#define _POSIX_C_SOURCE 200112L
#include <wayland-client.h>
#include <wayland-client-protocol.h>
#include "xdg-shell-client-protocol.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/mman.h>
#include <fcntl.h>

struct wl_display* display = NULL;
struct wl_registry* registry = NULL;
struct wl_compositor* compositor = NULL;
struct xdg_wm_base* wm_base = NULL;
struct wl_surface* surface = NULL;
struct xdg_surface* xdg_surface = NULL;
struct xdg_toplevel* xdg_toplevel = NULL;
struct wl_shm* shm = NULL;
struct wl_buffer* buffer = NULL;
void* pixel_data = NULL;
int width = 1024, height = 768;
int running = 1;

static void xdg_wm_base_ping(void *data, struct xdg_wm_base *xdg_wm_base, uint32_t serial)
{
    xdg_wm_base_pong(xdg_wm_base, serial);
}

static const struct xdg_wm_base_listener wm_base_listener = {
    .ping = xdg_wm_base_ping,
};

static void xdg_surface_configure(void *data, struct xdg_surface *xdg_surface, uint32_t serial)
{
    xdg_surface_ack_configure(xdg_surface, serial);
}

static const struct xdg_surface_listener xdg_surface_listener = {
    .configure = xdg_surface_configure,
};

static void xdg_toplevel_configure(void *data, struct xdg_toplevel *xdg_toplevel,
    int32_t w, int32_t h, struct wl_array *states)
{
    if (w > 0 && h > 0) {
        width = w;
        height = h;
    }
}

static void xdg_toplevel_close(void *data, struct xdg_toplevel *xdg_toplevel)
{
    running = 0;
}

static const struct xdg_toplevel_listener xdg_toplevel_listener = {
    .configure = xdg_toplevel_configure,
    .close = xdg_toplevel_close,
};

static void registry_handle_global(void *data, struct wl_registry *reg, uint32_t id,
    const char *interface, uint32_t version)
{
    if (strcmp(interface, wl_compositor_interface.name) == 0) {
        compositor = wl_registry_bind(reg, id, &wl_compositor_interface, 4);
    } else if (strcmp(interface, xdg_wm_base_interface.name) == 0) {
        wm_base = wl_registry_bind(reg, id, &xdg_wm_base_interface, 1);
        xdg_wm_base_add_listener(wm_base, &wm_base_listener, NULL);
    } else if (strcmp(interface, wl_shm_interface.name) == 0) {
        shm = wl_registry_bind(reg, id, &wl_shm_interface, 1);
    }
}

static void registry_handle_global_remove(void *data, struct wl_registry *reg, uint32_t id)
{
}

static const struct wl_registry_listener registry_listener = {
    .global = registry_handle_global,
    .global_remove = registry_handle_global_remove,
};

struct wl_buffer* create_buffer(int w, int h, void** data_out) {
    int stride = w * 4;
    int size = stride * h;
    int fd = shm_open("/wl_shm", O_CREAT | O_RDWR, 0600);
    if (fd < 0) return NULL;
    if (ftruncate(fd, size) < 0) {
        close(fd);
        return NULL;
    }
    void* data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if (data == MAP_FAILED) {
        close(fd);
        return NULL;
    }
    struct wl_shm_pool* pool = wl_shm_create_pool(shm, fd, size);
    struct wl_buffer* buf = wl_shm_pool_create_buffer(pool, 0, w, h, stride, WL_SHM_FORMAT_ARGB8888);
    wl_shm_pool_destroy(pool);
    close(fd);
    shm_unlink("/wl_shm");
    *data_out = data;
    return buf;
}

void draw_window() {
    uint32_t* pixels = (uint32_t*)pixel_data;
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            if (x > 100 && x < 300 && y > 100 && y < 200)
                pixels[y * width + x] = 0xFFFF0000;
            else
                pixels[y * width + x] = 0xFF202020;
        }
    }
}

int main(void)
{
    display = wl_display_connect(NULL);
    if (!display) {
        fprintf(stderr, "can't connect\n");
        return 1;
    }

    registry = wl_display_get_registry(display);
    wl_registry_add_listener(registry, &registry_listener, NULL);
    wl_display_roundtrip(display);
    wl_display_roundtrip(display);

    if (!compositor || !wm_base || !shm) {
        fprintf(stderr, "missing required interfaces\n");
        return 1;
    }

    surface = wl_compositor_create_surface(compositor);
    xdg_surface = xdg_wm_base_get_xdg_surface(wm_base, surface);
    xdg_surface_add_listener(xdg_surface, &xdg_surface_listener, NULL);

    xdg_toplevel = xdg_surface_get_toplevel(xdg_surface);
    xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, NULL);
    xdg_toplevel_set_title(xdg_toplevel, "wayland window");

    wl_surface_commit(surface);
    wl_display_roundtrip(display);

    buffer = create_buffer(width, height, &pixel_data);
    if (!buffer) {
        fprintf(stderr, "failed to create buffer\n");
        return 1;
    }

    draw_window();

    wl_surface_attach(surface, buffer, 0, 0);
    wl_surface_damage(surface, 0, 0, width, height);
    wl_surface_commit(surface);

    printf("window open, running...\n");

    while (running && wl_display_dispatch(display) != -1) {
    }

    wl_display_disconnect(display);
    return 0;
}