package wristband

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
	"time"
)

// memoryBackend is wristband's own in-memory Backend/Tx implementation
// (08-CONTEXT.md D-07: "wristband ships an in-memory store for its own
// tests"). One mutex guards the whole transaction closure so concurrency
// tests model the seam, not individual map operations (08-PATTERNS.md).
type memoryBackend struct {
	mu      sync.Mutex
	clients []*ClientRecord
	codes   []*AuthCodeRecord
	refresh []*RefreshTokenRecord
	tokens  []*IssuedToken
	// revoked tracks IssuedToken.ID -> revoked, since IssuedToken itself
	// carries no status field (it is the one-time mint result, not a
	// queryable row). 08-06-PLAN.md's rotation/replay/revoke tests need to
	// observe access-token revocation the same way real Postgres tests
	// observe models.ApiToken.RevokedAt.
	revoked map[uint]bool
	nextID  uint
}

func newMemoryBackend() *memoryBackend {
	return &memoryBackend{}
}

func (b *memoryBackend) WithinTx(ctx context.Context, fn func(Tx) error) error {
	b.mu.Lock()
	defer b.mu.Unlock()
	return fn(&memoryTx{b: b})
}

type memoryTx struct{ b *memoryBackend }

var _ Tx = (*memoryTx)(nil)

func (t *memoryTx) ByClientID(ctx context.Context, clientID string) (*ClientRecord, error) {
	for _, c := range t.b.clients {
		if c.ClientID == clientID {
			cp := *c
			return &cp, nil
		}
	}
	return nil, nil
}

func (t *memoryTx) CreateWithCap(ctx context.Context, rec *ClientRecord, cap int) error {
	count := 0
	for _, c := range t.b.clients {
		if c.RevokedAt == nil {
			count++
		}
	}
	if count >= cap {
		return ErrClientCapReached
	}
	t.b.nextID++
	rec.ID = t.b.nextID
	rec.CreatedAt = time.Now()
	cp := *rec
	t.b.clients = append(t.b.clients, &cp)
	return nil
}

func (t *memoryTx) SweepUnconsented(ctx context.Context, olderThan time.Time) error {
	kept := t.b.clients[:0:0]
	for _, c := range t.b.clients {
		if c.ConsentedAt == nil && c.RegistrationIP != nil && c.CreatedAt.Before(olderThan) {
			continue
		}
		kept = append(kept, c)
	}
	t.b.clients = kept
	return nil
}

func (t *memoryTx) CreatePending(ctx context.Context, rec *AuthCodeRecord) error {
	t.b.nextID++
	rec.ID = t.b.nextID
	cp := *rec
	t.b.codes = append(t.b.codes, &cp)
	return nil
}

func (t *memoryTx) ByRequestID(ctx context.Context, requestID string) (*AuthCodeRecord, error) {
	for _, c := range t.b.codes {
		if c.RequestID != nil && *c.RequestID == requestID {
			cp := *c
			return &cp, nil
		}
	}
	return nil, nil
}

func (t *memoryTx) ByCodeHashForUpdate(ctx context.Context, codeHash string) (*AuthCodeRecord, error) {
	for _, c := range t.b.codes {
		if c.CodeHash != nil && *c.CodeHash == codeHash {
			cp := *c
			return &cp, nil
		}
	}
	return nil, nil
}

func (t *memoryTx) MarkIssued(ctx context.Context, id uint, codeHash string, userID uint, scopes []string, collectionIDs []uint, expiresAt time.Time) error {
	for _, c := range t.b.codes {
		if c.ID == id {
			c.RequestID = nil
			c.CodeHash = &codeHash
			c.UserID = &userID
			c.Scopes = scopes
			c.CollectionIDs = collectionIDs
			c.ExpiresAt = expiresAt
			return nil
		}
	}
	return nil
}

func (t *memoryTx) MarkConsented(ctx context.Context, clientID string) error {
	for _, c := range t.b.clients {
		if c.ClientID == clientID {
			if c.ConsentedAt == nil {
				now := time.Now()
				c.ConsentedAt = &now
			}
			return nil
		}
	}
	return nil
}

func (t *memoryTx) MarkUsed(ctx context.Context, id uint) error {
	now := time.Now()
	for _, c := range t.b.codes {
		if c.ID == id {
			c.UsedAt = &now
			return nil
		}
	}
	return nil
}

func (t *memoryTx) Create(ctx context.Context, rec *RefreshTokenRecord) error {
	t.b.nextID++
	rec.ID = t.b.nextID
	cp := *rec
	t.b.refresh = append(t.b.refresh, &cp)
	return nil
}

func (t *memoryTx) ByTokenHashForUpdate(ctx context.Context, tokenHash string) (*RefreshTokenRecord, error) {
	for _, r := range t.b.refresh {
		if r.TokenHash == tokenHash {
			cp := *r
			return &cp, nil
		}
	}
	return nil, nil
}

func (t *memoryTx) ByAPITokenIDForUpdate(ctx context.Context, apiTokenID uint) (*RefreshTokenRecord, error) {
	for _, r := range t.b.refresh {
		if r.APITokenID != nil && *r.APITokenID == apiTokenID {
			cp := *r
			return &cp, nil
		}
	}
	return nil, nil
}

func (t *memoryTx) MarkRotated(ctx context.Context, id uint, successorID uint) error {
	for _, r := range t.b.refresh {
		if r.ID == id {
			sid := successorID
			r.RotatedToID = &sid
			return nil
		}
	}
	return nil
}

// RevokeLineage walks forward through RotatedToID starting at startID,
// stamping RevokedAt on every visited refresh row and marking each row's
// linked access token revoked too (08-06-PLAN.md: mirrors the GORM
// adapter's RevokeLineage so T-08-REFRESH-REPLAY's "kill the whole lineage"
// contract is provable against the in-memory backend, not just real
// Postgres).
func (t *memoryTx) RevokeLineage(ctx context.Context, startID uint) error {
	now := time.Now()
	id := startID
	for {
		var found *RefreshTokenRecord
		for _, r := range t.b.refresh {
			if r.ID == id {
				found = r
				break
			}
		}
		if found == nil {
			return nil
		}
		if found.RevokedAt == nil {
			found.RevokedAt = &now
		}
		if found.APITokenID != nil {
			if t.b.revoked == nil {
				t.b.revoked = map[uint]bool{}
			}
			t.b.revoked[*found.APITokenID] = true
		}
		if found.RotatedToID == nil {
			return nil
		}
		id = *found.RotatedToID
	}
}

func (t *memoryTx) DeleteExpiredCodes(ctx context.Context, now time.Time) error {
	kept := t.b.codes[:0:0]
	for _, c := range t.b.codes {
		if c.ExpiresAt.Before(now) {
			continue
		}
		kept = append(kept, c)
	}
	t.b.codes = kept
	return nil
}

func (t *memoryTx) DeleteExpiredRefreshTokens(ctx context.Context, now time.Time) error {
	kept := t.b.refresh[:0:0]
	for _, r := range t.b.refresh {
		if r.ExpiresAt.Before(now) {
			continue
		}
		kept = append(kept, r)
	}
	t.b.refresh = kept
	return nil
}

// Mint's secret embeds the freshly-allocated id so two mints for the same
// client name (e.g. across a rotation) never collide on an identical
// "mem_<name>" string -- 08-06-PLAN.md's rotation tests distinguish the old
// and new access tokens by their returned secret.
func (t *memoryTx) Mint(ctx context.Context, userID uint, name string, scopes []string, expiresAt time.Time, collectionIDs []uint, clientID string) (IssuedToken, error) {
	t.b.nextID++
	tok := IssuedToken{ID: t.b.nextID, Secret: fmt.Sprintf("mem_%d_%s", t.b.nextID, name)}
	t.b.tokens = append(t.b.tokens, &tok)
	return tok, nil
}

func (t *memoryTx) Revoke(ctx context.Context, tokenID uint) error {
	if t.b.revoked == nil {
		t.b.revoked = map[uint]bool{}
	}
	t.b.revoked[tokenID] = true
	return nil
}

func newTestServer(backend Backend) *Server {
	opts := DefaultOptions()
	opts.Issuer = "https://plytarium.com"
	srv := NewServer(opts)
	srv.SetBackend(backend)
	return srv
}

func registerRequest(t *testing.T, body string, contentType string) *httptest.ResponseRecorder {
	t.Helper()
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", contentType)
	rec := httptest.NewRecorder()
	return rec
}

// TestPhase8RedRegistration is the Phase 8 Wave 2 RED anchor (08-02-PLAN.md
// Task 2, D-02/D-05/D-06/D-21). It asserts the exact RFC 7591 public-client
// success contract and fails with the PHASE8_RED:registration sentinel
// while Server.Register is a 501 stub; scripts/check-phase8-red.sh verifies
// this failure is fail-closed.
func TestPhase8RedRegistration(t *testing.T) {
	srv := newTestServer(newMemoryBackend())

	body := `{"redirect_uris":["https://client.example.test/callback"]}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	if rec.Code != http.StatusCreated {
		t.Fatalf("PHASE8_RED:registration: status = %d, want %d (body=%s)", rec.Code, http.StatusCreated, rec.Body.String())
	}
	var got map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatalf("PHASE8_RED:registration: decode response: %v", err)
	}
	if got["client_name"] != "MCP client" {
		t.Fatalf("PHASE8_RED:registration: client_name = %v, want default \"MCP client\"", got["client_name"])
	}
	if _, hasSecret := got["client_secret"]; hasSecret {
		t.Fatal("PHASE8_RED:registration: public client response has a client_secret, want none")
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("PHASE8_RED:registration: Cache-Control = %q, want \"no-store, private\"", cc)
	}
}

func TestRegisterPublicClientResponse(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `{"redirect_uris":["https://client.example.test/callback"],"client_name":"My Client"}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	if rec.Code != http.StatusCreated {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	var got map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatal(err)
	}
	if got["client_name"] != "My Client" {
		t.Fatalf("client_name = %v", got["client_name"])
	}
	if got["token_endpoint_auth_method"] != "none" {
		t.Fatalf("token_endpoint_auth_method = %v, want none", got["token_endpoint_auth_method"])
	}
	if _, hasSecret := got["client_secret"]; hasSecret {
		t.Fatal("public client response carries client_secret")
	}
	if _, hasExpires := got["client_secret_expires_at"]; hasExpires {
		t.Fatal("public client response carries client_secret_expires_at")
	}
	if strings.HasSuffix(rec.Body.String(), "\n") {
		t.Fatal("body has a trailing newline")
	}
	if _, hasData := got["data"]; hasData {
		t.Fatal("body has a house \"data\" envelope")
	}
}

func TestRegisterConfidentialClientReturnsSecretOnce(t *testing.T) {
	backend := newMemoryBackend()
	srv := newTestServer(backend)
	body := `{"redirect_uris":["https://client.example.test/callback"],"token_endpoint_auth_method":"client_secret_post"}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	if rec.Code != http.StatusCreated {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	var got map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatal(err)
	}
	secret, _ := got["client_secret"].(string)
	if secret == "" {
		t.Fatal("confidential client response has no client_secret")
	}
	if got["client_secret_expires_at"] != float64(0) {
		t.Fatalf("client_secret_expires_at = %v, want 0", got["client_secret_expires_at"])
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	if len(backend.clients) != 1 {
		t.Fatalf("stored clients = %d, want 1", len(backend.clients))
	}
	stored := backend.clients[0]
	if stored.ClientSecretHash == nil || *stored.ClientSecretHash == secret {
		t.Fatal("stored record must hold a hash, never the raw secret")
	}
	if *stored.ClientSecretHash != sha256Hex(secret) {
		t.Fatal("stored hash does not match sha256Hex(secret)")
	}
	if strings.Contains(rec.Body.String(), *stored.ClientSecretHash) {
		t.Fatal("response body must not also contain the persisted hash")
	}
}

func TestRegisterWrongContentType(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `redirect_uris=https://client.example.test/callback`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "Request must be application/json")
}

func TestRegisterMalformedJSON(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(`{not json`))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "Request must be application/json")
}

func TestRegisterOversizedBody(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	srv.opts.RegisterMaxBodyBytes = 64 * 1024

	// D-21: exactly one byte past the 64 KiB bound.
	padding := strings.Repeat("a", 65537)
	body := `{"redirect_uris":["https://client.example.test/callback"],"client_name":"` + padding + `"}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "Request must be application/json")
}

func TestRegisterRedirectURIBounds(t *testing.T) {
	cases := []struct {
		name string
		uris string
		want string
	}{
		{"missing", `[]`, "redirect_uris is required"},
		{"empty-entry", `["https://a.test/cb",""]`, "redirect_uris must be an array of URI strings"},
		{"too-many", `["https://a.test/1","https://a.test/2","https://a.test/3","https://a.test/4","https://a.test/5","https://a.test/6"]`, "A client may have at most 5 redirect URIs"},
		{"http-non-loopback", `["http://evil.example.test/cb"]`, "Redirect URI must be https:// or loopback http://127.0.0.1 / http://localhost: http://evil.example.test/cb"},
		{"not-a-url", `["not-a-url"]`, "Redirect URI is not a valid URL: not-a-url"},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			srv := newTestServer(newMemoryBackend())
			body := `{"redirect_uris":` + tc.uris + `}`
			req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
			req.Header.Set("Content-Type", "application/json")
			rec := httptest.NewRecorder()
			srv.Register(rec, req)
			assertRegisterError(t, rec, http.StatusBadRequest, "invalid_redirect_uri", tc.want)
		})
	}

	t.Run("too-long", func(t *testing.T) {
		srv := newTestServer(newMemoryBackend())
		longURI := "https://a.test/" + strings.Repeat("x", 512)
		bodyBytes, _ := json.Marshal(map[string][]string{"redirect_uris": {longURI}})
		req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", bytes.NewReader(bodyBytes))
		req.Header.Set("Content-Type", "application/json")
		rec := httptest.NewRecorder()
		srv.Register(rec, req)
		assertRegisterError(t, rec, http.StatusBadRequest, "invalid_redirect_uri", "Each redirect URI must be at most 512 characters.")
	})
}

func TestRegisterUnsupportedAuthMethod(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `{"redirect_uris":["https://client.example.test/callback"],"token_endpoint_auth_method":"bogus"}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)
	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "token_endpoint_auth_method is not supported")
}

func TestRegisterUnsupportedGrantType(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `{"redirect_uris":["https://client.example.test/callback"],"grant_types":["client_credentials"]}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)
	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "grant_types contains an unsupported value")
}

func TestRegisterGrantTypesMustIncludeAuthorizationCode(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `{"redirect_uris":["https://client.example.test/callback"],"grant_types":["refresh_token"]}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)
	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "grant_types must include authorization_code")
}

func TestRegisterUnsupportedResponseType(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	body := `{"redirect_uris":["https://client.example.test/callback"],"response_types":["token"]}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)
	assertRegisterError(t, rec, http.StatusBadRequest, "invalid_client_metadata", "response_types must be code")
}

func TestRegisterControlCharacterNameCleaning(t *testing.T) {
	srv := newTestServer(newMemoryBackend())
	dirty := "Evil\x00Name\x1FWith\x7FControls"
	bodyBytes, _ := json.Marshal(map[string]any{
		"redirect_uris": []string{"https://client.example.test/callback"},
		"client_name":   dirty,
	})
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", bytes.NewReader(bodyBytes))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)

	if rec.Code != http.StatusCreated {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}
	var got map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatal(err)
	}
	name, _ := got["client_name"].(string)
	if strings.ContainsAny(name, "\x00\x1f\x7f") {
		t.Fatalf("client_name %q still contains control characters", name)
	}
	if name != "EvilNameWithControls" {
		t.Fatalf("client_name = %q, want stripped \"EvilNameWithControls\"", name)
	}
}

func TestRegisterCapReached(t *testing.T) {
	backend := newMemoryBackend()
	srv := newTestServer(backend)
	srv.opts.DCRClientCap = 1

	body := `{"redirect_uris":["https://client.example.test/callback"]}`

	req1 := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req1.Header.Set("Content-Type", "application/json")
	rec1 := httptest.NewRecorder()
	srv.Register(rec1, req1)
	if rec1.Code != http.StatusCreated {
		t.Fatalf("first registration status = %d, body=%s", rec1.Code, rec1.Body.String())
	}

	req2 := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req2.Header.Set("Content-Type", "application/json")
	rec2 := httptest.NewRecorder()
	srv.Register(rec2, req2)
	assertRegisterError(t, rec2, http.StatusBadRequest, "invalid_client_metadata", "Registration temporarily unavailable")
}

func TestRegisterSweepsStaleUnconsentedButKeepsArtisanClients(t *testing.T) {
	backend := newMemoryBackend()
	srv := newTestServer(backend)

	staleIP := "203.0.113.9"
	backend.clients = append(backend.clients,
		&ClientRecord{ClientID: "stale-dynamic", RegistrationIP: &staleIP, CreatedAt: time.Now().Add(-48 * time.Hour)},
		&ClientRecord{ClientID: "artisan-client", RegistrationIP: nil, CreatedAt: time.Now().Add(-48 * time.Hour)},
	)

	body := `{"redirect_uris":["https://client.example.test/callback"]}`
	req := httptest.NewRequest(http.MethodPost, "/oauth/mcp/register", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	srv.Register(rec, req)
	if rec.Code != http.StatusCreated {
		t.Fatalf("status = %d, body=%s", rec.Code, rec.Body.String())
	}

	backend.mu.Lock()
	defer backend.mu.Unlock()
	var ids []string
	for _, c := range backend.clients {
		ids = append(ids, c.ClientID)
	}
	if containsString(ids, "stale-dynamic") {
		t.Fatalf("stale unconsented dynamic client survived sweep: %v", ids)
	}
	if !containsString(ids, "artisan-client") {
		t.Fatalf("artisan client (nil RegistrationIP) was swept: %v", ids)
	}
}

func containsString(ss []string, v string) bool {
	for _, s := range ss {
		if s == v {
			return true
		}
	}
	return false
}

func assertRegisterError(t *testing.T, rec *httptest.ResponseRecorder, status int, code, description string) {
	t.Helper()
	if rec.Code != status {
		t.Fatalf("status = %d, want %d (body=%s)", rec.Code, status, rec.Body.String())
	}
	var got map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode error body: %v (body=%s)", err, rec.Body.String())
	}
	if got["error"] != code {
		t.Fatalf("error = %v, want %q", got["error"], code)
	}
	if got["error_description"] != description {
		t.Fatalf("error_description = %v, want %q", got["error_description"], description)
	}
	if cc := rec.Header().Get("Cache-Control"); cc != "no-store, private" {
		t.Fatalf("Cache-Control = %q, want \"no-store, private\"", cc)
	}
}