package realtime

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"net/netip"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/golang-jwt/jwt/v5"
	"github.com/gorilla/websocket"
	"github.com/multica-ai/multica/server/internal/auth"
)

const testWorkspaceID = "test-workspace"
const testUserID = "test-user"

// mockMembershipChecker always returns true.
type mockMembershipChecker struct{}

func (m *mockMembershipChecker) IsMember(_ context.Context, _, _ string) bool {
	return true
}

func makeTestToken(t *testing.T) string {
	t.Helper()
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
		"sub": testUserID,
	})
	signed, err := token.SignedString(auth.JWTSecret())
	if err != nil {
		t.Fatalf("failed to sign test JWT: %v", err)
	}
	return signed
}

func newTestHub(t *testing.T) (*Hub, *httptest.Server) {
	t.Helper()
	hub := NewHub()
	go hub.Run()

	mc := &mockMembershipChecker{}
	mux := http.NewServeMux()
	mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
		HandleWebSocket(hub, mc, nil, nil, w, r)
	})
	server := httptest.NewServer(mux)
	return hub, server
}

func connectWS(t *testing.T, server *httptest.Server) *websocket.Conn {
	t.Helper()
	token := makeTestToken(t)
	wsURL := "ws" + strings.TrimPrefix(server.URL, "http") + "/ws?workspace_id=" + testWorkspaceID
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
	if err != nil {
		t.Fatalf("failed to connect WebSocket: %v", err)
	}
	authMsg, _ := json.Marshal(map[string]any{
		"type":    "auth",
		"payload": map[string]string{"token": token},
	})
	if err := conn.WriteMessage(websocket.TextMessage, authMsg); err != nil {
		t.Fatalf("failed to send auth message: %v", err)
	}
	// Read auth_ack before returning the connection.
	conn.SetReadDeadline(time.Now().Add(2 * time.Second))
	_, ack, err := conn.ReadMessage()
	if err != nil {
		t.Fatalf("failed to read auth_ack: %v", err)
	}
	if !strings.Contains(string(ack), "auth_ack") {
		t.Fatalf("expected auth_ack, got %s", ack)
	}
	conn.SetReadDeadline(time.Time{})
	return conn
}

// totalClients counts all currently registered clients.
func totalClients(hub *Hub) int {
	hub.mu.RLock()
	defer hub.mu.RUnlock()
	return len(hub.clients)
}

func TestHub_ClientRegistration(t *testing.T) {
	hub, server := newTestHub(t)
	defer server.Close()

	conn := connectWS(t, server)
	defer conn.Close()

	time.Sleep(50 * time.Millisecond)

	count := totalClients(hub)
	if count != 1 {
		t.Fatalf("expected 1 client, got %d", count)
	}
}

func TestHub_Broadcast(t *testing.T) {
	hub, server := newTestHub(t)
	defer server.Close()

	conn1 := connectWS(t, server)
	defer conn1.Close()
	conn2 := connectWS(t, server)
	defer conn2.Close()

	time.Sleep(50 * time.Millisecond)

	msg := []byte(`{"type":"issue:created","data":"test"}`)
	hub.Broadcast(msg)

	conn1.SetReadDeadline(time.Now().Add(2 * time.Second))
	_, received1, err := conn1.ReadMessage()
	if err != nil {
		t.Fatalf("client 1 read error: %v", err)
	}
	if string(received1) != string(msg) {
		t.Fatalf("client 1: expected %s, got %s", msg, received1)
	}

	conn2.SetReadDeadline(time.Now().Add(2 * time.Second))
	_, received2, err := conn2.ReadMessage()
	if err != nil {
		t.Fatalf("client 2 read error: %v", err)
	}
	if string(received2) != string(msg) {
		t.Fatalf("client 2: expected %s, got %s", msg, received2)
	}
}

func TestHub_ClientDisconnect(t *testing.T) {
	hub, server := newTestHub(t)
	defer server.Close()

	conn := connectWS(t, server)

	time.Sleep(50 * time.Millisecond)

	countBefore := totalClients(hub)
	if countBefore != 1 {
		t.Fatalf("expected 1 client before disconnect, got %d", countBefore)
	}

	conn.Close()
	time.Sleep(100 * time.Millisecond)

	countAfter := totalClients(hub)
	if countAfter != 0 {
		t.Fatalf("expected 0 clients after disconnect, got %d", countAfter)
	}
}

func TestHub_BroadcastToMultipleClients(t *testing.T) {
	hub, server := newTestHub(t)
	defer server.Close()

	const numClients = 5
	conns := make([]*websocket.Conn, numClients)
	for i := 0; i < numClients; i++ {
		conns[i] = connectWS(t, server)
		defer conns[i].Close()
	}

	time.Sleep(50 * time.Millisecond)

	count := totalClients(hub)
	if count != numClients {
		t.Fatalf("expected %d clients, got %d", numClients, count)
	}

	msg := []byte(`{"type":"test","count":5}`)
	hub.Broadcast(msg)

	for i, conn := range conns {
		conn.SetReadDeadline(time.Now().Add(2 * time.Second))
		_, received, err := conn.ReadMessage()
		if err != nil {
			t.Fatalf("client %d read error: %v", i, err)
		}
		if string(received) != string(msg) {
			t.Fatalf("client %d: expected %s, got %s", i, msg, received)
		}
	}
}

func TestHub_MultipleBroadcasts(t *testing.T) {
	hub, server := newTestHub(t)
	defer server.Close()

	conn := connectWS(t, server)
	defer conn.Close()

	time.Sleep(50 * time.Millisecond)

	messages := []string{
		`{"type":"issue:created"}`,
		`{"type":"issue:updated"}`,
		`{"type":"issue:deleted"}`,
	}

	for _, msg := range messages {
		hub.Broadcast([]byte(msg))
	}

	for i, expected := range messages {
		conn.SetReadDeadline(time.Now().Add(2 * time.Second))
		_, received, err := conn.ReadMessage()
		if err != nil {
			t.Fatalf("message %d read error: %v", i, err)
		}
		if string(received) != expected {
			t.Fatalf("message %d: expected %s, got %s", i, expected, received)
		}
	}
}

// TestHandleWebSocket_ClientIdentityFromQuery verifies that client_platform,
// client_version, and client_os query params on the WS upgrade URL are read
// by the handler and surfaced to the access log. Browsers cannot set custom
// headers on WS upgrades, so this query-param channel is the only way to
// preserve the same observability dimensions HTTP clients get via X-Client-*.
func TestHandleWebSocket_ClientIdentityFromQuery(t *testing.T) {
	var buf bytes.Buffer
	var mu sync.Mutex
	handler := slog.NewJSONHandler(&lockedWriter{w: &buf, mu: &mu}, &slog.HandlerOptions{Level: slog.LevelDebug})
	prevDefault := slog.Default()
	slog.SetDefault(slog.New(handler))
	t.Cleanup(func() { slog.SetDefault(prevDefault) })

	_, server := newTestHub(t)
	defer server.Close()

	token := makeTestToken(t)
	wsURL := "ws" + strings.TrimPrefix(server.URL, "http") +
		"/ws?workspace_id=" + testWorkspaceID +
		"&client_platform=desktop&client_version=1.2.3&client_os=macos"
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
	if err != nil {
		t.Fatalf("dial: %v", err)
	}
	defer conn.Close()

	authMsg, _ := json.Marshal(map[string]any{
		"type":    "auth",
		"payload": map[string]string{"token": token},
	})
	if err := conn.WriteMessage(websocket.TextMessage, authMsg); err != nil {
		t.Fatalf("write auth: %v", err)
	}
	conn.SetReadDeadline(time.Now().Add(2 * time.Second))
	if _, _, err := conn.ReadMessage(); err != nil {
		t.Fatalf("read auth_ack: %v", err)
	}

	// Wait briefly for the "websocket connected" log line to be flushed.
	deadline := time.Now().Add(2 * time.Second)
	var found map[string]any
	for time.Now().Before(deadline) {
		mu.Lock()
		raw := buf.String()
		mu.Unlock()
		for _, line := range strings.Split(raw, "\n") {
			if line == "" {
				continue
			}
			var entry map[string]any
			if err := json.Unmarshal([]byte(line), &entry); err != nil {
				continue
			}
			if msg, _ := entry["msg"].(string); msg == "websocket connected" {
				found = entry
				break
			}
		}
		if found != nil {
			break
		}
		time.Sleep(20 * time.Millisecond)
	}

	if found == nil {
		t.Fatalf("did not observe \"websocket connected\" log entry; buffered logs:\n%s", buf.String())
	}
	if got, _ := found["client_platform"].(string); got != "desktop" {
		t.Errorf("client_platform = %q, want %q", got, "desktop")
	}
	if got, _ := found["client_version"].(string); got != "1.2.3" {
		t.Errorf("client_version = %q, want %q", got, "1.2.3")
	}
	if got, _ := found["client_os"].(string); got != "macos" {
		t.Errorf("client_os = %q, want %q", got, "macos")
	}
}

// lockedWriter is a thread-safe writer used to capture concurrent slog output.
type lockedWriter struct {
	w  *bytes.Buffer
	mu *sync.Mutex
}

func (l *lockedWriter) Write(p []byte) (int, error) {
	l.mu.Lock()
	defer l.mu.Unlock()
	return l.w.Write(p)
}

type failingWSWriter struct {
	err error
}

func (f failingWSWriter) WriteMessage(int, []byte) error {
	return f.err
}

func TestWriteWSAuthFrameLogsWriteErrors(t *testing.T) {
	var buf bytes.Buffer
	prevDefault := slog.Default()
	slog.SetDefault(slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelWarn})))
	t.Cleanup(func() { slog.SetDefault(prevDefault) })

	ok := writeWSAuthFrame(
		failingWSWriter{err: errors.New("write blocked")},
		[]byte(`{"error":"invalid token"}`),
		"auth_error",
		"workspace_id", testWorkspaceID,
	)

	if ok {
		t.Fatal("expected writeWSAuthFrame to report failed write")
	}
	logs := buf.String()
	if !strings.Contains(logs, "ws: failed to send auth frame") {
		t.Fatalf("expected auth frame write failure log, got:\n%s", logs)
	}
	if !strings.Contains(logs, "write blocked") {
		t.Fatalf("expected write error in log, got:\n%s", logs)
	}
	if !strings.Contains(logs, "auth_error") {
		t.Fatalf("expected frame kind in log, got:\n%s", logs)
	}
	if !strings.Contains(logs, testWorkspaceID) {
		t.Fatalf("expected workspace id in log, got:\n%s", logs)
	}
}

func TestCheckOrigin(t *testing.T) {
	prev := allowedWSOrigins.Load().([]string)
	SetAllowedOrigins([]string{
		"http://localhost:3000",
		"https://multica.ai",
	})
	t.Cleanup(func() { SetAllowedOrigins(prev) })

	prevProxies := trustedProxies.Load().([]netip.Prefix)
	SetTrustedProxies([]netip.Prefix{
		netip.MustParsePrefix("127.0.0.1/32"),
		netip.MustParsePrefix("10.0.0.0/8"),
		netip.MustParsePrefix("::1/128"),
	})
	t.Cleanup(func() { SetTrustedProxies(prevProxies) })

	cases := []struct {
		name       string
		host       string
		origin     string
		fwdHost    string
		remoteAddr string
		want       bool
	}{
		{"empty origin allowed", "api.multica.ai", "", "", "1.2.3.4:5678", true},
		{"same-origin allowed (native client default)", "localhost:8080", "http://localhost:8080", "", "1.2.3.4:5678", true},
		{"same-origin allowed (https)", "api.multica.ai", "https://api.multica.ai", "", "1.2.3.4:5678", true},
		{"same-origin allowed (case-insensitive host, RFC 7230)", "API.Multica.AI", "https://api.multica.ai", "", "1.2.3.4:5678", true},
		{"whitelisted origin allowed (web cross-origin)", "localhost:8080", "http://localhost:3000", "", "1.2.3.4:5678", true},
		{"whitelisted origin allowed (prod web)", "api.multica.ai", "https://multica.ai", "", "1.2.3.4:5678", true},
		{"unknown origin rejected (CSWSH defense)", "api.multica.ai", "https://evil.com", "", "1.2.3.4:5678", false},
		{"different port rejected", "localhost:8080", "http://localhost:9999", "", "1.2.3.4:5678", false},
		{"X-Forwarded-Host from trusted proxy matches origin", "internal.proxy", "https://multica.ai", "multica.ai", "127.0.0.1:5678", true},
		{"X-Forwarded-Host from trusted proxy case-insensitive", "internal.proxy", "https://Multica.AI", "multica.ai", "10.0.0.1:5678", true},
		{"X-Forwarded-Host from untrusted source rejected", "internal.proxy", "https://example.com", "example.com", "1.2.3.4:5678", false},
		{"X-Forwarded-Host from trusted proxy but evil origin rejected", "internal.proxy", "https://evil.com", "multica.ai", "127.0.0.1:5678", false},
		{"X-Forwarded-Host present but origin matches direct Host", "multica.ai", "https://multica.ai", "other.host", "1.2.3.4:5678", true},
		{"X-Forwarded-Host spoofed by attacker rejected", "internal.proxy", "https://evil.com", "evil.com", "1.2.3.4:5678", false},
		{"X-Forwarded-Host from trusted CIDR range matches origin", "internal.proxy", "https://multica.ai", "multica.ai", "10.5.6.7:5678", true},
		{"X-Forwarded-Host from trusted IPv6 proxy matches origin", "internal.proxy", "https://multica.ai", "multica.ai", "[::1]:5678", true},
		{"X-Forwarded-Host comma list uses first (client-facing) value", "internal.proxy", "https://multica.ai", "multica.ai, proxy.internal", "127.0.0.1:5678", true},
		{"X-Forwarded-Host comma list ignores trailing values", "internal.proxy", "https://app.multica.ai", "proxy.internal, app.multica.ai", "127.0.0.1:5678", false},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			r := httptest.NewRequest(http.MethodGet, "/ws", nil)
			r.Host = tc.host
			r.RemoteAddr = tc.remoteAddr
			if tc.origin != "" {
				r.Header.Set("Origin", tc.origin)
			}
			if tc.fwdHost != "" {
				r.Header.Set("X-Forwarded-Host", tc.fwdHost)
			}
			if got := checkOrigin(r); got != tc.want {
				t.Fatalf("checkOrigin(host=%q, origin=%q, X-Forwarded-Host=%q, remoteAddr=%q) = %v, want %v", tc.host, tc.origin, tc.fwdHost, tc.remoteAddr, got, tc.want)
			}
		})
	}
}