// Copyright 2013 Max Eliaser
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <cmath>
#include <cstring>
#include <X11/XKBlib.h>

#include "InputCommon/ControllerInterface/Xlib/XInput2.h"

// This is an input plugin using the XInput 2.0 extension to the X11 protocol,
// loosely based on the old XLib plugin. (Has nothing to do with the XInput
// API on Windows.)

// This plugin creates one KeyboardMouse object for each master pointer/
// keyboard pair. Each KeyboardMouse object exports four types of controls:
// *    Mouse button controls: hardcoded at five of them, but could be made to
//      support infinitely many mouse buttons in theory; XInput2 has no limit.
// *    Mouse cursor controls: one for each cardinal direction. Calculated by
//      comparing the absolute position of the mouse pointer on screen to the
//      center of the emulator window.
// *    Mouse axis controls: one for each cardinal direction. Calculated using
//      a running average of relative mouse motion on each axis.
// *    Key controls: these correspond to a limited subset of the keyboard
//      keys.


// Mouse axis control tuning. Unlike absolute mouse position, relative mouse
// motion data needs to be tweaked and smoothed out a bit to be usable.

// Mouse axis control output is simply divided by this number. In practice,
// that just means you can use a smaller "dead zone" if you bind axis controls
// to a joystick. No real need to make this customizable.
#define MOUSE_AXIS_SENSITIVITY 8.0f

// The mouse axis controls use a weighted running average. Each frame, the new
// value is the average of the old value and the amount of relative mouse
// motion during that frame. The old value is weighted by a ratio of
// MOUSE_AXIS_SMOOTHING:1 compared to the new value. Increasing
// MOUSE_AXIS_SMOOTHING makes the controls smoother, decreasing it makes them
// more responsive. This might be useful as a user-customizable option.
#define MOUSE_AXIS_SMOOTHING 1.5f

namespace ciface
{
namespace XInput2
{

// This function will add zero or more KeyboardMouse objects to devices.
void Init(std::vector<Core::Device*>& devices, void* const hwnd)
{
	Display* dpy = XOpenDisplay(nullptr);

	// xi_opcode is important; it will be used to identify XInput events by
	// the polling loop in UpdateInput.
	int xi_opcode, event, error;

	// verify that the XInput extension is available
	if (!XQueryExtension(dpy, "XInputExtension", &xi_opcode, &event, &error))
		return;

	// verify that the XInput extension is at at least version 2.0
	int major = 2, minor = 0;

	if (XIQueryVersion(dpy, &major, &minor) != Success)
		return;

	// register all master devices with Dolphin

	XIDeviceInfo* all_masters;
	XIDeviceInfo* current_master;
	int           num_masters;

	all_masters = XIQueryDevice(dpy, XIAllMasterDevices, &num_masters);

	for (int i = 0; i < num_masters; i++)
	{
		current_master = &all_masters[i];
		if (current_master->use == XIMasterPointer)
			// Since current_master is a master pointer, its attachment must
			// be a master keyboard.
			devices.push_back(new KeyboardMouse((Window)hwnd, xi_opcode, current_master->deviceid, current_master->attachment));
	}

	XCloseDisplay(dpy);

	XIFreeDeviceInfo(all_masters);
}

// Apply the event mask to the device and all its slaves. Only used in the
// constructor. Remember, each KeyboardMouse has its own copy of the event
// stream, which is how multiple event masks can "coexist."
void KeyboardMouse::SelectEventsForDevice(Window window, XIEventMask *mask, int deviceid)
{
	// Set the event mask for the master device.
	mask->deviceid = deviceid;
	XISelectEvents(m_display, window, mask, 1);

	// Query all the master device's slaves and set the same event mask for
	// those too. There are two reasons we want to do this. For mouse devices,
	// we want the raw motion events, and only slaves (i.e. physical hardware
	// devices) emit those. For keyboard devices, selecting slaves avoids
	// dealing with key focus.

	XIDeviceInfo* all_slaves;
	XIDeviceInfo* current_slave;
	int           num_slaves;

	all_slaves = XIQueryDevice(m_display, XIAllDevices, &num_slaves);

	for (int i = 0; i < num_slaves; i++)
	{
		current_slave = &all_slaves[i];
		if ((current_slave->use != XISlavePointer && current_slave->use != XISlaveKeyboard) || current_slave->attachment != deviceid)
			continue;
		mask->deviceid = current_slave->deviceid;
		XISelectEvents(m_display, window, mask, 1);
	}

	XIFreeDeviceInfo(all_slaves);
}

KeyboardMouse::KeyboardMouse(Window window, int opcode, int pointer, int keyboard)
	: m_window(window), xi_opcode(opcode), pointer_deviceid(pointer), keyboard_deviceid(keyboard)
{
	memset(&m_state, 0, sizeof(m_state));

	// The cool thing about each KeyboardMouse object having its own Display
	// is that each one gets its own separate copy of the X11 event stream,
	// which it can individually filter to get just the events it's interested
	// in. So be aware that each KeyboardMouse object actually has its own X11
	// "context."
	m_display = XOpenDisplay(nullptr);

	int min_keycode, max_keycode;
	XDisplayKeycodes(m_display, &min_keycode, &max_keycode);

	int unused; // should always be 1
	XIDeviceInfo* pointer_device = XIQueryDevice(m_display, pointer_deviceid, &unused);
	name = std::string(pointer_device->name);
	XIFreeDeviceInfo(pointer_device);

	XIEventMask   mask;
	unsigned char mask_buf[(XI_LASTEVENT + 7)/8];

	mask.mask_len = sizeof(mask_buf);
	mask.mask = mask_buf;
	memset(mask_buf, 0, sizeof(mask_buf));

	XISetMask(mask_buf, XI_ButtonPress);
	XISetMask(mask_buf, XI_ButtonRelease);
	XISetMask(mask_buf, XI_RawMotion);
	XISetMask(mask_buf, XI_KeyPress);
	XISetMask(mask_buf, XI_KeyRelease);

	SelectEventsForDevice(DefaultRootWindow(m_display), &mask, pointer_deviceid);
	SelectEventsForDevice(DefaultRootWindow(m_display), &mask, keyboard_deviceid);

	// Keyboard Keys
	for (int i = min_keycode; i <= max_keycode; ++i)
	{
		Key* temp_key = new Key(m_display, i, m_state.keyboard);
		if (temp_key->m_keyname.length())
			AddInput(temp_key);
		else
			delete temp_key;
	}

	// Mouse Buttons
	for (int i = 0; i < 5; i++)
		AddInput(new Button(i, &m_state.buttons));

	// Mouse Cursor, X-/+ and Y-/+
	for (int i = 0; i != 4; ++i)
		AddInput(new Cursor(!!(i & 2), !!(i & 1), (i & 2) ? &m_state.cursor.y : &m_state.cursor.x));

	// Mouse Axis, X-/+ and Y-/+
	for (int i = 0; i != 4; ++i)
		AddInput(new Axis(!!(i & 2), !!(i & 1), (i & 2) ? &m_state.axis.y : &m_state.axis.x));
}

KeyboardMouse::~KeyboardMouse()
{
	XCloseDisplay(m_display);
}

// Update the mouse cursor controls
void KeyboardMouse::UpdateCursor()
{
	double root_x, root_y, win_x, win_y;
	Window root, child;

	// unused-- we're not interested in button presses here, as those are
	// updated using events
	XIButtonState button_state;
	XIModifierState mods;
	XIGroupState group;

	XIQueryPointer(m_display, pointer_deviceid, m_window, &root, &child, &root_x, &root_y, &win_x, &win_y, &button_state, &mods, &group);

	free (button_state.mask);

	XWindowAttributes win_attribs;
	XGetWindowAttributes(m_display, m_window, &win_attribs);

	// the mouse position as a range from -1 to 1
	m_state.cursor.x = win_x / (float)win_attribs.width * 2 - 1;
	m_state.cursor.y = win_y / (float)win_attribs.height * 2 - 1;
}

void KeyboardMouse::UpdateInput()
{
	XFlush(m_display);

	// Get the absolute position of the mouse pointer
	UpdateCursor();

	// for the axis controls
	float delta_x = 0.0f, delta_y = 0.0f;
	double delta_delta;

	// Iterate through the event queue - update the axis controls, mouse
	// button controls, and keyboard controls.
	XEvent event;
	while (XPending(m_display))
	{
		XNextEvent(m_display, &event);

		if (event.xcookie.type != GenericEvent)
			continue;
		if (event.xcookie.extension != xi_opcode)
			continue;
		if (!XGetEventData(m_display, &event.xcookie))
			continue;

		// only one of these will get used
		XIDeviceEvent* dev_event = (XIDeviceEvent*)event.xcookie.data;
		XIRawEvent* raw_event = (XIRawEvent*)event.xcookie.data;

		switch (event.xcookie.evtype)
		{
		case XI_ButtonPress:
			m_state.buttons |= 1<<(dev_event->detail-1);
			break;
		case XI_ButtonRelease:
			m_state.buttons &= ~(1<<(dev_event->detail-1));
			break;
		case XI_KeyPress:
			m_state.keyboard[dev_event->detail / 8] |= 1<<(dev_event->detail % 8);
			break;
		case XI_KeyRelease:
			m_state.keyboard[dev_event->detail / 8] &= ~(1<<(dev_event->detail % 8));
			break;
		case XI_RawMotion:
			// always safe because there is always at least one byte in
			// raw_event->valuators.mask, and if a bit is set in the mask,
			// then the value in raw_values is also available.
			if (XIMaskIsSet(raw_event->valuators.mask, 0))
			{
				delta_delta = raw_event->raw_values[0];
				// test for inf and nan
				if (delta_delta == delta_delta && 1+delta_delta != delta_delta)
					delta_x += delta_delta;
			}
			if (XIMaskIsSet(raw_event->valuators.mask, 1))
			{
				delta_delta = raw_event->raw_values[1];
				// test for inf and nan
				if (delta_delta == delta_delta && 1+delta_delta != delta_delta)
					delta_y += delta_delta;
			}
			break;
		}

		XFreeEventData(m_display, &event.xcookie);
	}

	// apply axis smoothing
	m_state.axis.x *= MOUSE_AXIS_SMOOTHING;
	m_state.axis.x += delta_x;
	m_state.axis.x /= MOUSE_AXIS_SMOOTHING+1.0f;
	m_state.axis.y *= MOUSE_AXIS_SMOOTHING;
	m_state.axis.y += delta_y;
	m_state.axis.y /= MOUSE_AXIS_SMOOTHING+1.0f;
}

std::string KeyboardMouse::GetName() const
{
	// This is the name string we got from the X server for this master
	// pointer/keyboard pair.
	return name;
}

std::string KeyboardMouse::GetSource() const
{
	return "XInput2";
}

int KeyboardMouse::GetId() const
{
	return -1;
}

KeyboardMouse::Key::Key(Display* const display, KeyCode keycode, const char* keyboard)
	: m_display(display), m_keyboard(keyboard), m_keycode(keycode)
{
	int i = 0;
	KeySym keysym = 0;
	do
	{
		keysym = XkbKeycodeToKeysym(m_display, keycode, i, 0);
		i++;
	}
	while (keysym == NoSymbol && i < 8);

	// Convert to upper case for the keyname
	if (keysym >= 97 && keysym <= 122)
		keysym -= 32;

	// 0x0110ffff is the top of the unicode character range according
	// to keysymdef.h although it is probably more than we need.
	if (keysym == NoSymbol || keysym > 0x0110ffff ||
		XKeysymToString(keysym) == nullptr)
		m_keyname = std::string();
	else
		m_keyname = std::string(XKeysymToString(keysym));
}

ControlState KeyboardMouse::Key::GetState() const
{
	return (m_keyboard[m_keycode / 8] & (1 << (m_keycode % 8))) != 0;
}

KeyboardMouse::Button::Button(unsigned int index, unsigned int* buttons)
	: m_buttons(buttons), m_index(index)
{
	// this will be a problem if we remove the hardcoded five-button limit
	name = std::string("Click ") + (char)('1' + m_index);
}

ControlState KeyboardMouse::Button::GetState() const
{
	return ((*m_buttons & (1 << m_index)) != 0);
}

KeyboardMouse::Cursor::Cursor(u8 index, bool positive, const float* cursor)
	: m_cursor(cursor), m_index(index), m_positive(positive)
{
	name = std::string("Cursor ") + (char)('X' + m_index) + (m_positive ? '+' : '-');
}

ControlState KeyboardMouse::Cursor::GetState() const
{
	return std::max(0.0f, *m_cursor / (m_positive ? 1.0f : -1.0f));
}

KeyboardMouse::Axis::Axis(u8 index, bool positive, const float* axis)
	: m_axis(axis), m_index(index), m_positive(positive)
{
	name = std::string("Axis ") + (char)('X' + m_index) + (m_positive ? '+' : '-');
}

ControlState KeyboardMouse::Axis::GetState() const
{
	return std::max(0.0f, *m_axis / (m_positive ? MOUSE_AXIS_SENSITIVITY : -MOUSE_AXIS_SENSITIVITY));
}

}
}