/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2016. All Rights Reserved.                             */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

#include "SerialHelper.h"

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <regex>

#include "HAL/Errors.h"
#include "llvm/StringRef.h"
#include "visa/visa.h"

constexpr const char* OnboardResource = "ASRL1::INSTR";
constexpr const char* MxpResource = "ASRL2::INSTR";

namespace hal {
std::string SerialHelper::m_usbNames[2]{"", ""};

priority_mutex SerialHelper::m_nameMutex;

SerialHelper::SerialHelper(int32_t resourceHandle)
    : m_resourceHandle(resourceHandle) {}

std::string SerialHelper::GetSerialPortName(HAL_SerialPort port,
                                            int32_t* status) {
  if (port == HAL_SerialPort::HAL_SerialPort_Onboard) {
    return OnboardResource;
  } else if (port == HAL_SerialPort::HAL_SerialPort_MXP) {
    return MxpResource;
  }

  QueryHubPaths(status);

  // If paths are empty or status error, return error
  if (*status != 0 || m_visaResource.empty() || m_osResource.empty() ||
      m_sortedHubPath.empty()) {
    *status = HAL_SERIAL_PORT_NOT_FOUND;
    return "";
  }

  // Hold lock whenever we're using the names array
  std::lock_guard<priority_mutex> lock(m_nameMutex);

  std::string portString = m_usbNames[port - 2];

  llvm::SmallVector<int32_t, 4> indices;

  // If port has not been assigned, find the one to assign
  if (portString.empty()) {
    for (size_t i = 0; i < 2; i++) {
      // Remove all used ports
      auto idx = std::find(m_sortedHubPath.begin(), m_sortedHubPath.end(),
                           m_usbNames[i]);
      if (idx != m_sortedHubPath.end()) {
        // found
        m_sortedHubPath.erase(idx);
      }
      if (m_usbNames[i] == "") {
        indices.push_back(i);
      }
    }

    int32_t idx = -1;
    for (size_t i = 0; i < indices.size(); i++) {
      if (indices[i] == port - 2) {
        idx = i;
        break;
      }
    }

    if (idx == -1) {
      *status = HAL_SERIAL_PORT_NOT_FOUND;
      return "";
    }

    if (idx >= static_cast<int32_t>(m_sortedHubPath.size())) {
      *status = HAL_SERIAL_PORT_NOT_FOUND;
      return "";
    }

    portString = m_sortedHubPath[idx].str();
    m_usbNames[port - 2] = portString;
  }

  int visaIndex = -1;

  for (size_t i = 0; i < m_sortedHubPath.size(); i++) {
    if (m_sortedHubPath[i].equals(portString)) {
      visaIndex = i;
      break;
    }
  }

  if (visaIndex == -1) {
    *status = HAL_SERIAL_PORT_NOT_FOUND;
    return "";
    // Error
  } else {
    return m_visaResource[visaIndex].str();
  }
}

void SerialHelper::SortHubPathVector() {
  m_sortedHubPath.clear();
  m_sortedHubPath = m_unsortedHubPath;
  std::sort(m_sortedHubPath.begin(), m_sortedHubPath.end(),
            [](llvm::SmallVectorImpl<char>& lhs,
               llvm::SmallVectorImpl<char>& rhs) -> int {
              llvm::StringRef lhsRef(lhs.begin(), lhs.size());
              llvm::StringRef rhsRef(rhs.begin(), rhs.size());
              return lhsRef.compare(rhsRef);
            });
}

void SerialHelper::CoiteratedSort(
    llvm::SmallVectorImpl<llvm::SmallString<16>>& vec) {
  llvm::SmallVector<llvm::SmallString<16>, 4> sortedVec;
  for (auto& str : m_sortedHubPath) {
    for (size_t i = 0; i < m_unsortedHubPath.size(); i++) {
      if (llvm::StringRef{m_unsortedHubPath[i].begin(),
                          m_unsortedHubPath[i].size()}
              .equals(llvm::StringRef{str.begin(), str.size()})) {
        sortedVec.push_back(vec[i]);
        break;
      }
    }
  }
  vec = sortedVec;
}

void SerialHelper::QueryHubPaths(int32_t* status) {
  // VISA resource matching string
  const char* str = "?*";
  // Items needed for VISA
  ViUInt32 retCnt = 0;
  ViFindList viList = 0;
  ViChar desc[VI_FIND_BUFLEN];
  *status = viFindRsrc(m_resourceHandle, const_cast<char*>(str), &viList,
                       &retCnt, desc);

  if (*status < 0) {
    // Handle the bad status elsewhere
    // Note let positive statii (warnings) continue
    return;
  }
  // Status might be positive, so reset it to 0
  *status = 0;

  // Storage buffers for Visa calls and system exec calls
  char osName[256];
  char execBuffer[128];

  // Regex to filter out the device name
  // Will be index 1 on success
  std::regex devMatch("[^\\s]+\\s+\\(\\/dev\\/([^\\s]+)\\)");

  // Loop through all returned VISA objects.
  // Increment the internal VISA ptr every loop
  for (size_t i = 0; i < retCnt; i++, viFindNext(viList, desc)) {
    // Ignore any matches to the 2 onboard ports
    if (std::strcmp(OnboardResource, desc) == 0 ||
        std::strcmp(MxpResource, desc) == 0) {
      continue;
    }

    // Open the resource, grab its interface name, and close it.
    ViSession vSession;
    *status = viOpen(m_resourceHandle, desc, VI_NULL, VI_NULL, &vSession);
    if (*status < 0) return;
    *status = 0;

    *status = viGetAttribute(vSession, VI_ATTR_INTF_INST_NAME, &osName);
    // Ignore an error here, as we want to close the session on an error
    // Use a seperate close variable so we can check
    ViStatus closeStatus = viClose(vSession);
    if (*status < 0) return;
    if (closeStatus < 0) return;
    *status = 0;

    std::smatch regexMatcher;
    auto regexVal =
        std::regex_match(std::string(osName), regexMatcher, devMatch);

    if (regexVal > 0 && regexMatcher.size() > 1) {
      // Store our match string, as output was ocassionally being corrupted
      // before being accessed
      auto matchString = regexMatcher[1].str();

      // Run find using pipe to get a list of system accessors
      llvm::SmallString<128> val(
          "sh -c \"find /sys/devices/soc0 | grep amba | grep usb | grep ");
      val += matchString;
      val += "\"";

      // Pipe code found on StackOverflow
      // http://stackoverflow.com/questions/478898/how-to-execute-a-command-and-get-output-of-command-within-c-using-posix

      // Using std::string because this is guarenteed to be large
      std::string output = "";

      std::shared_ptr<FILE> pipe(popen(val.c_str(), "r"), pclose);
      // Just check the next item on a pipe failure
      if (!pipe) continue;
      while (!feof(pipe.get())) {
        if (std::fgets(execBuffer, 128, pipe.get()) != 0) output += execBuffer;
      }

      if (!output.empty()) {
        llvm::SmallVector<llvm::StringRef, 16> pathSplitVec;
        // Split output by line, grab first line, and split it into
        // individual directories
        llvm::StringRef{output}.split('\n').first.split(pathSplitVec, '/', -1,
                                                        false);

        // Find each individual item index

        const char* usb1 = "usb1";
        const char* tty = "tty";

        int findusb = -1;
        int findtty = -1;
        int findregex = -1;
        for (size_t i = 0; i < pathSplitVec.size(); i++) {
          if (findusb == -1 && pathSplitVec[i].equals(usb1)) {
            findusb = i;
          }
          if (findtty == -1 && pathSplitVec[i].equals(tty)) {
            findtty = i;
          }
          if (findregex == -1 && pathSplitVec[i].equals(matchString)) {
            findregex = i;
          }
        }

        // Get the index for our device
        int hubIndex = findtty;
        if (findtty == -1) hubIndex = findregex;

        int devStart = findusb + 1;

        if (hubIndex < devStart) continue;

        // Add our devices to our list
        m_unsortedHubPath.push_back(
            llvm::StringRef{pathSplitVec[hubIndex - 2]});
        m_visaResource.push_back(llvm::StringRef{desc});
        m_osResource.push_back(llvm::StringRef{matchString});
      }
    }
  }

  SortHubPathVector();

  CoiteratedSort(m_visaResource);
  CoiteratedSort(m_osResource);
}
}  // namespace hal