {
		for _, lang := range []string{"ru", "en"} {
			text, _ := startText(lang, "", "")
			if strings.Contains(text, "@") {
				t.Errorf("lang %q: text shows a dangling @: %q", lang, text)
			}
		}
		// The generic nouns are present in each language.
		ru, _ := startText("ru", "", "")
		if !strings.Contains(ru, "на канал") || !strings.Contains(ru, "в нашем чате") {
			t.Errorf("russian generic fallback missing: %q", ru)
		}
		en, _ := startText("en", "", "")
		if !strings.Contains(en, "Follow the channel") || !strings.Contains(en, "in our group chat") {
			t.Errorf("english generic fallback missing: %q", en)
		}
	})
	t.Run("only the missing slot degrades", func(t *testing.T) {
		// Channel resolved, chat missing: the channel keeps its @handle, the chat is generic.
		en, _ := startText("en", "erudit", "")
		if !strings.Contains(en, "@erudit") || strings.Contains(en, "@erudite") {
			t.Errorf("channel handle not shown / chat handle leaked: %q", en)
		}
		if !strings.Contains(en, "in our group chat") {
			t.Errorf("chat slot did not degrade to a generic noun: %q", en)
		}
	})
}