package domain

import (
	"testing"
	"unicode/utf16"
)

func TestOfficialWelcomeMessageLinksUpdatesChannel(t *testing.T) {
	for _, method := range []string{"phone number", "email"} {
		msg, err := OfficialWelcomeMessage(1780243200, method, 1_700_000_000)
		if err != nil {
			t.Fatalf("method %q: %v", method, err)
		}
		if len(msg.Entities) != 1 {
			t.Fatalf("method %q: entities = %+v, want one mention", method, msg.Entities)
		}
		ent := msg.Entities[0]
		if ent.Type != MessageEntityMention {
			t.Fatalf("entity type = %q, want mention", ent.Type)
		}
		units := utf16.Encode([]rune(msg.Body))
		if ent.Offset < 0 || ent.Length <= 0 || ent.Offset+ent.Length > len(units) {
			t.Fatalf("entity %+v out of bounds for body of %d utf16 units", ent, len(units))
		}
		if got := string(utf16.Decode(units[ent.Offset : ent.Offset+ent.Length])); got != officialUpdatesChannelMention {
			t.Fatalf("entity spans %q, want %q", got, officialUpdatesChannelMention)
		}
	}
}