crosspoint-reader/src/network/CrossPointWebServer.cpp

#include "CrossPointWebServer.h"

#include <ArduinoJson.h>
#include <FsHelpers.h>
#include <SDCardManager.h>
#include <WiFi.h>
#include <esp_task_wdt.h>

#include <algorithm>

#include "html/FilesPageHtml.generated.h"
#include "html/HomePageHtml.generated.h"

namespace {
// Folders/files to hide from the web interface file browser
// Note: Items starting with "." are automatically hidden
const char* HIDDEN_ITEMS[] = {"System Volume Information", "XTCache"};
constexpr size_t HIDDEN_ITEMS_COUNT = sizeof(HIDDEN_ITEMS) / sizeof(HIDDEN_ITEMS[0]);

// Static pointer for WebSocket callback (WebSocketsServer requires C-style callback)
CrossPointWebServer* wsInstance = nullptr;

// WebSocket upload state
FsFile wsUploadFile;
String wsUploadFileName;
String wsUploadPath;
size_t wsUploadSize = 0;
size_t wsUploadReceived = 0;
unsigned long wsUploadStartTime = 0;
bool wsUploadInProgress = false;
}  // namespace

// File listing page template - now using generated headers:
// - HomePageHtml (from html/HomePage.html)
// - FilesPageHeaderHtml (from html/FilesPageHeader.html)
// - FilesPageFooterHtml (from html/FilesPageFooter.html)
CrossPointWebServer::CrossPointWebServer() {}

CrossPointWebServer::~CrossPointWebServer() { stop(); }

void CrossPointWebServer::begin() {
  if (running) {
    Serial.printf("[%lu] [WEB] Web server already running\n", millis());
    return;
  }

  // Check if we have a valid network connection (either STA connected or AP mode)
  const wifi_mode_t wifiMode = WiFi.getMode();
  const bool isStaConnected = (wifiMode & WIFI_MODE_STA) && (WiFi.status() == WL_CONNECTED);
  const bool isInApMode = (wifiMode & WIFI_MODE_AP) && (WiFi.softAPgetStationNum() >= 0);  // AP is running

  if (!isStaConnected && !isInApMode) {
    Serial.printf("[%lu] [WEB] Cannot start webserver - no valid network (mode=%d, status=%d)\n", millis(), wifiMode,
                  WiFi.status());
    return;
  }

  // Store AP mode flag for later use (e.g., in handleStatus)
  apMode = isInApMode;

  Serial.printf("[%lu] [WEB] [MEM] Free heap before begin: %d bytes\n", millis(), ESP.getFreeHeap());
  Serial.printf("[%lu] [WEB] Network mode: %s\n", millis(), apMode ? "AP" : "STA");

  Serial.printf("[%lu] [WEB] Creating web server on port %d...\n", millis(), port);
  server.reset(new WebServer(port));

  // Disable WiFi sleep to improve responsiveness and prevent 'unreachable' errors.
  // This is critical for reliable web server operation on ESP32.
  WiFi.setSleep(false);

  // Note: WebServer class doesn't have setNoDelay() in the standard ESP32 library.
  // We rely on disabling WiFi sleep for responsiveness.

  Serial.printf("[%lu] [WEB] [MEM] Free heap after WebServer allocation: %d bytes\n", millis(), ESP.getFreeHeap());

  if (!server) {
    Serial.printf("[%lu] [WEB] Failed to create WebServer!\n", millis());
    return;
  }

  // Setup routes
  Serial.printf("[%lu] [WEB] Setting up routes...\n", millis());
  server->on("/", HTTP_GET, [this] { handleRoot(); });
  server->on("/files", HTTP_GET, [this] { handleFileList(); });

  server->on("/api/status", HTTP_GET, [this] { handleStatus(); });
  server->on("/api/files", HTTP_GET, [this] { handleFileListData(); });

  // Upload endpoint with special handling for multipart form data
  server->on("/upload", HTTP_POST, [this] { handleUploadPost(); }, [this] { handleUpload(); });

  // Create folder endpoint
  server->on("/mkdir", HTTP_POST, [this] { handleCreateFolder(); });

  // Delete file/folder endpoint
  server->on("/delete", HTTP_POST, [this] { handleDelete(); });

  server->onNotFound([this] { handleNotFound(); });
  Serial.printf("[%lu] [WEB] [MEM] Free heap after route setup: %d bytes\n", millis(), ESP.getFreeHeap());

  server->begin();

  // Start WebSocket server for fast binary uploads
  Serial.printf("[%lu] [WEB] Starting WebSocket server on port %d...\n", millis(), wsPort);
  wsServer.reset(new WebSocketsServer(wsPort));
  wsInstance = const_cast<CrossPointWebServer*>(this);
  wsServer->begin();
  wsServer->onEvent(wsEventCallback);
  Serial.printf("[%lu] [WEB] WebSocket server started\n", millis());

  running = true;

  Serial.printf("[%lu] [WEB] Web server started on port %d\n", millis(), port);
  // Show the correct IP based on network mode
  const String ipAddr = apMode ? WiFi.softAPIP().toString() : WiFi.localIP().toString();
  Serial.printf("[%lu] [WEB] Access at http://%s/\n", millis(), ipAddr.c_str());
  Serial.printf("[%lu] [WEB] WebSocket at ws://%s:%d/\n", millis(), ipAddr.c_str(), wsPort);
  Serial.printf("[%lu] [WEB] [MEM] Free heap after server.begin(): %d bytes\n", millis(), ESP.getFreeHeap());
}

void CrossPointWebServer::stop() {
  if (!running || !server) {
    Serial.printf("[%lu] [WEB] stop() called but already stopped (running=%d, server=%p)\n", millis(), running,
                  server.get());
    return;
  }

  Serial.printf("[%lu] [WEB] STOP INITIATED - setting running=false first\n", millis());
  running = false;  // Set this FIRST to prevent handleClient from using server

  Serial.printf("[%lu] [WEB] [MEM] Free heap before stop: %d bytes\n", millis(), ESP.getFreeHeap());

  // Close any in-progress WebSocket upload
  if (wsUploadInProgress && wsUploadFile) {
    wsUploadFile.close();
    wsUploadInProgress = false;
  }

  // Stop WebSocket server
  if (wsServer) {
    Serial.printf("[%lu] [WEB] Stopping WebSocket server...\n", millis());
    wsServer->close();
    wsServer.reset();
    wsInstance = nullptr;
    Serial.printf("[%lu] [WEB] WebSocket server stopped\n", millis());
  }

  // Brief delay to allow any in-flight handleClient() calls to complete
  delay(20);

  server->stop();
  Serial.printf("[%lu] [WEB] [MEM] Free heap after server->stop(): %d bytes\n", millis(), ESP.getFreeHeap());

  // Brief delay before deletion
  delay(10);

  server.reset();
  Serial.printf("[%lu] [WEB] Web server stopped and deleted\n", millis());
  Serial.printf("[%lu] [WEB] [MEM] Free heap after delete server: %d bytes\n", millis(), ESP.getFreeHeap());

  // Note: Static upload variables (uploadFileName, uploadPath, uploadError) are declared
  // later in the file and will be cleared when they go out of scope or on next upload
  Serial.printf("[%lu] [WEB] [MEM] Free heap final: %d bytes\n", millis(), ESP.getFreeHeap());
}

void CrossPointWebServer::handleClient() const {
  static unsigned long lastDebugPrint = 0;

  // Check running flag FIRST before accessing server
  if (!running) {
    return;
  }

  // Double-check server pointer is valid
  if (!server) {
    Serial.printf("[%lu] [WEB] WARNING: handleClient called with null server!\n", millis());
    return;
  }

  // Print debug every 10 seconds to confirm handleClient is being called
  if (millis() - lastDebugPrint > 10000) {
    Serial.printf("[%lu] [WEB] handleClient active, server running on port %d\n", millis(), port);
    lastDebugPrint = millis();
  }

  server->handleClient();

  // Handle WebSocket events
  if (wsServer) {
    wsServer->loop();
  }
}

void CrossPointWebServer::handleRoot() const {
  server->send(200, "text/html", HomePageHtml);
  Serial.printf("[%lu] [WEB] Served root page\n", millis());
}

void CrossPointWebServer::handleNotFound() const {
  String message = "404 Not Found\n\n";
  message += "URI: " + server->uri() + "\n";
  server->send(404, "text/plain", message);
}

void CrossPointWebServer::handleStatus() const {
  // Get correct IP based on AP vs STA mode
  const String ipAddr = apMode ? WiFi.softAPIP().toString() : WiFi.localIP().toString();

  JsonDocument doc;
  doc["version"] = CROSSPOINT_VERSION;
  doc["ip"] = ipAddr;
  doc["mode"] = apMode ? "AP" : "STA";
  doc["rssi"] = apMode ? 0 : WiFi.RSSI();
  doc["freeHeap"] = ESP.getFreeHeap();
  doc["uptime"] = millis() / 1000;

  String json;
  serializeJson(doc, json);
  server->send(200, "application/json", json);
}

void CrossPointWebServer::scanFiles(const char* path, const std::function<void(FileInfo)>& callback) const {
  FsFile root = SdMan.open(path);
  if (!root) {
    Serial.printf("[%lu] [WEB] Failed to open directory: %s\n", millis(), path);
    return;
  }

  if (!root.isDirectory()) {
    Serial.printf("[%lu] [WEB] Not a directory: %s\n", millis(), path);
    root.close();
    return;
  }

  Serial.printf("[%lu] [WEB] Scanning files in: %s\n", millis(), path);

  FsFile file = root.openNextFile();
  char name[500];
  while (file) {
    file.getName(name, sizeof(name));
    auto fileName = String(name);

    // Skip hidden items (starting with ".")
    bool shouldHide = fileName.startsWith(".");

    // Check against explicitly hidden items list
    if (!shouldHide) {
      for (size_t i = 0; i < HIDDEN_ITEMS_COUNT; i++) {
        if (fileName.equals(HIDDEN_ITEMS[i])) {
          shouldHide = true;
          break;
        }
      }
    }

    if (!shouldHide) {
      FileInfo info;
      info.name = fileName;
      info.isDirectory = file.isDirectory();

      if (info.isDirectory) {
        info.size = 0;
        info.isEpub = false;
      } else {
        info.size = file.size();
        info.isEpub = isEpubFile(info.name);
      }

      callback(info);
    }

    file.close();
    yield();               // Yield to allow WiFi and other tasks to process during long scans
    esp_task_wdt_reset();  // Reset watchdog to prevent timeout on large directories
    file = root.openNextFile();
  }
  root.close();
}

bool CrossPointWebServer::isEpubFile(const String& filename) const {
  String lower = filename;
  lower.toLowerCase();
  return lower.endsWith(".epub");
}

void CrossPointWebServer::handleFileList() const { server->send(200, "text/html", FilesPageHtml); }

void CrossPointWebServer::handleFileListData() const {
  // Get current path from query string (default to root)
  String currentPath = "/";
  if (server->hasArg("path")) {
    currentPath = server->arg("path");
    // Ensure path starts with /
    if (!currentPath.startsWith("/")) {
      currentPath = "/" + currentPath;
    }
    // Remove trailing slash unless it's root
    if (currentPath.length() > 1 && currentPath.endsWith("/")) {
      currentPath = currentPath.substring(0, currentPath.length() - 1);
    }
  }

  server->setContentLength(CONTENT_LENGTH_UNKNOWN);
  server->send(200, "application/json", "");
  server->sendContent("[");
  char output[512];
  constexpr size_t outputSize = sizeof(output);
  bool seenFirst = false;
  JsonDocument doc;

  scanFiles(currentPath.c_str(), [this, &output, &doc, seenFirst](const FileInfo& info) mutable {
    doc.clear();
    doc["name"] = info.name;
    doc["size"] = info.size;
    doc["isDirectory"] = info.isDirectory;
    doc["isEpub"] = info.isEpub;

    const size_t written = serializeJson(doc, output, outputSize);
    if (written >= outputSize) {
      // JSON output truncated; skip this entry to avoid sending malformed JSON
      Serial.printf("[%lu] [WEB] Skipping file entry with oversized JSON for name: %s\n", millis(), info.name.c_str());
      return;
    }

    if (seenFirst) {
      server->sendContent(",");
    } else {
      seenFirst = true;
    }
    server->sendContent(output);
  });
  server->sendContent("]");
  // End of streamed response, empty chunk to signal client
  server->sendContent("");
  Serial.printf("[%lu] [WEB] Served file listing page for path: %s\n", millis(), currentPath.c_str());
}

// Static variables for upload handling
static FsFile uploadFile;
static String uploadFileName;
static String uploadPath = "/";
static size_t uploadSize = 0;
static bool uploadSuccess = false;
static String uploadError = "";

// Upload write buffer - batches small writes into larger SD card operations
// 4KB is a good balance: large enough to reduce syscall overhead, small enough
// to keep individual write times short and avoid watchdog issues
constexpr size_t UPLOAD_BUFFER_SIZE = 4096;  // 4KB buffer
static uint8_t uploadBuffer[UPLOAD_BUFFER_SIZE];
static size_t uploadBufferPos = 0;

// Diagnostic counters for upload performance analysis
static unsigned long uploadStartTime = 0;
static unsigned long totalWriteTime = 0;
static size_t writeCount = 0;

static bool flushUploadBuffer() {
  if (uploadBufferPos > 0 && uploadFile) {
    esp_task_wdt_reset();  // Reset watchdog before potentially slow SD write
    const unsigned long writeStart = millis();
    const size_t written = uploadFile.write(uploadBuffer, uploadBufferPos);
    totalWriteTime += millis() - writeStart;
    writeCount++;
    esp_task_wdt_reset();  // Reset watchdog after SD write

    if (written != uploadBufferPos) {
      Serial.printf("[%lu] [WEB] [UPLOAD] Buffer flush failed: expected %d, wrote %d\n", millis(), uploadBufferPos,
                    written);
      uploadBufferPos = 0;
      return false;
    }
    uploadBufferPos = 0;
  }
  return true;
}

void CrossPointWebServer::handleUpload() const {
  static size_t lastLoggedSize = 0;

  // Reset watchdog at start of every upload callback - HTTP parsing can be slow
  esp_task_wdt_reset();

  // Safety check: ensure server is still valid
  if (!running || !server) {
    Serial.printf("[%lu] [WEB] [UPLOAD] ERROR: handleUpload called but server not running!\n", millis());
    return;
  }

  const HTTPUpload& upload = server->upload();

  if (upload.status == UPLOAD_FILE_START) {
    // Reset watchdog - this is the critical 1% crash point
    esp_task_wdt_reset();

    uploadFileName = upload.filename;
    uploadSize = 0;
    uploadSuccess = false;
    uploadError = "";
    uploadStartTime = millis();
    lastLoggedSize = 0;
    uploadBufferPos = 0;
    totalWriteTime = 0;
    writeCount = 0;

    // Get upload path from query parameter (defaults to root if not specified)
    // Note: We use query parameter instead of form data because multipart form
    // fields aren't available until after file upload completes
    if (server->hasArg("path")) {
      uploadPath = server->arg("path");
      // Ensure path starts with /
      if (!uploadPath.startsWith("/")) {
        uploadPath = "/" + uploadPath;
      }
      // Remove trailing slash unless it's root
      if (uploadPath.length() > 1 && uploadPath.endsWith("/")) {
        uploadPath = uploadPath.substring(0, uploadPath.length() - 1);
      }
    } else {
      uploadPath = "/";
    }

    Serial.printf("[%lu] [WEB] [UPLOAD] START: %s to path: %s\n", millis(), uploadFileName.c_str(), uploadPath.c_str());
    Serial.printf("[%lu] [WEB] [UPLOAD] Free heap: %d bytes\n", millis(), ESP.getFreeHeap());

    // Create file path
    String filePath = uploadPath;
    if (!filePath.endsWith("/")) filePath += "/";
    filePath += uploadFileName;

    // Check if file already exists - SD operations can be slow
    esp_task_wdt_reset();
    if (SdMan.exists(filePath.c_str())) {
      Serial.printf("[%lu] [WEB] [UPLOAD] Overwriting existing file: %s\n", millis(), filePath.c_str());
      esp_task_wdt_reset();
      SdMan.remove(filePath.c_str());
    }

    // Open file for writing - this can be slow due to FAT cluster allocation
    esp_task_wdt_reset();
    if (!SdMan.openFileForWrite("WEB", filePath, uploadFile)) {
      uploadError = "Failed to create file on SD card";
      Serial.printf("[%lu] [WEB] [UPLOAD] FAILED to create file: %s\n", millis(), filePath.c_str());
      return;
    }
    esp_task_wdt_reset();

    Serial.printf("[%lu] [WEB] [UPLOAD] File created successfully: %s\n", millis(), filePath.c_str());
  } else if (upload.status == UPLOAD_FILE_WRITE) {
    if (uploadFile && uploadError.isEmpty()) {
      // Buffer incoming data and flush when buffer is full
      // This reduces SD card write operations and improves throughput
      const uint8_t* data = upload.buf;
      size_t remaining = upload.currentSize;

      while (remaining > 0) {
        const size_t space = UPLOAD_BUFFER_SIZE - uploadBufferPos;
        const size_t toCopy = (remaining < space) ? remaining : space;

        memcpy(uploadBuffer + uploadBufferPos, data, toCopy);
        uploadBufferPos += toCopy;
        data += toCopy;
        remaining -= toCopy;

        // Flush buffer when full
        if (uploadBufferPos >= UPLOAD_BUFFER_SIZE) {
          if (!flushUploadBuffer()) {
            uploadError = "Failed to write to SD card - disk may be full";
            uploadFile.close();
            return;
          }
        }
      }

      uploadSize += upload.currentSize;

      // Log progress every 100KB
      if (uploadSize - lastLoggedSize >= 102400) {
        const unsigned long elapsed = millis() - uploadStartTime;
        const float kbps = (elapsed > 0) ? (uploadSize / 1024.0) / (elapsed / 1000.0) : 0;
        Serial.printf("[%lu] [WEB] [UPLOAD] %d bytes (%.1f KB), %.1f KB/s, %d writes\n", millis(), uploadSize,
                      uploadSize / 1024.0, kbps, writeCount);
        lastLoggedSize = uploadSize;
      }
    }
  } else if (upload.status == UPLOAD_FILE_END) {
    if (uploadFile) {
      // Flush any remaining buffered data
      if (!flushUploadBuffer()) {
        uploadError = "Failed to write final data to SD card";
      }
      uploadFile.close();

      if (uploadError.isEmpty()) {
        uploadSuccess = true;
        const unsigned long elapsed = millis() - uploadStartTime;
        const float avgKbps = (elapsed > 0) ? (uploadSize / 1024.0) / (elapsed / 1000.0) : 0;
        const float writePercent = (elapsed > 0) ? (totalWriteTime * 100.0 / elapsed) : 0;
        Serial.printf("[%lu] [WEB] [UPLOAD] Complete: %s (%d bytes in %lu ms, avg %.1f KB/s)\n", millis(),
                      uploadFileName.c_str(), uploadSize, elapsed, avgKbps);
        Serial.printf("[%lu] [WEB] [UPLOAD] Diagnostics: %d writes, total write time: %lu ms (%.1f%%)\n", millis(),
                      writeCount, totalWriteTime, writePercent);
      }
    }
  } else if (upload.status == UPLOAD_FILE_ABORTED) {
    uploadBufferPos = 0;  // Discard buffered data
    if (uploadFile) {
      uploadFile.close();
      // Try to delete the incomplete file
      String filePath = uploadPath;
      if (!filePath.endsWith("/")) filePath += "/";
      filePath += uploadFileName;
      SdMan.remove(filePath.c_str());
    }
    uploadError = "Upload aborted";
    Serial.printf("[%lu] [WEB] Upload aborted\n", millis());
  }
}

void CrossPointWebServer::handleUploadPost() const {
  if (uploadSuccess) {
    server->send(200, "text/plain", "File uploaded successfully: " + uploadFileName);
  } else {
    const String error = uploadError.isEmpty() ? "Unknown error during upload" : uploadError;
    server->send(400, "text/plain", error);
  }
}

void CrossPointWebServer::handleCreateFolder() const {
  // Get folder name from form data
  if (!server->hasArg("name")) {
    server->send(400, "text/plain", "Missing folder name");
    return;
  }

  const String folderName = server->arg("name");

  // Validate folder name
  if (folderName.isEmpty()) {
    server->send(400, "text/plain", "Folder name cannot be empty");
    return;
  }

  // Get parent path
  String parentPath = "/";
  if (server->hasArg("path")) {
    parentPath = server->arg("path");
    if (!parentPath.startsWith("/")) {
      parentPath = "/" + parentPath;
    }
    if (parentPath.length() > 1 && parentPath.endsWith("/")) {
      parentPath = parentPath.substring(0, parentPath.length() - 1);
    }
  }

  // Build full folder path
  String folderPath = parentPath;
  if (!folderPath.endsWith("/")) folderPath += "/";
  folderPath += folderName;

  Serial.printf("[%lu] [WEB] Creating folder: %s\n", millis(), folderPath.c_str());

  // Check if already exists
  if (SdMan.exists(folderPath.c_str())) {
    server->send(400, "text/plain", "Folder already exists");
    return;
  }

  // Create the folder
  if (SdMan.mkdir(folderPath.c_str())) {
    Serial.printf("[%lu] [WEB] Folder created successfully: %s\n", millis(), folderPath.c_str());
    server->send(200, "text/plain", "Folder created: " + folderName);
  } else {
    Serial.printf("[%lu] [WEB] Failed to create folder: %s\n", millis(), folderPath.c_str());
    server->send(500, "text/plain", "Failed to create folder");
  }
}

void CrossPointWebServer::handleDelete() const {
  // Get path from form data
  if (!server->hasArg("path")) {
    server->send(400, "text/plain", "Missing path");
    return;
  }

  String itemPath = server->arg("path");
  const String itemType = server->hasArg("type") ? server->arg("type") : "file";

  // Validate path
  if (itemPath.isEmpty() || itemPath == "/") {
    server->send(400, "text/plain", "Cannot delete root directory");
    return;
  }

  // Ensure path starts with /
  if (!itemPath.startsWith("/")) {
    itemPath = "/" + itemPath;
  }

  // Security check: prevent deletion of protected items
  const String itemName = itemPath.substring(itemPath.lastIndexOf('/') + 1);

  // Check if item starts with a dot (hidden/system file)
  if (itemName.startsWith(".")) {
    Serial.printf("[%lu] [WEB] Delete rejected - hidden/system item: %s\n", millis(), itemPath.c_str());
    server->send(403, "text/plain", "Cannot delete system files");
    return;
  }

  // Check against explicitly protected items
  for (size_t i = 0; i < HIDDEN_ITEMS_COUNT; i++) {
    if (itemName.equals(HIDDEN_ITEMS[i])) {
      Serial.printf("[%lu] [WEB] Delete rejected - protected item: %s\n", millis(), itemPath.c_str());
      server->send(403, "text/plain", "Cannot delete protected items");
      return;
    }
  }

  // Check if item exists
  if (!SdMan.exists(itemPath.c_str())) {
    Serial.printf("[%lu] [WEB] Delete failed - item not found: %s\n", millis(), itemPath.c_str());
    server->send(404, "text/plain", "Item not found");
    return;
  }

  Serial.printf("[%lu] [WEB] Attempting to delete %s: %s\n", millis(), itemType.c_str(), itemPath.c_str());

  bool success = false;

  if (itemType == "folder") {
    // For folders, try to remove (will fail if not empty)
    FsFile dir = SdMan.open(itemPath.c_str());
    if (dir && dir.isDirectory()) {
      // Check if folder is empty
      FsFile entry = dir.openNextFile();
      if (entry) {
        // Folder is not empty
        entry.close();
        dir.close();
        Serial.printf("[%lu] [WEB] Delete failed - folder not empty: %s\n", millis(), itemPath.c_str());
        server->send(400, "text/plain", "Folder is not empty. Delete contents first.");
        return;
      }
      dir.close();
    }
    success = SdMan.rmdir(itemPath.c_str());
  } else {
    // For files, use remove
    success = SdMan.remove(itemPath.c_str());
  }

  if (success) {
    Serial.printf("[%lu] [WEB] Successfully deleted: %s\n", millis(), itemPath.c_str());
    server->send(200, "text/plain", "Deleted successfully");
  } else {
    Serial.printf("[%lu] [WEB] Failed to delete: %s\n", millis(), itemPath.c_str());
    server->send(500, "text/plain", "Failed to delete item");
  }
}

// WebSocket callback trampoline
void CrossPointWebServer::wsEventCallback(uint8_t num, WStype_t type, uint8_t* payload, size_t length) {
  if (wsInstance) {
    wsInstance->onWebSocketEvent(num, type, payload, length);
  }
}

// WebSocket event handler for fast binary uploads
// Protocol:
//   1. Client sends TEXT message: "START:<filename>:<size>:<path>"
//   2. Client sends BINARY messages with file data chunks
//   3. Server sends TEXT "PROGRESS:<received>:<total>" after each chunk
//   4. Server sends TEXT "DONE" or "ERROR:<message>" when complete
void CrossPointWebServer::onWebSocketEvent(uint8_t num, WStype_t type, uint8_t* payload, size_t length) {
  switch (type) {
    case WStype_DISCONNECTED:
      Serial.printf("[%lu] [WS] Client %u disconnected\n", millis(), num);
      // Clean up any in-progress upload
      if (wsUploadInProgress && wsUploadFile) {
        wsUploadFile.close();
        // Delete incomplete file
        String filePath = wsUploadPath;
        if (!filePath.endsWith("/")) filePath += "/";
        filePath += wsUploadFileName;
        SdMan.remove(filePath.c_str());
        Serial.printf("[%lu] [WS] Deleted incomplete upload: %s\n", millis(), filePath.c_str());
      }
      wsUploadInProgress = false;
      break;

    case WStype_CONNECTED: {
      Serial.printf("[%lu] [WS] Client %u connected\n", millis(), num);
      break;
    }

    case WStype_TEXT: {
      // Parse control messages
      String msg = String((char*)payload);
      Serial.printf("[%lu] [WS] Text from client %u: %s\n", millis(), num, msg.c_str());

      if (msg.startsWith("START:")) {
        // Parse: START:<filename>:<size>:<path>
        int firstColon = msg.indexOf(':', 6);
        int secondColon = msg.indexOf(':', firstColon + 1);

        if (firstColon > 0 && secondColon > 0) {
          wsUploadFileName = msg.substring(6, firstColon);
          wsUploadSize = msg.substring(firstColon + 1, secondColon).toInt();
          wsUploadPath = msg.substring(secondColon + 1);
          wsUploadReceived = 0;
          wsUploadStartTime = millis();

          // Ensure path is valid
          if (!wsUploadPath.startsWith("/")) wsUploadPath = "/" + wsUploadPath;
          if (wsUploadPath.length() > 1 && wsUploadPath.endsWith("/")) {
            wsUploadPath = wsUploadPath.substring(0, wsUploadPath.length() - 1);
          }

          // Build file path
          String filePath = wsUploadPath;
          if (!filePath.endsWith("/")) filePath += "/";
          filePath += wsUploadFileName;

          Serial.printf("[%lu] [WS] Starting upload: %s (%d bytes) to %s\n", millis(), wsUploadFileName.c_str(),
                        wsUploadSize, filePath.c_str());

          // Check if file exists and remove it
          esp_task_wdt_reset();
          if (SdMan.exists(filePath.c_str())) {
            SdMan.remove(filePath.c_str());
          }

          // Open file for writing
          esp_task_wdt_reset();
          if (!SdMan.openFileForWrite("WS", filePath, wsUploadFile)) {
            wsServer->sendTXT(num, "ERROR:Failed to create file");
            wsUploadInProgress = false;
            return;
          }
          esp_task_wdt_reset();

          wsUploadInProgress = true;
          wsServer->sendTXT(num, "READY");
        } else {
          wsServer->sendTXT(num, "ERROR:Invalid START format");
        }
      }
      break;
    }

    case WStype_BIN: {
      if (!wsUploadInProgress || !wsUploadFile) {
        wsServer->sendTXT(num, "ERROR:No upload in progress");
        return;
      }

      // Write binary data directly to file
      esp_task_wdt_reset();
      size_t written = wsUploadFile.write(payload, length);
      esp_task_wdt_reset();

      if (written != length) {
        wsUploadFile.close();
        wsUploadInProgress = false;
        wsServer->sendTXT(num, "ERROR:Write failed - disk full?");
        return;
      }

      wsUploadReceived += written;

      // Send progress update (every 64KB or at end)
      static size_t lastProgressSent = 0;
      if (wsUploadReceived - lastProgressSent >= 65536 || wsUploadReceived >= wsUploadSize) {
        String progress = "PROGRESS:" + String(wsUploadReceived) + ":" + String(wsUploadSize);
        wsServer->sendTXT(num, progress);
        lastProgressSent = wsUploadReceived;
      }

      // Check if upload complete
      if (wsUploadReceived >= wsUploadSize) {
        wsUploadFile.close();
        wsUploadInProgress = false;

        unsigned long elapsed = millis() - wsUploadStartTime;
        float kbps = (elapsed > 0) ? (wsUploadSize / 1024.0) / (elapsed / 1000.0) : 0;

        Serial.printf("[%lu] [WS] Upload complete: %s (%d bytes in %lu ms, %.1f KB/s)\n", millis(),
                      wsUploadFileName.c_str(), wsUploadSize, elapsed, kbps);

        wsServer->sendTXT(num, "DONE");
        lastProgressSent = 0;
      }
      break;
    }

    default:
      break;
  }
}