// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2020 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#include "MantidQtWidgets/Common/FitScriptGeneratorDataTable.h"

#include <QAbstractItemView>
#include <QColor>
#include <QDoubleValidator>
#include <QHeaderView>
#include <QHoverEvent>
#include <QItemSelectionModel>
#include <QLineEdit>
#include <QStringList>
#include <QValidator>

namespace {

int WS_INDEX_MIN(0);
int WS_INDEX_MAX(100000);
double X_EXTENT(100000.0);
int X_PRECISION(5);

QStringList const COLUMN_HEADINGS({"Name", "WS Index", "StartX", "EndX"});
QColor const FUNCTION_INDEX_COLOR(QColor(30, 144, 255));
QString const TABLE_STYLESHEET("QTableWidget {\n"
                               "    font-size: 8pt;\n"
                               "    border: 1px solid #828790;\n"
                               "}\n"
                               "\n"
                               "QTableWidget::item:selected {\n"
                               "    background-color: #c7e0ff;\n"
                               "    color: #000000;\n"
                               "}"
                               "\n"
                               "QTableWidget::item:hover {\n"
                               "    background-color: #c7e0ff;\n"
                               "}");

QValidator *createXValidator() {
  auto validator = new QDoubleValidator(-X_EXTENT, X_EXTENT, X_PRECISION);
  validator->setNotation(QDoubleValidator::Notation::StandardNotation);
  return validator;
}

QValidator *createWSIndexValidator() {
  return new QIntValidator(WS_INDEX_MIN, WS_INDEX_MAX);
}

QTableWidgetItem *createTableItem(QString const &value,
                                  Qt::AlignmentFlag const &alignment,
                                  bool editable,
                                  QColor const &color = QColor(0, 0, 0)) {
  auto item = new QTableWidgetItem(value);
  item->setData(Qt::ForegroundRole, color);
  item->setTextAlignment(alignment);
  if (!editable)
    item->setFlags(item->flags() ^ Qt::ItemIsEditable);
  return item;
}

QTableWidgetItem *createWSIndexTableItem(int value,
                                         Qt::AlignmentFlag const &alignment,
                                         bool editable) {
  return createTableItem(QString::number(value), alignment, editable);
}

QTableWidgetItem *createXTableItem(double value,
                                   Qt::AlignmentFlag const &alignment,
                                   bool editable) {
  return createTableItem(QString::number(value, 'f', X_PRECISION), alignment,
                         editable);
}

QString toFunctionIndex(MantidQt::MantidWidgets::FitDomainIndex index) {
  return "f" + QString::number(index.value) + ".";
}

} // namespace

namespace MantidQt {
namespace MantidWidgets {

/**
 * FitScriptGeneratorDataTable class methods.
 */

FitScriptGeneratorDataTable::FitScriptGeneratorDataTable(QWidget *parent)
    : QTableWidget(parent), m_selectedRows(), m_selectedColumn(-1),
      m_selectedValue(0.0), m_lastHoveredIndex(QPersistentModelIndex()) {
  this->setSelectionBehavior(QAbstractItemView::SelectRows);
  this->setSelectionMode(QAbstractItemView::ExtendedSelection);
  this->setShowGrid(false);
  this->setColumnCount(COLUMN_HEADINGS.size());
  this->setRowCount(0);
  this->horizontalHeader()->setHighlightSections(false);
  this->horizontalHeader()->setStretchLastSection(true);

  this->setColumnWidth(ColumnIndex::WorkspaceName, 280);
  this->setColumnWidth(ColumnIndex::WorkspaceIndex, 80);
  this->setColumnWidth(ColumnIndex::StartX, 100);
  this->setColumnWidth(ColumnIndex::EndX, 100);

  this->setHorizontalHeaderLabels(COLUMN_HEADINGS);

  this->setStyleSheet(TABLE_STYLESHEET);

  this->viewport()->installEventFilter(this);

  this->setItemDelegateForColumn(
      ColumnIndex::WorkspaceName,
      new CustomItemDelegate(this, ColumnIndex::WorkspaceName));
  this->setItemDelegateForColumn(
      ColumnIndex::WorkspaceIndex,
      new CustomItemDelegate(this, ColumnIndex::WorkspaceIndex));
  this->setItemDelegateForColumn(
      ColumnIndex::StartX, new CustomItemDelegate(this, ColumnIndex::StartX));
  this->setItemDelegateForColumn(
      ColumnIndex::EndX, new CustomItemDelegate(this, ColumnIndex::EndX));

  connect(this, SIGNAL(itemClicked(QTableWidgetItem *)), this,
          SLOT(handleItemClicked(QTableWidgetItem *)));
  connect(this, SIGNAL(itemSelectionChanged()), this,
          SLOT(handleItemSelectionChanged()));
  disconnect(this->verticalHeader(), SIGNAL(sectionPressed(int)), this,
             SLOT(selectRow(int)));
}

bool FitScriptGeneratorDataTable::eventFilter(QObject *widget, QEvent *event) {
  if (widget == this->viewport()) {
    auto index = hoveredRowIndex(event);

    if (index != m_lastHoveredIndex) {
      if (this->item(m_lastHoveredIndex.row(), m_lastHoveredIndex.column()))
        emit itemExited(index.isValid() ? index.row() : -1);
      m_lastHoveredIndex = QPersistentModelIndex(index);
    }
  }
  return QTableWidget::eventFilter(widget, event);
}

void FitScriptGeneratorDataTable::handleItemClicked(QTableWidgetItem *item) {
  m_selectedRows = selectedRows();
  m_selectedColumn = item->column();
  if (m_selectedColumn == ColumnIndex::StartX ||
      m_selectedColumn == ColumnIndex::EndX)
    m_selectedValue = item->text().toDouble();
}

void FitScriptGeneratorDataTable::handleItemSelectionChanged() {
  auto *selectionModel = this->selectionModel();

  if (!selectionModel->hasSelection()) {
    this->blockSignals(true);

    // Makes sure that multi-selection rows are stored within the selectionModel
    // as should be expected. This prevents a bug where not all selected rows
    // were being stored in the selection model.
    auto itemSelection = selectionModel->selection();
    for (auto const &selectedRow : m_selectedRows) {
      this->selectRow(static_cast<int>(selectedRow.value));
      itemSelection.merge(selectionModel->selection(),
                          QItemSelectionModel::Select);
    }
    selectionModel->clearSelection();
    selectionModel->select(itemSelection, QItemSelectionModel::Select);

    this->blockSignals(false);
  } else {
    m_selectedRows = selectedRows();
  }
}

QPersistentModelIndex
FitScriptGeneratorDataTable::hoveredRowIndex(QEvent *event) {
  auto index = m_lastHoveredIndex;
  auto const eventType = event->type();
  if (eventType == QEvent::HoverMove)
    index = QPersistentModelIndex(
        this->indexAt(static_cast<QHoverEvent *>(event)->pos()));
  else if (eventType == QEvent::Leave)
    index = QPersistentModelIndex(QModelIndex());

  return index;
}

std::string
FitScriptGeneratorDataTable::workspaceName(FitDomainIndex row) const {
  return getText(row, ColumnIndex::WorkspaceName).toStdString();
}

WorkspaceIndex
FitScriptGeneratorDataTable::workspaceIndex(FitDomainIndex row) const {
  return getText(row, ColumnIndex::WorkspaceIndex).toInt();
}

double FitScriptGeneratorDataTable::startX(FitDomainIndex row) const {
  return getText(row, ColumnIndex::StartX).toDouble();
}

double FitScriptGeneratorDataTable::endX(FitDomainIndex row) const {
  return getText(row, ColumnIndex::EndX).toDouble();
}

std::vector<FitDomainIndex> FitScriptGeneratorDataTable::allRows() const {
  std::vector<FitDomainIndex> rowIndices;
  rowIndices.reserve(this->rowCount());
  for (auto index = 0; index < this->rowCount(); ++index)
    rowIndices.emplace_back(FitDomainIndex(index));

  std::sort(rowIndices.rbegin(), rowIndices.rend());
  return rowIndices;
}

std::vector<FitDomainIndex> FitScriptGeneratorDataTable::selectedRows() const {
  std::vector<FitDomainIndex> rowIndices;

  auto const selectionModel = this->selectionModel();
  if (selectionModel->hasSelection()) {

    for (auto const &rowIndex : selectionModel->selectedRows())
      rowIndices.emplace_back(
          FitDomainIndex(static_cast<std::size_t>(rowIndex.row())));

    std::sort(rowIndices.rbegin(), rowIndices.rend());
  }
  return rowIndices;
}

bool FitScriptGeneratorDataTable::hasLoadedData() const {
  return this->rowCount() > 0;
}

QString FitScriptGeneratorDataTable::selectedDomainFunctionPrefix() const {
  auto const rows = selectedRows();
  if (rows.empty())
    return "";
  return this->verticalHeaderItem(static_cast<int>(rows[0].value))->text();
}

void FitScriptGeneratorDataTable::removeDomain(
    std::string const &workspaceName,
    MantidWidgets::WorkspaceIndex workspaceIndex) {
  auto const removeIndex = indexOfDomain(workspaceName, workspaceIndex);
  if (removeIndex != -1) {
    this->removeRow(removeIndex);
    updateVerticalHeaders();
  }

  m_selectedRows = selectedRows();

  if (m_selectedRows.empty() && this->rowCount() > 0)
    this->selectRow(0);

  m_selectedRows = selectedRows();
}

void FitScriptGeneratorDataTable::addDomain(
    QString const &workspaceName, MantidWidgets::WorkspaceIndex workspaceIndex,
    double startX, double endX) {
  this->blockSignals(true);

  auto const rowIndex = this->rowCount();
  this->insertRow(rowIndex);

  this->setVerticalHeaderItem(
      rowIndex, createTableItem(toFunctionIndex(FitDomainIndex(rowIndex)),
                                Qt::AlignCenter, false, FUNCTION_INDEX_COLOR));
  this->setItem(rowIndex, ColumnIndex::WorkspaceName,
                createTableItem(workspaceName, Qt::AlignVCenter, false));
  this->setItem(rowIndex, ColumnIndex::WorkspaceIndex,
                createWSIndexTableItem(static_cast<int>(workspaceIndex.value),
                                       Qt::AlignCenter, false));
  this->setItem(rowIndex, ColumnIndex::StartX,
                createXTableItem(startX, Qt::AlignCenter, true));
  this->setItem(rowIndex, ColumnIndex::EndX,
                createXTableItem(endX, Qt::AlignCenter, true));

  if (!this->selectionModel()->hasSelection()) {
    m_selectedRows.emplace_back(rowIndex);
    this->selectRow(rowIndex);
  }

  this->blockSignals(false);
}

void FitScriptGeneratorDataTable::updateVerticalHeaders() {
  for (auto i = FitDomainIndex(0); i < FitDomainIndex(this->rowCount()); ++i)
    this->setVerticalHeaderItem(static_cast<int>(i.value),
                                createTableItem(toFunctionIndex(i),
                                                Qt::AlignCenter, false,
                                                FUNCTION_INDEX_COLOR));
}

int FitScriptGeneratorDataTable::indexOfDomain(
    std::string const &workspaceName,
    MantidWidgets::WorkspaceIndex workspaceIndex) const {
  for (auto rowIndex = 0; rowIndex < this->rowCount(); ++rowIndex) {
    if (this->workspaceName(rowIndex) == workspaceName &&
        this->workspaceIndex(rowIndex) == workspaceIndex)
      return rowIndex;
  }
  return -1;
}

QString FitScriptGeneratorDataTable::getText(FitDomainIndex row,
                                             int column) const {
  return this->item(static_cast<int>(row.value), column)->text();
}

void FitScriptGeneratorDataTable::formatSelection() {
  if (!m_selectedRows.empty())
    setSelectedXValue(
        this->item(static_cast<int>(m_selectedRows[0].value), m_selectedColumn)
            ->text()
            .toDouble());
}

void FitScriptGeneratorDataTable::resetSelection() {
  setSelectedXValue(m_selectedValue);
}

void FitScriptGeneratorDataTable::setFunctionPrefixVisible(bool visible) {
  this->verticalHeader()->setVisible(visible);
}

void FitScriptGeneratorDataTable::setSelectedXValue(double xValue) {
  this->blockSignals(true);
  if (!m_selectedRows.empty())
    this->setItem(static_cast<int>(m_selectedRows[0].value), m_selectedColumn,
                  createXTableItem(xValue, Qt::AlignCenter, true));
  this->blockSignals(false);
}

/**
 * CustomItemDelegate class methods.
 */

CustomItemDelegate::CustomItemDelegate(FitScriptGeneratorDataTable *parent,
                                       ColumnIndex const &index)
    : QStyledItemDelegate(parent), m_tableWidget(parent), m_columnIndex(index),
      m_hoveredIndex(-1) {
  m_tableWidget = parent;
  m_tableWidget->setMouseTracking(true);

  connect(m_tableWidget, SIGNAL(itemEntered(QTableWidgetItem *)), this,
          SLOT(handleItemEntered(QTableWidgetItem *)));
  connect(m_tableWidget, SIGNAL(itemExited(int)), this,
          SLOT(handleItemExited(int)));
}

void CustomItemDelegate::handleItemEntered(QTableWidgetItem *item) {
  m_hoveredIndex = item->row();
  m_tableWidget->viewport()->update();
}

void CustomItemDelegate::handleItemExited(int newRowIndex) {
  m_hoveredIndex = newRowIndex;
}

QWidget *CustomItemDelegate::createEditor(QWidget *parent,
                                          QStyleOptionViewItem const &option,
                                          QModelIndex const &index) const {
  Q_UNUSED(option);
  Q_UNUSED(index);

  auto lineEdit = new QLineEdit(parent);
  switch (m_columnIndex) {
  case ColumnIndex::WorkspaceName:
    break;
  case ColumnIndex::WorkspaceIndex:
    lineEdit->setValidator(createWSIndexValidator());
    break;
  case ColumnIndex::StartX:
    lineEdit->setValidator(createXValidator());
    break;
  case ColumnIndex::EndX:
    lineEdit->setValidator(createXValidator());
    break;
  }

  return lineEdit;
}

void CustomItemDelegate::paint(QPainter *painter,
                               QStyleOptionViewItem const &option,
                               QModelIndex const &index) const {
  auto opt = QStyleOptionViewItem(option);
  if (index.row() == m_hoveredIndex)
    opt.state |= QStyle::State_MouseOver;
  QStyledItemDelegate::paint(painter, opt, index);
}

} // namespace MantidWidgets
} // namespace MantidQt