#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#include <assert.h>
#include <wayland-server.h>
#include <wlr/types/wlr_keyboard.h>
#include <wlr/interfaces/wlr_keyboard.h>
#include <wlr/util/log.h>
#include <wlr/util/signal.h>

int os_create_anonymous_file(off_t size);

static void keyboard_led_update(struct wlr_keyboard *keyboard) {
	if (keyboard->xkb_state == NULL) {
		return;
	}

	uint32_t leds = 0;
	for (uint32_t i = 0; i < WLR_LED_COUNT; ++i) {
		if (xkb_state_led_index_is_active(keyboard->xkb_state,
				keyboard->led_indexes[i])) {
			leds |= (1 << i);
		}
	}
	wlr_keyboard_led_update(keyboard, leds);
}

/**
 * Update the modifier state of the wlr-keyboard. Returns true if the modifier
 * state changed.
 */
static bool keyboard_modifier_update(struct wlr_keyboard *keyboard) {
	if (keyboard->xkb_state == NULL) {
		return false;
	}

	xkb_mod_mask_t depressed = xkb_state_serialize_mods(keyboard->xkb_state,
		XKB_STATE_MODS_DEPRESSED);
	xkb_mod_mask_t latched = xkb_state_serialize_mods(keyboard->xkb_state,
		XKB_STATE_MODS_LATCHED);
	xkb_mod_mask_t locked = xkb_state_serialize_mods(keyboard->xkb_state,
		XKB_STATE_MODS_LOCKED);
	xkb_mod_mask_t group = xkb_state_serialize_layout(keyboard->xkb_state,
		XKB_STATE_LAYOUT_EFFECTIVE);
	if (depressed == keyboard->modifiers.depressed &&
			latched == keyboard->modifiers.latched &&
			locked == keyboard->modifiers.locked &&
			group == keyboard->modifiers.group) {
		return false;
	}

	keyboard->modifiers.depressed = depressed;
	keyboard->modifiers.latched = latched;
	keyboard->modifiers.locked = locked;
	keyboard->modifiers.group = group;

	return true;
}

// https://www.geeksforgeeks.org/move-zeroes-end-array/
static size_t push_zeroes_to_end(uint32_t arr[], size_t n) {
	size_t count = 0;

	for (size_t i = 0; i < n; i++) {
		if (arr[i] != 0) {
			arr[count++] = arr[i];
		}
	}

	size_t ret = count;

	while (count < n) {
		arr[count++] = 0;
	}

	return ret;
}

static void keyboard_key_update(struct wlr_keyboard *keyboard,
		struct wlr_event_keyboard_key *event) {
	bool found = false;
	size_t i = 0;
	for (; i < keyboard->num_keycodes; ++i) {
		if (keyboard->keycodes[i] == event->keycode) {
			found = true;
			break;
		}
	}

	if (event->state == WLR_KEY_PRESSED && !found &&
			keyboard->num_keycodes < WLR_KEYBOARD_KEYS_CAP) {
		keyboard->keycodes[keyboard->num_keycodes++] = event->keycode;
	}
	if (event->state == WLR_KEY_RELEASED && found) {
		keyboard->keycodes[i] = 0;
		keyboard->num_keycodes = push_zeroes_to_end(keyboard->keycodes, WLR_KEYBOARD_KEYS_CAP);
	}

	assert(keyboard->num_keycodes <= WLR_KEYBOARD_KEYS_CAP);
}

void wlr_keyboard_notify_modifiers(struct wlr_keyboard *keyboard,
		uint32_t mods_depressed, uint32_t mods_latched, uint32_t mods_locked,
		uint32_t group) {
	if (keyboard->xkb_state == NULL) {
		return;
	}
	xkb_state_update_mask(keyboard->xkb_state, mods_depressed, mods_latched,
		mods_locked, 0, 0, group);

	bool updated = keyboard_modifier_update(keyboard);
	if (updated) {
		wlr_signal_emit_safe(&keyboard->events.modifiers, keyboard);
	}
}

void wlr_keyboard_notify_key(struct wlr_keyboard *keyboard,
		struct wlr_event_keyboard_key *event) {
	if (keyboard->xkb_state == NULL) {
		return;
	}
	if (event->update_state) {
		uint32_t keycode = event->keycode + 8;
		xkb_state_update_key(keyboard->xkb_state, keycode,
			event->state == WLR_KEY_PRESSED ? XKB_KEY_DOWN : XKB_KEY_UP);
	}
	keyboard_led_update(keyboard);

	bool updated = keyboard_modifier_update(keyboard);
	if (updated) {
		wlr_signal_emit_safe(&keyboard->events.modifiers, keyboard);
	}

	keyboard_key_update(keyboard, event);
	wlr_signal_emit_safe(&keyboard->events.key, event);
}

void wlr_keyboard_init(struct wlr_keyboard *kb,
		struct wlr_keyboard_impl *impl) {
	kb->impl = impl;
	wl_signal_init(&kb->events.key);
	wl_signal_init(&kb->events.modifiers);
	wl_signal_init(&kb->events.keymap);
	wl_signal_init(&kb->events.repeat_info);

	// Sane defaults
	kb->repeat_info.rate = 25;
	kb->repeat_info.delay = 600;
}

void wlr_keyboard_destroy(struct wlr_keyboard *kb) {
	if (kb == NULL) {
		return;
	}
	if (kb->impl && kb->impl->destroy) {
		kb->impl->destroy(kb);
	} else {
		wl_list_remove(&kb->events.key.listener_list);
	}
	xkb_state_unref(kb->xkb_state);
	xkb_keymap_unref(kb->keymap);
	close(kb->keymap_fd);
	free(kb);
}

void wlr_keyboard_led_update(struct wlr_keyboard *kb, uint32_t leds) {
	if (kb->impl && kb->impl->led_update) {
		kb->impl->led_update(kb, leds);
	}
}

void wlr_keyboard_set_keymap(struct wlr_keyboard *kb,
		struct xkb_keymap *keymap) {
	char *keymap_str = NULL;

	xkb_keymap_unref(kb->keymap);
	kb->keymap = xkb_keymap_ref(keymap);

	xkb_state_unref(kb->xkb_state);
	kb->xkb_state = xkb_state_new(kb->keymap);
	if (kb->xkb_state == NULL) {
		wlr_log(L_ERROR, "Failed to create XKB state");
		goto err;
	}

	const char *led_names[WLR_LED_COUNT] = {
		XKB_LED_NAME_NUM,
		XKB_LED_NAME_CAPS,
		XKB_LED_NAME_SCROLL,
	};
	for (size_t i = 0; i < WLR_LED_COUNT; ++i) {
		kb->led_indexes[i] = xkb_map_led_get_index(kb->keymap, led_names[i]);
	}

	const char *mod_names[WLR_MODIFIER_COUNT] = {
		XKB_MOD_NAME_SHIFT,
		XKB_MOD_NAME_CAPS,
		XKB_MOD_NAME_CTRL, // "Control"
		XKB_MOD_NAME_ALT, // "Mod1"
		XKB_MOD_NAME_NUM, // "Mod2"
		"Mod3",
		XKB_MOD_NAME_LOGO, // "Mod4"
		"Mod5",
	};
	// TODO: there's also "Ctrl", "Alt"?
	for (size_t i = 0; i < WLR_MODIFIER_COUNT; ++i) {
		kb->mod_indexes[i] = xkb_map_mod_get_index(kb->keymap, mod_names[i]);
	}

	keymap_str = xkb_keymap_get_as_string(kb->keymap,
		XKB_KEYMAP_FORMAT_TEXT_V1);
	kb->keymap_size = strlen(keymap_str) + 1;
	if (kb->keymap_fd) {
		close(kb->keymap_fd);
	}
	kb->keymap_fd = os_create_anonymous_file(kb->keymap_size);
	if (kb->keymap_fd < 0) {
		wlr_log(L_ERROR, "creating a keymap file for %zu bytes failed", kb->keymap_size);
		goto err;
	}
	void *ptr = mmap(NULL, kb->keymap_size,
		PROT_READ | PROT_WRITE, MAP_SHARED, kb->keymap_fd, 0);
	if (ptr == (void*)-1) {
		wlr_log(L_ERROR, "failed to mmap() %zu bytes", kb->keymap_size);
		goto err;
	}
	strcpy(ptr, keymap_str);
	free(keymap_str);

	for (size_t i = 0; i < kb->num_keycodes; ++i) {
		xkb_keycode_t keycode = kb->keycodes[i] + 8;
		xkb_state_update_key(kb->xkb_state, keycode, XKB_KEY_DOWN);
	}

	keyboard_modifier_update(kb);

	wlr_signal_emit_safe(&kb->events.keymap, kb);
	return;

err:
	xkb_state_unref(kb->xkb_state);
	kb->xkb_state = NULL;
	xkb_keymap_unref(keymap);
	kb->keymap = NULL;
	close(kb->keymap_fd);
	free(keymap_str);
}

void wlr_keyboard_set_repeat_info(struct wlr_keyboard *kb, int32_t rate,
		int32_t delay) {
	if (kb->repeat_info.rate == rate && kb->repeat_info.delay == delay) {
		return;
	}
	kb->repeat_info.rate = rate;
	kb->repeat_info.delay = delay;
	wlr_signal_emit_safe(&kb->events.repeat_info, kb);
}

uint32_t wlr_keyboard_get_modifiers(struct wlr_keyboard *kb) {
	xkb_mod_mask_t mask = kb->modifiers.depressed | kb->modifiers.latched;
	uint32_t modifiers = 0;
	for (size_t i = 0; i < WLR_MODIFIER_COUNT; ++i) {
		if (kb->mod_indexes[i] != XKB_MOD_INVALID &&
				(mask & (1 << kb->mod_indexes[i]))) {
			modifiers |= (1 << i);
		}
	}
	return modifiers;
}