// Copyright 2026 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "DolphinQt/Config/ShaderOverrideWidget.h"

#include <QHBoxLayout>
#include <QColor>
#include <QLabel>
#include <QListWidget>
#include <QPushButton>
#include <QStringList>
#include <QVBoxLayout>

#include <unordered_map>

#include "DolphinQt/Config/ShaderOverrideAddEditDialog.h"
#include "DolphinQt/Debugger/ShaderHunterWidget.h"
#include "DolphinQt/QtUtils/NonDefaultQPushButton.h"
#include "DolphinQt/Settings.h"
#include "VideoCommon/ShaderHunter.h"

ShaderOverrideWidget::ShaderOverrideWidget(std::string game_id)
    : m_game_id(std::move(game_id))
{
  CreateWidgets();
  ConnectWidgets();
  LoadOverrides();
}

ShaderOverrideWidget::~ShaderOverrideWidget() = default;

void ShaderOverrideWidget::CreateWidgets()
{
  m_code_list = new QListWidget;

  auto* info_label = new QLabel(
      tr("Shader overrides control how individual shaders are handled.\n"
         "Use Add/Edit to create overrides manually, or add them from the Shader Hunter tool.\n"
         "Handling: Skip = hide, Screen = world-fixed, Head Locked = follows head,\n"
         "Fullscreen = no VR, Fullscreen Mono = no VR + mono texture layer sampling.\n"
         "Units per Meter = temporary per-shader VR scale override.\n"
         "Flag = detect shader presence to conditionally enable other overrides.\n"
         "Clear EFB = clear the next EFB copy to transparent (removes post-processing effects)."));
  info_label->setWordWrap(true);

  m_code_add = new NonDefaultQPushButton(tr("&Add Override"));
  m_code_edit = new NonDefaultQPushButton(tr("&Edit Override"));
  m_code_edit->setEnabled(false);
  m_code_remove = new NonDefaultQPushButton(tr("&Remove Override"));
  m_code_remove->setEnabled(false);

  m_code_refresh = new NonDefaultQPushButton(tr("Re&fresh List"));
  m_code_reload = new NonDefaultQPushButton(tr("Reload &Shaders"));
  m_shader_hunter = new NonDefaultQPushButton(tr("Shader Hunter"));

  auto* button_layout = new QHBoxLayout;
  button_layout->addWidget(m_shader_hunter);
  button_layout->addWidget(m_code_add);
  button_layout->addWidget(m_code_edit);
  button_layout->addWidget(m_code_remove);
  button_layout->addStretch();
  button_layout->addWidget(m_code_refresh);
  button_layout->addWidget(m_code_reload);

  auto* layout = new QVBoxLayout{this};
  layout->addWidget(info_label);
  layout->addWidget(m_code_list);
  layout->addLayout(button_layout);
}

void ShaderOverrideWidget::ConnectWidgets()
{
  connect(m_code_list, &QListWidget::itemChanged, this, &ShaderOverrideWidget::OnItemChanged);
  connect(m_code_list, &QListWidget::itemSelectionChanged, this,
          &ShaderOverrideWidget::OnSelectionChanged);
  connect(m_code_add, &QPushButton::clicked, this, &ShaderOverrideWidget::OnAddClicked);
  connect(m_code_edit, &QPushButton::clicked, this, &ShaderOverrideWidget::OnEditClicked);
  connect(m_code_remove, &QPushButton::clicked, this, &ShaderOverrideWidget::OnRemoveClicked);
  connect(m_code_refresh, &QPushButton::clicked, this, &ShaderOverrideWidget::OnRefreshClicked);
  connect(m_code_reload, &QPushButton::clicked, this, &ShaderOverrideWidget::OnReloadClicked);
  connect(&Settings::Instance(), &Settings::ShaderOverridesChanged, this,
          [this] { LoadOverrides(); });
  connect(m_shader_hunter, &QPushButton::clicked, this, [this] {
    if (m_shader_hunter_widget)
    {
      m_shader_hunter_widget->show();
      m_shader_hunter_widget->raise();
      m_shader_hunter_widget->activateWindow();
      return;
    }

    m_shader_hunter_widget = new ShaderHunterWidget(this);
    m_shader_hunter_widget->setAttribute(Qt::WA_DeleteOnClose, true);
    connect(m_shader_hunter_widget, &ShaderHunterWidget::OverridesChanged, this,
            [this] { LoadOverrides(); });
    m_shader_hunter_widget->show();
    connect(m_shader_hunter_widget, &QObject::destroyed, this,
            [this] { m_shader_hunter_widget = nullptr; });
  });
}

void ShaderOverrideWidget::LoadOverrides()
{
  m_overrides = ShaderHunter::LoadOverridesFromINI(m_game_id);

  m_code_list->setEnabled(!m_game_id.empty());
  m_code_remove->setEnabled(false);
  m_code_edit->setEnabled(false);

  UpdateList();
}

void ShaderOverrideWidget::SaveOverrides()
{
  ShaderHunter::SaveOverridesToINI(m_game_id, m_overrides);
}

void ShaderOverrideWidget::UpdateList()
{
  // Block signals to prevent itemChanged → SaveOverrides() during list construction.
  const QSignalBlocker blocker(m_code_list);
  m_code_list->clear();

  struct HandlingHashKey
  {
    int handling = 0;
    u64 hash = 0;

    bool operator==(const HandlingHashKey& other) const
    {
      return handling == other.handling && hash == other.hash;
    }
  };
  struct HandlingHashKeyHasher
  {
    size_t operator()(const HandlingHashKey& key) const noexcept
    {
      return std::hash<u64>{}(key.hash) ^ (std::hash<int>{}(key.handling) << 1);
    }
  };

  std::unordered_map<u64, size_t> hash_counts;
  std::unordered_map<HandlingHashKey, size_t, HandlingHashKeyHasher> handling_hash_counts;
  hash_counts.reserve(m_overrides.size());
  handling_hash_counts.reserve(m_overrides.size());
  for (const auto& ovr : m_overrides)
  {
    ++hash_counts[ovr.hash];
    ++handling_hash_counts[{static_cast<int>(ovr.handling), ovr.hash}];
  }

  // Build sorted display order: Flag overrides first, then their conditionals, then standalone.
  std::vector<size_t> sorted_indices;
  sorted_indices.reserve(m_overrides.size());

  // 1. Overrides that set a flag (Flag-only or combined), then their conditionals
  for (size_t i = 0; i < m_overrides.size(); i++)
  {
    if (!m_overrides[i].flag_group.empty())
    {
      sorted_indices.push_back(i);
      // 2. Conditionals that depend on this flag
      const auto& flag = m_overrides[i].flag_group;
      for (size_t j = 0; j < m_overrides.size(); j++)
      {
        if (j != i && m_overrides[j].condition_flag == flag &&
            std::find(sorted_indices.begin(), sorted_indices.end(), j) == sorted_indices.end())
          sorted_indices.push_back(j);
      }
    }
  }
  // 3. Standalone overrides (no flag_group, no condition)
  for (size_t i = 0; i < m_overrides.size(); i++)
  {
    if (m_overrides[i].flag_group.empty() && m_overrides[i].condition_flag.empty() &&
        std::find(sorted_indices.begin(), sorted_indices.end(), i) == sorted_indices.end())
    {
      sorted_indices.push_back(i);
    }
  }
  // 4. Any conditional overrides whose flag doesn't exist (orphaned)
  for (size_t i = 0; i < m_overrides.size(); i++)
  {
    if (!m_overrides[i].condition_flag.empty() &&
        std::find(sorted_indices.begin(), sorted_indices.end(), i) == sorted_indices.end())
    {
      sorted_indices.push_back(i);
    }
  }

  for (size_t idx : sorted_indices)
  {
    const auto& ovr = m_overrides[idx];

    const char* type_str = ovr.type == ShaderHunter::ShaderType::Vertex   ? "VS" :
                           ovr.type == ShaderHunter::ShaderType::Geometry  ? "GS" :
                                                                             "PS";
    const char* handling_str = ovr.handling == ShaderHunter::HandlingType::Screen      ? "screen" :
                               ovr.handling == ShaderHunter::HandlingType::Fullscreen  ? "fullscreen" :
                               ovr.handling == ShaderHunter::HandlingType::FullscreenMono ?
                                   "fullscreen_mono" :
                               ovr.handling == ShaderHunter::HandlingType::HeadLocked  ? "headlocked" :
                               ovr.handling == ShaderHunter::HandlingType::Flag        ? "flag" :
                               ovr.handling == ShaderHunter::HandlingType::UnitsPerMeter ?
                                   "units_per_meter" :
                                                                                         "skip";

    QString label;
    if (ovr.handling == ShaderHunter::HandlingType::Flag)
    {
      label = QStringLiteral("%1  [%2 %3] (flag -> '%4')")
                  .arg(QString::fromStdString(ovr.name))
                  .arg(QString::fromLatin1(type_str))
                  .arg(ovr.hash, 16, 16, QLatin1Char('0'))
                  .arg(QString::fromStdString(ovr.flag_group));
    }
    else if (!ovr.flag_group.empty())
    {
      // Non-Flag override that also sets a flag
      label = QStringLiteral("%1  [%2 %3] (%4, flag -> '%5')")
                  .arg(QString::fromStdString(ovr.name))
                  .arg(QString::fromLatin1(type_str))
                  .arg(ovr.hash, 16, 16, QLatin1Char('0'))
                  .arg(QString::fromLatin1(handling_str))
                  .arg(QString::fromStdString(ovr.flag_group));
    }
    else
    {
      label = QStringLiteral("%1  [%2 %3] (%4)")
                  .arg(QString::fromStdString(ovr.name))
                  .arg(QString::fromLatin1(type_str))
                  .arg(ovr.hash, 16, 16, QLatin1Char('0'))
                  .arg(QString::fromLatin1(handling_str));
    }

    if (ovr.handling == ShaderHunter::HandlingType::Screen ||
        ovr.handling == ShaderHunter::HandlingType::HeadLocked)
    {
      if (ovr.layer >= 0)
        label += QStringLiteral(" L%1").arg(ovr.layer);
      if (ovr.element_depth >= 0.0f)
        label += QStringLiteral(" D%1").arg(ovr.element_depth, 0, 'f', 4);
    }
    else if (ovr.handling == ShaderHunter::HandlingType::UnitsPerMeter && ovr.units_per_meter > 0.0f)
    {
      label += QStringLiteral(" UPM%1").arg(ovr.units_per_meter, 0, 'f', 2);
    }

    if (ovr.hash_family_match)
      label += QStringLiteral(" family");

    if (ovr.clear_efb)
    {
      if (ovr.clear_efb_min_width > 0 || ovr.clear_efb_max_width > 0)
        label += QStringLiteral(" +clearEFB(%1-%2)")
                     .arg(ovr.clear_efb_min_width)
                     .arg(ovr.clear_efb_max_width > 0 ? ovr.clear_efb_max_width : 640);
      else
        label += QStringLiteral(" +clearEFB");
    }

    if (ovr.element_start >= 0 && ovr.element_end >= 0)
    {
      label += QStringLiteral(" elem[%1-%2]").arg(ovr.element_start).arg(ovr.element_end);
      if (ovr.element_reference_total > 0)
        label += QStringLiteral("@%1").arg(ovr.element_reference_total);
    }

    if (!ovr.texture_hashes.empty())
    {
      QStringList texture_hashes;
      for (u64 texture_hash : ovr.texture_hashes)
      {
        texture_hashes.append(
            QString::number(texture_hash, 16).rightJustified(16, QLatin1Char('0')));
      }
      label += QStringLiteral(" tex(%1):%2")
                   .arg(ovr.texture_hashes_excluded ? QStringLiteral("exclude") :
                                                     QStringLiteral("include"))
                   .arg(texture_hashes.join(QStringLiteral(",")));
    }

    if (!ovr.condition_flag.empty())
    {
      const QString condition_text = ovr.condition_inverted ?
                                         QStringLiteral("[when not '%1']").arg(
                                             QString::fromStdString(ovr.condition_flag)) :
                                         QStringLiteral("[when '%1']").arg(
                                             QString::fromStdString(ovr.condition_flag));
      label = QStringLiteral("  \u2514 ") + label + QStringLiteral(" ") + condition_text;
    }

    const bool has_duplicate_handling_hash =
        handling_hash_counts[{static_cast<int>(ovr.handling), ovr.hash}] > 1;
    const bool has_duplicate_hash = hash_counts[ovr.hash] > 1;
    const bool has_hash_only_duplicate = has_duplicate_hash && !has_duplicate_handling_hash;
    if (has_duplicate_handling_hash)
      label += QStringLiteral("  [DUPLICATE HANDLING+HASH]");
    else if (has_hash_only_duplicate)
      label += QStringLiteral("  [DUPLICATE HASH]");

    auto* item = new QListWidgetItem(label);

    item->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsUserCheckable);
    item->setCheckState(ovr.enabled ? Qt::Checked : Qt::Unchecked);
    item->setData(Qt::UserRole, static_cast<int>(idx));
    if (has_duplicate_handling_hash)
    {
      item->setForeground(QColor(220, 85, 85));
      item->setToolTip(
          tr("Duplicate Handling+Hash: another override in this list has the same handling mode and hash."));
    }
    else if (has_hash_only_duplicate)
    {
      item->setForeground(QColor(214, 160, 0));
      item->setToolTip(
          tr("Duplicate Hash: another override in this list has the same hash but a different shader "
             "type."));
    }

    m_code_list->addItem(item);
  }
}

void ShaderOverrideWidget::OnItemChanged(QListWidgetItem* item)
{
  const int idx = item->data(Qt::UserRole).toInt();
  if (idx < 0 || idx >= static_cast<int>(m_overrides.size()))
    return;

  m_overrides[idx].enabled = (item->checkState() == Qt::Checked);
  SaveOverrides();
  ShaderHunter::GetInstance().LoadOverrides(m_game_id);
}

void ShaderOverrideWidget::OnSelectionChanged()
{
  const auto items = m_code_list->selectedItems();
  const bool has_selection = !items.empty();
  m_code_remove->setEnabled(has_selection);
  m_code_edit->setEnabled(has_selection);
}

std::vector<std::string> ShaderOverrideWidget::CollectAvailableFlags() const
{
  std::vector<std::string> flags;
  for (const auto& ovr : m_overrides)
  {
    if (!ovr.flag_group.empty())
    {
      if (std::find(flags.begin(), flags.end(), ovr.flag_group) == flags.end())
        flags.push_back(ovr.flag_group);
    }
  }
  return flags;
}

void ShaderOverrideWidget::OnAddClicked()
{
  ShaderOverrideAddEditDialog dialog(this, nullptr, CollectAvailableFlags());
  if (dialog.exec() != QDialog::Accepted)
    return;

  m_overrides.push_back(dialog.GetResult());
  SaveOverrides();
  UpdateList();
  ShaderHunter::GetInstance().LoadOverrides(m_game_id);
}

void ShaderOverrideWidget::OnEditClicked()
{
  const auto items = m_code_list->selectedItems();
  if (items.empty())
    return;

  const int idx = items[0]->data(Qt::UserRole).toInt();
  if (idx < 0 || idx >= static_cast<int>(m_overrides.size()))
    return;

  ShaderOverrideAddEditDialog dialog(this, &m_overrides[idx], CollectAvailableFlags());
  if (dialog.exec() != QDialog::Accepted)
    return;

  auto result = dialog.GetResult();
  result.enabled = m_overrides[idx].enabled;  // Preserve enabled state
  m_overrides[idx] = result;
  SaveOverrides();
  UpdateList();
  ShaderHunter::GetInstance().LoadOverrides(m_game_id);
}

void ShaderOverrideWidget::OnRemoveClicked()
{
  const auto items = m_code_list->selectedItems();
  if (items.empty())
    return;

  const int idx = items[0]->data(Qt::UserRole).toInt();
  if (idx < 0 || idx >= static_cast<int>(m_overrides.size()))
    return;

  m_overrides.erase(m_overrides.begin() + idx);

  SaveOverrides();
  UpdateList();
  ShaderHunter::GetInstance().LoadOverrides(m_game_id);

  m_code_remove->setEnabled(false);
  m_code_edit->setEnabled(false);
}

void ShaderOverrideWidget::OnRefreshClicked()
{
  // Re-read overrides from the INI file and refresh the list display
  LoadOverrides();
}

void ShaderOverrideWidget::OnReloadClicked()
{
  // Force the runtime ShaderHunter to reload overrides from the INI,
  // so enabled/disabled changes take effect in the running game without restarting.
  auto& hunter = ShaderHunter::GetInstance();
  hunter.LoadOverrides(m_game_id);
}