package server_test

import (
	"bytes"
	"context"
	"errors"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/audit"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/auth"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/auth/flow"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/auth/totp"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/config"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/httpx"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/middleware"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/routing"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/server"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/store"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/users"
)

// ── fakes / wrappers ─────────────────────────────────────────────────────────

// The counting wrappers embed the real interface and increment a counter before
// delegating, so a test can prove "the door never touched this" (AC-2).
type countingResolver struct {
	routing.Resolver
	calls *int
}

func (c countingResolver) GUID(g string) (bool, bool) { *c.calls++; return c.Resolver.GUID(g) }

type countingSessions struct {
	auth.Sessions
	calls *int
}

func (c countingSessions) Validate(ctx context.Context, id string) (auth.Session, error) {
	*c.calls++
	return c.Sessions.Validate(ctx, id)
}

type countingIdentities struct {
	auth.Identities
	calls *int
}

func (c countingIdentities) ByGUID(ctx context.Context, g string) (auth.Identity, error) {
	*c.calls++
	return c.Identities.ByGUID(ctx, g)
}

type countingUsers struct {
	users.Users
	calls *int
}

func (c countingUsers) Get(ctx context.Context, id int64) (users.User, error) {
	*c.calls++
	return c.Users.Get(ctx, id)
}

// probeCapture records what the door handed to a module function.
type probeCapture struct {
	rc     *server.RequestContext
	meta   audit.Meta
	metaOK bool
}

// ── registry ─────────────────────────────────────────────────────────────────

func testRegistry(cap *probeCapture) *server.MapRegistry {
	reg := server.NewMapRegistry()

	reg.RegisterCore("home", server.Home)
	reg.RegisterCore("login", server.LoginPlaceholder)
	reg.RegisterCore("enroll", server.EnrollPlaceholder)
	reg.RegisterCore("setup", server.SetupPlaceholder)
	reg.RegisterCore("access", server.AccessPlaceholder)

	reg.RegisterModule(server.NewModule("home").
		SetDefault("dashboard", server.Home).
		AddRoute("home", "home", server.Home))

	reg.RegisterModule(server.NewModule("hr").
		AddAction("save-data", "save-data", func(w http.ResponseWriter, _ *http.Request, _ *server.RequestContext) error {
			w.WriteHeader(http.StatusOK)
			_, err := w.Write([]byte("saved"))
			return err
		}))

	reg.RegisterModule(server.NewModule("probe").
		AddRoute("show", "show", func(w http.ResponseWriter, r *http.Request, rc *server.RequestContext) error {
			if cap != nil {
				cap.rc = rc
				cap.meta, cap.metaOK = audit.MetaFrom(r.Context())
			}
			w.WriteHeader(http.StatusOK)
			_, err := w.Write([]byte("probe"))
			return err
		}))

	return reg
}

// ── harness ──────────────────────────────────────────────────────────────────

type harness struct {
	t        *testing.T
	ctx      context.Context
	db       *store.DB
	users    *users.Store
	ids      *auth.IdentitiesService
	sessions *auth.SessionsService
	csrf     *httpx.CSRF
	pre      *httpx.PreSessionCSRF
	wa       *fakeWebAuthn
	totp     *totp.Generator
	srv      *server.Server

	adminID int64
	guid    string
	session auth.Session
}

func newHarness(t *testing.T, opts ...func(*server.Deps)) *harness {
	t.Helper()
	ctx := context.Background()

	db, err := store.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("store.Open: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	if err := db.Migrate(); err != nil {
		t.Fatalf("Migrate: %v", err)
	}

	aud := audit.New(db.DB)
	us := users.New(db.DB, aud)

	adminID, err := us.Create(ctx, 0, "admin@example.com", "Admin", users.RoleAdmin)
	if err != nil {
		t.Fatalf("bootstrap admin: %v", err)
	}

	sealer, err := auth.NewAEADSealer(bytes.Repeat([]byte{0x42}, auth.KeySize))
	if err != nil {
		t.Fatalf("NewAEADSealer: %v", err)
	}
	core := auth.New(db.DB, aud, auth.WithSealer(sealer))
	ids := core.Identities()
	sessions := core.Sessions()

	idID, guid, err := ids.Mint(ctx, adminID)
	if err != nil {
		t.Fatalf("Mint: %v", err)
	}
	if err := ids.Activate(ctx, idID); err != nil {
		t.Fatalf("Activate: %v", err)
	}
	sess, err := sessions.Mint(ctx, idID, "127.0.0.1", "test")
	if err != nil {
		t.Fatalf("session Mint: %v", err)
	}

	const (
		csrfKey      = "test-csrf-key-0123456789abcdef"
		cookieSecret = "test-cookie-secret-0123456789abcdef"
	)
	csrf, err := httpx.NewCSRF([]byte(csrfKey))
	if err != nil {
		t.Fatalf("NewCSRF: %v", err)
	}
	pre, err := httpx.NewPreSessionCSRF([]byte(cookieSecret), false)
	if err != nil {
		t.Fatalf("NewPreSessionCSRF: %v", err)
	}

	cfg := &config.Config{
		Setup:    false,
		Server:   config.Server{Listen: "127.0.0.1:8080", BaseURL: "http://127.0.0.1:8080"},
		Database: config.Database{Path: db.Path()},
		Secrets:  config.Secrets{CSRFKey: csrfKey, CookieSecret: cookieSecret},
	}

	wa := &fakeWebAuthn{}
	totpSvc := totp.New("MyDay", ids)

	deps := server.Deps{
		Config:     cfg,
		Resolver:   ids,
		Sessions:   sessions,
		Identities: ids,
		Users:      us,
		Audit:      aud,
		CSRF:       csrf,
		PreSession: pre,
	}
	for _, o := range opts {
		o(&deps)
	}

	// Build the SPEC-006 flow with the (possibly overridden) logger + CSRF, and
	// register it unless the test supplied its own registry.
	authFlow, err := flow.New(flow.Deps{
		Identities:  ids,
		Credentials: ids,
		Sessions:    sessions,
		Users:       us,
		WebAuthn:    wa,
		TOTP:        totpSvc,
		CSRF:        deps.PreSession,
		Audit:       aud,
		Logger:      deps.Logger,
		// The passkey nudge (SPEC-006 §8) is suppressed in setup mode; the
		// door's SetupMode is the same predicate (nil = nudge enabled).
		SuppressNudge: deps.SetupMode,
	})
	if err != nil {
		t.Fatalf("flow.New: %v", err)
	}
	if deps.Registry == nil {
		reg := testRegistry(nil)
		server.RegisterAuthFlow(reg, authFlow)
		deps.Registry = reg
	}

	srv, err := server.New(deps)
	if err != nil {
		t.Fatalf("server.New: %v", err)
	}

	return &harness{
		t: t, ctx: ctx, db: db, users: us, ids: ids, sessions: sessions,
		csrf: csrf, pre: pre, wa: wa, totp: totpSvc, srv: srv,
		adminID: adminID, guid: guid, session: sess,
	}
}

// preCSRF mints a signed pre-session token plus its cookie, as the enroll/login
// screens would (A15).
func (h *harness) preCSRF() (*http.Cookie, string) {
	h.t.Helper()
	tok, err := h.pre.Token()
	if err != nil {
		h.t.Fatalf("pre-session Token: %v", err)
	}
	return &http.Cookie{Name: httpx.PreSessionCookieName, Value: tok}, tok
}

func (h *harness) cookie() *http.Cookie {
	return &http.Cookie{Name: httpx.SessionCookieName, Value: h.session.ID}
}

// request issues a request directly against the door (no network).
func request(h http.Handler, method, target string, cookies ...*http.Cookie) *httptest.ResponseRecorder {
	req := httptest.NewRequest(method, target, nil)
	for _, c := range cookies {
		req.AddCookie(c)
	}
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)
	return rec
}

// ── AC-1 ─────────────────────────────────────────────────────────────────────

func TestAC1_RedirectAndNotFound(t *testing.T) {
	h := newHarness(t)

	rec := request(h.srv, "GET", "/")
	if rec.Code != http.StatusFound {
		t.Fatalf("GET / = %d, want 302", rec.Code)
	}
	if loc := rec.Header().Get("Location"); loc != "/home" {
		t.Errorf("Location = %q, want /home", loc)
	}

	rec = request(h.srv, "GET", "/holy-shit")
	if rec.Code != http.StatusNotFound {
		t.Errorf("GET /holy-shit = %d, want 404", rec.Code)
	}
}

// ── AC-2 ─────────────────────────────────────────────────────────────────────

func TestAC2_HomeNoSessionNoDB(t *testing.T) {
	var resolverCalls, validateCalls, byGUIDCalls, getCalls int
	h := newHarness(t, func(d *server.Deps) {
		d.Resolver = countingResolver{Resolver: d.Resolver, calls: &resolverCalls}
		d.Sessions = countingSessions{Sessions: d.Sessions, calls: &validateCalls}
		d.Identities = countingIdentities{Identities: d.Identities, calls: &byGUIDCalls}
		d.Users = countingUsers{Users: d.Users, calls: &getCalls}
	})

	rec := request(h.srv, "GET", "/home")
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /home = %d, want 200", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "MyDay") {
		t.Error("GET /home did not render the landing page")
	}

	if resolverCalls != 0 || validateCalls != 0 || byGUIDCalls != 0 || getCalls != 0 {
		t.Errorf("/home touched storage: resolver=%d sessions=%d identities=%d users=%d (AC-2)",
			resolverCalls, validateCalls, byGUIDCalls, getCalls)
	}
}

// ── AC-3 ─────────────────────────────────────────────────────────────────────

func TestAC3_GUIDWithAndWithoutSession(t *testing.T) {
	h := newHarness(t)

	// No session -> the login screen (a rendered page: 200, F-1).
	rec := request(h.srv, "GET", "/"+h.guid)
	if rec.Code != http.StatusOK {
		t.Errorf("GET /{guid} without a session = %d, want 200 (login screen, F-1)", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "Sign in") {
		t.Error("GET /{guid} without a session did not render the login screen (AC-3)")
	}

	// Valid session -> the module function (the dashboard).
	rec = request(h.srv, "GET", "/"+h.guid, h.cookie())
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /{guid} with a session = %d, want 200", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "MyDay") {
		t.Error("the module function did not render the dashboard")
	}

	// /{GUID}/home is the same user landing.
	rec = request(h.srv, "GET", "/"+h.guid+"/home", h.cookie())
	if rec.Code != http.StatusOK {
		t.Errorf("GET /{guid}/home with a session = %d, want 200", rec.Code)
	}
}

// ── AC-4 ─────────────────────────────────────────────────────────────────────

func TestAC4_SessionUserMismatchRejected(t *testing.T) {
	h := newHarness(t)

	// A second user with an active identity.
	otherID, err := h.users.Create(h.ctx, h.adminID, "b@example.com", "B", users.RoleTeam)
	if err != nil {
		t.Fatalf("create other user: %v", err)
	}
	idOther, guidOther, err := h.ids.Mint(h.ctx, otherID)
	if err != nil {
		t.Fatalf("Mint other: %v", err)
	}
	if err := h.ids.Activate(h.ctx, idOther); err != nil {
		t.Fatalf("Activate other: %v", err)
	}

	// The admin's session must NOT open the other user's GUID: the door hands
	// off to the login screen (200, a rendered page — F-1), never the module.
	rec := request(h.srv, "GET", "/"+guidOther, h.cookie())
	if rec.Code != http.StatusOK {
		t.Errorf("GET /{other-guid} with a foreign session = %d, want 200 (login screen, AC-4)", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "Sign in") {
		t.Error("a foreign session did not land on the login screen (AC-4)")
	}
	// The dashboard marker proves the module function was never reached (the
	// shell's own chrome carries "MyDay" on every page, login included).
	if strings.Contains(rec.Body.String(), "Your day, at a glance.") {
		t.Error("a foreign session reached the module function (AC-4)")
	}
}

// ── AC-5 ─────────────────────────────────────────────────────────────────────

func TestAC5_EmptyOrMissingSessionRejected(t *testing.T) {
	h := newHarness(t)

	empty := &http.Cookie{Name: httpx.SessionCookieName, Value: ""}
	cases := []struct {
		name   string
		target string
		cookie *http.Cookie
	}{
		{"missing id on /{guid}", "/" + h.guid, nil},
		{"empty id on /{guid}", "/" + h.guid, empty},
		{"missing id on /{guid}/home", "/" + h.guid + "/home", nil},
		{"empty id on /{guid}/home", "/" + h.guid + "/home", empty},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			var rec *httptest.ResponseRecorder
			if tc.cookie == nil {
				rec = request(h.srv, "GET", tc.target)
			} else {
				rec = request(h.srv, "GET", tc.target, tc.cookie)
			}
			// The door rejects the empty/missing session and renders the login
			// screen (200, F-1) — it must never reach the module.
			if rec.Code != http.StatusOK {
				t.Errorf("%s = %d, want 200 (login screen, A2/F-1)", tc.target, rec.Code)
			}
			if !strings.Contains(rec.Body.String(), "Sign in") {
				t.Errorf("%s did not render the login screen (A2)", tc.target)
			}
		})
	}
}

// ── AC-6 ─────────────────────────────────────────────────────────────────────

func TestAC6_ActionRequiresCSRF(t *testing.T) {
	h := newHarness(t)
	base := "/" + h.guid + "?do=hr&action=save-data"

	// No CSRF token -> rejected.
	rec := request(h.srv, "POST", base, h.cookie())
	if rec.Code != http.StatusForbidden {
		t.Errorf("action without a CSRF token = %d, want 403 (AC-6)", rec.Code)
	}

	// A wrong token -> rejected.
	rec = request(h.srv, "POST", base+"&csrf=wrong", h.cookie())
	if rec.Code != http.StatusForbidden {
		t.Errorf("action with a bad CSRF token = %d, want 403", rec.Code)
	}

	// The correct, session-bound token -> dispatched.
	token := url.QueryEscape(h.csrf.Token(h.session.ID))
	rec = request(h.srv, "POST", base+"&csrf="+token, h.cookie())
	if rec.Code != http.StatusOK {
		t.Fatalf("action with a valid CSRF token = %d, want 200", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "saved") {
		t.Error("the action handler did not run")
	}
}

// ── AC-7 ─────────────────────────────────────────────────────────────────────

func TestAC7_LoopbackEnforcement(t *testing.T) {
	cases := []struct {
		setup  bool
		listen string
		want   bool // want an error?
	}{
		{true, "0.0.0.0:8080", true},
		{true, ":8080", true},
		{true, "192.168.1.5:8080", true},
		{true, "127.0.0.1:8080", false},
		{true, "localhost:8080", false},
		{true, "[::1]:8080", false},
		{false, "0.0.0.0:8080", false}, // productive: a public bind is allowed
	}
	for _, tc := range cases {
		err := server.CheckSetupBind(tc.setup, tc.listen)
		if tc.want && !errors.Is(err, server.ErrNonLoopbackSetup) {
			t.Errorf("CheckSetupBind(%v, %q) = %v, want ErrNonLoopbackSetup", tc.setup, tc.listen, err)
		}
		if !tc.want && err != nil {
			t.Errorf("CheckSetupBind(%v, %q) = %v, want nil", tc.setup, tc.listen, err)
		}
	}

	// The full Serve path refuses to bind too (no listener is opened).
	h := newHarness(t, func(d *server.Deps) { d.SetupMode = func() bool { return true } })
	if err := h.srv.Serve("0.0.0.0:0"); !errors.Is(err, server.ErrNonLoopbackSetup) {
		t.Errorf("Serve with a public listen in setup mode = %v, want ErrNonLoopbackSetup (AC-7)", err)
	}
}

// ── AC-8 ─────────────────────────────────────────────────────────────────────

func TestAC8_CorrelationAndRedaction(t *testing.T) {
	var logs bytes.Buffer
	h := newHarness(t, func(d *server.Deps) {
		d.Logger = slog.New(slog.NewTextHandler(&logs, nil))
	})

	rec := request(h.srv, "GET", "/home")
	cid := rec.Header().Get(middleware.CorrelationHeader)
	if cid == "" {
		t.Fatal("the response carries no correlation id (AC-8)")
	}
	if !strings.Contains(logs.String(), cid) {
		t.Errorf("the log does not echo the correlation id %q (AC-8)", cid)
	}

	// A credential riding the path is redacted in the log.
	logs.Reset()
	request(h.srv, "GET", "/setup/token/SUPERSECRETTOKEN")
	out := logs.String()
	if strings.Contains(out, "SUPERSECRETTOKEN") {
		t.Error("the access log leaked a path credential (A8/AC-8)")
	}
	if !strings.Contains(out, httpx.Redacted) {
		t.Errorf("the access log did not mark the redaction (%q)", out)
	}
}

// ── AC-9 ─────────────────────────────────────────────────────────────────────

func TestAC9_RateLimiterOnAuthRoutes(t *testing.T) {
	h := newHarness(t, func(d *server.Deps) {
		d.RateLimit = 2
		d.RateWindow = time.Minute
	})

	for i := 0; i < 2; i++ {
		if rec := request(h.srv, "GET", "/access"); rec.Code != http.StatusOK {
			t.Fatalf("request %d = %d, want 200", i+1, rec.Code)
		}
	}
	rec := request(h.srv, "GET", "/access")
	if rec.Code != http.StatusTooManyRequests {
		t.Fatalf("third request = %d, want 429 (AC-9)", rec.Code)
	}
	if rec.Header().Get("Retry-After") == "" {
		t.Error("429 is missing a Retry-After header")
	}
}

// ── supporting behaviour ─────────────────────────────────────────────────────

// TestRequestContextHandover proves §5: the module function receives the
// resolved identification, and the door attached audit.Meta (R-1).
func TestRequestContextHandover(t *testing.T) {
	var cap probeCapture
	h := newHarness(t, func(d *server.Deps) { d.Registry = testRegistry(&cap) })

	rec := request(h.srv, "GET", "/"+h.guid+"/probe/show", h.cookie())
	if rec.Code != http.StatusOK {
		t.Fatalf("probe/show = %d, want 200", rec.Code)
	}
	if cap.rc == nil {
		t.Fatal("the module function was never invoked")
	}
	if cap.rc.UserID != h.adminID {
		t.Errorf("rc.UserID = %d, want %d", cap.rc.UserID, h.adminID)
	}
	if want := "user:" + strconv.FormatInt(h.adminID, 10); cap.rc.Principal != want {
		t.Errorf("rc.Principal = %q, want %q", cap.rc.Principal, want)
	}
	if cap.rc.Workflow != h.guid {
		t.Errorf("rc.Workflow = %q, want the GUID %q", cap.rc.Workflow, h.guid)
	}
	if cap.rc.Function != "show" {
		t.Errorf("rc.Function = %q, want show", cap.rc.Function)
	}
	if cap.rc.Correlation == "" || cap.rc.ClientIP == "" {
		t.Errorf("rc correlation/client IP not set: %+v", cap.rc)
	}

	if !cap.metaOK {
		t.Fatal("audit.Meta was not attached to the context (R-1)")
	}
	if cap.meta.ActorUserID != h.adminID {
		t.Errorf("meta.ActorUserID = %d, want %d", cap.meta.ActorUserID, h.adminID)
	}
	if cap.meta.CorrelationID != cap.rc.Correlation {
		t.Errorf("meta.CorrelationID = %q, want %q", cap.meta.CorrelationID, cap.rc.Correlation)
	}
}

// TestSetupModeRouting: /setup is served only in setup mode (SPEC-003 §4).
func TestSetupModeRouting(t *testing.T) {
	productive := newHarness(t)
	if rec := request(productive.srv, "GET", "/setup"); rec.Code != http.StatusNotFound {
		t.Errorf("GET /setup in productive mode = %d, want 404", rec.Code)
	}
	// The action door must also 404 /setup in productive mode.
	if rec := request(productive.srv, "POST", "/setup?do=setup&action=begin"); rec.Code != http.StatusNotFound {
		t.Errorf("POST /setup?do=setup in productive mode = %d, want 404", rec.Code)
	}

	inSetup := newHarness(t, func(d *server.Deps) { d.SetupMode = func() bool { return true } })
	if rec := request(inSetup.srv, "GET", "/setup"); rec.Code != http.StatusOK {
		t.Errorf("GET /setup in setup mode = %d, want 200", rec.Code)
	}
}

// TestEnrollRouting: a pending identity routes to the enrollment screen.
func TestEnrollRouting(t *testing.T) {
	h := newHarness(t)

	pendingUser, err := h.users.Create(h.ctx, h.adminID, "pending@example.com", "P", users.RoleTeam)
	if err != nil {
		t.Fatalf("create pending user: %v", err)
	}
	_, guidPending, err := h.ids.Mint(h.ctx, pendingUser) // pending_enrollment
	if err != nil {
		t.Fatalf("Mint pending: %v", err)
	}

	rec := request(h.srv, "GET", "/"+guidPending)
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /{pending-guid} = %d, want 200 (enroll)", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "Enrollment") {
		t.Error("a pending GUID did not route to the enrollment screen")
	}
}

// TestTrustedProxyClientIPAtTheDoor: only a trusted peer's XFF is honoured.
func TestTrustedProxyClientIPAtTheDoor(t *testing.T) {
	h := newHarness(t, func(d *server.Deps) {
		d.Config.Server.TrustedProxies = []string{"127.0.0.1"}
	})

	req := httptest.NewRequest("GET", "/home", nil)
	req.RemoteAddr = "127.0.0.1:9999"
	req.Header.Set("X-Forwarded-For", "203.0.113.77")
	rec := httptest.NewRecorder()
	h.srv.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}
	if got := req.Header.Get("X-Forwarded-For"); got != "203.0.113.77" {
		t.Errorf("X-Forwarded-For = %q, want the client value SET (never appended)", got)
	}
}