/*************************************************************************/
/*  joypad_linux.cpp                                                     */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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/*************************************************************************/

#ifdef JOYDEV_ENABLED

#include "joypad_linux.h"

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/input.h>
#include <unistd.h>

#ifdef UDEV_ENABLED
#include "libudev-so_wrap.h"
#endif

#define LONG_BITS (sizeof(long) * 8)
#define test_bit(nr, addr) (((1UL << ((nr) % LONG_BITS)) & ((addr)[(nr) / LONG_BITS])) != 0)
#define NBITS(x) ((((x)-1) / LONG_BITS) + 1)

#ifdef UDEV_ENABLED
static const char *ignore_str = "/dev/input/js";
#endif

JoypadLinux::Joypad::~Joypad() {
	for (int i = 0; i < MAX_ABS; i++) {
		if (abs_info[i]) {
			memdelete(abs_info[i]);
		}
	}
}

void JoypadLinux::Joypad::reset() {
	dpad = HatMask::CENTER;
	fd = -1;
	for (int i = 0; i < MAX_ABS; i++) {
		abs_map[i] = -1;
		curr_axis[i] = 0;
	}
}

JoypadLinux::JoypadLinux(Input *in) {
#ifdef UDEV_ENABLED
#ifdef DEBUG_ENABLED
	int dylibloader_verbose = 1;
#else
	int dylibloader_verbose = 0;
#endif
	use_udev = initialize_libudev(dylibloader_verbose) == 0;
	if (use_udev) {
		print_verbose("JoypadLinux: udev enabled and loaded successfully.");
	} else {
		print_verbose("JoypadLinux: udev enabled, but couldn't be loaded. Falling back to /dev/input to detect joypads.");
	}
#else
	print_verbose("JoypadLinux: udev disabled, parsing /dev/input to detect joypads.");
#endif
	input = in;
	joy_thread.start(joy_thread_func, this);
}

JoypadLinux::~JoypadLinux() {
	exit_monitor.set();
	joy_thread.wait_to_finish();
	close_joypad();
}

void JoypadLinux::joy_thread_func(void *p_user) {
	if (p_user) {
		JoypadLinux *joy = (JoypadLinux *)p_user;
		joy->run_joypad_thread();
	}
}

void JoypadLinux::run_joypad_thread() {
#ifdef UDEV_ENABLED
	if (use_udev) {
		udev *_udev = udev_new();
		if (!_udev) {
			use_udev = false;
			ERR_PRINT("Failed getting an udev context, falling back to parsing /dev/input.");
			monitor_joypads();
		} else {
			enumerate_joypads(_udev);
			monitor_joypads(_udev);
			udev_unref(_udev);
		}
	} else {
		monitor_joypads();
	}
#else
	monitor_joypads();
#endif
}

#ifdef UDEV_ENABLED
void JoypadLinux::enumerate_joypads(udev *p_udev) {
	udev_enumerate *enumerate;
	udev_list_entry *devices, *dev_list_entry;
	udev_device *dev;

	enumerate = udev_enumerate_new(p_udev);
	udev_enumerate_add_match_subsystem(enumerate, "input");

	udev_enumerate_scan_devices(enumerate);
	devices = udev_enumerate_get_list_entry(enumerate);
	udev_list_entry_foreach(dev_list_entry, devices) {
		const char *path = udev_list_entry_get_name(dev_list_entry);
		dev = udev_device_new_from_syspath(p_udev, path);
		const char *devnode = udev_device_get_devnode(dev);

		if (devnode) {
			String devnode_str = devnode;
			if (devnode_str.find(ignore_str) == -1) {
				MutexLock lock(joy_mutex);
				open_joypad(devnode);
			}
		}
		udev_device_unref(dev);
	}
	udev_enumerate_unref(enumerate);
}

void JoypadLinux::monitor_joypads(udev *p_udev) {
	udev_device *dev = nullptr;
	udev_monitor *mon = udev_monitor_new_from_netlink(p_udev, "udev");
	udev_monitor_filter_add_match_subsystem_devtype(mon, "input", nullptr);
	udev_monitor_enable_receiving(mon);
	int fd = udev_monitor_get_fd(mon);

	while (!exit_monitor.is_set()) {
		fd_set fds;
		struct timeval tv;
		int ret;

		FD_ZERO(&fds);
		FD_SET(fd, &fds);
		tv.tv_sec = 0;
		tv.tv_usec = 0;

		ret = select(fd + 1, &fds, nullptr, nullptr, &tv);

		/* Check if our file descriptor has received data. */
		if (ret > 0 && FD_ISSET(fd, &fds)) {
			/* Make the call to receive the device.
			   select() ensured that this will not block. */
			dev = udev_monitor_receive_device(mon);

			if (dev && udev_device_get_devnode(dev) != nullptr) {
				MutexLock lock(joy_mutex);
				String action = udev_device_get_action(dev);
				const char *devnode = udev_device_get_devnode(dev);
				if (devnode) {
					String devnode_str = devnode;
					if (devnode_str.find(ignore_str) == -1) {
						if (action == "add") {
							open_joypad(devnode);
						} else if (String(action) == "remove") {
							close_joypad(get_joy_from_path(devnode));
						}
					}
				}

				udev_device_unref(dev);
			}
		}
		usleep(50000);
	}
	udev_monitor_unref(mon);
}
#endif

void JoypadLinux::monitor_joypads() {
	while (!exit_monitor.is_set()) {
		{
			MutexLock lock(joy_mutex);

			DIR *input_directory;
			input_directory = opendir("/dev/input");
			if (input_directory) {
				struct dirent *current;
				char fname[64];

				while ((current = readdir(input_directory)) != nullptr) {
					if (strncmp(current->d_name, "event", 5) != 0) {
						continue;
					}
					sprintf(fname, "/dev/input/%.*s", 16, current->d_name);
					if (attached_devices.find(fname) == -1) {
						open_joypad(fname);
					}
				}
			}
			closedir(input_directory);
		}
		usleep(1000000); // 1s
	}
}

int JoypadLinux::get_joy_from_path(String p_path) const {
	for (int i = 0; i < JOYPADS_MAX; i++) {
		if (joypads[i].devpath == p_path) {
			return i;
		}
	}
	return -2;
}

void JoypadLinux::close_joypad(int p_id) {
	if (p_id == -1) {
		for (int i = 0; i < JOYPADS_MAX; i++) {
			close_joypad(i);
		};
		return;
	} else if (p_id < 0) {
		return;
	}

	Joypad &joy = joypads[p_id];

	if (joy.fd != -1) {
		close(joy.fd);
		joy.fd = -1;
		attached_devices.remove_at(attached_devices.find(joy.devpath));
		input->joy_connection_changed(p_id, false, "");
	};
}

static String _hex_str(uint8_t p_byte) {
	static const char *dict = "0123456789abcdef";
	char ret[3];
	ret[2] = 0;

	ret[0] = dict[p_byte >> 4];
	ret[1] = dict[p_byte & 0xF];

	return ret;
}

void JoypadLinux::setup_joypad_properties(int p_id) {
	Joypad *joy = &joypads[p_id];

	unsigned long keybit[NBITS(KEY_MAX)] = { 0 };
	unsigned long absbit[NBITS(ABS_MAX)] = { 0 };

	int num_buttons = 0;
	int num_axes = 0;

	if ((ioctl(joy->fd, EVIOCGBIT(EV_KEY, sizeof(keybit)), keybit) < 0) ||
			(ioctl(joy->fd, EVIOCGBIT(EV_ABS, sizeof(absbit)), absbit) < 0)) {
		return;
	}
	for (int i = BTN_JOYSTICK; i < KEY_MAX; ++i) {
		if (test_bit(i, keybit)) {
			joy->key_map[i] = num_buttons++;
		}
	}
	for (int i = BTN_MISC; i < BTN_JOYSTICK; ++i) {
		if (test_bit(i, keybit)) {
			joy->key_map[i] = num_buttons++;
		}
	}
	for (int i = 0; i < ABS_MISC; ++i) {
		/* Skip hats */
		if (i == ABS_HAT0X) {
			i = ABS_HAT3Y;
			continue;
		}
		if (test_bit(i, absbit)) {
			joy->abs_map[i] = num_axes++;
			joy->abs_info[i] = memnew(input_absinfo);
			if (ioctl(joy->fd, EVIOCGABS(i), joy->abs_info[i]) < 0) {
				memdelete(joy->abs_info[i]);
				joy->abs_info[i] = nullptr;
			}
		}
	}

	joy->force_feedback = false;
	joy->ff_effect_timestamp = 0;
	unsigned long ffbit[NBITS(FF_CNT)];
	if (ioctl(joy->fd, EVIOCGBIT(EV_FF, sizeof(ffbit)), ffbit) != -1) {
		if (test_bit(FF_RUMBLE, ffbit)) {
			joy->force_feedback = true;
		}
	}
}

void JoypadLinux::open_joypad(const char *p_path) {
	int joy_num = input->get_unused_joy_id();
	int fd = open(p_path, O_RDWR | O_NONBLOCK);
	if (fd != -1 && joy_num != -1) {
		unsigned long evbit[NBITS(EV_MAX)] = { 0 };
		unsigned long keybit[NBITS(KEY_MAX)] = { 0 };
		unsigned long absbit[NBITS(ABS_MAX)] = { 0 };

		// add to attached devices so we don't try to open it again
		attached_devices.push_back(String(p_path));

		if ((ioctl(fd, EVIOCGBIT(0, sizeof(evbit)), evbit) < 0) ||
				(ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(keybit)), keybit) < 0) ||
				(ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(absbit)), absbit) < 0)) {
			close(fd);
			return;
		}

		// Check if the device supports basic gamepad events
		bool has_abs_left = (test_bit(ABS_X, absbit) && test_bit(ABS_Y, absbit));
		bool has_abs_right = (test_bit(ABS_RX, absbit) && test_bit(ABS_RY, absbit));
		if (!(test_bit(EV_KEY, evbit) && test_bit(EV_ABS, evbit) && (has_abs_left || has_abs_right))) {
			close(fd);
			return;
		}

		char uid[128];
		char namebuf[128];
		String name = "";
		input_id inpid;
		if (ioctl(fd, EVIOCGNAME(sizeof(namebuf)), namebuf) >= 0) {
			name = namebuf;
		}

		if (ioctl(fd, EVIOCGID, &inpid) < 0) {
			close(fd);
			return;
		}

		joypads[joy_num].reset();

		Joypad &joy = joypads[joy_num];
		joy.fd = fd;
		joy.devpath = String(p_path);
		setup_joypad_properties(joy_num);
		sprintf(uid, "%04x%04x", BSWAP16(inpid.bustype), 0);
		if (inpid.vendor && inpid.product && inpid.version) {
			uint16_t vendor = BSWAP16(inpid.vendor);
			uint16_t product = BSWAP16(inpid.product);
			uint16_t version = BSWAP16(inpid.version);

			sprintf(uid + String(uid).length(), "%04x%04x%04x%04x%04x%04x", vendor, 0, product, 0, version, 0);
			input->joy_connection_changed(joy_num, true, name, uid);
		} else {
			String uidname = uid;
			int uidlen = MIN(name.length(), 11);
			for (int i = 0; i < uidlen; i++) {
				uidname = uidname + _hex_str(name[i]);
			}
			uidname += "00";
			input->joy_connection_changed(joy_num, true, name, uidname);
		}
	}
}

void JoypadLinux::joypad_vibration_start(int p_id, float p_weak_magnitude, float p_strong_magnitude, float p_duration, uint64_t p_timestamp) {
	Joypad &joy = joypads[p_id];
	if (!joy.force_feedback || joy.fd == -1 || p_weak_magnitude < 0.f || p_weak_magnitude > 1.f || p_strong_magnitude < 0.f || p_strong_magnitude > 1.f) {
		return;
	}
	if (joy.ff_effect_id != -1) {
		joypad_vibration_stop(p_id, p_timestamp);
	}

	struct ff_effect effect;
	effect.type = FF_RUMBLE;
	effect.id = -1;
	effect.u.rumble.weak_magnitude = floor(p_weak_magnitude * (float)0xffff);
	effect.u.rumble.strong_magnitude = floor(p_strong_magnitude * (float)0xffff);
	effect.replay.length = floor(p_duration * 1000);
	effect.replay.delay = 0;

	if (ioctl(joy.fd, EVIOCSFF, &effect) < 0) {
		return;
	}

	struct input_event play;
	play.type = EV_FF;
	play.code = effect.id;
	play.value = 1;
	if (write(joy.fd, (const void *)&play, sizeof(play)) == -1) {
		print_verbose("Couldn't write to Joypad device.");
	}

	joy.ff_effect_id = effect.id;
	joy.ff_effect_timestamp = p_timestamp;
}

void JoypadLinux::joypad_vibration_stop(int p_id, uint64_t p_timestamp) {
	Joypad &joy = joypads[p_id];
	if (!joy.force_feedback || joy.fd == -1 || joy.ff_effect_id == -1) {
		return;
	}

	if (ioctl(joy.fd, EVIOCRMFF, joy.ff_effect_id) < 0) {
		return;
	}

	joy.ff_effect_id = -1;
	joy.ff_effect_timestamp = p_timestamp;
}

float JoypadLinux::axis_correct(const input_absinfo *p_abs, int p_value) const {
	int min = p_abs->minimum;
	int max = p_abs->maximum;
	// Convert to a value between -1.0f and 1.0f.
	return 2.0f * (p_value - min) / (max - min) - 1.0f;
}

void JoypadLinux::process_joypads() {
	if (joy_mutex.try_lock() != OK) {
		return;
	}
	for (int i = 0; i < JOYPADS_MAX; i++) {
		if (joypads[i].fd == -1) {
			continue;
		}

		input_event events[32];
		Joypad *joy = &joypads[i];

		int len;

		while ((len = read(joy->fd, events, (sizeof events))) > 0) {
			len /= sizeof(events[0]);
			for (int j = 0; j < len; j++) {
				input_event &ev = events[j];

				// ev may be tainted and out of MAX_KEY range, which will cause
				// joy->key_map[ev.code] to crash
				if (ev.code >= MAX_KEY) {
					return;
				}

				switch (ev.type) {
					case EV_KEY:
						input->joy_button(i, (JoyButton)joy->key_map[ev.code], ev.value);
						break;

					case EV_ABS:

						switch (ev.code) {
							case ABS_HAT0X:
								if (ev.value != 0) {
									if (ev.value < 0) {
										joy->dpad = (HatMask)((joy->dpad | HatMask::LEFT) & ~HatMask::RIGHT);
									} else {
										joy->dpad = (HatMask)((joy->dpad | HatMask::RIGHT) & ~HatMask::LEFT);
									}
								} else {
									joy->dpad &= ~(HatMask::LEFT | HatMask::RIGHT);
								}

								input->joy_hat(i, (HatMask)joy->dpad);
								break;

							case ABS_HAT0Y:
								if (ev.value != 0) {
									if (ev.value < 0) {
										joy->dpad = (HatMask)((joy->dpad | HatMask::UP) & ~HatMask::DOWN);
									} else {
										joy->dpad = (HatMask)((joy->dpad | HatMask::DOWN) & ~HatMask::UP);
									}
								} else {
									joy->dpad &= ~(HatMask::UP | HatMask::DOWN);
								}

								input->joy_hat(i, (HatMask)joy->dpad);
								break;

							default:
								if (ev.code >= MAX_ABS) {
									return;
								}
								if (joy->abs_map[ev.code] != -1 && joy->abs_info[ev.code]) {
									float value = axis_correct(joy->abs_info[ev.code], ev.value);
									joy->curr_axis[joy->abs_map[ev.code]] = value;
								}
								break;
						}
						break;
				}
			}
		}
		for (int j = 0; j < MAX_ABS; j++) {
			int index = joy->abs_map[j];
			if (index != -1) {
				input->joy_axis(i, (JoyAxis)index, joy->curr_axis[index]);
			}
		}
		if (len == 0 || (len < 0 && errno != EAGAIN)) {
			close_joypad(i);
		};

		if (joy->force_feedback) {
			uint64_t timestamp = input->get_joy_vibration_timestamp(i);
			if (timestamp > joy->ff_effect_timestamp) {
				Vector2 strength = input->get_joy_vibration_strength(i);
				float duration = input->get_joy_vibration_duration(i);
				if (strength.x == 0 && strength.y == 0) {
					joypad_vibration_stop(i, timestamp);
				} else {
					joypad_vibration_start(i, strength.x, strength.y, duration, timestamp);
				}
			}
		}
	}
	joy_mutex.unlock();
}
#endif