/*
    * Copyright 2016-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.hardware.platform.linux;
   
   import static oshi.software.os.linux.LinuxOperatingSystem.HAS_UDEV;
   
   import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.jna.platform.linux.Udev;
  import com.sun.jna.platform.linux.Udev.UdevDevice;
  import com.sun.jna.platform.linux.Udev.UdevEnumerate;
  import com.sun.jna.platform.linux.Udev.UdevListEntry;
  
  import oshi.annotation.concurrent.Immutable;
  import oshi.hardware.UsbDevice;
  import oshi.hardware.common.AbstractUsbDevice;
  
  /**
   * Linux Usb Device
   */
  @Immutable
  public class LinuxUsbDevice extends AbstractUsbDevice {
  
      private static final Logger LOG = LoggerFactory.getLogger(LinuxUsbDevice.class);
  
      private static final String SUBSYSTEM_USB = "usb";
      private static final String DEVTYPE_USB_DEVICE = "usb_device";
      private static final String ATTR_PRODUCT = "product";
      private static final String ATTR_MANUFACTURER = "manufacturer";
      private static final String ATTR_VENDOR_ID = "idVendor";
      private static final String ATTR_PRODUCT_ID = "idProduct";
      private static final String ATTR_SERIAL = "serial";
  
      public LinuxUsbDevice(String name, String vendor, String vendorId, String productId, String serialNumber,
              String uniqueDeviceId, List<UsbDevice> connectedDevices) {
          super(name, vendor, vendorId, productId, serialNumber, uniqueDeviceId, connectedDevices);
      }
  
      /**
       * Instantiates a list of {@link oshi.hardware.UsbDevice} objects, representing devices connected via a usb port
       * (including internal devices).
       * <p>
       * If the value of {@code tree} is true, the top level devices returned from this method are the USB Controllers;
       * connected hubs and devices in its device tree share that controller's bandwidth. If the value of {@code tree} is
       * false, USB devices (not controllers) are listed in a single flat list.
       *
       * @param tree If true, returns a list of controllers, which requires recursive iteration of connected devices. If
       *             false, returns a flat list of devices excluding controllers.
       * @return a list of {@link oshi.hardware.UsbDevice} objects.
       */
      public static List<UsbDevice> getUsbDevices(boolean tree) {
          List<UsbDevice> devices = getUsbDevices();
          if (tree) {
              return devices;
          }
          List<UsbDevice> deviceList = new ArrayList<>();
          // Top level is controllers; they won't be added to the list, but all
          // their connected devices will be
          for (UsbDevice device : devices) {
              deviceList.add(new LinuxUsbDevice(device.getName(), device.getVendor(), device.getVendorId(),
                      device.getProductId(), device.getSerialNumber(), device.getUniqueDeviceId(),
                      Collections.emptyList()));
              addDevicesToList(deviceList, device.getConnectedDevices());
          }
          return deviceList;
      }
  
      private static List<UsbDevice> getUsbDevices() {
          if (!HAS_UDEV) {
              LOG.warn("USB Device information requires libudev, which is not present.");
              return Collections.emptyList();
          }
          // Build a list of devices with no parent; these will be the roots
          List<String> usbControllers = new ArrayList<>();
  
          // Maps to store information using device syspath as the key
          Map<String, String> nameMap = new HashMap<>();
          Map<String, String> vendorMap = new HashMap<>();
          Map<String, String> vendorIdMap = new HashMap<>();
          Map<String, String> productIdMap = new HashMap<>();
          Map<String, String> serialMap = new HashMap<>();
          Map<String, List<String>> hubMap = new HashMap<>();
  
          // Enumerate all usb devices and build information maps
          Udev.UdevContext udev = Udev.INSTANCE.udev_new();
          try {
              UdevEnumerate enumerate = udev.enumerateNew();
              try {
                  enumerate.addMatchSubsystem(SUBSYSTEM_USB);
                  enumerate.scanDevices();
 
                 // For each item enumerated, store information in the maps
                 for (UdevListEntry entry = enumerate.getListEntry(); entry != null; entry = entry.getNext()) {
                     String syspath = entry.getName();
                     UdevDevice device = udev.deviceNewFromSyspath(syspath);
                     if (device != null) {
                         try {
                             // Only include usb_device devtype, skipping usb_interface
                             if (DEVTYPE_USB_DEVICE.equals(device.getDevtype())) {
                                 String value = device.getSysattrValue(ATTR_PRODUCT);
                                 if (value != null) {
                                     nameMap.put(syspath, value);
                                 }
                                 value = device.getSysattrValue(ATTR_MANUFACTURER);
                                 if (value != null) {
                                     vendorMap.put(syspath, value);
                                 }
                                 value = device.getSysattrValue(ATTR_VENDOR_ID);
                                 if (value != null) {
                                     vendorIdMap.put(syspath, value);
                                 }
                                 value = device.getSysattrValue(ATTR_PRODUCT_ID);
                                 if (value != null) {
                                     productIdMap.put(syspath, value);
                                 }
                                 value = device.getSysattrValue(ATTR_SERIAL);
                                 if (value != null) {
                                     serialMap.put(syspath, value);
                                 }
 
                                 UdevDevice parent = device.getParentWithSubsystemDevtype(SUBSYSTEM_USB,
                                         DEVTYPE_USB_DEVICE);
                                 if (parent == null) {
                                     // This is a controller with no parent, add to list
                                     usbControllers.add(syspath);
                                 } else {
                                     // Add child syspath to parent's path
                                     String parentPath = parent.getSyspath();
                                     hubMap.computeIfAbsent(parentPath, x -> new ArrayList<>()).add(syspath);
                                 }
                             }
                         } finally {
                             device.unref();
                         }
                     }
                 }
             } finally {
                 enumerate.unref();
             }
         } finally {
             udev.unref();
         }
 
         // Build tree and return
         List<UsbDevice> controllerDevices = new ArrayList<>();
         for (String controller : usbControllers) {
             controllerDevices.add(getDeviceAndChildren(controller, "0000", "0000", nameMap, vendorMap, vendorIdMap,
                     productIdMap, serialMap, hubMap));
         }
         return controllerDevices;
     }
 
     private static void addDevicesToList(List<UsbDevice> deviceList, List<UsbDevice> list) {
         for (UsbDevice device : list) {
             deviceList.add(device);
             addDevicesToList(deviceList, device.getConnectedDevices());
         }
     }
 
     /**
      * Recursively creates LinuxUsbDevices by fetching information from maps to populate fields
      *
      * @param devPath      The device node path.
      * @param vid          The default (parent) vendor ID
      * @param pid          The default (parent) product ID
      * @param nameMap      the map of names
      * @param vendorMap    the map of vendors
      * @param vendorIdMap  the map of vendorIds
      * @param productIdMap the map of productIds
      * @param serialMap    the map of serial numbers
      * @param hubMap       the map of hubs
      * @return A LinuxUsbDevice corresponding to this device
      */
     private static LinuxUsbDevice getDeviceAndChildren(String devPath, String vid, String pid,
             Map<String, String> nameMap, Map<String, String> vendorMap, Map<String, String> vendorIdMap,
             Map<String, String> productIdMap, Map<String, String> serialMap, Map<String, List<String>> hubMap) {
         String vendorId = vendorIdMap.getOrDefault(devPath, vid);
         String productId = productIdMap.getOrDefault(devPath, pid);
         List<String> childPaths = hubMap.getOrDefault(devPath, new ArrayList<>());
         List<UsbDevice> usbDevices = new ArrayList<>();
         for (String path : childPaths) {
             usbDevices.add(getDeviceAndChildren(path, vendorId, productId, nameMap, vendorMap, vendorIdMap,
                     productIdMap, serialMap, hubMap));
         }
         Collections.sort(usbDevices);
         return new LinuxUsbDevice(nameMap.getOrDefault(devPath, vendorId + ":" + productId),
                 vendorMap.getOrDefault(devPath, ""), vendorId, productId, serialMap.getOrDefault(devPath, ""), devPath,
                 usbDevices);
     }
 }