FrameworkGUIDevicesGraph.cxx

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
#include "FrameworkGUIDevicesGraph.h"
#include "FrameworkGUIDataRelayerUsage.h"
#include "FrameworkGUIState.h"
#include "PaletteHelpers.h"
#include "Framework/DeviceSpec.h"
#include "Framework/DeviceInfo.h"
#include "Framework/LogParsingHelpers.h"
#include "Framework/Logger.h"
#include "FrameworkGUIDeviceInspector.h"
#include "Framework/Logger.h"
#include "../src/WorkflowHelpers.h"
#include "DebugGUI/imgui.h"
#include <DebugGUI/icons_font_awesome.h>
#include <algorithm>
#include <cmath>
#include <fstream>
#include <iomanip>
#include <sstream>
#include <string>
#include <string_view>
#include <vector>
 
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
static inline ImVec2 operator+(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x + rhs.x, lhs.y + rhs.y); }
static inline ImVec2 operator-(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x - rhs.x, lhs.y - rhs.y); }
static inline ImVec2 operator*(const ImVec2& lhs, float rhs) { return ImVec2(lhs.x * rhs, lhs.y * rhs); }
static inline ImVec2 operator/(const ImVec2& lhs, float rhs) { return ImVec2(lhs.x / rhs, lhs.y / rhs); }
 
namespace o2::framework::gui
{
struct NodeColor {
  ImVec4 normal;
  ImVec4 hovered;
  ImVec4 title;
  ImVec4 title_hovered;
};
 
using LogLevel = LogParsingHelpers::LogLevel;
 
NodeColor decideColorForNode(const DeviceInfo& info, bool lightMode)
{
  if (lightMode) {
    // Dark-on-bright: rich medium-dark cards on a white canvas, white text on nodes
    if (info.active == false) {
      return NodeColor{
        .normal = ImVec4(0xb5 / 255.f, 0x26 / 255.f, 0x18 / 255.f, 1), // dark crimson
        .hovered = ImVec4(0xc2 / 255.f, 0x2d / 255.f, 0x1d / 255.f, 1)};
    }
    switch (info.streamingState) {
      case StreamingState::EndOfStreaming:
        return NodeColor{
          .normal = ImVec4(0x8c / 255.f, 0x6c / 255.f, 0x00 / 255.f, 1), // dark amber
          .hovered = ImVec4(0x9e / 255.f, 0x7a / 255.f, 0x00 / 255.f, 1),
          .title = ImVec4(0x6e / 255.f, 0x54 / 255.f, 0x00 / 255.f, 1),
          .title_hovered = ImVec4(0x5a / 255.f, 0x44 / 255.f, 0x00 / 255.f, 1)};
      case StreamingState::Idle:
        return NodeColor{
          .normal = ImVec4(0x1a / 255.f, 0x80 / 255.f, 0x40 / 255.f, 1), // dark forest green
          .hovered = ImVec4(0x22 / 255.f, 0x8b / 255.f, 0x47 / 255.f, 1),
          .title = ImVec4(0x11 / 255.f, 0x60 / 255.f, 0x2e / 255.f, 1),
          .title_hovered = ImVec4(0x0a / 255.f, 0x4d / 255.f, 0x23 / 255.f, 1)};
      case StreamingState::Streaming:
      default:
        return NodeColor{
          .normal = ImVec4(0x3a / 255.f, 0x3a / 255.f, 0x3c / 255.f, 1), // macOS tertiary dark
          .hovered = ImVec4(0x48 / 255.f, 0x48 / 255.f, 0x4a / 255.f, 1),
          .title = ImVec4(0x2c / 255.f, 0x2c / 255.f, 0x2e / 255.f, 1),
          .title_hovered = ImVec4(0x1c / 255.f, 0x1c / 255.f, 0x1e / 255.f, 1)};
    }
  }
  if (info.active == false) {
    return NodeColor{
      .normal = PaletteHelpers::RED,
      .hovered = PaletteHelpers::SHADED_RED};
  }
  switch (info.streamingState) {
    case StreamingState::EndOfStreaming:
      return NodeColor{
        .normal = PaletteHelpers::SHADED_YELLOW,
        .hovered = PaletteHelpers::YELLOW,
        .title = PaletteHelpers::YELLOW,
        .title_hovered = PaletteHelpers::DARK_YELLOW};
    case StreamingState::Idle:
      return NodeColor{
        .normal = PaletteHelpers::SHADED_GREEN,
        .hovered = PaletteHelpers::GREEN,
        .title = PaletteHelpers::GREEN,
        .title_hovered = PaletteHelpers::DARK_GREEN};
    case StreamingState::Streaming:
    default:
      return NodeColor{
        .normal = PaletteHelpers::GRAY,
        .hovered = PaletteHelpers::LIGHT_GRAY,
        .title = PaletteHelpers::GRAY,
        .title_hovered = PaletteHelpers::BLACK};
  }
}
 
const static ImColor INPUT_SLOT_COLOR = {150, 150, 150, 150};
const static ImColor OUTPUT_SLOT_COLOR = {150, 150, 150, 150};
const static ImColor NODE_LABEL_BACKGROUND_COLOR = {45, 45, 45, 255};
const static ImColor NODE_LABEL_TEXT_COLOR = {244, 244, 244, 255};
const static ImVec4& ERROR_MESSAGE_COLOR = PaletteHelpers::RED;
const static ImVec4& WARNING_MESSAGE_COLOR = PaletteHelpers::YELLOW;
const static ImColor ARROW_BACKGROUND_COLOR = {100, 100, 0};
const static ImColor ARROW_HALFGROUND_COLOR = {170, 170, 70};
const static ImColor ARROW_COLOR = {200, 200, 100};
const static ImColor ARROW_SELECTED_COLOR = {200, 0, 100};
const static ImU32 GRID_COLOR = ImColor(150, 150, 150, 80);
const static ImColor NODE_BORDER_COLOR = {100, 100, 100};
const static ImColor LEGEND_COLOR = {100, 100, 100};
 
const static float GRID_SZ = 64.0f;
const static float ARROW_BACKGROUND_THICKNESS = 1.f;
const static float ARROW_HALFGROUND_THICKNESS = 2.f;
const static float ARROW_THICKNESS = 3.f;
const static float NODE_BORDER_THICKNESS = 4.f;
const static ImVec4 LEGEND_BACKGROUND_COLOR = {0.125, 0.180, 0.196, 1};
 
const static ImVec4 SLOT_EMPTY_COLOR = {0.275, 0.275, 0.275, 1.};
const static ImVec4& SLOT_PENDING_COLOR = PaletteHelpers::RED;
const static ImVec4& SLOT_DISPATCHED_COLOR = PaletteHelpers::YELLOW;
const static ImVec4& SLOT_DONE_COLOR = PaletteHelpers::GREEN;
 
const float NODE_SLOT_RADIUS = 4.0f;
const ImVec2 NODE_WINDOW_PADDING(8.0f, 8.0f);
 
float clampZoom(float zoom)
{
  return std::clamp(zoom, 0.15f, 2.50f);
}
 
ImVec2 graphToScreen(ImVec2 graphPos, ImVec2 canvasOrigin, ImVec2 scrolling, float zoom)
{
  return canvasOrigin + (graphPos - scrolling) * zoom;
}
 
void displayGrid(bool show_grid, ImVec2 scrolling, float zoom, ImDrawList* draw_list)
{
  if (show_grid == false) {
    return;
  }
  ImVec2 win_pos = ImGui::GetCursorScreenPos();
  ImVec2 canvas_sz = ImGui::GetWindowSize();
  float gridSize = GRID_SZ * zoom;
  for (float x = fmodf(-scrolling.x * zoom, gridSize); x < canvas_sz.x; x += gridSize) {
    draw_list->AddLine(ImVec2(x, 0.0f) + win_pos, ImVec2(x, canvas_sz.y) + win_pos, GRID_COLOR);
  }
  for (float y = fmodf(-scrolling.y * zoom, gridSize); y < canvas_sz.y; y += gridSize) {
    draw_list->AddLine(ImVec2(0.0f, y) + win_pos, ImVec2(canvas_sz.x, y) + win_pos, GRID_COLOR);
  }
}
 
void displayLegend(bool show_legend, ImVec2 offset, ImDrawList* draw_list)
{
  if (show_legend == false) {
    return;
  }
  struct LegendItem {
    std::string label;
    const ImVec4& color;
  };
  static auto legend = {
    LegendItem{"   Slot empty", SLOT_EMPTY_COLOR},
    LegendItem{"   Slot pending", SLOT_PENDING_COLOR},
    LegendItem{"   Slot dispatched", SLOT_DISPATCHED_COLOR},
    LegendItem{"   Slot done", SLOT_DONE_COLOR},
  };
  ImGui::PushStyleColor(ImGuiCol_WindowBg, LEGEND_BACKGROUND_COLOR);
  ImGui::PushStyleColor(ImGuiCol_TitleBg, LEGEND_BACKGROUND_COLOR);
  ImGui::PushStyleColor(ImGuiCol_ResizeGrip, 0);
 
  ImGui::Begin("Legend");
  ImGui::Dummy(ImVec2(0.0f, 10.0f));
  for (auto [label, color] : legend) {
    ImVec2 vMin = ImGui::GetWindowPos() + ImGui::GetCursorPos() + ImVec2(9, 0);
    ImVec2 vMax = vMin + ImGui::CalcTextSize(" ");
    ImGui::PushStyleColor(ImGuiCol_ChildBg, color);
    ImGui::GetWindowDrawList()->AddRectFilled(vMin, vMax, ImColor(color));
    ImGui::GetWindowDrawList()->AddRect(vMin, vMax, GRID_COLOR);
    ImGui::Text("%s", label.data());
    ImGui::PopStyleColor();
  }
  ImGui::End();
  ImGui::PopStyleColor(3);
}
 
#define MAX_GROUP_NAME_SIZE 128
 
// Private helper struct to keep track of node groups
struct Group {
  int ID;
  char name[MAX_GROUP_NAME_SIZE];
  size_t metadataId;
  Group(int id, char const* n, size_t mid)
  {
    ID = id;
    strncpy(name, n, MAX_GROUP_NAME_SIZE);
    name[MAX_GROUP_NAME_SIZE - 1] = 0;
    metadataId = mid;
  }
};
 
constexpr int MAX_SLOTS = 512;
constexpr int MAX_INPUT_VALUE_SIZE = 24;
 
struct OldestPossibleInput {
  size_t value;
  char buffer[MAX_INPUT_VALUE_SIZE] = "unknown";
  float textSize = ImGui::CalcTextSize("unknown").x;
};
 
struct OldestPossibleOutput {
  size_t value;
  char buffer[MAX_INPUT_VALUE_SIZE] = "unknown";
  float textSize = ImGui::CalcTextSize("unknown").x;
};
 
// Private helper struct for the graph model
struct Node {
  int ID;
  int GroupID;
  char Name[64];
  ImVec2 Size;
  float Value;
  ImVec4 Color;
  int InputsCount, OutputsCount;
  OldestPossibleInput oldestPossibleInput[MAX_SLOTS];
  OldestPossibleOutput oldestPossibleOutput[MAX_SLOTS];
 
  Node(int id, int groupID, char const* name, float value, const ImVec4& color, int inputs_count, int outputs_count)
  {
    ID = id;
    GroupID = groupID;
    strncpy(Name, name, 63);
    Name[63] = 0;
    Size = ImVec2(150.f, 128.f);
    Value = value;
    Color = color;
    InputsCount = inputs_count;
    OutputsCount = outputs_count;
  }
};
 
// Private helper struct for the layout of the graph
struct NodePos {
  ImVec2 pos;
  static ImVec2 GetInputSlotPos(ImVector<Node> const& infos, ImVector<NodePos> const& positions, int nodeId, int slot_no)
  {
    ImVec2 const& pos = positions[nodeId].pos;
    ImVec2 const& size = infos[nodeId].Size;
    float inputsCount = infos[nodeId].InputsCount;
    return ImVec2(pos.x, pos.y + size.y * ((float)slot_no + 1) / (inputsCount + 1));
  }
  static ImVec2 GetOutputSlotPos(ImVector<Node> const& infos, ImVector<NodePos> const& positions, int nodeId, int slot_no)
  {
    ImVec2 const& pos = positions[nodeId].pos;
    ImVec2 const& size = infos[nodeId].Size;
    float outputsCount = infos[nodeId].OutputsCount;
    return ImVec2(pos.x + size.x, pos.y + size.y * ((float)slot_no + 1) / (outputsCount + 1));
  }
};
 
// Private helper struct for the edges in the graph
struct NodeLink {
  int InputIdx, InputSlot, OutputIdx, OutputSlot;
 
  NodeLink(int input_idx, int input_slot, int output_idx, int output_slot)
  {
    InputIdx = input_idx;
    InputSlot = input_slot;
    OutputIdx = output_idx;
    OutputSlot = output_slot;
  }
};
 
std::string xmlEscape(const char* text)
{
  std::string result;
  for (char c : std::string_view{text}) {
    switch (c) {
      case '&':
        result += "&amp;";
        break;
      case '<':
        result += "&lt;";
        break;
      case '>':
        result += "&gt;";
        break;
      case '"':
        result += "&quot;";
        break;
      case '\'':
        result += "&apos;";
        break;
      default:
        result += c;
        break;
    }
  }
  return result;
}
 
std::string dotEscape(const char* text)
{
  std::string result;
  for (char c : std::string_view{text}) {
    if (c == '"' || c == '\\') {
      result += '\\';
    }
    result += c;
  }
  return result;
}
 
std::string colorToHex(ImVec4 color)
{
  auto component = [](float value) {
    return std::clamp(static_cast<int>(std::round(value * 255.f)), 0, 255);
  };
  std::ostringstream out;
  out << "#" << std::hex << std::setfill('0') << std::setw(2) << component(color.x)
      << std::setw(2) << component(color.y)
      << std::setw(2) << component(color.z);
  return out.str();
}
 
bool topologyBounds(ImVector<Node> const& nodes, ImVector<NodePos> const& positions, ImVec2& minPos, ImVec2& maxPos)
{
  if (nodes.Size == 0 || positions.Size == 0) {
    return false;
  }
  minPos = positions[0].pos;
  maxPos = positions[0].pos + nodes[0].Size;
  for (int i = 1; i < nodes.Size; ++i) {
    minPos.x = std::min(minPos.x, positions[i].pos.x);
    minPos.y = std::min(minPos.y, positions[i].pos.y);
    maxPos.x = std::max(maxPos.x, positions[i].pos.x + nodes[i].Size.x);
    maxPos.y = std::max(maxPos.y, positions[i].pos.y + nodes[i].Size.y);
  }
  return true;
}
 
bool exportTopologySVG(const char* filename,
                       ImVector<Node> const& nodes,
                       ImVector<NodePos> const& positions,
                       ImVector<NodeLink> const& links,
                       std::vector<DeviceInfo> const& infos,
                       bool lightMode)
{
  ImVec2 minPos;
  ImVec2 maxPos;
  if (!topologyBounds(nodes, positions, minPos, maxPos)) {
    return false;
  }
  constexpr float MARGIN = 80.f;
  auto toSVG = [minPos](ImVec2 p) {
    return p - minPos + ImVec2(80.f, 80.f);
  };
  ImVec2 canvasSize = maxPos - minPos + ImVec2(2.f * MARGIN, 2.f * MARGIN);
 
  std::ofstream out(filename);
  if (!out.is_open()) {
    return false;
  }
  out << std::fixed << std::setprecision(2);
  out << R"(<?xml version="1.0" encoding="UTF-8"?>)" << "\n";
  out << R"(<svg xmlns="http://www.w3.org/2000/svg" width=")" << canvasSize.x << "\" height=\"" << canvasSize.y
      << "\" viewBox=\"0 0 " << canvasSize.x << " " << canvasSize.y << "\">\n";
  out << "  <defs>\n";
  out << "    <marker id=\"arrow\" viewBox=\"0 0 10 10\" refX=\"9\" refY=\"5\" markerWidth=\"6\" markerHeight=\"6\" orient=\"auto-start-reverse\">\n";
  out << "      <path d=\"M 0 0 L 10 5 L 0 10 z\" fill=\"#c8c864\"/>\n";
  out << "    </marker>\n";
  out << "  </defs>\n";
  out << R"(  <rect width="100%" height="100%" fill=")" << (lightMode ? "#fafafc" : "#2c2c2e") << "\"/>\n";
  out << "  <g id=\"links\" fill=\"none\" stroke=\"#c8c864\" stroke-width=\"3\" marker-end=\"url(#arrow)\">\n";
  for (int i = 0; i < links.Size; ++i) {
    auto const& link = links[i];
    ImVec2 p1 = toSVG(NodePos::GetOutputSlotPos(nodes, positions, link.InputIdx, link.InputSlot));
    ImVec2 p2 = toSVG(NodePos::GetInputSlotPos(nodes, positions, link.OutputIdx, link.OutputSlot) + ImVec2(-3 * NODE_SLOT_RADIUS, 0));
    out << "    <path id=\"edge-" << i << "\" d=\"M " << p1.x << " " << p1.y
        << " C " << p1.x + 50.f << " " << p1.y << ", " << p2.x - 50.f << " " << p2.y
        << ", " << p2.x << " " << p2.y << "\"/>\n";
  }
  out << "  </g>\n";
  out << "  <g id=\"nodes\" font-family=\"sans-serif\" font-size=\"13\" fill=\"#f4f4f4\">\n";
  for (int i = 0; i < nodes.Size; ++i) {
    auto const& node = nodes[i];
    if (i >= infos.size()) {
      continue;
    }
    auto const& info = infos[i];
    auto colors = decideColorForNode(info, lightMode);
    auto titleColor = colors.title.w == 0.f ? colors.normal : colors.title;
    ImVec2 p = toSVG(positions[i].pos);
    out << "    <g id=\"node-" << i << "\" data-label=\"" << xmlEscape(node.Name) << "\">\n";
    out << "      <rect x=\"" << p.x + 3.f << "\" y=\"" << p.y + 3.f << "\" width=\"" << node.Size.x
        << "\" height=\"" << node.Size.y << "\" rx=\"4\" fill=\"#000000\" opacity=\"0.28\"/>\n";
    out << "      <rect x=\"" << p.x << "\" y=\"" << p.y << "\" width=\"" << node.Size.x
        << "\" height=\"" << node.Size.y << R"(" rx="4" fill=")" << colorToHex(colors.normal)
        << "\" stroke=\"#646464\" stroke-width=\"4\"/>\n";
    out << "      <rect x=\"" << p.x << "\" y=\"" << p.y << "\" width=\"" << node.Size.x
        << R"(" height="24" rx="4" fill=")" << colorToHex(titleColor) << "\"/>\n";
    out << "      <text x=\"" << p.x + NODE_WINDOW_PADDING.x << "\" y=\"" << p.y + 17.f << "\">"
        << xmlEscape(node.Name) << "</text>\n";
    for (int slot = 0; slot < node.InputsCount; ++slot) {
      ImVec2 slotPos = toSVG(NodePos::GetInputSlotPos(nodes, positions, i, slot));
      out << "      <circle cx=\"" << slotPos.x << "\" cy=\"" << slotPos.y << "\" r=\"" << NODE_SLOT_RADIUS << "\" fill=\"#969696\" opacity=\"0.6\"/>\n";
    }
    for (int slot = 0; slot < node.OutputsCount; ++slot) {
      ImVec2 slotPos = toSVG(NodePos::GetOutputSlotPos(nodes, positions, i, slot));
      out << "      <circle cx=\"" << slotPos.x << "\" cy=\"" << slotPos.y << "\" r=\"" << NODE_SLOT_RADIUS << "\" fill=\"#969696\" opacity=\"0.6\"/>\n";
    }
    out << "    </g>\n";
  }
  out << "  </g>\n";
  out << "</svg>\n";
  return true;
}
 
bool exportTopologyDOT(const char* filename,
                       ImVector<Node> const& nodes,
                       ImVector<NodePos> const& positions,
                       ImVector<NodeLink> const& links,
                       std::vector<DeviceInfo> const& infos,
                       bool lightMode)
{
  std::ofstream out(filename);
  if (!out.is_open()) {
    return false;
  }
  out << "digraph dpl_topology {\n";
  out << "  graph [rankdir=LR, splines=curved, outputorder=edgesfirst];\n";
  out << "  node [shape=box, style=\"rounded,filled\", fontname=\"Helvetica\", fontsize=10];\n";
  out << "  edge [color=\"#c8c864\"];\n";
  for (int i = 0; i < nodes.Size; ++i) {
    if (i >= infos.size()) {
      continue;
    }
    auto colors = decideColorForNode(infos[i], lightMode);
    out << "  n" << i << " [label=\"" << dotEscape(nodes[i].Name)
        << "\", fillcolor=\"" << colorToHex(colors.normal)
        << R"(", fontcolor="white", pos=")" << positions[i].pos.x / 72.f << "," << -positions[i].pos.y / 72.f << "!\"];\n";
  }
  for (int i = 0; i < links.Size; ++i) {
    out << "  n" << links[i].InputIdx << " -> n" << links[i].OutputIdx << ";\n";
  }
  out << "}\n";
  return true;
}
 
template <typename RECORD, typename ITEM, typename CONTEXT>
struct MetricsPainter {
  using NumRecordsCallback = std::function<size_t(void)>;
  using RecordCallback = std::function<RECORD(size_t)>;
  using NumItemsCallback = std::function<size_t(RECORD const&)>;
  using ItemCallback = std::function<ITEM const&(RECORD const&, size_t)>;
  using ValueCallback = std::function<int(ITEM const&)>;
  using ColorCallback = std::function<ImU32(int value)>;
  using ContextCallback = std::function<CONTEXT&()>;
  using PaintCallback = std::function<void(int row, int column, int value, ImU32 color, CONTEXT const& context)>;
 
  static void draw(const char* name,
                   ImVec2 const& offset,
                   ImVec2 const& sizeHint,
                   CONTEXT const& context,
                   NumRecordsCallback const& getNumRecords,
                   RecordCallback const& getRecord,
                   NumItemsCallback const& getNumItems,
                   ItemCallback const& getItem,
                   ValueCallback const& getValue,
                   ColorCallback const& getColor,
                   PaintCallback const& describeCell)
  {
    for (size_t ri = 0; ri < getNumRecords(); ++ri) {
      auto record = getRecord(ri);
      for (size_t ii = 0; ii < getNumItems(record); ++ii) {
        auto item = getItem(record, ii);
        int value = getValue(item);
        ImU32 color = getColor(value);
        ImVec2 pos = ImGui::GetCursorScreenPos();
        describeCell(ri, ii, value, color, context);
      }
    }
  }
 
  static NumRecordsCallback metric1D()
  {
    return []() -> size_t { return 1UL; };
  }
 
  static NumRecordsCallback metric2D(Metric2DViewIndex& viewIndex)
  {
    return [&viewIndex]() -> size_t {
      if (viewIndex.isComplete()) {
        return viewIndex.w;
      }
      return 0;
    };
  }
 
  static NumItemsCallback items1D()
  {
    return [](RECORD const& record) -> size_t { return 1UL; };
  }
 
  static NumItemsCallback items2D(Metric2DViewIndex const& viewIndex)
  {
    return [&viewIndex](int record) -> int {
      if (viewIndex.isComplete()) {
        return viewIndex.h;
      }
      return 0;
    };
  }
 
  template <typename T>
  static ItemCallback latestMetric(DeviceMetricsInfo const& metrics,
                                   Metric2DViewIndex const& viewIndex)
  {
    return [&metrics, &viewIndex](RECORD const& record, size_t i) -> ITEM const& {
      // Calculate the index in the viewIndex.
      auto idx = record * viewIndex.h + i;
      assert(viewIndex.indexes.size() > idx);
      MetricInfo const& metricInfo = metrics.metrics[viewIndex.indexes[idx]];
      auto& data = DeviceMetricsInfoHelpers::get<T, metricStorageSize<T>()>(metrics, metricInfo.storeIdx);
      return data[(metricInfo.pos - 1) % data.size()];
    };
  }
 
  template <typename T>
  static RecordCallback simpleRecord()
  {
    return [](size_t i) -> int {
      return i;
    };
  }
 
  template <typename T>
  static ValueCallback simpleValue()
  {
    return [](ITEM const& item) -> T { return item; };
  }
 
  static ColorCallback colorPalette(std::vector<ImU32> const& colors, int minValue, int maxValue)
  {
    return [colors, minValue, maxValue](int const& value) -> ImU32 {
      if (value < minValue) {
        return colors[0];
      } else if (value > maxValue) {
        return colors[colors.size() - 1];
      } else {
        int idx = (value - minValue) * (colors.size() - 1) / (maxValue - minValue);
        return colors[idx];
      }
    };
  }
};
 
struct MetricLabelsContext {
  ImVector<Node>* nodes;
  int nodeIdx;
  ImVector<NodePos>* positions;
  ImDrawList* draw_list;
  ImVec2 canvasOrigin;
  ImVec2 scrolling;
  float zoom;
};
 
void showTopologyNodeGraph(WorkspaceGUIState& state,
                           std::vector<DeviceInfo> const& infos,
                           std::vector<DeviceSpec> const& specs,
                           std::vector<DataProcessingStates> const& allStates,
                           std::vector<DataProcessorInfo> const& metadata,
                           std::vector<DeviceControl>& controls,
                           std::vector<DeviceMetricsInfo> const& metricsInfos)
{
  ImGui::SetNextWindowPos(ImVec2(0, 0), 0);
  if (state.bottomPaneVisible) {
    ImGui::SetNextWindowSize(ImVec2(ImGui::GetIO().DisplaySize.x, ImGui::GetIO().DisplaySize.y - state.bottomPaneSize), 0);
  } else {
    ImGui::SetNextWindowSize(ImVec2(ImGui::GetIO().DisplaySize.x, ImGui::GetIO().DisplaySize.y), 0);
  }
 
  ImGui::Begin("Physical topology view", nullptr, ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize);
 
  static ImVector<Node> nodes;
  static ImVector<Group> groups;
  static ImVector<NodeLink> links;
  static ImVector<NodePos> positions;
 
  static bool inited = false;
  static ImVec2 scrolling = ImVec2(0.0f, 0.0f);
  static float zoom = 1.0f;
  static bool show_grid = true;
  static bool show_legend = true;
  static int node_selected = -1;
  static char exportStatus[256] = "";
  bool fitRequested = false;
 
  auto prepareChannelView = [&specs, &metricsInfos, &metadata](ImVector<Node>& nodeList, ImVector<Group>& groupList) {
    struct LinkInfo {
      int specId;
      int outputId;
    };
    std::map<std::string, LinkInfo> linkToIndex;
    for (int si = 0; si < specs.size(); ++si) {
      int oi = 0;
      for (auto&& output : specs[si].outputChannels) {
        linkToIndex.insert(std::make_pair(output.name, LinkInfo{si, oi}));
        oi += 1;
      }
    }
    // Prepare the list of groups.
    std::string workflow = "Ungrouped";
    int groupId = 0;
    for (size_t mi = 0; mi < metadata.size(); ++mi) {
      auto const& metadatum = metadata[mi];
      if (metadatum.executable == workflow) {
        continue;
      }
      workflow = metadatum.executable;
      char* groupBasename = strrchr(workflow.data(), '/');
      char const* groupName = groupBasename ? groupBasename + 1 : workflow.data();
      bool hasDuplicate = false;
      for (size_t gi = 0; gi < groupList.Size; ++gi) {
        if (strncmp(groupName, groupList[gi].name, MAX_GROUP_NAME_SIZE - 1) == 0) {
          hasDuplicate = true;
          break;
        }
      }
      if (hasDuplicate == false) {
        groupList.push_back(Group(groupId++, groupName, mi));
      }
    }
    // Do matching between inputs and outputs
    for (int si = 0; si < specs.size(); ++si) {
      auto& spec = specs[si];
      int groupId = 0;
 
      auto metadatum = std::find_if(metadata.begin(), metadata.end(),
                                    [&name = spec.name](DataProcessorInfo const& info) { return info.name == name; });
 
      for (size_t gi = 0; gi < groupList.Size; ++gi) {
        if (metadatum == metadata.end()) {
          break;
        }
        const char* groupName = strrchr(metadatum->executable.data(), '/');
        if (strncmp(groupList[gi].name, groupName ? groupName + 1 : metadatum->executable.data(), 127) == 0) {
          groupId = gi;
          break;
        }
      }
      nodeList.push_back(Node(si, groupId, spec.id.c_str(), 0.5f,
                              ImColor(255, 100, 100),
                              spec.inputChannels.size(),
                              spec.outputChannels.size()));
      int ii = 0;
      for (auto& input : spec.inputChannels) {
        auto const& outName = input.name;
        auto const& out = linkToIndex.find(input.name);
        if (out == linkToIndex.end()) {
          LOG(error) << "Could not find suitable node for " << outName;
          continue;
        }
        links.push_back(NodeLink{out->second.specId, out->second.outputId, si, ii});
        ii += 1;
      }
    }
 
    // ImVector does boudary checks, so I bypass the case there is no
    // edges.
    std::vector<TopoIndexInfo> sortedNodes = {{0, 0}};
    if (links.size()) {
      sortedNodes = WorkflowHelpers::topologicalSort(specs.size(), &(links[0].InputIdx), &(links[0].OutputIdx), sizeof(links[0]), links.size());
    }
    // This is to protect for the cases in which there is a loop in the
    // definition of the inputs and of the outputs due to the
    // way the forwarding creates hidden dependencies between processes.
    // This should not happen, but apparently it does.
    for (auto di = 0; di < specs.size(); ++di) {
      auto fn = std::find_if(sortedNodes.begin(), sortedNodes.end(), [di](TopoIndexInfo const& info) {
        return di == info.index;
      });
      if (fn == sortedNodes.end()) {
        sortedNodes.push_back({(int)di, 0});
      }
    }
    assert(specs.size() == sortedNodes.size());
    std::sort(sortedNodes.begin(), sortedNodes.end());
 
    std::vector<int> layerEntries(1024, 0);
    std::vector<int> layerMax(1024, 0);
    for (auto& node : sortedNodes) {
      layerMax[node.layer < 1023 ? node.layer : 1023] += 1;
    }
 
    // FIXME: display nodes using topological sort
    // Update positions
    for (int si = 0; si < specs.size(); ++si) {
      auto& node = sortedNodes[si];
      assert(node.index == si);
      int xpos = 40 + 240 * node.layer;
      int ypos = 300 + (std::max(600, 60 * (int)layerMax[node.layer]) / (layerMax[node.layer] + 1)) * (layerEntries[node.layer] - layerMax[node.layer] / 2);
      positions.push_back(NodePos{ImVec2(xpos, ypos)});
      layerEntries[node.layer] += 1;
    }
  };
 
  if (!inited) {
    prepareChannelView(nodes, groups);
    inited = true;
  }
 
  // Create our child canvas
  ImGui::BeginGroup();
  ImGui::Checkbox("Show grid", &show_grid);
  ImGui::SameLine();
  ImGui::Checkbox("Show legend", &show_legend);
  ImGui::SameLine();
  ImGui::Checkbox("Light mode", &state.topologyLightMode);
  ImGui::SameLine();
  if (ImGui::Button("Center")) {
    scrolling = ImVec2(0., 0.);
    zoom = 1.0f;
  }
  ImGui::SameLine();
  if (ImGui::Button("-")) {
    zoom = clampZoom(zoom / 1.15f);
  }
  ImGui::SameLine();
  if (ImGui::Button("+")) {
    zoom = clampZoom(zoom * 1.15f);
  }
  ImGui::SameLine();
  if (ImGui::Button("Fit")) {
    fitRequested = true;
  }
  ImGui::SameLine();
  ImGui::Text("%.0f%%", zoom * 100.f);
  ImGui::SameLine();
  if (ImGui::Button("100%")) {
    zoom = 1.0f;
  }
  ImGui::SameLine();
  if (ImGui::Button("Export SVG")) {
    if (exportTopologySVG("dpl-topology.svg", nodes, positions, links, infos, state.topologyLightMode)) {
      snprintf(exportStatus, sizeof(exportStatus), "Exported dpl-topology.svg");
    } else {
      snprintf(exportStatus, sizeof(exportStatus), "Could not export dpl-topology.svg");
    }
  }
  ImGui::SameLine();
  if (ImGui::Button("Export DOT")) {
    if (exportTopologyDOT("dpl-topology.dot", nodes, positions, links, infos, state.topologyLightMode)) {
      snprintf(exportStatus, sizeof(exportStatus), "Exported dpl-topology.dot");
    } else {
      snprintf(exportStatus, sizeof(exportStatus), "Could not export dpl-topology.dot");
    }
  }
  if (exportStatus[0] != '\0') {
    ImGui::SameLine();
    ImGui::TextUnformatted(exportStatus);
  }
  ImGui::SameLine();
  if (state.leftPaneVisible == false && ImGui::Button("Show tree")) {
    state.leftPaneVisible = true;
  }
  if (state.leftPaneVisible == true && ImGui::Button("Hide tree")) {
    state.leftPaneVisible = false;
  }
  ImGui::SameLine();
  if (state.bottomPaneVisible == false && ImGui::Button("Show metrics")) {
    state.bottomPaneVisible = true;
  }
  if (state.bottomPaneVisible == true && ImGui::Button("Hide metrics")) {
    state.bottomPaneVisible = false;
  }
  ImGui::SameLine();
  if (state.rightPaneVisible == false && ImGui::Button("Show inspector")) {
    state.rightPaneVisible = true;
  }
  if (state.rightPaneVisible == true && ImGui::Button("Hide inspector")) {
    state.rightPaneVisible = false;
  }
  ImGui::Separator();
  ImGui::EndGroup();
  auto toolbarSize = ImGui::GetItemRectSize();
  // Draw a list of nodes on the left side
  bool open_context_menu = false;
  int node_hovered_in_list = -1;
  int node_hovered_in_scene = -1;
  if (state.leftPaneVisible) {
    ImGui::BeginChild("node_list", ImVec2(state.leftPaneSize, 0));
    ImGui::Text("Workflows %d", groups.Size);
    ImGui::Separator();
    for (int groupId = 0; groupId < groups.Size; groupId++) {
      Group* group = &groups[groupId];
      if (ImGui::TreeNodeEx(group->name, ImGuiTreeNodeFlags_DefaultOpen)) {
        for (int node_idx = 0; node_idx < nodes.Size; node_idx++) {
          Node* node = &nodes[node_idx];
          if (node->GroupID != groupId) {
            continue;
          }
          ImGui::Indent(15);
          ImGui::PushID(node->ID);
          if (ImGui::Selectable(node->Name, node->ID == node_selected)) {
            if (ImGui::IsMouseDoubleClicked(0)) {
              controls[node_selected].logVisible = true;
            }
            node_selected = node->ID;
          }
          if (ImGui::IsItemHovered()) {
            node_hovered_in_list = node->ID;
            open_context_menu |= ImGui::IsMouseClicked(1);
          }
          ImGui::PopID();
          ImGui::Unindent(15);
        }
        ImGui::TreePop();
      }
    }
    ImGui::EndChild();
    ImGui::SameLine();
  }
 
  ImGui::BeginGroup();
 
  ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(1, 1));
  ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0, 0));
  auto canvasBg = state.topologyLightMode ? (ImU32)ImColor(250, 250, 252, 255) : (ImU32)ImColor(44, 44, 46, 255);
  auto canvasText = (ImU32)ImColor(235, 235, 245, 255); // nodes are always dark, so text is always light
  ImGui::PushStyleColor(ImGuiCol_ChildBg, canvasBg);
  ImGui::PushStyleColor(ImGuiCol_Text, canvasText);
  ImVec2 graphSize = ImGui::GetWindowSize();
  if (state.leftPaneVisible) {
    graphSize.x -= state.leftPaneSize;
  }
  if (state.rightPaneVisible) {
    graphSize.x -= state.rightPaneSize;
  }
  graphSize.y -= toolbarSize.y + 20;
  ImGui::BeginChild("scrolling_region", graphSize, true, ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoScrollWithMouse);
  ImGui::PushItemWidth(graphSize.x);
 
  ImVec2 canvasOrigin = ImGui::GetCursorScreenPos();
  ImDrawList* draw_list = ImGui::GetWindowDrawList();
  ImGuiIO& io = ImGui::GetIO();
  if (fitRequested && nodes.Size > 0) {
    ImVec2 minPos(positions[0].pos.x, positions[0].pos.y);
    ImVec2 maxPos = positions[0].pos + nodes[0].Size;
    for (int i = 1; i < nodes.Size; ++i) {
      minPos.x = std::min(minPos.x, positions[i].pos.x);
      minPos.y = std::min(minPos.y, positions[i].pos.y);
      maxPos.x = std::max(maxPos.x, positions[i].pos.x + nodes[i].Size.x);
      maxPos.y = std::max(maxPos.y, positions[i].pos.y + nodes[i].Size.y);
    }
    ImVec2 graphBounds = maxPos - minPos;
    constexpr float FIT_PADDING = 80.f;
    float fitZoomX = graphSize.x / std::max(graphBounds.x + FIT_PADDING, 1.f);
    float fitZoomY = graphSize.y / std::max(graphBounds.y + FIT_PADDING, 1.f);
    zoom = clampZoom(std::min(fitZoomX, fitZoomY));
    ImVec2 visibleGraphSize = graphSize / zoom;
    scrolling = minPos - (visibleGraphSize - graphBounds) / 2.f;
  }
  if (ImGui::IsWindowHovered() && io.MouseWheel != 0.f) {
    ImVec2 mouseGraphPos = scrolling + (io.MousePos - canvasOrigin) / zoom;
    float newZoom = clampZoom(zoom * (io.MouseWheel > 0.f ? 1.12f : 1.f / 1.12f));
    scrolling = mouseGraphPos - (io.MousePos - canvasOrigin) / newZoom;
    zoom = newZoom;
  }
  ImVec2 offset = canvasOrigin - scrolling * zoom;
  // Number of layers we need. 2 per node, plus 2 for
  // the background stuff.
  draw_list->ChannelsSplit((nodes.Size + 2) * 2);
 
  // Display grid
  displayGrid(show_grid, scrolling, zoom, draw_list);
 
  ImVec2 win_pos = ImGui::GetCursorScreenPos();
  ImVec2 canvas_sz = ImGui::GetWindowSize();
 
  // Arrow colors — richer amber in light mode to stand out on white canvas
  const ImColor arrowBgColor = state.topologyLightMode ? ImColor(140, 80, 0) : ARROW_BACKGROUND_COLOR;
  const ImColor arrowHalfColor = state.topologyLightMode ? ImColor(180, 110, 0) : ARROW_HALFGROUND_COLOR;
  const ImColor arrowColor = state.topologyLightMode ? ImColor(220, 140, 0) : ARROW_COLOR;
 
  // Display links but only if they are inside the view.
  for (int link_idx = 0; link_idx < links.Size; link_idx++) {
    // Do the geometry culling upfront.
    NodeLink const& link = links[link_idx];
    ImVec2 p1 = graphToScreen(NodePos::GetOutputSlotPos(nodes, positions, link.InputIdx, link.InputSlot), canvasOrigin, scrolling, zoom);
    ImVec2 p2 = graphToScreen(NodePos::GetInputSlotPos(nodes, positions, link.OutputIdx, link.OutputSlot) + ImVec2(-3 * NODE_SLOT_RADIUS, 0), canvasOrigin, scrolling, zoom);
 
    if ((p1.x > win_pos.x + canvas_sz.x + 50) && (p2.x > win_pos.x + canvas_sz.x + 50)) {
      continue;
    }
 
    if ((p1.y > win_pos.y + canvas_sz.y + 50) && (p2.y > win_pos.y + canvas_sz.y + 50)) {
      continue;
    }
 
    if ((p1.y < win_pos.y) && (p2.y < win_pos.y)) {
      continue;
    }
 
    if ((p1.x < win_pos.x) && (p2.x < win_pos.x)) {
      continue;
    }
    draw_list->ChannelsSetCurrent(0); // Background
    auto color = arrowBgColor;
    auto thickness = ARROW_BACKGROUND_THICKNESS;
 
    bool p1Inside = false;
    bool p2Inside = false;
    if ((p1.x > win_pos.x) && (p1.x < (win_pos.x + canvas_sz.x)) && (p1.y < (win_pos.y + canvas_sz.y)) && (p1.y > win_pos.y)) {
      p1Inside = true;
    }
 
    if ((p2.x > win_pos.x) && (p2.x < (win_pos.x + canvas_sz.x)) && (p2.y < (win_pos.y + canvas_sz.y)) && (p2.y > win_pos.y)) {
      p2Inside = true;
    }
 
    if (p1Inside && p2Inside) {
      // Whatever the two edges completely within the view, gets brighter color and foreground.
      draw_list->ChannelsSetCurrent(2);
      color = arrowColor;
      thickness = ARROW_THICKNESS;
    } else if (p1Inside || p2Inside) {
      draw_list->ChannelsSetCurrent(1);
      // Whenever one of the two ends is within the view, increase the color but keep the background
      color = arrowHalfColor;
      thickness = ARROW_HALFGROUND_THICKNESS;
    }
 
    // If something belongs to a selected node, it gets the selected color.
    if (link.InputIdx == node_selected || link.OutputIdx == node_selected) {
      auto foregroundLayer = (nodes.Size + 1) * 2 + 1;
      draw_list->ChannelsSetCurrent(foregroundLayer);
      color = ARROW_SELECTED_COLOR;
      thickness = thickness + 2;
    }
 
    draw_list->AddBezierCurve(p1, p1 + ImVec2(+50 * zoom, 0), p2 + ImVec2(-50 * zoom, 0), p2, color, std::max(thickness * zoom, 1.f));
  }
 
  auto fgDrawList = ImGui::GetForegroundDrawList();
  // Display nodes
  for (int node_idx = 0; node_idx < nodes.Size; node_idx++) {
    auto backgroundLayer = (node_idx + 1) * 2;
    auto foregroundLayer = (node_idx + 1) * 2 + 1;
    // Selected node goes to front
    if (node_selected == node_idx) {
      backgroundLayer = (nodes.Size + 1) * 2;
      foregroundLayer = (nodes.Size + 1) * 2 + 1;
    }
    Node* node = &nodes[node_idx];
    NodePos* pos = &positions[node_idx];
    const DeviceInfo& info = infos[node_idx];
 
    ImVec2 node_rect_min = graphToScreen(pos->pos, canvasOrigin, scrolling, zoom);
 
    // Do not even start if we are sure the box is not visible
    if ((node_rect_min.x > ImGui::GetCursorScreenPos().x + ImGui::GetWindowSize().x + 50) ||
        (node_rect_min.y > ImGui::GetCursorScreenPos().y + ImGui::GetWindowSize().y + 50)) {
      continue;
    }
 
    ImGui::PushID(node->ID);
 
    // Display node contents first
    draw_list->ChannelsSetCurrent(foregroundLayer);
    bool old_any_active = ImGui::IsAnyItemActive();
    ImGui::SetWindowFontScale(zoom);
    ImGui::SetCursorScreenPos(node_rect_min + NODE_WINDOW_PADDING * zoom);
    ImGui::BeginGroup(); // Lock horizontal position
    ImGui::TextUnformatted(node->Name);
    switch (info.maxLogLevel) {
      case LogLevel::Critical:
        ImGui::SameLine();
        ImGui::TextColored(ERROR_MESSAGE_COLOR, "%s", ICON_FA_EXCLAMATION_CIRCLE);
        break;
      case LogLevel::Error:
        ImGui::SameLine();
        ImGui::TextColored(ERROR_MESSAGE_COLOR, "%s", ICON_FA_EXCLAMATION_CIRCLE);
        break;
      case LogLevel::Alarm:
        ImGui::SameLine();
        ImGui::TextColored(WARNING_MESSAGE_COLOR, "%s", ICON_FA_EXCLAMATION_TRIANGLE);
        break;
      case LogLevel::Warning:
        ImGui::SameLine();
        ImGui::TextColored(WARNING_MESSAGE_COLOR, "%s", ICON_FA_EXCLAMATION_TRIANGLE);
        break;
      default:
        break;
    }
 
    gui::displayDataRelayer(metricsInfos[node->ID], infos[node->ID], specs[node->ID], allStates[node->ID], ImVec2(200., 160.) * zoom, controls[node->ID].firstWnd);
    ImGui::EndGroup();
 
    // Save the size of what we have emitted and whether any of the widgets are being used
    bool node_widgets_active = (!old_any_active && ImGui::IsAnyItemActive());
    float attemptX = std::max(ImGui::GetItemRectSize().x / zoom, 150.f);
    float attemptY = std::min(ImGui::GetItemRectSize().y / zoom, 128.f);
    node->Size = ImVec2(attemptX, attemptY) + NODE_WINDOW_PADDING + NODE_WINDOW_PADDING;
    ImVec2 node_screen_size = node->Size * zoom;
    ImVec2 node_rect_max = node_rect_min + node_screen_size;
    ImVec2 node_rect_title = node_rect_min + ImVec2(node_screen_size.x, 24 * zoom);
 
    if (node_rect_min.x > 20 + 2 * NODE_WINDOW_PADDING.x + state.leftPaneSize + graphSize.x) {
      ImGui::PopID();
      continue;
    }
    if (node_rect_min.y > 20 + 2 * NODE_WINDOW_PADDING.y + toolbarSize.y + graphSize.y) {
      ImGui::PopID();
      continue;
    }
 
    // Display node box
    draw_list->ChannelsSetCurrent(backgroundLayer); // Background
    ImGui::SetCursorScreenPos(node_rect_min);
    ImGui::InvisibleButton("node", node_screen_size);
    if (ImGui::IsItemHovered()) {
      node_hovered_in_scene = node->ID;
      open_context_menu |= ImGui::IsMouseClicked(1);
      if (ImGui::IsMouseDoubleClicked(0)) {
        controls[node->ID].logVisible = true;
      }
    }
    bool node_moving_active = ImGui::IsItemActive();
    if (node_widgets_active || node_moving_active) {
      node_selected = node->ID;
    }
    if (node_moving_active && ImGui::IsMouseDragging(0)) {
      pos->pos = pos->pos + ImGui::GetIO().MouseDelta / zoom;
    }
    if (ImGui::IsWindowHovered() && !node_moving_active && ImGui::IsMouseDragging(0)) {
      scrolling = scrolling - ImVec2(ImGui::GetIO().MouseDelta.x / 4.f, ImGui::GetIO().MouseDelta.y / 4.f) / zoom;
    }
 
    auto nodeBg = decideColorForNode(info, state.topologyLightMode);
 
    auto hovered = (node_hovered_in_list == node->ID || node_hovered_in_scene == node->ID || (node_hovered_in_list == -1 && node_selected == node->ID));
    ImVec4 nodeBgColor = hovered ? nodeBg.hovered : nodeBg.normal;
    ImVec4 nodeTitleColor = hovered ? nodeBg.title_hovered : nodeBg.title;
    ImU32 node_bg_color = ImGui::ColorConvertFloat4ToU32(nodeBgColor);
    ImU32 node_title_color = ImGui::ColorConvertFloat4ToU32(nodeTitleColor);
 
    draw_list->AddRectFilled(node_rect_min + ImVec2(3.f, 3.f) * zoom, node_rect_max + ImVec2(3.f, 3.f) * zoom, ImColor(0, 0, 0, 70), 4.0f * zoom);
    draw_list->AddRectFilled(node_rect_min, node_rect_max, node_bg_color, 4.0f * zoom);
    draw_list->AddRectFilled(node_rect_min, node_rect_title, node_title_color, 4.0f * zoom);
    draw_list->AddRect(node_rect_min, node_rect_max, NODE_BORDER_COLOR, 4.0f * zoom, 0, std::max(NODE_BORDER_THICKNESS * zoom, 1.f));
 
    for (int slot_idx = 0; slot_idx < node->InputsCount; slot_idx++) {
      draw_list->ChannelsSetCurrent(backgroundLayer); // Background
      ImVec2 p1(-3 * NODE_SLOT_RADIUS, NODE_SLOT_RADIUS), p2(-3 * NODE_SLOT_RADIUS, -NODE_SLOT_RADIUS), p3(0, 0);
      auto slotPos = NodePos::GetInputSlotPos(nodes, positions, node_idx, slot_idx);
      auto slotScreenPos = graphToScreen(slotPos, canvasOrigin, scrolling, zoom);
      auto pp1 = p1 * zoom + slotScreenPos;
      auto pp2 = p2 * zoom + slotScreenPos;
      auto pp3 = p3 * zoom + slotScreenPos;
      auto color = arrowColor;
      if (node_idx == node_selected) {
        color = ARROW_SELECTED_COLOR;
      }
      draw_list->AddTriangleFilled(pp1, pp2, pp3, color);
      draw_list->AddCircleFilled(slotScreenPos, NODE_SLOT_RADIUS * zoom, INPUT_SLOT_COLOR);
    }
 
    draw_list->ChannelsSetCurrent(foregroundLayer);
    MetricLabelsContext context{&nodes, node_idx, &positions, draw_list, canvasOrigin, scrolling, zoom};
    MetricsPainter<int, uint64_t, MetricLabelsContext>::draw(
      "input_labels",
      offset,
      ImVec2{node->Size.x, node->Size.y},
      context,
      MetricsPainter<int, uint64_t, MetricLabelsContext>::metric1D(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::simpleRecord<int>(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::items2D(info.inputChannelMetricsViewIndex),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::latestMetric<uint64_t>(metricsInfos[node->ID], info.inputChannelMetricsViewIndex),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::simpleValue<uint64_t>(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::colorPalette(std::vector<ImU32>{{ImColor(0, 100, 0, 255), ImColor(0, 0, 100, 255), ImColor(100, 0, 0, 255)}}, 0, 3),
      [](int, int item, int value, ImU32 color, MetricLabelsContext const& context) {
        auto draw_list = context.draw_list;
        auto& nodes = *context.nodes;
        auto& positions = *context.positions;
        auto slotPos = NodePos::GetInputSlotPos(nodes, positions, context.nodeIdx, item);
        auto slotScreenPos = graphToScreen(slotPos, context.canvasOrigin, context.scrolling, context.zoom);
        Node* node = &nodes[context.nodeIdx];
        auto& label = node->oldestPossibleInput[item];
        // Avoid recomputing if the value is the same.
        if (label.value != value) {
          label.value = value;
          snprintf(label.buffer, sizeof(label.buffer), "%d", value);
        }
        label.textSize = ImGui::CalcTextSize(label.buffer).x;
        draw_list->AddRectFilled(slotScreenPos - ImVec2{node->oldestPossibleInput[item].textSize + 5.f * NODE_SLOT_RADIUS * context.zoom, 2 * NODE_SLOT_RADIUS * context.zoom},
                                 slotScreenPos + ImVec2{-4.5f * NODE_SLOT_RADIUS * context.zoom, 2 * NODE_SLOT_RADIUS * context.zoom}, NODE_LABEL_BACKGROUND_COLOR, 2.f * context.zoom, ImDrawFlags_RoundCornersAll);
        draw_list->AddText(nullptr, 12 * context.zoom,
                           slotScreenPos - ImVec2{node->oldestPossibleInput[item].textSize + 4.5f * NODE_SLOT_RADIUS * context.zoom, 2 * NODE_SLOT_RADIUS * context.zoom},
                           NODE_LABEL_TEXT_COLOR,
                           node->oldestPossibleInput[item].buffer);
      });
 
    for (int slot_idx = 0; slot_idx < node->OutputsCount; slot_idx++) {
      draw_list->AddCircleFilled(graphToScreen(NodePos::GetOutputSlotPos(nodes, positions, node_idx, slot_idx), canvasOrigin, scrolling, zoom), NODE_SLOT_RADIUS * zoom, OUTPUT_SLOT_COLOR);
    }
 
    MetricsPainter<int, uint64_t, MetricLabelsContext>::draw(
      "output_labels",
      offset,
      ImVec2{node->Size.x, node->Size.y},
      context,
      MetricsPainter<int, uint64_t, MetricLabelsContext>::metric1D(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::simpleRecord<int>(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::items2D(info.outputChannelMetricsViewIndex),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::latestMetric<uint64_t>(metricsInfos[node->ID], info.outputChannelMetricsViewIndex),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::simpleValue<uint64_t>(),
      MetricsPainter<int, uint64_t, MetricLabelsContext>::colorPalette(std::vector<ImU32>{{ImColor(0, 100, 0, 255), ImColor(0, 0, 100, 255), ImColor(100, 0, 0, 255)}}, 0, 3),
      [](int, int item, int value, ImU32 color, MetricLabelsContext const& context) {
        auto draw_list = context.draw_list;
        auto& nodes = *context.nodes;
        auto& positions = *context.positions;
        auto slotPos = NodePos::GetOutputSlotPos(nodes, positions, context.nodeIdx, item);
        auto slotScreenPos = graphToScreen(slotPos, context.canvasOrigin, context.scrolling, context.zoom);
        Node* node = &nodes[context.nodeIdx];
        auto& label = node->oldestPossibleOutput[item];
        // Avoid recomputing if the value is the same.
        if (label.value != value) {
          label.value = value;
          snprintf(label.buffer, sizeof(label.buffer), "%d", value);
        }
        label.textSize = ImGui::CalcTextSize(label.buffer).x;
        auto rectTL = ImVec2{4.5f * NODE_SLOT_RADIUS * context.zoom, -2 * NODE_SLOT_RADIUS * context.zoom};
        auto rectBR = ImVec2{node->oldestPossibleOutput[item].textSize + 5.f * NODE_SLOT_RADIUS * context.zoom, 2 * NODE_SLOT_RADIUS * context.zoom};
        draw_list->AddRectFilled(slotScreenPos + rectTL,
                                 slotScreenPos + rectBR, NODE_LABEL_BACKGROUND_COLOR, 2.f * context.zoom, ImDrawFlags_RoundCornersAll);
        draw_list->AddText(nullptr, 12 * context.zoom,
                           slotScreenPos + rectTL,
                           NODE_LABEL_TEXT_COLOR,
                           node->oldestPossibleOutput[item].buffer);
      });
 
    ImGui::PopID();
  }
  ImGui::SetWindowFontScale(1.0f);
  draw_list->ChannelsMerge();
  displayLegend(show_legend, offset, draw_list);
 
  // Open context menu
  if (!ImGui::IsAnyItemHovered() && ImGui::IsWindowHovered(ImGuiHoveredFlags_AnyWindow) && ImGui::IsMouseClicked(1)) {
    node_selected = node_hovered_in_list = node_hovered_in_scene = -1;
    open_context_menu = true;
  }
  if (open_context_menu) {
    ImGui::OpenPopup("context_menu");
    if (node_hovered_in_list != -1) {
      node_selected = node_hovered_in_list;
    }
    if (node_hovered_in_scene != -1) {
      node_selected = node_hovered_in_scene;
    }
  }
 
  // Scrolling
  // if (ImGui::IsWindowHovered() && !ImGui::IsAnyItemActive() && ImGui::IsMouseDragging(2, 0.0f))
  //    scrolling = scrolling - ImGui::GetIO().MouseDelta;
 
  ImGui::PopItemWidth();
  ImGui::EndChild();
  ImGui::PopStyleColor(2);
  ImGui::PopStyleVar(2);
  ImGui::EndGroup();
 
  if (state.rightPaneVisible) {
    ImGui::SameLine();
    ImGui::BeginGroup();
    ImGui::BeginChild("inspector");
    ImGui::TextUnformatted("Device Inspector");
    ImGui::Separator();
    if (node_selected != -1) {
      auto& node = nodes[node_selected];
      auto& spec = specs[node_selected];
      auto& states = allStates[node_selected];
      auto& control = controls[node_selected];
      auto& info = infos[node_selected];
      auto& metrics = metricsInfos[node_selected];
      auto& group = groups[node.GroupID];
      auto& metadatum = metadata[group.metadataId];
 
      if (state.rightPaneVisible) {
        gui::displayDeviceInspector(spec, info, states, metrics, metadatum, control);
      }
    } else {
      ImGui::TextWrapped("Select a node in the topology to display information about it");
    }
    ImGui::EndChild();
    ImGui::EndGroup();
  }
  ImGui::End();
}
 
} // namespace o2::framework::gui
#pragma GGC diagnostic pop