package lang

import (
	"strings"
	"testing"
)

// TestEmbeddedVersionMutation is the П0 acceptance test (D39.60 §6.1, "bytes ARE version" for the embed
// plane): a byte edit of an embedded data file MUST move EmbeddedVersion — so, once it is folded into the
// snapshot, an edit is a loud --resnapshot, never a silent verdict/wire change. It also pins the format and
// reproducibility (the same bytes always hash the same).
func TestEmbeddedVersionMutation(t *testing.T) {
	got := EmbeddedVersion()
	if !strings.HasPrefix(got, embedAlgoVersion+"-") {
		t.Fatalf("EmbeddedVersion() = %q, want %s-<hash>", got, embedAlgoVersion)
	}

	files := embeddedDataFiles()
	if len(files) == 0 {
		t.Fatal("no embedded data files")
	}
	if base := hashEmbeddedFiles(files); base != got {
		t.Fatalf("EmbeddedVersion not reproducible from embeddedDataFiles(): %s != %s", base, got)
	}

	// Mutate ONE byte of a verdict-bearing file (target-ru.txt drives the sanitizer) and a wire-bearing file
	// (injection.txt rides the request) — each must diverge the hash on its own.
	for _, target := range []string{"target-ru.txt", "injection.txt"} {
		mutated := make([]embeddedFile, len(files))
		copy(mutated, files)
		var found bool
		for i := range mutated {
			if mutated[i].name == target {
				b := append([]byte(nil), mutated[i].data...)
				b[len(b)/2] ^= 0x01 // flip a content byte
				mutated[i].data = b
				found = true
				break
			}
		}
		if !found {
			t.Fatalf("%s is not embedded", target)
		}
		if mut := hashEmbeddedFiles(mutated); mut == got {
			t.Errorf("a byte edit of %s did NOT move EmbeddedVersion (%s) — the embed plane would drift silently", target, mut)
		}
	}
}

// TestTheInjectionKeysAreOneVocabulary pins the property the key table exists for: the keys the PARSER
// accepts and the keys a guard may REQUIRE are the same set, read from one place. A guard naming its own
// literals would pass forever on a key the file stopped carrying, and the run it was supposed to refuse —
// a bank its target cannot state — is silent by construction.
func TestTheInjectionKeysAreOneVocabulary(t *testing.T) {
	// Every key the parser accepts must be answerable by Authored. A key that parses into a field nothing
	// can read back is a row a guard cannot see.
	for key := range injectionFields {
		parsed, err := parseInjection([]byte("xx\t" + key + "\tзначение"))
		if err != nil {
			t.Fatalf("the parser accepts %q but this file could not be parsed: %v", key, err)
		}
		if !parsed["xx"].Authored(key) {
			t.Errorf("key %q parses into a field Authored cannot read back — a guard asking for it would never see the row", key)
		}
		if parsed["xx"].Authored("no_such_key") {
			t.Errorf("an unknown key must never read as authored (%q)", key)
		}
	}
	if _, err := parseInjection([]byte("xx\tno_such_key\tзначение")); err == nil {
		t.Error("an unknown injection key must fail the parse loudly — a typo that parses is a row nobody renders")
	}
}

// TestAPartialInjectionSetIsVisibleToTheGuard is the predicate half of the write-path refusal (pipeline:
// checkInjectionTexts). It lives here and not there because the EMBEDDED data carries exactly one target
// (ru), and giving it a second, synthetic one to test against would re-mint the unit id of every book
// alive: injection.txt is folded byte-for-byte into EmbeddedVersion. So the wiring is pinned end-to-end on
// a target with NO rows, and the half-authored shapes are pinned here, on bytes.
func TestAPartialInjectionSetIsVisibleToTheGuard(t *testing.T) {
	required := []string{InjectionKeyGlossaryHeader, InjectionKeyEditorHeader}
	for _, tc := range []struct {
		name    string
		rows    string
		missing []string
		gaps    []string
	}{
		{
			name:    "a target with no rows at all is missing both headers",
			rows:    "",
			missing: []string{InjectionKeyGlossaryHeader, InjectionKeyEditorHeader},
		},
		{
			// The half-step the HasData gate cannot see: it reads the glossary header alone, so this target
			// passes it and hands the editor a law list with an EMPTY line where its instruction belongs.
			name:    "a glossary header without an editor header",
			rows:    "xx\tglossary_header\tГЛОССАРИЙ:\n",
			missing: []string{InjectionKeyEditorHeader},
		},
		{
			name: "both headers and no gender directives is a gender-free target, not a gap",
			rows: "xx\tglossary_header\tГЛОССАРИЙ:\nxx\teditor_header\tКАНОН:\n",
		},
		{
			name: "two gender directives out of three is a gap, and it names the missing one",
			rows: "xx\tglossary_header\tГЛОССАРИЙ:\nxx\teditor_header\tКАНОН:\n" +
				"xx\tgender_male\t (муж.)\nxx\tgender_female\t (жен.)\n",
			gaps: []string{InjectionKeyGenderHidden},
		},
		{
			// gender_neuter is documented optional: not every target language has a neuter to name.
			name: "all three directives and no neuter is complete",
			rows: "xx\tglossary_header\tГЛОССАРИЙ:\nxx\teditor_header\tКАНОН:\n" +
				"xx\tgender_male\t (муж.)\nxx\tgender_female\t (жен.)\nxx\tgender_hidden\t (скрыт)\n",
		},
	} {
		t.Run(tc.name, func(t *testing.T) {
			parsed, err := parseInjection([]byte(tc.rows))
			if err != nil {
				t.Fatal(err)
			}
			tx := InjectionTexts{}
			if p, ok := parsed["xx"]; ok {
				tx = *p
			}
			if got := tx.MissingKeys(required); !equalStrings(got, tc.missing) {
				t.Errorf("MissingKeys = %v, want %v", got, tc.missing)
			}
			if got := tx.GenderKeyGaps(); !equalStrings(got, tc.gaps) {
				t.Errorf("GenderKeyGaps = %v, want %v", got, tc.gaps)
			}
		})
	}

	// ⛔ AND THE SHIPPING TARGET, because every assertion above is about synthetic bytes. The one target
	// this engine ships must author everything the guard requires AND the whole gender set — otherwise the
	// refusal and the warning above would fire on the only pair in production.
	ru := InjectionTextsFor("ru")
	if m := ru.MissingKeys(required); len(m) > 0 {
		t.Errorf("the shipping target `ru` is missing injection rows the write path requires: %v", m)
	}
	if g := ru.GenderKeyGaps(); len(g) > 0 {
		t.Errorf("the shipping target `ru` authors a PARTIAL gender set (%v) — the warning would fire on every production run", g)
	}
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}