#define _POSIX_C_SOURCE 199309L
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <inttypes.h>
#include <wayland-server.h>
#include <GLES3/gl3.h>
#include <wlr/backend.h>
#include <wlr/session.h>
#include <wlr/types.h>
#include <xkbcommon/xkbcommon.h>

struct state {
	float color[3];
	int dec;
	bool exit;
	struct timespec last_frame;
	struct xkb_keymap *keymap;
	struct xkb_state *xkb_state;

	struct wl_list keyboards;
	struct wl_listener input_add;
	struct wl_listener input_remove;

	struct wl_listener output_add;
	struct wl_listener output_remove;
	struct wl_list outputs;
};

struct output_state {
	struct state *state;
	struct wlr_output *output;
	struct wl_listener frame;
	struct wl_list link;
};

struct keyboard_state {
	struct state *state;
	struct wlr_input_device *device;
	struct wl_listener key;
	struct wl_list link;
};

void output_frame(struct wl_listener *listener, void *data) {
	struct output_state *ostate = wl_container_of(listener, ostate, frame);
	struct state *s = ostate->state;

	struct timespec now;
	clock_gettime(CLOCK_MONOTONIC, &now);

	long ms = (now.tv_sec - s->last_frame.tv_sec) * 1000 +
		(now.tv_nsec - s->last_frame.tv_nsec) / 1000000;
	int inc = (s->dec + 1) % 3;

	s->color[inc] += ms / 2000.0f;
	s->color[s->dec] -= ms / 2000.0f;

	if (s->color[s->dec] < 0.0f) {
		s->color[inc] = 1.0f;
		s->color[s->dec] = 0.0f;
		s->dec = inc;
	}

	s->last_frame = now;

	glClearColor(s->color[0], s->color[1], s->color[2], 1.0);
	glClear(GL_COLOR_BUFFER_BIT);
}

void output_add(struct wl_listener *listener, void *data) {
	struct wlr_output *output = data;
	struct state *state = wl_container_of(listener, state, output_add);
	fprintf(stderr, "Output '%s' added\n", output->name);
	fprintf(stderr, "%s %s %"PRId32"mm x %"PRId32"mm\n", output->make, output->model,
		output->phys_width, output->phys_height);
	wlr_output_set_mode(output, output->modes->items[0]);
	struct output_state *ostate = calloc(1, sizeof(struct output_state));
	ostate->output = output;
	ostate->state = state;
	ostate->frame.notify = output_frame;
	wl_list_init(&ostate->frame.link);
	wl_signal_add(&output->events.frame, &ostate->frame);
	wl_list_insert(&state->outputs, &ostate->link);
}

void output_remove(struct wl_listener *listener, void *data) {
	struct wlr_output *output = data;
	struct state *state = wl_container_of(listener, state, output_remove);
	struct output_state *ostate = NULL, *_ostate;
	wl_list_for_each(_ostate, &state->outputs, link) {
		if (_ostate->output == output) {
			ostate = _ostate;
			break;
		}
	}
	if (!ostate) {
		return; // We are unfamiliar with this output
	}
	wl_list_remove(&ostate->link);
	wl_list_remove(&ostate->frame.link);
}

static void handle_keysym(struct state *state, xkb_keysym_t sym,
		enum wlr_key_state key_state) {
	char name[64];
	int l = xkb_keysym_get_name(sym, name, sizeof(name));
	if (l != -1 && l != sizeof(name)) {
		fprintf(stderr, "Key event: %s %s\n", name,
				key_state == WLR_KEY_PRESSED ? "pressed" : "released");
	}
	if (sym == XKB_KEY_Escape) {
		state->exit = true;
	}
}

static void keyboard_key(struct wl_listener *listener, void *data) {
	struct wlr_keyboard_key *event = data;
	struct keyboard_state *kbstate = wl_container_of(listener, kbstate, key);
	uint32_t keycode = event->keycode + 8;
	const xkb_keysym_t *syms;
	int nsyms = xkb_state_key_get_syms(kbstate->state->xkb_state, keycode, &syms);
	for (int i = 0; i < nsyms; ++i) {
		handle_keysym(kbstate->state, syms[i], event->state);
	}
	xkb_state_update_key(kbstate->state->xkb_state, keycode,
		event->state == WLR_KEY_PRESSED ?  XKB_KEY_DOWN : XKB_KEY_UP);
}

void input_add(struct wl_listener *listener, void *data) {
	struct wlr_input_device *device = data;
	struct state *state = wl_container_of(listener, state, input_add);
	if (device->type != WLR_INPUT_DEVICE_KEYBOARD) {
		return;
	}
	struct keyboard_state *kbstate = calloc(sizeof(struct keyboard_state), 1);
	kbstate->device = device;
	kbstate->state = state;
	wl_list_init(&kbstate->key.link);
	kbstate->key.notify = keyboard_key;
	wl_signal_add(&device->keyboard->events.key, &kbstate->key);
	wl_list_insert(&state->keyboards, &kbstate->link);
}

void input_remove(struct wl_listener *listener, void *data) {
	struct wlr_input_device *device = data;
	struct state *state = wl_container_of(listener, state, input_add);
	if (device->type != WLR_INPUT_DEVICE_KEYBOARD) {
		return;
	}
	struct keyboard_state *kbstate = NULL, *_kbstate;
	wl_list_for_each(_kbstate, &state->keyboards, link) {
		if (_kbstate->device == device) {
			kbstate = kbstate;
			break;
		}
	}
	if (!kbstate) {
		return; // We are unfamiliar with this keyboard
	}
	wl_list_remove(&kbstate->link);
	wl_list_remove(&kbstate->key.link);
}

int main() {
	struct state state = {
		.color = { 1.0, 0.0, 0.0 },
		.dec = 0,
		.exit = false,
		.input_add = { .notify = input_add },
		.input_remove = { .notify = input_remove },
		.output_add = { .notify = output_add },
		.output_remove = { .notify = output_remove },
	};

	struct xkb_rule_names rules;
	memset(&rules, 0, sizeof(rules));
	rules.rules = getenv("XKB_DEFAULT_RULES");
	rules.model = getenv("XKB_DEFAULT_MODEL");
	rules.layout = getenv("XKB_DEFAULT_LAYOUT");
	rules.variant = getenv("XKB_DEFAULT_VARIANT");
	rules.options = getenv("XKB_DEFAULT_OPTIONS");
	struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
	if (!context) {
		fprintf(stderr, "Failed to create XKB context\n");
		return 1;
	}
	state.keymap =
		xkb_map_new_from_names(context, &rules, XKB_KEYMAP_COMPILE_NO_FLAGS);
	if (!state.keymap) {
		fprintf(stderr, "Failed to create XKB keymap\n");
		return 1;
	}
	xkb_context_unref(context);
	state.xkb_state = xkb_state_new(state.keymap);

	wl_list_init(&state.keyboards);
	wl_list_init(&state.input_add.link);
	wl_list_init(&state.input_remove.link);

	wl_list_init(&state.outputs);
	wl_list_init(&state.output_remove.link);
	wl_list_init(&state.output_remove.link);
	clock_gettime(CLOCK_MONOTONIC, &state.last_frame);

	struct wl_display *display = wl_display_create();
	struct wl_event_loop *event_loop = wl_display_get_event_loop(display);

	struct wlr_session *session = wlr_session_start(display);
	if (!session) {
		return 1;
	}

	struct wlr_backend *wlr = wlr_backend_autocreate(display, session);
	wl_signal_add(&wlr->events.input_add, &state.input_add);
	wl_signal_add(&wlr->events.input_remove, &state.input_remove);
	wl_signal_add(&wlr->events.output_add, &state.output_add);
	wl_signal_add(&wlr->events.output_remove, &state.output_remove);
	if (!wlr || !wlr_backend_init(wlr)) {
		return 1;
	}

	while (!state.exit) {
		wl_event_loop_dispatch(event_loop, 0);
	}

	wlr_backend_destroy(wlr);
	wl_display_destroy(display);
}