// Copyright 2018 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "InputCommon/ControllerEmu/StickGate.h"

#include <algorithm>
#include <cmath>

#include <fmt/format.h>
#include <fmt/ranges.h>

#include "Common/Common.h"
#include "Common/MathUtil.h"
#include "Common/Matrix.h"
#include "Common/StringUtil.h"
#include "InputCommon/ControllerEmu/Control/Control.h"
#include "InputCommon/ControllerEmu/Setting/NumericSetting.h"

namespace
{
constexpr auto CALIBRATION_CONFIG_NAME = "Calibration";
constexpr auto CALIBRATION_DEFAULT_VALUE = 1.0;
constexpr auto CALIBRATION_CONFIG_SCALE = 100;

constexpr auto CENTER_CONFIG_NAME = "Center";
constexpr auto CENTER_CONFIG_SCALE = 100;

// Calculate distance to intersection of a ray with a line segment defined by two points.
std::optional<double> GetRayLineIntersection(Common::DVec2 ray, Common::DVec2 point1,
                                             Common::DVec2 point2)
{
  const auto diff = point2 - point1;

  const auto dot = diff.Dot({-ray.y, ray.x});
  if (std::abs(dot) < 0.00001)
  {
    // Both points are on top of eachother.
    return std::nullopt;
  }

  const auto segment_position = point1.Dot({ray.y, -ray.x}) / dot;
  if (segment_position < -0.00001 || segment_position > 1.00001)
  {
    // Ray does not pass through segment.
    return std::nullopt;
  }

  return diff.Cross(-point1) / dot;
}

double GetNearestNotch(double angle, double virtual_notch_angle)
{
  constexpr auto sides = 8;
  constexpr auto rounding = MathUtil::TAU / sides;
  const auto closest_notch = std::round(angle / rounding) * rounding;
  const auto angle_diff =
      std::fmod(angle - closest_notch + MathUtil::PI, MathUtil::TAU) - MathUtil::PI;
  return std::abs(angle_diff) < virtual_notch_angle / 2 ? closest_notch : angle;
}

Common::DVec2 GetPointFromAngleAndLength(double angle, double length)
{
  return Common::DVec2{std::cos(angle), std::sin(angle)} * length;
}
}  // namespace

namespace ControllerEmu
{
constexpr int ReshapableInput::CALIBRATION_SAMPLE_COUNT;

std::optional<u32> StickGate::GetIdealCalibrationSampleCount() const
{
  return std::nullopt;
}

OctagonStickGate::OctagonStickGate(ControlState radius) : m_radius(radius)
{
}

ControlState OctagonStickGate::GetRadiusAtAngle(double angle) const
{
  constexpr int sides = 8;
  constexpr double sum_int_angles = (sides - 2) * MathUtil::PI;
  constexpr double half_int_angle = sum_int_angles / sides / 2;

  angle = std::fmod(angle, MathUtil::TAU / sides);
  // Solve ASA triangle using The Law of Sines:
  return m_radius / std::sin(MathUtil::PI - angle - half_int_angle) * std::sin(half_int_angle);
}

std::optional<u32> OctagonStickGate::GetIdealCalibrationSampleCount() const
{
  return 8;
}

RoundStickGate::RoundStickGate(ControlState radius) : m_radius(radius)
{
}

ControlState RoundStickGate::GetRadiusAtAngle(double) const
{
  return m_radius;
}

std::optional<u32> RoundStickGate::GetIdealCalibrationSampleCount() const
{
  // The "radius" is the same at every angle so a single sample is enough.
  return 1;
}

SquareStickGate::SquareStickGate(ControlState half_width) : m_half_width(half_width)
{
}

ControlState SquareStickGate::GetRadiusAtAngle(double angle) const
{
  constexpr double section_angle = MathUtil::TAU / 4;
  return m_half_width /
         std::cos(std::fmod(angle + section_angle / 2, section_angle) - section_angle / 2);
}

std::optional<u32> SquareStickGate::GetIdealCalibrationSampleCount() const
{
  // Because angle:0 points to the right we must use 8 samples for our square.
  return 8;
}

ReshapableInput::ReshapableInput(std::string name_, std::string ui_name_, GroupType type_)
    : ControlGroup(std::move(name_), std::move(ui_name_), type_)
{
  // 50 is not always enough but users can set it to more with an expression
  AddDeadzoneSetting(&m_deadzone_setting, 50);
}

ControlState ReshapableInput::GetDeadzoneRadiusAtAngle(double angle) const
{
  // FYI: deadzone is scaled by input radius which allows the shape to match.
  return GetInputRadiusAtAngle(angle) * GetDeadzonePercentage();
}

ControlState ReshapableInput::GetInputRadiusAtAngle(double angle) const
{
  // Handle the "default" state.
  if (m_calibration.empty())
  {
    return GetDefaultInputRadiusAtAngle(angle);
  }

  return GetCalibrationDataRadiusAtAngle(m_calibration, angle);
}

ControlState ReshapableInput::GetDeadzonePercentage() const
{
  return m_deadzone_setting.GetValue() / 100;
}

ControlState ReshapableInput::GetCalibrationDataRadiusAtAngle(const CalibrationData& data,
                                                              double angle)
{
  const auto sample_pos = angle / MathUtil::TAU * data.size();
  // Interpolate the radius between 2 calibration samples.
  const u32 sample1_index = u32(sample_pos) % data.size();
  const u32 sample2_index = (sample1_index + 1) % data.size();
  const double sample1_angle = sample1_index * MathUtil::TAU / data.size();
  const double sample2_angle = sample2_index * MathUtil::TAU / data.size();

  const auto intersection =
      GetRayLineIntersection(GetPointFromAngleAndLength(angle, 1.0),
                             GetPointFromAngleAndLength(sample1_angle, data[sample1_index]),
                             GetPointFromAngleAndLength(sample2_angle, data[sample2_index]));

  // Intersection has no value when points are on top of eachother.
  return intersection.value_or(data[sample1_index]);
}

ControlState ReshapableInput::GetDefaultInputRadiusAtAngle(double angle) const
{
  // This will normally be the same as the gate radius.
  // Unless a sub-class is doing weird things with the gate radius (e.g. Tilt)
  return GetGateRadiusAtAngle(angle);
}

void ReshapableInput::SetCalibrationToDefault()
{
  m_calibration.clear();
}

void ReshapableInput::SetCalibrationFromGate(const StickGate& gate)
{
  m_calibration.resize(gate.GetIdealCalibrationSampleCount().value_or(CALIBRATION_SAMPLE_COUNT));

  u32 i = 0;
  for (auto& val : m_calibration)
    val = gate.GetRadiusAtAngle(MathUtil::TAU * i++ / m_calibration.size());
}

void ReshapableInput::UpdateCalibrationData(CalibrationData& data, Common::DVec2 point1,
                                            Common::DVec2 point2)
{
  for (u32 i = 0; i != data.size(); ++i)
  {
    const auto angle = i * MathUtil::TAU / data.size();
    const auto intersection =
        GetRayLineIntersection(GetPointFromAngleAndLength(angle, 1.0), point1, point2);

    data[i] = std::max(data[i], intersection.value_or(data[i]));
  }
}

const ReshapableInput::CalibrationData& ReshapableInput::GetCalibrationData() const
{
  return m_calibration;
}

void ReshapableInput::SetCalibrationData(CalibrationData data)
{
  m_calibration = std::move(data);
}

const ReshapableInput::ReshapeData& ReshapableInput::GetCenter() const
{
  return m_center;
}

void ReshapableInput::SetCenter(ReshapableInput::ReshapeData center)
{
  m_center = center;
}

void ReshapableInput::LoadConfig(Common::IniFile::Section* section,
                                 const std::string& default_device, const std::string& base_name)
{
  ControlGroup::LoadConfig(section, default_device, base_name);

  const std::string group(base_name + name + '/');

  // Special handling for "Modifier" button "Range" settings which default to 50% instead of 100%.
  if (const auto* modifier_input = GetModifierInput())
  {
    section->Get(group + modifier_input->name + "/Range", &modifier_input->control_ref->range,
                 50.0);
    modifier_input->control_ref->range /= 100;
  }

  std::string load_str;
  section->Get(group + CALIBRATION_CONFIG_NAME, &load_str, "");
  const auto load_data = SplitString(load_str, ' ');

  m_calibration.assign(load_data.size(), CALIBRATION_DEFAULT_VALUE);

  auto it = load_data.begin();
  for (auto& sample : m_calibration)
  {
    if (TryParse(*(it++), &sample))
      sample /= CALIBRATION_CONFIG_SCALE;
  }

  section->Get(group + CENTER_CONFIG_NAME, &load_str, "");
  const auto center_data = SplitString(load_str, ' ');

  m_center = Common::DVec2();

  if (center_data.size() == 2)
  {
    if (TryParse(center_data[0], &m_center.x))
      m_center.x /= CENTER_CONFIG_SCALE;

    if (TryParse(center_data[1], &m_center.y))
      m_center.y /= CENTER_CONFIG_SCALE;
  }
}

void ReshapableInput::SaveConfig(Common::IniFile::Section* section,
                                 const std::string& default_device, const std::string& base_name)
{
  ControlGroup::SaveConfig(section, default_device, base_name);

  const std::string group(base_name + name + '/');

  // Special handling for "Modifier" button "Range" settings which default to 50% instead of 100%.
  if (const auto* modifier_input = GetModifierInput())
  {
    section->Set(group + modifier_input->name + "/Range", modifier_input->control_ref->range * 100,
                 50.0);
  }

  std::vector<std::string> save_data(m_calibration.size());
  std::transform(
      m_calibration.begin(), m_calibration.end(), save_data.begin(),
      [](ControlState val) { return fmt::format("{:.2f}", val * CALIBRATION_CONFIG_SCALE); });
  section->Set(group + CALIBRATION_CONFIG_NAME, fmt::to_string(fmt::join(save_data, " ")), "");

  // Save center value.
  static constexpr char center_format[] = "{:.2f} {:.2f}";
  const auto center_data = fmt::format(center_format, m_center.x * CENTER_CONFIG_SCALE,
                                       m_center.y * CENTER_CONFIG_SCALE);
  section->Set(group + CENTER_CONFIG_NAME, center_data, fmt::format(center_format, 0.0, 0.0));
}

ReshapableInput::ReshapeData ReshapableInput::Reshape(ControlState x, ControlState y,
                                                      ControlState modifier,
                                                      ControlState clamp) const
{
  x -= m_center.x;
  y -= m_center.y;

  // We run this even if both x and y will be zero.
  // In that case, std::atan2(0, 0) returns a valid non-NaN value, but the exact value
  // (which depends on the signs of x and y) does not matter here as dist is zero

  // TODO: make the AtAngle functions work with negative angles:
  ControlState angle = std::atan2(y, x) + MathUtil::TAU;

  const ControlState input_max_dist = GetInputRadiusAtAngle(angle);
  ControlState gate_max_dist = GetGateRadiusAtAngle(angle);

  // If input radius (from calibration) is zero apply no scaling to prevent division by zero.
  const ControlState max_dist = input_max_dist ? input_max_dist : gate_max_dist;

  ControlState dist = Common::DVec2{x, y}.Length() / max_dist;

  const double virtual_notch_size = GetVirtualNotchSize();

  if (virtual_notch_size > 0.0 && dist >= MINIMUM_NOTCH_DISTANCE)
  {
    angle = GetNearestNotch(angle, virtual_notch_size);
    gate_max_dist = GetGateRadiusAtAngle(angle);
  }

  // If the modifier is pressed, scale the distance by the modifier's value.
  // This is affected by the modifier's "range" setting which defaults to 50%.
  if (modifier)
  {
    dist *= modifier;
  }

  // Apply deadzone as a percentage of the user-defined calibration shape/size:
  dist = ApplyDeadzone(dist, GetDeadzonePercentage());

  // Scale to the gate shape/radius:
  dist *= gate_max_dist;

  return {std::clamp(std::cos(angle) * dist, -clamp, clamp),
          std::clamp(std::sin(angle) * dist, -clamp, clamp)};
}

Control* ReshapableInput::GetModifierInput() const
{
  return nullptr;
}

}  // namespace ControllerEmu