package wristband

import (
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"
	"time"
)

// insertAuthorizeTestClient inserts an already-usable ClientRecord directly
// into backend (bypassing CreateWithCap's cap/sweep policy, which this
// plan's tests do not exercise) and returns it.
func insertAuthorizeTestClient(backend *memoryBackend, clientID string, redirectURIs []string, ceiling []string) *ClientRecord {
	backend.mu.Lock()
	defer backend.mu.Unlock()
	backend.nextID++
	rec := &ClientRecord{
		ID:                      backend.nextID,
		ClientID:                clientID,
		ClientName:              "Test Client",
		RedirectURIs:            redirectURIs,
		GrantTypes:              []string{"authorization_code", "refresh_token"},
		TokenEndpointAuthMethod: "client_secret_post",
		ScopeCeiling:            ceiling,
		CreatedAt:               time.Now(),
	}
	backend.clients = append(backend.clients, rec)
	return rec
}

// s256Pair returns a random PKCE verifier and its S256 challenge, matching
// the byte transform every Phase 8 PHP/Go PKCE fixture shares.
func s256Pair(t *testing.T) (verifier, challenge string) {
	t.Helper()
	v, err := randomBase64URL(32)
	if err != nil {
		t.Fatal(err)
	}
	return v, s256Challenge(v)
}

// authorizeQuery builds a GET /oauth/mcp/authorize request from an ordered
// param map (net/url.Values handles encoding fine for *requests*: only
// response Location construction is bound by the RFC3986 ordered-pair
// requirement).
func authorizeRequest(params map[string]string) *http.Request {
	q := url.Values{}
	for k, v := range params {
		q.Set(k, v)
	}
	return httptest.NewRequest(http.MethodGet, "/oauth/mcp/authorize?"+q.Encode(), nil)
}

// queryOf parses the query component of a redirect Location header into a
// flat map (every Phase 8 authorize fixture uses at most one value per key).
func queryOf(t *testing.T, location string) map[string]string {
	t.Helper()
	u, err := url.Parse(location)
	if err != nil {
		t.Fatalf("parse Location %q: %v", location, err)
	}
	out := map[string]string{}
	for k, v := range u.Query() {
		if len(v) > 0 {
			out[k] = v[0]
		}
	}
	return out
}

// TestPhase8RedAuthorize is the Phase 8 Wave 3 RED anchor (08-03-PLAN.md
// Task 1, D-02/D-04/D-05). It drives one valid S256 authorize request
// through the real (in-memory-backed) Server.Authorize and asserts the
// exact success contract: 302 to <issuer>/connect?request=<opaque> with no
// state/code leaked onto our own redirect and Cache-Control: no-store. It
// fails with the PHASE8_RED:authorize sentinel while Authorize is the 501
// stub; scripts/check-phase8-red.sh verifies this failure is fail-closed.
func TestPhase8RedAuthorize(t *testing.T) {
	backend := newMemoryBackend()
	srv := newTestServer(backend)
	insertAuthorizeTestClient(backend, "cli-red", []string{"https://chatgpt.com/connector/oauth/cb"}, nil)
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-red",
		"redirect_uri":          "https://chatgpt.com/connector/oauth/cb",
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read write",
		"state":                 "must-not-appear-on-our-url",
		"resource":              "https://mcp.plytarium.com/mcp",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusFound {
		t.Fatalf("PHASE8_RED:authorize: status = %d, want %d (body=%s)", rec.Code, http.StatusFound, rec.Body.String())
	}
	loc := rec.Header().Get("Location")
	if !strings.HasPrefix(loc, "https://plytarium.com/connect?") {
		t.Fatalf("PHASE8_RED:authorize: Location = %q, want prefix \"https://plytarium.com/connect?\"", loc)
	}
	q := queryOf(t, loc)
	if q["request"] == "" {
		t.Fatalf("PHASE8_RED:authorize: Location %q missing non-empty request param", loc)
	}
	if _, has := q["state"]; has {
		t.Fatalf("PHASE8_RED:authorize: Location %q leaks state onto our own redirect", loc)
	}
	if _, has := q["code"]; has {
		t.Fatalf("PHASE8_RED:authorize: Location %q leaks a code onto our own redirect", loc)
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("PHASE8_RED:authorize: Cache-Control = %q, want \"no-store, private\"", cc)
	}
}

const authorizeTestRedirect = "https://chatgpt.com/connector/oauth/cb"

func newAuthorizeTestServer() (*Server, *memoryBackend) {
	backend := newMemoryBackend()
	return newTestServer(backend), backend
}

func pendingCount(backend *memoryBackend) int {
	backend.mu.Lock()
	defer backend.mu.Unlock()
	return len(backend.codes)
}

func TestAuthorizeUnknownClientReturnsLocal400NoLocation(t *testing.T) {
	srv, _ := newAuthorizeTestServer()
	req := authorizeRequest(map[string]string{
		"client_id":    "does-not-exist",
		"redirect_uri": authorizeTestRedirect,
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d (body=%s)", rec.Code, http.StatusBadRequest, rec.Body.String())
	}
	if loc := rec.Header().Get("Location"); loc != "" {
		t.Fatalf("Location = %q, want none", loc)
	}
	if ct := rec.Header().Get("Content-Type"); ct != "text/plain; charset=UTF-8" {
		t.Fatalf("Content-Type = %q, want text/plain; charset=UTF-8", ct)
	}
	if body := rec.Body.String(); body != "Unknown client." {
		t.Fatalf("body = %q, want %q", body, "Unknown client.")
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("Cache-Control = %q, want no-store, private", cc)
	}
}

func TestAuthorizeRevokedClientIsUnknown(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	rec := insertAuthorizeTestClient(backend, "cli-revoked", []string{authorizeTestRedirect}, nil)
	now := time.Now()
	rec.RevokedAt = &now

	req := authorizeRequest(map[string]string{
		"client_id":    "cli-revoked",
		"redirect_uri": authorizeTestRedirect,
	})
	w := httptest.NewRecorder()
	srv.Authorize(w, req)
	if w.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", w.Code, http.StatusBadRequest)
	}
}

func TestAuthorizeUnregisteredRedirectURIReturnsLocal400NoLocation(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-redirect", []string{authorizeTestRedirect}, nil)

	req := authorizeRequest(map[string]string{
		"client_id":    "cli-redirect",
		"redirect_uri": "https://evil.test/cb",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
	}
	if loc := rec.Header().Get("Location"); loc != "" {
		t.Fatalf("Location = %q, want none", loc)
	}
	if strings.Contains(rec.Body.String(), "https://evil.test/cb") {
		t.Fatal("body echoes the untrusted redirect URI")
	}
}

func TestAuthorizeTrailingSlashMismatchIsUnregistered(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-slash", []string{authorizeTestRedirect}, nil)

	req := authorizeRequest(map[string]string{
		"client_id":    "cli-slash",
		"redirect_uri": authorizeTestRedirect + "/",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
	}
	if loc := rec.Header().Get("Location"); loc != "" {
		t.Fatalf("Location = %q, want none", loc)
	}
}

func TestAuthorizeUnsupportedResponseTypeRedirectsWithIssAndState(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-resptype", []string{authorizeTestRedirect}, nil)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-resptype",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "token",
		"code_challenge":        strings.Repeat("b", 43),
		"code_challenge_method": "S256",
		"state":                 "iss-state",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusFound)
	}
	loc := rec.Header().Get("Location")
	if !strings.HasPrefix(loc, authorizeTestRedirect) {
		t.Fatalf("Location = %q, want prefix %q", loc, authorizeTestRedirect)
	}
	q := queryOf(t, loc)
	if q["error"] != "unsupported_response_type" {
		t.Fatalf("error = %q, want unsupported_response_type", q["error"])
	}
	if q["iss"] != "https://plytarium.com" {
		t.Fatalf("iss = %q, want https://plytarium.com", q["iss"])
	}
	if q["state"] != "iss-state" {
		t.Fatalf("state = %q, want iss-state", q["state"])
	}
}

func TestPKCEChallengeMethodMustBeS256(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-plain", []string{authorizeTestRedirect}, nil)
	state := "state-plain"

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-plain",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        strings.Repeat("a", 43),
		"code_challenge_method": "plain",
		"state":                 state,
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusFound)
	}
	q := queryOf(t, rec.Header().Get("Location"))
	if q["error"] != "invalid_request" {
		t.Fatalf("error = %q, want invalid_request", q["error"])
	}
	if q["state"] != state {
		t.Fatalf("state = %q, want %q", q["state"], state)
	}
	if q["iss"] != "https://plytarium.com" {
		t.Fatalf("iss = %q, want https://plytarium.com", q["iss"])
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("Cache-Control = %q, want no-store, private", cc)
	}
}

func TestPKCEChallengeLengthBounds(t *testing.T) {
	cases := []struct {
		name      string
		challenge string
	}{
		{"too-short", strings.Repeat("a", 42)},
		{"too-long", strings.Repeat("a", 129)},
		{"empty", ""},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			srv, backend := newAuthorizeTestServer()
			insertAuthorizeTestClient(backend, "cli-len-"+tc.name, []string{authorizeTestRedirect}, nil)
			req := authorizeRequest(map[string]string{
				"client_id":             "cli-len-" + tc.name,
				"redirect_uri":          authorizeTestRedirect,
				"response_type":         "code",
				"code_challenge":        tc.challenge,
				"code_challenge_method": "S256",
			})
			rec := httptest.NewRecorder()
			srv.Authorize(rec, req)
			if rec.Code != http.StatusFound {
				t.Fatalf("status = %d, want %d", rec.Code, http.StatusFound)
			}
			q := queryOf(t, rec.Header().Get("Location"))
			if q["error"] != "invalid_request" {
				t.Fatalf("error = %q, want invalid_request", q["error"])
			}
			if q["error_description"] != "code_challenge is required" {
				t.Fatalf("error_description = %q, want %q", q["error_description"], "code_challenge is required")
			}
		})
	}
}

func TestAuthorizeValidRequestRedirectsToConnectWithOpaqueHandleOnly(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-valid", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)
	state := "must-not-appear-on-our-url"

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-valid",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read write",
		"state":                 state,
		"resource":              "https://mcp.plytarium.com/mcp",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)

	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, want %d (body=%s)", rec.Code, http.StatusFound, rec.Body.String())
	}
	loc := rec.Header().Get("Location")
	if !strings.HasPrefix(loc, "https://plytarium.com/connect?") {
		t.Fatalf("Location = %q, want prefix https://plytarium.com/connect?", loc)
	}
	q := queryOf(t, loc)
	if q["request"] == "" {
		t.Fatal("Location missing non-empty request param")
	}
	if _, has := q["code"]; has {
		t.Fatal("Location leaks a code")
	}
	if _, has := q["state"]; has {
		t.Fatal("Location leaks state")
	}
	if _, has := q["client_secret"]; has {
		t.Fatal("Location leaks client_secret")
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("Cache-Control = %q, want no-store, private", cc)
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	if len(backend.codes) != 1 {
		t.Fatalf("pending rows = %d, want 1", len(backend.codes))
	}
	pending := backend.codes[0]
	if pending.RequestID == nil || *pending.RequestID != q["request"] {
		t.Fatalf("pending.RequestID = %v, want %q", pending.RequestID, q["request"])
	}
	if pending.CodeHash != nil {
		t.Fatal("pending row already has a code hash")
	}
	if pending.UserID != nil {
		t.Fatal("pending row already has a user id")
	}
	if pending.State == nil || *pending.State != state {
		t.Fatalf("pending.State = %v, want %q", pending.State, state)
	}
	if pending.ExpiresAt.Before(time.Now().Add(500*time.Second)) || pending.ExpiresAt.After(time.Now().Add(700*time.Second)) {
		t.Fatalf("pending.ExpiresAt = %v, want ~600s from now", pending.ExpiresAt)
	}
}

func TestAuthorizeIssIsPresentOnEveryErrorRedirect(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-iss", []string{authorizeTestRedirect}, nil)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-iss",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "token",
		"code_challenge":        strings.Repeat("b", 43),
		"code_challenge_method": "S256",
		"state":                 "iss-state",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	q := queryOf(t, rec.Header().Get("Location"))
	if q["iss"] != "https://plytarium.com" {
		t.Fatalf("iss = %q, want https://plytarium.com", q["iss"])
	}
	if q["state"] != "iss-state" {
		t.Fatalf("state = %q, want iss-state", q["state"])
	}
	if q["error"] != "unsupported_response_type" {
		t.Fatalf("error = %q, want unsupported_response_type", q["error"])
	}
}

func TestAuthorizeScopeDefaultsToRead(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-default-scope", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-default-scope",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusFound)
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	if len(backend.codes) != 1 {
		t.Fatalf("pending rows = %d, want 1", len(backend.codes))
	}
	if got := backend.codes[0].Scopes; len(got) != 1 || got[0] != "read" {
		t.Fatalf("scopes = %v, want [read]", got)
	}
}

func TestAuthorizeScopeInvalidValueRedirectsInvalidScope(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-bad-scope", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)
	before := pendingCount(backend)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-bad-scope",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read bogus",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusFound)
	}
	q := queryOf(t, rec.Header().Get("Location"))
	if q["error"] != "invalid_scope" {
		t.Fatalf("error = %q, want invalid_scope", q["error"])
	}
	if q["error_description"] != "scope contains an unsupported value" {
		t.Fatalf("error_description = %q", q["error_description"])
	}
	if got := pendingCount(backend); got != before {
		t.Fatalf("pending rows = %d, want unchanged %d", got, before)
	}
}

func TestAuthorizeNullCeilingPreservesAiScope(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-null-ceiling", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-null-ceiling",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read write ai",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	got := backend.codes[len(backend.codes)-1].Scopes
	want := []string{"read", "write", "ai"}
	if len(got) != len(want) {
		t.Fatalf("scopes = %v, want %v", got, want)
	}
	for i := range want {
		if got[i] != want[i] {
			t.Fatalf("scopes = %v, want %v", got, want)
		}
	}
}

func TestAuthorizeCeilingTruncatesAiWithoutError(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-ceiling-trunc", []string{authorizeTestRedirect}, []string{"read", "write"})
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-ceiling-trunc",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read write ai",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	got := backend.codes[len(backend.codes)-1].Scopes
	if stringSliceContains(got, "ai") {
		t.Fatalf("scopes = %v, still contains ai", got)
	}
	want := []string{"read", "write"}
	if len(got) != len(want) || got[0] != want[0] || got[1] != want[1] {
		t.Fatalf("scopes = %v, want %v", got, want)
	}
}

func TestAuthorizeCeilingPreservesOfflineAccessFlag(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-ceiling-offline", []string{authorizeTestRedirect}, []string{"read", "write"})
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-ceiling-offline",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "read write ai offline_access",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	pending := backend.codes[len(backend.codes)-1]
	want := []string{"read", "write"}
	if len(pending.Scopes) != len(want) || pending.Scopes[0] != want[0] || pending.Scopes[1] != want[1] {
		t.Fatalf("scopes = %v, want %v", pending.Scopes, want)
	}
	if !pending.OfflineAccess {
		t.Fatal("OfflineAccess = false, want true")
	}
}

func TestAuthorizeCeilingRejectsAiOnlyAsInvalidScopeOnTrustedRedirect(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-ceiling-ai-only", []string{authorizeTestRedirect}, []string{"read", "write"})
	_, challenge := s256Pair(t)
	state := "state-ai-only"
	before := pendingCount(backend)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-ceiling-ai-only",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "ai",
		"state":                 state,
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	loc := rec.Header().Get("Location")
	if !strings.HasPrefix(loc, authorizeTestRedirect) {
		t.Fatalf("Location = %q, want prefix %q", loc, authorizeTestRedirect)
	}
	q := queryOf(t, loc)
	if q["error"] != "invalid_scope" {
		t.Fatalf("error = %q, want invalid_scope", q["error"])
	}
	if q["state"] != state {
		t.Fatalf("state = %q, want %q", q["state"], state)
	}
	if q["iss"] != "https://plytarium.com" {
		t.Fatalf("iss = %q, want https://plytarium.com", q["iss"])
	}
	if got := pendingCount(backend); got != before {
		t.Fatalf("pending rows = %d, want unchanged %d", got, before)
	}
}

func TestAuthorizeCeilingRejectsAiPlusOfflineAccessAsInvalidScope(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-ceiling-ai-offline", []string{authorizeTestRedirect}, []string{"read", "write"})
	_, challenge := s256Pair(t)
	state := "state-ai-offline"
	before := pendingCount(backend)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-ceiling-ai-offline",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"scope":                 "ai offline_access",
		"state":                 state,
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	q := queryOf(t, rec.Header().Get("Location"))
	if q["error"] != "invalid_scope" {
		t.Fatalf("error = %q, want invalid_scope", q["error"])
	}
	if q["state"] != state {
		t.Fatalf("state = %q, want %q", q["state"], state)
	}
	if got := pendingCount(backend); got != before {
		t.Fatalf("pending rows = %d, want unchanged %d", got, before)
	}
}

func TestAuthorizeResourceMismatchRedirectsInvalidTarget(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-resource", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)
	before := pendingCount(backend)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-resource",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
		"resource":              "https://wrong.example.test/mcp",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	q := queryOf(t, rec.Header().Get("Location"))
	if q["error"] != "invalid_target" {
		t.Fatalf("error = %q, want invalid_target", q["error"])
	}
	if q["error_description"] != "resource does not match this server" {
		t.Fatalf("error_description = %q", q["error_description"])
	}
	if got := pendingCount(backend); got != before {
		t.Fatalf("pending rows = %d, want unchanged %d", got, before)
	}
}

func TestAuthorizeResourceOmittedIsAccepted(t *testing.T) {
	srv, backend := newAuthorizeTestServer()
	insertAuthorizeTestClient(backend, "cli-resource-omitted", []string{authorizeTestRedirect}, nil)
	_, challenge := s256Pair(t)

	req := authorizeRequest(map[string]string{
		"client_id":             "cli-resource-omitted",
		"redirect_uri":          authorizeTestRedirect,
		"response_type":         "code",
		"code_challenge":        challenge,
		"code_challenge_method": "S256",
	})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusFound {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
}

// TestOrderedRedirectQueryEncodingIsRFC3986 proves the redirect query
// encoder differs from net/url.Values.Encode exactly where PHP
// http_build_query(..., PHP_QUERY_RFC3986) does: spaces become %20 (not
// '+'), reserved characters are percent-encoded, and key order is
// preserved (not sorted) — Pitfall 5.
func TestOrderedRedirectQueryEncodingIsRFC3986(t *testing.T) {
	got := buildOrderedQuery([][2]string{
		{"error", "invalid_scope"},
		{"error_description", "requested scope is outside this client's ceiling"},
		{"iss", "https://plytarium.com"},
		{"state", "a b&c=d"},
	})
	want := "error=invalid_scope&error_description=requested%20scope%20is%20outside%20this%20client%27s%20ceiling&iss=https%3A%2F%2Fplytarium.com&state=a%20b%26c%3Dd"
	if got != want {
		t.Fatalf("got:  %s\nwant: %s", got, want)
	}
}

func TestOrderedRedirectAppendsToExistingQuery(t *testing.T) {
	got := appendOrderedQuery("https://client.example.test/cb?already=here", [][2]string{
		{"error", "invalid_request"},
		{"iss", "https://plytarium.com"},
	})
	want := "https://client.example.test/cb?already=here&error=invalid_request&iss=https%3A%2F%2Fplytarium.com"
	if got != want {
		t.Fatalf("got:  %s\nwant: %s", got, want)
	}
}

func TestAuthorizeBackendUnavailableIsOpaque500(t *testing.T) {
	opts := DefaultOptions()
	opts.Issuer = "https://plytarium.com"
	srv := NewServer(opts)
	req := authorizeRequest(map[string]string{"client_id": "anything"})
	rec := httptest.NewRecorder()
	srv.Authorize(rec, req)
	if rec.Code != http.StatusInternalServerError {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusInternalServerError)
	}
}