package layer_test

import (
	"os"
	"path/filepath"
	"runtime"
	"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), "..", ".."))
}