package decision_test

import (
	"bytes"
	"context"
	"encoding/json"
	"testing"

	"github.com/netkingdom/flex-auth/pkg/api"
)

// A registry fact is an authority statement; the same key on the request is the
// caller's proposal about itself. Enrichment once let the proposal survive, which
// made every registry ceiling and allowlist advisory — a caller supplying
// resource.attributes.max_ttl_hours raised its own ceiling, and one supplying
// allowed_subjects authorized a subject the registry did not know
// (FLEX-DEC-2026-012).
//
// These tests assert the registry value reaches policy on a request that
// contradicts it. They are written against attribute keys real packages branch
// on, because a test over an unused key would pass while the escalation stayed
// open.
func TestRegistryFactsOverrideCallerSuppliedAttributes(t *testing.T) {
	store := newTestStore(t)
	if err := store.ImportResourceManifest(api.ResourceManifest{
		ID:     "ceilings",
		System: "test-system",
		Resources: []api.Resource{{
			ID:         "resource:ceiling",
			Type:       "document",
			Attributes: map[string]any{"max_ttl_hours": 8, "allowed_subjects": []any{"user:alice"}},
		}},
	}); err != nil {
		t.Fatalf("ImportResourceManifest: %v", err)
	}
	engine := newTestEngineWithStore(t, store)

	decision, err := engine.Check(context.Background(), api.CheckRequest{
		Subject: api.SubjectRef{ID: "user:alice"},
		Action:  "read",
		Resource: api.ResourceRef{
			ID:     "resource:ceiling",
			System: "test-system",
			Attributes: map[string]any{
				"max_ttl_hours":    99,
				"allowed_subjects": []any{"user:mallory"},
			},
		},
	})
	if err != nil {
		t.Fatalf("Check: %v", err)
	}

	attributes := decision.Binding.Resource.Attributes
	if got := attributes["max_ttl_hours"]; !equalJSON(t, got, 8) {
		t.Fatalf("max_ttl_hours = %v; want the registry's 8, not the caller's 99", got)
	}
	if got := attributes["allowed_subjects"]; !equalJSON(t, got, []any{"user:alice"}) {
		t.Fatalf("allowed_subjects = %v; caller displaced the registry allowlist", got)
	}

	// The override must be visible. A registry that silently discards a
	// contradicting claim hides that a caller asserted authority it did not have,
	// which is the half worth alerting on even though the decision is now correct.
	overrode, _ := decision.Diagnostics["registry_overrode"].([]string)
	if !containsAll(overrode, "resource.max_ttl_hours", "resource.allowed_subjects") {
		t.Fatalf("registry_overrode = %v; want both displaced keys named", overrode)
	}
}

// Tenant is a registry fact and the registry wins. subject.type deliberately does
// NOT, and the asymmetry is the finding rather than an oversight: the registry's
// Type is CARING vocabulary (Human, Agent, Automation, Service) while the
// request's is the protected system's actor vocabulary (service, adm, agt, atm).
// Two fields sharing a name. Overwriting substituted one vocabulary for the other
// and denied every secrets-engine allow, because "Service" is not "service".
//
// This test pins both halves so the residual cannot be closed by accident, and so
// a later reader sees the exclusion is reasoned. FLEX-WP-0025 separates them.
func TestRegistryTenantWinsWhileSubjectTypeVocabularyIsPreserved(t *testing.T) {
	store := newTestStore(t)
	if err := store.ImportSubjectManifest(api.SubjectManifest{
		ID:      "principals",
		Tenants: []api.Tenant{{ID: "tenant:real"}},
		Subjects: []api.Subject{{
			ID:     "subject:claimant",
			Type:   "human",
			Tenant: "tenant:real",
		}},
	}); err != nil {
		t.Fatalf("ImportSubjectManifest: %v", err)
	}
	engine := newTestEngineWithStore(t, store)

	decision, err := engine.Check(context.Background(), api.CheckRequest{
		Tenant:   "tenant:claimed",
		Subject:  api.SubjectRef{ID: "subject:claimant", Type: "service", Tenant: "tenant:claimed"},
		Action:   "read",
		Resource: api.ResourceRef{ID: "document:internal-note", System: "markitect-tool"},
	})
	if err != nil {
		t.Fatalf("Check: %v", err)
	}
	if got := decision.Binding.Subject.Type; got != "service" {
		t.Fatalf("subject.type = %q; the caller's actor vocabulary must survive", got)
	}
	if got := decision.Binding.Subject.Tenant; got != "tenant:real" {
		t.Fatalf("subject.tenant = %q; want the registry's tenant:real", got)
	}
}

// An unregistered subject or resource has no facts to overlay, so what the caller
// sent stands. That is the stated residual rather than an oversight: a policy
// reading a key its manifest omits is consuming caller input, and no override
// should be reported for a key nobody contradicted.
func TestUnregisteredResourceKeepsCallerAttributesAndReportsNoOverride(t *testing.T) {
	engine := newTestEngine(t)

	decision, err := engine.Check(context.Background(), api.CheckRequest{
		Subject: api.SubjectRef{ID: "user:alice"},
		Action:  "read",
		Resource: api.ResourceRef{
			ID:         "document:not-in-registry",
			System:     "markitect-tool",
			Attributes: map[string]any{"stage": "prod"},
		},
	})
	if err != nil {
		t.Fatalf("Check: %v", err)
	}
	if got := decision.Binding.Resource.Attributes["stage"]; got != "prod" {
		t.Fatalf("stage = %v; caller attributes on an unregistered resource must survive", got)
	}
	if overrode, _ := decision.Diagnostics["registry_overrode"].([]string); len(overrode) != 0 {
		t.Fatalf("registry_overrode = %v; nothing was contradicted", overrode)
	}
}

func equalJSON(t *testing.T, got, want any) bool {
	t.Helper()
	left, err := json.Marshal(got)
	if err != nil {
		return false
	}
	right, err := json.Marshal(want)
	if err != nil {
		return false
	}
	return bytes.Equal(left, right)
}

func containsAll(values []string, wanted ...string) bool {
	for _, want := range wanted {
		found := false
		for _, value := range values {
			if value == want {
				found = true
				break
			}
		}
		if !found {
			return false
		}
	}
	return true
}

// binding.request_digest is computed over the ENRICHED request, so a consumer
// recomputing it over what it sent gets a different value on every request whose
// subject or resource the registry knows. It was published as the §6.4.2 replay
// test for consumers, which it cannot be. submitted_request_digest is that test:
// RequestDigest over the request exactly as received (FLEX-DEC-2026-012).
func TestSubmittedRequestDigestIsComputableByTheConsumer(t *testing.T) {
	engine := newTestEngine(t)

	request := api.CheckRequest{
		Tenant:   "tenant:platform",
		Subject:  api.SubjectRef{ID: "user:alice"},
		Action:   "read",
		Resource: api.ResourceRef{ID: "document:internal-note", System: "markitect-tool"},
	}

	decision, err := engine.Check(context.Background(), request)
	if err != nil {
		t.Fatalf("Check: %v", err)
	}

	// The consumer holds only the request it sent. This is the whole property.
	if got, want := decision.Binding.SubmittedRequestDigest, api.RequestDigest(request); got != want {
		t.Fatalf("submitted_request_digest = %q; consumer computes %q", got, want)
	}

	// And it must genuinely differ from the enriched digest here, or the test
	// would pass on a request the registry never touched and prove nothing.
	if decision.Binding.SubmittedRequestDigest == decision.Binding.RequestDigest {
		t.Fatal("digests agree on an enriched request; the distinction is not being exercised")
	}
}