package main

import (
	"net"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"sync"
	"testing"
	"time"

	cs "fn-registry/functions/cybersecurity"

	"github.com/enmanuel/unibus/pkg/blobstore"
	"github.com/enmanuel/unibus/pkg/client"
	"github.com/enmanuel/unibus/pkg/embeddednats"
	"github.com/enmanuel/unibus/pkg/frame"
	"github.com/enmanuel/unibus/pkg/membership"
	"github.com/enmanuel/unibus/pkg/room"
)

// testHarness boots an isolated embedded NATS server + in-process membershipd on
// their OWN free ports (never the productive 8470/4250 nor the user's running
// playground on 7700/8480/4260) and tears everything down by handle. This mirrors
// the unibus client_test harness so the echobot is exercised against the real bus.
type testHarness struct {
	natsURL string
	ctrlURL string
}

func freePort(t *testing.T) int {
	t.Helper()
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("free port: %v", err)
	}
	defer l.Close()
	return l.Addr().(*net.TCPAddr).Port
}

func newHarness(t *testing.T) *testHarness {
	t.Helper()
	dir := t.TempDir()

	ns, err := embeddednats.Start(filepath.Join(dir, "js"), freePort(t))
	if err != nil {
		t.Fatalf("embedded nats: %v", err)
	}

	store, err := membership.Open(filepath.Join(dir, "unibus.db"))
	if err != nil {
		ns.Shutdown()
		t.Fatalf("membership store: %v", err)
	}
	blobs, err := blobstore.New(filepath.Join(dir, "blobs"))
	if err != nil {
		store.Close()
		ns.Shutdown()
		t.Fatalf("blob store: %v", err)
	}
	srv := membership.NewServer(store, blobs)
	httpts := httptest.NewServer(srv)

	t.Cleanup(func() {
		httpts.Close()
		store.Close()
		ns.Shutdown()
		ns.WaitForShutdown()
	})

	return &testHarness{natsURL: embeddednats.ClientURL(ns), ctrlURL: httpts.URL}
}

func waitHealth(t *testing.T, ctrlURL string) {
	t.Helper()
	deadline := time.Now().Add(3 * time.Second)
	for time.Now().Before(deadline) {
		resp, err := http.Get(ctrlURL + "/healthz")
		if err == nil && resp.StatusCode == 200 {
			resp.Body.Close()
			return
		}
		if resp != nil {
			resp.Body.Close()
		}
		time.Sleep(50 * time.Millisecond)
	}
	t.Fatalf("membershipd never became healthy")
}

func mustIdentity(t *testing.T) cs.Identity {
	t.Helper()
	id, err := cs.GenerateIdentity()
	if err != nil {
		t.Fatalf("generate identity: %v", err)
	}
	return id
}

func waitFor(mu *sync.Mutex, slice *[]string, pred func([]string) bool, timeout time.Duration) bool {
	deadline := time.Now().Add(timeout)
	for time.Now().Before(deadline) {
		mu.Lock()
		cp := append([]string(nil), (*slice)...)
		mu.Unlock()
		if pred(cp) {
			return true
		}
		time.Sleep(25 * time.Millisecond)
	}
	return false
}

func snapshot(mu *sync.Mutex, slice *[]string) []string {
	mu.Lock()
	defer mu.Unlock()
	return append([]string(nil), (*slice)...)
}

func contains(rs []string, want string) bool {
	for _, r := range rs {
		if r == want {
			return true
		}
	}
	return false
}

// startEchobot wires up the echobot's chat + rpc behaviour against the given bus,
// using the same logic the main() entry point runs. It returns the bot client and
// its endpoint id so callers can assert the anti-loop guard. Cleanup is registered
// on the test.
func startEchobot(t *testing.T, h *testHarness, roomSubject, rpcSubject string) (*client.Client, string) {
	t.Helper()
	bot, err := client.New(h.natsURL, h.ctrlURL, mustIdentity(t))
	if err != nil {
		t.Fatalf("connect echobot: %v", err)
	}
	selfID := bot.Endpoint().ID

	chatRoom, err := bot.CreateRoom(roomSubject, room.ModeNATS)
	if err != nil {
		bot.Close()
		t.Fatalf("echobot create chat room: %v", err)
	}
	chatSub, err := bot.Subscribe(chatRoom, func(f frame.Frame, plaintext []byte) {
		if f.Sender == selfID {
			return // anti-loop guard
		}
		_ = bot.Publish(chatRoom, []byte("echo: "+string(plaintext)))
	})
	if err != nil {
		bot.Close()
		t.Fatalf("echobot subscribe chat: %v", err)
	}
	rpcSub, err := bot.Reply(rpcSubject, func(body []byte) []byte {
		return []byte("echo: " + string(body))
	})
	if err != nil {
		chatSub.Unsubscribe()
		bot.Close()
		t.Fatalf("echobot reply: %v", err)
	}

	t.Cleanup(func() {
		rpcSub.Unsubscribe()
		chatSub.Unsubscribe()
		bot.Close()
	})
	return bot, selfID
}

// TestChatEcho: a "human" peer publishes "hola" on the echo subject; the echobot
// replies "echo: hola". Asserts the human receives the echo and that the echobot
// never echoes its own messages (no infinite loop).
func TestChatEcho(t *testing.T) {
	h := newHarness(t)
	waitHealth(t, h.ctrlURL)

	const subject = "room.echo.test"
	_, botID := startEchobot(t, h, subject, "rpc.echo.test")

	human, err := client.New(h.natsURL, h.ctrlURL, mustIdentity(t))
	if err != nil {
		t.Fatalf("connect human: %v", err)
	}
	defer human.Close()

	humanRoom, err := human.CreateRoom(subject, room.ModeNATS)
	if err != nil {
		t.Fatalf("human create room: %v", err)
	}

	var mu sync.Mutex
	var received []string
	var echoSenders []string
	hsub, err := human.Subscribe(humanRoom, func(f frame.Frame, plaintext []byte) {
		mu.Lock()
		received = append(received, string(plaintext))
		if string(plaintext) == "echo: hola" {
			echoSenders = append(echoSenders, f.Sender)
		}
		mu.Unlock()
	})
	if err != nil {
		t.Fatalf("human subscribe: %v", err)
	}
	defer hsub.Unsubscribe()

	// Let both subscriptions settle before publishing.
	time.Sleep(200 * time.Millisecond)

	if err := human.Publish(humanRoom, []byte("hola")); err != nil {
		t.Fatalf("human publish: %v", err)
	}

	if !waitFor(&mu, &received, func(rs []string) bool { return contains(rs, "echo: hola") }, 2*time.Second) {
		t.Fatalf("human never received the echo; got %v", snapshot(&mu, &received))
	}

	// The echo must come from the bot, not the human (sanity on routing).
	mu.Lock()
	senders := append([]string(nil), echoSenders...)
	mu.Unlock()
	for _, s := range senders {
		if s != botID {
			t.Fatalf("echo came from %q, expected echobot %q", s, botID)
		}
	}

	// Anti-loop: give the bus time to spin if the guard were broken, then assert
	// the bot did not re-echo its own "echo: hola" into "echo: echo: hola".
	time.Sleep(500 * time.Millisecond)
	for _, r := range snapshot(&mu, &received) {
		if r == "echo: echo: hola" {
			t.Fatalf("anti-loop guard broken: bot echoed its own message (%q)", r)
		}
	}
}

// TestRPCEcho: a process peer issues Request(rpc-subject, "ping") and gets back
// "echo: ping". The unibus client library exposes request/reply, so this mode is
// fully supported (see client.go: Client.Request / Client.Reply).
func TestRPCEcho(t *testing.T) {
	h := newHarness(t)
	waitHealth(t, h.ctrlURL)

	const rpcSubject = "rpc.echo.test"
	startEchobot(t, h, "room.echo.test", rpcSubject)

	caller, err := client.New(h.natsURL, h.ctrlURL, mustIdentity(t))
	if err != nil {
		t.Fatalf("connect caller: %v", err)
	}
	defer caller.Close()

	// Give the responder time to subscribe.
	time.Sleep(150 * time.Millisecond)

	resp, err := caller.Request(rpcSubject, []byte("ping"), 2*time.Second)
	if err != nil {
		t.Fatalf("rpc request: %v", err)
	}
	if got, want := string(resp), "echo: ping"; got != want {
		t.Fatalf("rpc echo mismatch: got %q want %q", got, want)
	}
}