package web

import (
	"context"
	"encoding/json"
	"net/url"
	"testing"
)

// R-39, Scenario B — the hub half of the fix: a re-issue must change the DESCRIPTOR BYTES.
//
// The agent re-applies only when the descriptor's content hash moves (felhom-agent
// internal/pbsdr/manager.go descriptorHash marshals the parsed struct). An ep0 re-key rotates the
// secret of an EXISTING token, so token_id / fingerprint / datastore / namespace all come back
// byte-identical — which is precisely why the 2026-07-18 N100 box short-circuited forever. The only
// field that moves is SecretGeneration.
//
// COMPANION RED-PROOF (run + recorded in REPORT.md): delete the `SecretGeneration` field from
// pbsDRDescriptor (or stop setting it in the re-issue path) → the two marshals below become
// byte-identical and this test FAILS, reproducing the defect exactly.
func TestPBSDRDescriptor_ReissueChangesTheBytes(t *testing.T) {
	// The descriptor as it stands after the FIRST provision.
	before := &pbsDRDescriptor{
		Enabled:          true,
		StorageID:        "felhom-pbs",
		PBSTunnelIP:      "10.77.0.1",
		Datastore:        "felhom-offsite",
		Namespace:        "demo-felhom",
		TokenID:          "felhom@pbs!demo-felhom",
		Fingerprint:      "c6:07:28:3f",
		SecretGeneration: 1,
	}
	// After a RE-KEY: everything the endpoint returns is identical — only the secret rotated.
	after := *before
	after.SecretGeneration = 2

	b1, err := json.Marshal(before)
	if err != nil {
		t.Fatalf("marshal before: %v", err)
	}
	b2, err := json.Marshal(&after)
	if err != nil {
		t.Fatalf("marshal after: %v", err)
	}
	if string(b1) == string(b2) {
		t.Fatalf("a re-issue left the descriptor BYTE-IDENTICAL — the agent will short-circuit and never "+
			"consume the fresh secret (this is the R-39 defect).\n  bytes: %s", b1)
	}

	// And the difference must be exactly the generation — not an accident of field ordering.
	var m1, m2 map[string]any
	if err := json.Unmarshal(b1, &m1); err != nil {
		t.Fatal(err)
	}
	if err := json.Unmarshal(b2, &m2); err != nil {
		t.Fatal(err)
	}
	for k, v1 := range m1 {
		if k == "secret_generation" {
			continue
		}
		if v2, ok := m2[k]; !ok || string(mustJSON(t, v1)) != string(mustJSON(t, v2)) {
			t.Errorf("a re-key must change ONLY secret_generation, but %q moved: %v -> %v", k, v1, m2[k])
		}
	}
	if m2["secret_generation"] == m1["secret_generation"] {
		t.Error("secret_generation did not advance")
	}
}

// The field must be OMITTED when zero, so a hub that has never minted for a host does not start
// emitting a new key into every legacy descriptor (which would itself be a spurious re-apply).
func TestPBSDRDescriptor_ZeroGenerationIsOmitted(t *testing.T) {
	b, err := json.Marshal(&pbsDRDescriptor{Enabled: true, StorageID: "felhom-pbs"})
	if err != nil {
		t.Fatal(err)
	}
	var m map[string]any
	if err := json.Unmarshal(b, &m); err != nil {
		t.Fatal(err)
	}
	if _, present := m["secret_generation"]; present {
		t.Errorf("zero generation must be omitted (omitempty) — emitting it would move the hash of every "+
			"pre-existing descriptor and cause a fleet-wide spurious re-apply. got: %s", b)
	}
}

// An UNKNOWN key must survive a round-trip through readPBSDR/mergePBSDR untouched — the Scenario-C
// compatibility direction, asserted from the hub side: an old agent's descriptor is not corrupted by
// a hub that now writes the new field.
func TestPBSDRDescriptor_RoundTripPreservesOtherKeys(t *testing.T) {
	desired := `{"operator":{"note":"keep me"},"pbs_dr":{"enabled":true,"storage_id":"felhom-pbs","secret_generation":7}}`
	cur := readPBSDR(desired)
	if cur == nil {
		t.Fatal("readPBSDR returned nil")
	}
	if cur.SecretGeneration != 7 {
		t.Fatalf("secret_generation round-trip = %d, want 7", cur.SecretGeneration)
	}
	cur.SecretGeneration = 8
	merged, err := mergePBSDR(desired, cur)
	if err != nil {
		t.Fatalf("merge: %v", err)
	}
	var m map[string]json.RawMessage
	if err := json.Unmarshal([]byte(merged), &m); err != nil {
		t.Fatal(err)
	}
	if _, ok := m["operator"]; !ok {
		t.Error("merge dropped a sibling key in desired_json")
	}
	if got := readPBSDR(merged); got == nil || got.SecretGeneration != 8 {
		t.Errorf("merged descriptor lost the advanced generation: %+v", got)
	}
}

func mustJSON(t *testing.T, v any) []byte {
	t.Helper()
	b, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	return b
}

// R-39, Scenario B at the FLOW level — the assertion that actually guards the shipped behaviour.
//
// The struct test above proves the field moves the bytes; this proves ReissuePBSDR *stamps* it.
// fakeTenancy returns an identical TokenID / Fingerprint / Datastore / Namespace on every call and
// rotates only the secret — which is exactly what an ep0 re-key does, and exactly why the descriptor
// used to come back byte-identical.
//
// COMPANION RED-PROOF (run + recorded): comment out `cur.SecretGeneration = secretGen` in
// ReissuePBSDR (keep the field declared so it still compiles) → the pbs_dr block is unchanged across
// the re-issue and this test FAILS with both identical blocks printed. That is the 2026-07-18 N100
// behaviour reproduced in a unit test.
func TestReissuePBSDR_ChangesTheStoredDescriptor(t *testing.T) {
	fake := &fakeTenancy{secret: "OLD"}
	s, st, _ := newPBSDRServer(t, fake)
	postUpdate(t, s, url.Values{"dr_tier": {"on"}}) // provision → descriptor + generation 1

	pbsBlockOf := func(what string) string {
		t.Helper()
		h, err := st.GetHost("peti-01")
		if err != nil || h == nil {
			t.Fatalf("%s: get host: %v", what, err)
		}
		var doc map[string]json.RawMessage
		if err := json.Unmarshal([]byte(h.DesiredJSON), &doc); err != nil {
			t.Fatalf("%s: parse desired_json: %v", what, err)
		}
		return string(doc["pbs_dr"])
	}

	before := pbsBlockOf("before")
	if before == "" {
		t.Fatal("no pbs_dr descriptor after provisioning")
	}

	// The agent consumes it and converges — the box is now pinned to this exact descriptor hash.
	if _, err := st.ConsumeHostPBSSecret("peti-01"); err != nil {
		t.Fatalf("consume: %v", err)
	}

	fake.secret = "FRESH" // the re-key: a new secret behind an unchanged token
	if err := s.ReissuePBSDR(context.Background(), "peti"); err != nil {
		t.Fatalf("ReissuePBSDR: %v", err)
	}
	after := pbsBlockOf("after")

	if after == before {
		t.Fatalf("the re-issue left the pbs_dr descriptor BYTE-IDENTICAL — a converged agent will "+
			"short-circuit on its content hash and never consume the fresh secret (R-39).\n  block: %s", before)
	}

	// The fresh secret must genuinely be re-armed for consumption, and the generation advanced.
	var b, a pbsDRDescriptor
	if err := json.Unmarshal([]byte(before), &b); err != nil {
		t.Fatal(err)
	}
	if err := json.Unmarshal([]byte(after), &a); err != nil {
		t.Fatal(err)
	}
	if a.SecretGeneration <= b.SecretGeneration {
		t.Errorf("secret_generation did not advance across a re-issue: %d -> %d", b.SecretGeneration, a.SecretGeneration)
	}
	// Everything else is identical — proving the generation is the ONLY thing carrying the signal.
	if a.TokenID != b.TokenID || a.Fingerprint != b.Fingerprint || a.Namespace != b.Namespace || a.Datastore != b.Datastore {
		t.Errorf("this fake models a re-key, so these must be unchanged; if they differ the test is no "+
			"longer exercising the defect shape.\n  before=%+v\n  after=%+v", b, a)
	}
	got, err := st.ConsumeHostPBSSecret("peti-01")
	if err != nil || got != "FRESH" {
		t.Errorf("post-reissue consume = (%q, %v), want (FRESH, nil) — the fresh secret must be consumable", got, err)
	}
}