package layer_test

import (
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"github.com/netkingdom/flex-auth/internal/layer"
	"gopkg.in/yaml.v3"
)

func TestLayerDeclarationConforms(t *testing.T) {
	root := repoRoot(t)
	if err := layer.Check(root); err != nil {
		t.Fatalf("layer conformance: %v", err)
	}

	decl, err := layer.LoadDeclaration(filepath.Join(root, "INTENT.md"))
	if err != nil {
		t.Fatalf("LoadDeclaration: %v", err)
	}
	if decl.Layer != "Engine" {
		t.Fatalf("layer = %q; want Engine", decl.Layer)
	}
	if decl.Role != "PDP" {
		t.Fatalf("role = %q; want PDP", decl.Role)
	}
	if decl.Framework != "netkingdom-security-layer-model" {
		t.Fatalf("framework = %q", decl.Framework)
	}
	// The declaration is a boundary and must NOT pin a standard version: the
	// role does not change when the standard text is amended. Version-scoped
	// conformance state lives in the derived record named below.
	if decl.StandardVersion != "" {
		t.Fatalf("standard_version = %q; want empty (boundary, not version-scoped)", decl.StandardVersion)
	}
	if decl.ConformanceRecord == "" {
		t.Fatal("conformance_record is empty; version-stamped state must have a home")
	}
	if _, err := os.Stat(filepath.Join(repoRoot(t), decl.ConformanceRecord)); err != nil {
		t.Fatalf("conformance_record %q does not exist: %v", decl.ConformanceRecord, err)
	}
	// GH-DEC-2026-018: flex-auth is the §4 source of evidence for the decision
	// record and owes a per-event-class emission guarantee. The declaration
	// must say so and must name the published inventory.
	if decl.SourceOfEvidence == nil || !*decl.SourceOfEvidence {
		t.Fatal("source_of_evidence must be true: GH-DEC-2026-018 §2")
	}
	if decl.EmissionGuarantee == "" {
		t.Fatal("emission_guarantee is empty; §11 requires it of a §4 evidence source")
	}
	if _, err := os.Stat(filepath.Join(repoRoot(t), decl.EmissionGuarantee)); err != nil {
		t.Fatalf("emission_guarantee %q does not exist: %v", decl.EmissionGuarantee, err)
	}
}

// The per-class rule is the operative half of GH-DEC-2026-018 §3: a single
// repository-level guarantee over a stream carrying both a high-volume allow
// and a rare deny is an average, not a declaration. Assert the published
// inventory actually classifies each class, so a later edit cannot collapse it
// back into one number.
func TestEmissionInventoryIsPerEventClass(t *testing.T) {
	root := repoRoot(t)
	body, err := os.ReadFile(filepath.Join(root, "cadence.yaml"))
	if err != nil {
		t.Fatal(err)
	}
	var doc struct {
		Source  string `yaml:"source"`
		Classes map[string]struct {
			Action         string   `yaml:"action"`
			EvidenceClass  string   `yaml:"evidence_class"`
			Rarity         string   `yaml:"rarity"`
			RateMonitoring string   `yaml:"rate_monitoring"`
			Detection      []string `yaml:"detection"`
		} `yaml:"classes"`
	}
	if err := yaml.Unmarshal(body, &doc); err != nil {
		t.Fatal(err)
	}
	if len(doc.Classes) < 2 {
		t.Fatal("cadence.yaml declares fewer than two event classes; §11 requires the guarantee per class, not per repository")
	}
	for name, c := range doc.Classes {
		if c.Action == "" || c.EvidenceClass == "" || c.Rarity == "" {
			t.Errorf("class %q: action, evidence_class and rarity must all be published — a run may not infer them (§11)", name)
		}
		// A rare load-bearing class MUST carry heartbeat AND reconciliation and
		// MUST NOT be covered by rate monitoring.
		if c.EvidenceClass == "load-bearing" && c.Rarity == "rare" {
			if c.RateMonitoring != "forbidden" {
				t.Errorf("class %q is rare load-bearing; rate_monitoring must be forbidden", name)
			}
			var heartbeat, reconciliation bool
			for _, d := range c.Detection {
				heartbeat = heartbeat || d == "heartbeat"
				reconciliation = reconciliation || d == "reconciliation"
			}
			if !heartbeat || !reconciliation {
				t.Errorf("class %q is rare load-bearing; it must carry heartbeat AND reconciliation, not either alone", name)
			}
		}
	}
}

func TestVersionPinInDeclarationIsRejected(t *testing.T) {
	err := layer.ValidateDeclaration(layer.Declaration{
		Layer: "Engine", Role: "PDP",
		ConformanceRecord: "docs/conformance/security-layer-conformance.md",
		StandardVersion:   "0.8",
	})
	if err == nil {
		t.Fatal("a standard_version pin in the boundary declaration was accepted")
	}
}

func TestEngineWithoutRoleIsRejected(t *testing.T) {
	err := layer.ValidateDeclaration(layer.Declaration{Layer: "Engine"})
	if err == nil {
		t.Fatal("Engine without role was accepted")
	}
}

func TestUnknownLayerIsRejected(t *testing.T) {
	err := layer.ValidateDeclaration(layer.Declaration{Layer: "ControlPlane", Role: "PDP"})
	if err == nil {
		t.Fatal("unknown layer was accepted")
	}
}

// The defect this validator carried: the vocabulary has FOUR tokens and this
// set admitted three, omitting the layer the standard itself occupies.
// railiance-master's `Taxonomy` was conforming and the checker was wrong.
func TestVocabularyHasFourTokensIncludingTaxonomy(t *testing.T) {
	want := map[string]bool{"Taxonomy": true, "Tooling": true, "Engine": true, "Staff": true}
	got := layer.Vocabulary()
	if len(got) != len(want) {
		t.Fatalf("vocabulary = %v; want the four §3 tokens", got)
	}
	for _, tok := range got {
		if !want[tok] {
			t.Errorf("unexpected token %q", tok)
		}
	}
	if canon, ok := layer.CanonicalLayer("Taxonomy"); !ok || canon != "Taxonomy" {
		t.Fatal("Taxonomy was rejected: §3.1 defines it, §4 catalogues it twice, and the standard is an instance of it")
	}
}

// GH-DEC-2026-017 §2: comparison is ASCII case-insensitive and a run MUST fold
// before comparing. A lowercase declaration is conforming, not tolerated.
func TestVocabularyComparisonFoldsCase(t *testing.T) {
	for _, in := range []string{"engine", "ENGINE", "Engine", " engine "} {
		canon, ok := layer.CanonicalLayer(in)
		if !ok {
			t.Fatalf("%q was rejected; comparison must fold ASCII case", in)
		}
		// §4's column form is canonical, so the folded result reports as `Engine`
		// however the declaration spelled it.
		if canon != "Engine" {
			t.Fatalf("CanonicalLayer(%q) = %q; want the §4 column spelling Engine", in, canon)
		}
	}
	if err := layer.ValidateDeclaration(layer.Declaration{
		Layer: "engine", Role: "PDP",
		ConformanceRecord: "docs/conformance/security-layer-conformance.md",
		SourceOfEvidence:  boolPtr(true), EmissionGuarantee: "cadence.yaml",
	}); err != nil {
		t.Fatalf("a lowercase declaration was rejected: %v", err)
	}
}

// §3's table heading reads `Engines`, plural, while §4's column reads `Engine`.
// A9 states the token once and it is §4's. A declaration of `Engines` is a
// declaration of a token the vocabulary does not have.
func TestPluralEnginesIsNotTheToken(t *testing.T) {
	if _, ok := layer.CanonicalLayer("Engines"); ok {
		t.Fatal("`Engines` was admitted; the token is `Engine`, as §4's Layer column carries it")
	}
}

// A §4 evidence source that names no emission guarantee is not conforming.
func TestEvidenceSourceWithoutEmissionGuaranteeIsRejected(t *testing.T) {
	err := layer.ValidateDeclaration(layer.Declaration{
		Layer: "Engine", Role: "PDP",
		ConformanceRecord: "docs/conformance/security-layer-conformance.md",
		SourceOfEvidence:  boolPtr(true),
	})
	if err == nil {
		t.Fatal("a marked evidence source with no emission_guarantee was accepted")
	}
}

func boolPtr(b bool) *bool { return &b }

func repoRoot(t *testing.T) string {
	t.Helper()
	_, file, _, ok := runtime.Caller(0)
	if !ok {
		t.Fatal("runtime.Caller failed")
	}
	return filepath.Clean(filepath.Join(filepath.Dir(file), "..", ".."))
}

// A12 r2 reaches CONTENT, not a key name (GH-DEC-2026-020 §1, §2). Each of these
// is a version of the standard or its companion that a key-name check on
// `standard_version` could not see. If any of them comes back into a
// declaration, this test fails.
func TestVersionAnywhereInDeclarationIsFound(t *testing.T) {
	for name, doc := range map[string]string{
		"versioned standard path":      "layer: Engine\nstandard: net-kingdom/canon/standards/security-layer-model_v0.7.md\n",
		"versioned companion path":     "layer: Engine\ncompanion: net-kingdom/SECURITY-COMPANION_v0.2.md\n",
		"companion_version":            "layer: Engine\ncompanion_version: \"0.2\"\n",
		"standard_version":             "layer: Engine\nstandard_version: \"0.8\"\n",
		"bare version under standard":  "layer: Engine\nstandard: \"v0.8\"\n",
		"nested versioned path":        "layer: Engine\nassented_by:\n  - ref: security-layer-model_v0.8.md\n",
		"version in a list of sources": "layer: Engine\nsources: [net-kingdom/canon/standards/security-layer-model_v0.6.md]\n",
		"prose version under standard": "layer: Engine\nstandard: security-layer-model v0.7\n",
		"version under companion":      "layer: Engine\ncompanion: SECURITY-COMPANION 0.2\n",
		"reviewed-version key":         "layer: Engine\nstandard_version_reviewed: \"0.7\"\n",
		"at-version reference":         "layer: Engine\nsource: net-kingdom@0.7\n",
	} {
		pins, err := layer.VersionPins(doc)
		if err != nil {
			t.Fatalf("%s: %v", name, err)
		}
		if len(pins) == 0 {
			t.Errorf("%s: version was not detected in %q", name, doc)
		}
	}
}

// What A12 r2 states it does NOT reach: comments, schema_version, and versions
// that are not versions of the standard or its companion. Unversioned standard
// and companion paths are the conforming form.
func TestVersionPinsLeavesWhatA12DoesNotReach(t *testing.T) {
	doc := "# declared against security-layer-model_v0.7.md, kept as history\n" +
		"schema_version: \"0.2\"\n" +
		"intent_version: 0.1.0\n" +
		"layer: engine            # v0.8 comment\n" +
		"standard: net-kingdom/canon/standards/security-layer-model\n" +
		"companion: net-kingdom/SECURITY-COMPANION.md\n" +
		"declared_at: \"2026-08-29\"\n" +
		"declared_by: decisions/decisions.md FLEX-DEC-2026-001\n" +
		"companion_version:\n" +
		// GH-DEC-2026-021 §1: a revision cited in prose is provenance, not a
		// pin, even under a standard_*-prefixed key that names no version.
		"standard_note: the standard's v0.5 scope rule\n" +
		"rationale: adopted under security-layer-model v0.7 and GH-DEC-2026-020\n"
	pins, err := layer.VersionPins(doc)
	if err != nil {
		t.Fatal(err)
	}
	if len(pins) != 0 {
		t.Fatalf("A12 r2 reached what it does not reach: %v", pins)
	}
}

// Check must fail on a declaration whose only pin is in the standard: path.
// Stance, claims and classification maps SHOULD carry the version of the text
// they answer; a run MUST NOT apply A12 to them (GH-DEC-2026-020 §3).
func TestCheckRejectsVersionedStandardPathButNotStanceMaps(t *testing.T) {
	good := "---\nlayer: Engine\nrole: PDP\nconformance_record: record.md\nsource_of_evidence: false\n" +
		"standard: net-kingdom/canon/standards/security-layer-model\n---\n\n# x\n"
	dir := t.TempDir()
	for name, body := range map[string]string{
		"INTENT.md":                    good,
		"record.md":                    "x\n",
		"pep-stance.yaml":              "standard_version: \"0.8\"\n",
		"pip-claims.yaml":              "standard_version: \"0.8\"\nstandard: security-layer-model_v0.8.md\n",
		"evidence-classification.yaml": "standard_version: \"0.8\"\n",
	} {
		if err := os.WriteFile(filepath.Join(dir, name), []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	if err := layer.Check(dir); err != nil {
		t.Fatalf("a version in a stance/claims/classification map failed the declaration check: %v", err)
	}
	for _, f := range []string{"pep-stance.yaml", "pip-claims.yaml", "evidence-classification.yaml"} {
		if _, err := layer.DeclarationVersionPins(filepath.Join(dir, f)); err == nil {
			t.Errorf("DeclarationVersionPins accepted %s; A12 r2 must not be applied to it", f)
		}
	}

	bad := strings.Replace(good, "security-layer-model\n", "security-layer-model_v0.7.md\n", 1)
	if err := os.WriteFile(filepath.Join(dir, "INTENT.md"), []byte(bad), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := layer.Check(dir); err == nil {
		t.Fatal("a versioned standard: path in INTENT.md was accepted")
	}
}

// flex-auth's own declaration carries no version under any key (A12 r2).
func TestOwnDeclarationCarriesNoVersionAnywhere(t *testing.T) {
	pins, err := layer.DeclarationVersionPins(filepath.Join(repoRoot(t), "INTENT.md"))
	if err != nil {
		t.Fatal(err)
	}
	if len(pins) != 0 {
		t.Fatalf("INTENT.md declaration carries a version: %v", pins)
	}
	if layer.ValidatedAgainst == "" {
		t.Fatal("the checker must state the version it validates against on every run")
	}
}