package i18n

import (
	"regexp"
	"strings"
	"testing"
)

// EnMissingCeiling is the number of Hungarian keys allowed to be missing from English. It is zero
// and it stays zero: a fallback that renders Hungarian into an English household's mail is the
// failure this bundle exists to prevent, so it must never be reachable in a shipped build.
const EnMissingCeiling = 0

func TestEveryLanguageCarriesEveryKey(t *testing.T) {
	b := Shared()
	for _, lang := range Supported {
		missing := b.MissingKeys(lang)
		if lang == Default && len(missing) != 0 {
			t.Fatalf("%s is the source and cannot be missing keys: %v", lang, missing)
		}
		if len(missing) > EnMissingCeiling {
			t.Errorf("%s is missing %d key(s) (ceiling %d): %v",
				lang, len(missing), EnMissingCeiling, missing)
		}
	}
}

// verbRe matches a Go format verb, including an explicit argument index (%[2]s).
var verbRe = regexp.MustCompile(`%(\[\d+\])?[-+# 0]*\d*(\.\d+)?[a-zA-Z%]`)

// TestFormatVerbsMatchAcrossLanguages is the test that stops a translation corrupting a mail.
//
// Msgf formats the TRANSLATED value with the arguments the Hungarian call site passes. A translation
// that drops a `%s` silently loses a customer's server name; one that adds a `%s` renders
// `%!s(MISSING)` into a real e-mail. Neither is visible to a reviewer reading the JSON, and neither
// would fail any other test here — the mail still sends.
//
// Explicit argument indexes (`%[2]s`) are how English reorders what Hungarian does not, so the check
// is on the MULTISET of verbs, not on their order.
func TestFormatVerbsMatchAcrossLanguages(t *testing.T) {
	b := Shared()
	for _, key := range b.Keys(Default) {
		huVerbs := verbCounts(b.Msg(Default, key))
		for _, lang := range Supported {
			if lang == Default || !b.Has(lang, key) {
				continue
			}
			got := verbCounts(b.Msg(lang, key))
			if len(got) != len(huVerbs) {
				t.Errorf("%s/%s has %d format verb(s), hu has %d — the mail would render wrong",
					lang, key, len(got), len(huVerbs))
				continue
			}
			for verb, n := range huVerbs {
				if got[verb] != n {
					t.Errorf("%s/%s uses %q %d time(s), hu uses it %d time(s)",
						lang, key, verb, got[verb], n)
				}
			}
		}
	}
}

// verbCounts counts each format verb, ignoring the escaped %% which formats nothing.
func verbCounts(s string) map[string]int {
	out := map[string]int{}
	for _, m := range verbRe.FindAllString(s, -1) {
		if m == "%%" {
			continue
		}
		// An indexed verb counts as its bare form: %[2]s and %s consume the same argument type.
		if i := strings.Index(m, "]"); i >= 0 {
			m = "%" + m[i+1:]
		}
		out[m]++
	}
	return out
}

func TestNormalizeAndIsSupported(t *testing.T) {
	for in, want := range map[string]string{
		"hu": "hu", "en": "en", "EN": "en", " en ": "en",
		"": "hu", "de": "hu", "en-GB": "hu", "garbage": "hu",
	} {
		if got := Normalize(in); got != want {
			t.Errorf("Normalize(%q) = %q, want %q", in, got, want)
		}
	}
	// IsSupported REFUSES where Normalize coerces — that difference is the whole reason both exist.
	for _, bad := range []string{"", "EN", " en ", "de", "en-GB"} {
		if IsSupported(bad) {
			t.Errorf("IsSupported(%q) is true — a bad input would be stored as a real language", bad)
		}
	}
	for _, good := range []string{"hu", "en"} {
		if !IsSupported(good) {
			t.Errorf("IsSupported(%q) is false", good)
		}
	}
}

// A key that exists nowhere must be LOUD, never blank: an empty string in a mail body is a hole
// nobody notices.
func TestUnknownKeyIsVisible(t *testing.T) {
	got := Shared().Msg("en", "mail.event.no_such_thing_exists")
	if got == "" {
		t.Fatal("an unknown key rendered as an empty string — the mail would have a silent hole")
	}
	if !strings.Contains(got, "no_such_thing_exists") {
		t.Errorf("an unknown key rendered as %q — it does not name the key", got)
	}
}

// An English key falls back to Hungarian rather than to nothing. Proven with a key deliberately
// absent from en.json would be circular (there are none), so it is proven on the mechanism: a
// language that carries no file at all.
func TestFallbackIsHungarianNotBlank(t *testing.T) {
	b := Shared()
	if got := b.Msg("de", "mail.event.backup_completed"); got != b.Msg(Default, "mail.event.backup_completed") {
		t.Errorf("an unsupported language did not fall back to Hungarian: %q", got)
	}
}

// The English bundle must not be a copy of the Hungarian one. A translation pass that silently
// copied the source would pass every other test in this file.
func TestEnglishIsActuallyTranslated(t *testing.T) {
	// The keys that are IDENTICAL IN BOTH LANGUAGES ON PURPOSE, each with the reason. An allowlist
	// rather than a count: a count lets the next untranslated key hide inside the budget, and the
	// question "why is this one the same?" then has no answer written down anywhere.
	sameOnPurpose := map[string]string{
		"mail.customer.subject":    `"[Felhom] %s: %s" — a format with no words in it; both halves are themselves translated`,
		"bind.placeholder.pairing": `"ABC-234" — a sample of a code the box prints, not prose`,
	}

	b := Shared()
	for _, key := range b.Keys(Default) {
		hu, en := b.Msg(Default, key), b.Msg("en", key)
		if hu != en {
			if _, listed := sameOnPurpose[key]; listed {
				t.Errorf("%s is allowlisted as identical but the two languages now differ — "+
					"remove it from sameOnPurpose", key)
			}
			continue
		}
		if _, ok := sameOnPurpose[key]; !ok {
			t.Errorf("%s is identical in hu and en — untranslated text would ship: %q", key, hu)
		}
	}
}