#define _XOPEN_SOURCE

#include <dirent.h>
#include <endian.h>
#include <err.h>
#include <fcntl.h>
#include <fnmatch.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "waypad.h"
#include "util.h"

struct gamepads gamepads;
static struct database {
	size_t len, cap;
 	struct mapping *mappings;
} database;

static const char *button_str_map[] = {
	[GAMEPAD_BUTTON_A] = "a",
	[GAMEPAD_BUTTON_B] = "b",
	[GAMEPAD_BUTTON_X] = "x",
	[GAMEPAD_BUTTON_Y] = "y",
	[GAMEPAD_BUTTON_BACK] = "back",
	[GAMEPAD_BUTTON_GUIDE] = "guide",
	[GAMEPAD_BUTTON_START] = "start",
	[GAMEPAD_BUTTON_LEFTSTICK] = "leftstick",
	[GAMEPAD_BUTTON_RIGHTSTICK] = "rightstick",
	[GAMEPAD_BUTTON_LEFTSHOULDER] = "leftshoulder",
	[GAMEPAD_BUTTON_RIGHTSHOULDER] = "rightshoulder",
	[GAMEPAD_BUTTON_DPAD_UP] = "dpup",
	[GAMEPAD_BUTTON_DPAD_DOWN] = "dpdown",
	[GAMEPAD_BUTTON_DPAD_LEFT] = "dpleft",
	[GAMEPAD_BUTTON_DPAD_RIGHT] = "dpright",
	[GAMEPAD_BUTTON_MISC1] = "misc1",
	[GAMEPAD_BUTTON_PADDLE1] = "paddle1",
	[GAMEPAD_BUTTON_PADDLE2] = "paddle2",
	[GAMEPAD_BUTTON_PADDLE3] = "paddle3",
	[GAMEPAD_BUTTON_PADDLE4] = "paddle4",
	[GAMEPAD_BUTTON_TOUCHPAD] = "touchpad",
};

enum gamepad_button str_to_button(const char *str) {
	for (size_t i = 0; i < GAMEPAD_BUTTON_MAX; i++) {
		if (strcasecmp(str, button_str_map[i]) == 0)
			return i;
	}
	return GAMEPAD_BUTTON_INVALID;
}

const char *axis_str_map[] = {
	[GAMEPAD_AXIS_LEFTX] = "leftx",
	[GAMEPAD_AXIS_LEFTY] = "lefty",
	[GAMEPAD_AXIS_RIGHTX] = "rightx",
	[GAMEPAD_AXIS_RIGHTY] = "righty",
	[GAMEPAD_AXIS_TRIGGERLEFT] = "triggerleft",
	[GAMEPAD_AXIS_TRIGGERRIGHT] = "triggerright",
};

enum gamepad_axis str_to_axis(const char *str) {
	for (size_t i = 0; i < GAMEPAD_AXIS_MAX; i++) {
		if (strcasecmp(str, axis_str_map[i]) == 0)
			return i;
	}
	return GAMEPAD_AXIS_INVALID;
}

static struct guid parse_dev_guid(struct libevdev *dev) {
	return (struct guid) {
		.guid = {
			[0] = htole16(libevdev_get_id_bustype(dev)),
			[2] = htole16(libevdev_get_id_vendor(dev)),
			[4] = htole16(libevdev_get_id_product(dev)),
			[6] = htole16(libevdev_get_id_version(dev)),
		}
	};
}

static struct guid parse_str_guid(const char *str) {
	struct guid out = {};
	uint16_t guid[8] = {};

	sscanf(str, "%4hx%4hx%4hx%4hx%4hx%4hx%4hx%4hx",
		&guid[0], &guid[1], &guid[2], &guid[3],
		&guid[4], &guid[5], &guid[6], &guid[7]);

#if __BYTE_ORDER == __LITTLE_ENDIAN
	swab(guid, out.guid, sizeof(out.guid));
#endif

	return out;
}

static inline uint64_t fmix64(uint64_t value) {
	value ^= value >> 33;
	value *= 0xff51afd7ed558ccd;
	value ^= value >> 33;
	value *= 0xc4ceb9fe1a85ec53;
	value ^= value >> 33;

	return value;
}

static uint64_t hash_guid(struct guid *guid) {
	uint64_t hash = 0;
	for (size_t i = 0; i < 2; i += 4)
		hash ^= fmix64(((uint64_t)guid->guid[i] << 48)
			| ((uint64_t)guid->guid[i + 1] << 32)
			| (guid->guid[i + 2] << 16)
			| guid->guid[i + 3]);
	return hash;
}

static bool guid_cmp(struct guid *lhs, struct guid *rhs) {
	for (size_t i = 0; i < 8; i++)
		if (lhs->guid[i] != rhs->guid[i])
			return false;
	return true;
}

static struct mapping *add_mapping(struct mapping map);
static void realloc_mappings() {
	struct mapping *old_mappings = database.mappings;
	size_t items = database.len, cap = database.cap;

	database.mappings = calloc(database.cap *= 2, sizeof(*database.mappings));

	for (size_t i = 0; i < cap; i++) {
		if (!old_mappings[i].name)
			continue;

		add_mapping(old_mappings[i]);

		if (!--items)
			break;
	}
}

static struct mapping *find_mapping(struct guid *guid) {
	uint64_t hash = hash_guid(guid) % database.cap;
	struct mapping *mapping = NULL;

	mapping = &database.mappings[hash % database.cap];

	while (mapping->name) {
		if (guid_cmp(&mapping->guid, guid))
			break;
		mapping = &database.mappings[++hash % database.cap];
	}

	return mapping;
}

static struct mapping *add_mapping(struct mapping map) {
	struct mapping *mapping;

	if (database.len * 4 >= database.cap * 3)
		realloc_mappings();

	mapping = find_mapping(&map.guid);
	free(mapping->name);
	*mapping = map;
	database.len++;

	return mapping;
}

static void parse_mappings(struct mapping *mapping, char *field) {
	char *button = field, *symbol = strsep(&button, ":");
	if (!symbol || !button)
		return;

	switch (button[0]) {
	case 'b':
		enum gamepad_button btn = str_to_button(symbol);
		if (btn == GAMEPAD_BUTTON_INVALID)
			return;
		mapping->buttons[btn] = atoi(&button[1]);
		break;
	case 'a':
		enum gamepad_axis axis = str_to_axis(symbol);
		if (axis == GAMEPAD_AXIS_INVALID)
			return;
		mapping->axis[axis] = atoi(&button[1]);
		break;
	case 'h':
		break;
	}
}

static bool load_database() {
	FILE *fp = fopen("/home/navi/.config/waypad/gamecontrollerdb.txt", "r");
	char *line = NULL;
	ssize_t len;
	size_t size;

	if (!fp)
		return false;

	database.cap = 32;
	database.mappings = calloc(database.cap, sizeof(*database.mappings));

	while ((len = getline(&line, &size, fp)) != -1) {
		char *name, *field, *rest = line;
		struct mapping *mapping;
		struct guid guid;

		if (len < 1 || line[0] == '#')
			continue;

		line[len--] = '\0';

		if (!(field = strsep(&rest, ",")))
			continue;
		guid = parse_str_guid(field);
		if (!(field = strsep(&rest, ",")))
			continue;
		name = strdup(field);

		mapping = add_mapping((struct mapping) {
			.name = name,
			.guid = guid,
		});

		while ((field = strsep(&rest, ",")))
			parse_mappings(mapping, field);
	}

	free(line);
	fclose(fp);
	return true;
}

bool load_gamepads() {
	if (!load_database())
		return false;

	DIR *input_dir = opendir("/dev/input/by-id");
	struct dirent *dirent;

	if (!input_dir)
		return false;

	gamepads.cap = 5;
	gamepads.loaded = calloc(gamepads.cap, sizeof(*gamepads.loaded));

	while ((dirent = readdir(input_dir))) {
		struct libevdev *dev;
		struct gamepad *pad;
		int gamepad_fd;

		if (dirent->d_name[0] == '.')
			continue;
		if (fnmatch("*-event-joystick", dirent->d_name, FNM_PATHNAME) != 0)
			continue;

		warnx("opening event joystick /dev/input/by-id/%s.", dirent->d_name);
		if ((gamepad_fd = openat(dirfd(input_dir), dirent->d_name, O_RDONLY | O_NONBLOCK | O_CLOEXEC)) == -1) {
			warnx("failed to open /dev/input/by-id/%s", dirent->d_name);
			continue;
		}

		warnx("opened /dev/input/by-id/%s on fd %d.", dirent->d_name, gamepad_fd);

		if (libevdev_new_from_fd(gamepad_fd, &dev) < 0) {
			warnx("failed to create libevdev from fd %d", gamepad_fd);
			close(gamepad_fd);
			continue;
		}

		struct guid guid = parse_dev_guid(dev);
		struct mapping *mapping = find_mapping(&guid);

		if (!mapping->name)
			continue;

		if (gamepads.len == gamepads.cap)
			gamepads.loaded = realloc(gamepads.loaded, (gamepads.cap *= 2) * sizeof(gamepads.loaded));
		pad = &gamepads.loaded[gamepads.len++];
		pad->mapping = mapping;
		pad->dev = dev;

		size_t nbuttons = 0;
		for (size_t i = BTN_JOYSTICK; i < KEY_MAX; ++i) {
			if (!libevdev_has_event_code(dev, EV_KEY, i))
				continue;
			warnx("%zu - Joystick has button: 0x%zu - %s", nbuttons, i, libevdev_event_code_get_name(EV_KEY, i));
			pad->map.button[i - BTN_MISC] = nbuttons++;
		}
		for (size_t i = BTN_MISC; i < BTN_JOYSTICK; ++i) {
			if (!libevdev_has_event_code(dev, EV_KEY, i))
				continue;
			warnx("%zu - Joystick has button: 0x%zu - %s", nbuttons, i, libevdev_event_code_get_name(EV_KEY, i));
			pad->map.button[i - BTN_MISC] = nbuttons++;
		}

		pad->nbuttons = nbuttons;
		pad->modes.base.buttons = calloc(nbuttons, sizeof(*pad->modes.base.buttons));

		size_t naxis = 0;
		for (size_t i = 0; i < ABS_MAX; ++i) {
			if (!libevdev_has_event_code(dev, EV_ABS, i))
				continue;
			const struct input_absinfo *absinfo = libevdev_get_abs_info(dev, i);
			warnx("%zu - Joystick has absolute axis: 0x%.2lx - %s", naxis, i, libevdev_event_code_get_name(EV_ABS, i));
			warnx("Values = { %d, %d, %d, %d, %d }", absinfo->value,
				absinfo->minimum, absinfo->maximum, absinfo->fuzz, absinfo->flat);
			pad->map.axis[i] = naxis++;
		}

		pad->naxis = naxis;
		pad->modes.base.axis = calloc(naxis, sizeof(*pad->modes.base.axis));

		pad->modes.current = &pad->modes.base;
		pad->modes.all = calloc((pad->modes.cap = 2), sizeof(*pad->modes.all));
	}

	closedir(input_dir);

	return true;
}

struct gamepad *find_gamepad(const char *name) {
	for (size_t i = 0; i < gamepads.len; i++)
		if (strcmp(name, gamepads.loaded[i].mapping->name) == 0)
			return &gamepads.loaded[i];
	return NULL;
}

struct mode *get_make_mode(struct gamepad *pad, const char *name) {
	for (size_t i = 0; i < pad->modes.len; i++)
		if (strcmp(name, pad->modes.all[i].name) == 0)
			return &pad->modes.all[i];
	if (pad->modes.cap == pad->modes.len)
		pad->modes.all = realloc(pad->modes.all, (pad->modes.cap *= 2) * sizeof(pad->modes.all));
	struct mode *mode = &pad->modes.all[pad->modes.len++];
	mode->name = strdup(name);
	mode->buttons = calloc(pad->nbuttons, sizeof(*mode->buttons));
	mode->axis = calloc(pad->naxis, sizeof(*mode->axis));
	return mode;
}

static void free_mode(struct mode *mode, size_t nbuttons) {
	for (size_t i = 0; i < nbuttons; i++) {
		switch (mode->buttons[i].type) {
		case ACTION_EXEC:
			for (char **arg = mode->buttons[i].exec; *arg; arg++)
				free(*arg);
			free(mode->buttons[i].exec);
		case ACTION_MODE:
		case ACTION_NONE:
		case ACTION_KEY:
		case ACTION_MOUSE:
		case ACTION_CLICK:
			break;
		}
	}
}

static void free_gamepad(struct gamepad *pad) {
	for (size_t i = 0; i < pad->modes.len; i++)
		free_mode(&pad->modes.all[i], pad->nbuttons);
}

void free_gamepads() {
	for (size_t i = 0; i < gamepads.len; i++)
		free_gamepad(&gamepads.loaded[i]);

	for (size_t i = 0; i < database.cap; i++) {
		if (!database.len)
			break;
		if (!database.mappings[i].name)
			continue;
		free(database.mappings[i].name);
		database.len--;
	}
}