#include "wayland.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <poll.h>

#include <sys/mman.h>
#include <linux/memfd.h>

#include <cairo.h>
#include <wayland-client.h>

#include <wlr-layer-shell-unstable-v1-client.h>

#define LOG_MODULE "bar:wayland"
#include "../log.h"
#include "../tllist.h"

#include "private.h"

struct buffer {
    bool busy;
    size_t size;
    void *mmapped;

    struct wl_buffer *wl_buf;

    cairo_surface_t *cairo_surface;
    cairo_t *cairo;
};

struct wayland_backend {
    struct wl_display *display;
    struct wl_registry *registry;
    struct wl_compositor *compositor;
    struct wl_output *output;
    struct wl_surface *surface;
    struct zwlr_layer_shell_v1 *layer_shell;
    struct zwlr_layer_surface_v1 *layer_surface;
    struct wl_shm *shm;
    struct wl_seat *seat;

    struct {
        struct wl_pointer *pointer;
        int x;
        int y;
    } pointer;

    /* TODO: set directly in bar instead */
    int width, height;

    /* Used to signal e.g. refresh */
    int pipe_fds[2];

    /* We're already waiting for a frame done callback */
    bool render_scheduled;

    tll(struct buffer) buffers;     /* List of SHM buffers */
    struct buffer *next_buffer;     /* Bar is rendering to this one */
    struct buffer *pending_buffer;  /* Finished, but not yet rendered */
};

void *
bar_backend_wayland_new(void)
{
    return calloc(1, sizeof(struct wayland_backend));
}

static void
shm_format(void *data, struct wl_shm *wl_shm, uint32_t format)
{
    printf("SHM format: 0x%08x\n", format);
}

static const struct wl_shm_listener shm_listener = {
    .format = &shm_format,
};

static void
wl_pointer_enter(void *data, struct wl_pointer *wl_pointer,
                 uint32_t serial, struct wl_surface *surface,
                 wl_fixed_t surface_x, wl_fixed_t surface_y)
{
}

static void
wl_pointer_leave(void *data, struct wl_pointer *wl_pointer,
                 uint32_t serial, struct wl_surface *surface)
{
}

static void
wl_pointer_motion(void *data, struct wl_pointer *wl_pointer,
                  uint32_t time, wl_fixed_t surface_x, wl_fixed_t surface_y)
{
    struct wayland_backend *backend = data;
    printf("MOTION: %dx%d\n", wl_fixed_to_int(surface_x), wl_fixed_to_int(surface_y));
    backend->pointer.x = wl_fixed_to_int(surface_x);
    backend->pointer.y = wl_fixed_to_int(surface_y);
}

static void
wl_pointer_button(void *data, struct wl_pointer *wl_pointer,
                  uint32_t serial, uint32_t time, uint32_t button, uint32_t state)
{
    if (state != WL_POINTER_BUTTON_STATE_PRESSED)
        return;

    struct wayland_backend *backend = data;
    printf("BUTTON: %dx%d\n", backend->pointer.x, backend->pointer.y);

    write(backend->pipe_fds[1], &(uint8_t){2}, sizeof(uint8_t));
    write(backend->pipe_fds[1], &backend->pointer.x, sizeof(backend->pointer.x));
    write(backend->pipe_fds[1], &backend->pointer.y, sizeof(backend->pointer.y));
}

static void
wl_pointer_axis(void *data, struct wl_pointer *wl_pointer,
                uint32_t time, uint32_t axis, wl_fixed_t value)
{
}

static void
wl_pointer_frame(void *data, struct wl_pointer *wl_pointer)
{
}

static void
wl_pointer_axis_source(void *data, struct wl_pointer *wl_pointer,
                       uint32_t axis_source)
{
}

static void
wl_pointer_axis_stop(void *data, struct wl_pointer *wl_pointer,
                     uint32_t time, uint32_t axis)
{
}

static void
wl_pointer_axis_discrete(void *data, struct wl_pointer *wl_pointer,
                         uint32_t axis, int32_t discrete)
{
}

static const struct wl_pointer_listener pointer_listener = {
    .enter = wl_pointer_enter,
    .leave = wl_pointer_leave,
    .motion = wl_pointer_motion,
    .button = wl_pointer_button,
    .axis = wl_pointer_axis,
    .frame = wl_pointer_frame,
    .axis_source = wl_pointer_axis_source,
    .axis_stop = wl_pointer_axis_stop,
    .axis_discrete = wl_pointer_axis_discrete,
};

static void
seat_handle_capabilities(void *data, struct wl_seat *wl_seat,
                         enum wl_seat_capability caps)
{
    struct wayland_backend *backend = data;

    if (backend->pointer.pointer != NULL) {
        wl_pointer_release(backend->pointer.pointer);
        backend->pointer.pointer = NULL;
    }

    if ((caps & WL_SEAT_CAPABILITY_POINTER)) {
        backend->pointer.pointer = wl_seat_get_pointer(wl_seat);
        wl_pointer_add_listener(backend->pointer.pointer, &pointer_listener, backend);
    }
}

static void
seat_handle_name(void *data, struct wl_seat *wl_seat, const char *name)
{
    printf("seat: name=%s\n", name);
}

static const struct wl_seat_listener seat_listener = {
    .capabilities = seat_handle_capabilities,
    .name = seat_handle_name,
};

static void
handle_global(void *data, struct wl_registry *registry,
              uint32_t name, const char *interface, uint32_t version)
{
    struct wayland_backend *backend = data;
    if (strcmp(interface, wl_compositor_interface.name) == 0) {
        backend->compositor = wl_registry_bind(
            registry, name, &wl_compositor_interface, 4);
    }

    else if (strcmp(interface, wl_shm_interface.name) == 0) {
        backend->shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
        wl_shm_add_listener(backend->shm, &shm_listener, backend);
    }

    else if (strcmp(interface, wl_output_interface.name) == 0) {
        backend->output = wl_registry_bind(registry, name, &wl_output_interface, 3);
        //output_add_listener(backend->output, &output_listener, backend);
    }

    else if (strcmp(interface, zwlr_layer_shell_v1_interface.name) == 0) {
        backend->layer_shell = wl_registry_bind(
            registry, name, &zwlr_layer_shell_v1_interface, 1);
    }

    else if (strcmp(interface, wl_seat_interface.name) == 0) {
        backend->seat = wl_registry_bind(registry, name, &wl_seat_interface, 3);
        wl_seat_add_listener(backend->seat, &seat_listener, backend);
    }
}

static void
handle_global_remove(void *data, struct wl_registry *registry, uint32_t name)
{
    //struct wayland_backend *backend = data;
}

static const struct wl_registry_listener registry_listener = {
    .global = &handle_global,
    .global_remove = &handle_global_remove,
};

static void
layer_surface_configure(void *data, struct zwlr_layer_surface_v1 *surface,
                        uint32_t serial, uint32_t w, uint32_t h)
{
    struct wayland_backend *backend = data;
    backend->width = w;
    backend->height = h;

    zwlr_layer_surface_v1_ack_configure(surface, serial);
}

static const struct zwlr_layer_surface_v1_listener layer_surface_listener = {
    .configure = layer_surface_configure,
};

static void
buffer_release(void *data, struct wl_buffer *wl_buffer)
{
    printf("buffer release\n");
    struct buffer *buffer = data;
    assert(buffer->busy);
    buffer->busy = false;
}

static const struct wl_buffer_listener buffer_listener = {
    .release = &buffer_release,
};

static struct buffer *
get_buffer(struct wayland_backend *backend)
{
    tll_foreach(backend->buffers, it) {
        if (!it->item.busy) {
            printf("re-using non-busy buffer\n");
            it->item.busy = true;
            return &it->item;
        }
    }

    printf("allocating a new buffer\n");

    struct buffer buffer;

    /* Backing memory for SHM */
    int pool_fd = memfd_create("wayland-test-buffer-pool", MFD_CLOEXEC);
    assert(pool_fd != -1);

    /* Allocate memory for our single buffer */
    uint32_t stride = backend->width * 4;
    buffer.size = stride * backend->height;
    ftruncate(pool_fd, buffer.size);

    buffer.mmapped = mmap(
        NULL, buffer.size, PROT_READ | PROT_WRITE, MAP_SHARED, pool_fd, 0);
    assert(buffer.mmapped != MAP_FAILED);

    struct wl_shm_pool *pool = wl_shm_create_pool(backend->shm, pool_fd, buffer.size);
    assert(pool != NULL);

    buffer.wl_buf = wl_shm_pool_create_buffer(
        pool, 0, backend->width, backend->height, stride, WL_SHM_FORMAT_ARGB8888);
    assert(buffer.wl_buf != NULL);
    buffer.busy = true;

    wl_shm_pool_destroy(pool);
    close(pool_fd);

    buffer.cairo_surface = cairo_image_surface_create_for_data(
        buffer.mmapped, CAIRO_FORMAT_ARGB32, backend->width, backend->height, stride);
    buffer.cairo = cairo_create(buffer.cairo_surface);
    assert(cairo_status(buffer.cairo) == CAIRO_STATUS_SUCCESS);

    tll_push_back(backend->buffers, buffer);

    struct buffer *ret = &tll_back(backend->buffers);
    wl_buffer_add_listener(buffer.wl_buf, &buffer_listener, ret);
    return ret;
}

static bool
setup(struct bar *_bar)
{
    struct private *bar = _bar->private;
    struct wayland_backend *backend = bar->backend.data;

    backend->display = wl_display_connect(NULL);
    assert(backend->display != NULL);

    backend->registry = wl_display_get_registry(backend->display);
    assert(backend->registry != NULL);

    wl_registry_add_listener(backend->registry, &registry_listener, backend);

    wl_display_roundtrip(backend->display);
    assert(backend->compositor != NULL &&
           backend->layer_shell != NULL &&
           backend->output != NULL);

    backend->surface = wl_compositor_create_surface(backend->compositor);
    assert(backend->surface != NULL);

    backend->layer_surface = zwlr_layer_shell_v1_get_layer_surface(
        backend->layer_shell, backend->surface, backend->output,
        ZWLR_LAYER_SHELL_V1_LAYER_BOTTOM, "f00bar");
    assert(backend->layer_surface != NULL);

    /* Aligned to top, maximum width */
    zwlr_layer_surface_v1_set_anchor(
        backend->layer_surface,
        ZWLR_LAYER_SURFACE_V1_ANCHOR_LEFT |
        ZWLR_LAYER_SURFACE_V1_ANCHOR_RIGHT |
        ZWLR_LAYER_SURFACE_V1_ANCHOR_TOP);

    zwlr_layer_surface_v1_set_size(backend->layer_surface, 0, bar->height_with_border);
    zwlr_layer_surface_v1_set_exclusive_zone(backend->layer_surface, bar->height_with_border);

    //zwlr_layer_surface_v1_set_margin(
    //   layer_surface, margin_top, margin_right, margin_bottom, margin_left);
    //zwlr_layer_surface_v1_set_keyboard_interactivity(
    //   layer_surface, keyboard_interactive);

    zwlr_layer_surface_v1_add_listener(
        backend->layer_surface, &layer_surface_listener, backend);

    /* Assign width/height */
    wl_surface_commit(backend->surface);
    wl_display_roundtrip(backend->display);

    assert(backend->width != -1 && backend->height == bar->height_with_border);
    bar->width = backend->width;

    pipe(backend->pipe_fds);
    backend->render_scheduled = false;

    wl_surface_commit(backend->surface);
    wl_display_roundtrip(backend->display);

    backend->next_buffer = get_buffer(backend);
    assert(backend->next_buffer != NULL && backend->next_buffer->busy);

    bar->cairo_surface = backend->next_buffer->cairo_surface;
    bar->cairo = backend->next_buffer->cairo;

    return true;
}

static void
cleanup(struct bar *_bar)
{
    struct private *bar = _bar->private;
    struct wayland_backend *backend = bar->backend.data;

    tll_foreach(backend->buffers, it) {
        wl_buffer_destroy(it->item.wl_buf);
        cairo_destroy(it->item.cairo);
        cairo_surface_destroy(it->item.cairo_surface);
        munmap(it->item.mmapped, it->item.size);

        tll_remove(backend->buffers, it);
    }

    /* TODO: move to bar */
    free(bar->cursor_name);

    zwlr_layer_surface_v1_destroy(backend->layer_surface);
    zwlr_layer_shell_v1_destroy(backend->layer_shell);
    wl_compositor_destroy(backend->compositor);
    wl_surface_destroy(backend->surface);
    wl_shm_destroy(backend->shm);
    wl_output_destroy(backend->output);
    wl_registry_destroy(backend->registry);
    wl_display_disconnect(backend->display);

    /* Destroyed when freeing buffer list */
    bar->cairo_surface = NULL;
    bar->cairo = NULL;

}

static void
loop(struct bar *_bar,
     void (*expose)(const struct bar *bar),
     void (*on_mouse)(struct bar *bar, enum mouse_event event, int x, int y))
{
    struct private *bar = _bar->private;
    struct wayland_backend *backend = bar->backend.data;

#if 0
    while (wl_display_prepare_read(backend->display) != 0){
        printf("initial wayland event\n");
        wl_display_dispatch_pending(backend->display);
    }
    wl_display_flush(backend->display);
#endif

    wl_display_dispatch_pending(backend->display);
    wl_display_flush(backend->display);

    while (true) {
        struct pollfd fds[] = {
            {.fd = _bar->abort_fd, .events = POLLIN},
            {.fd = wl_display_get_fd(backend->display), .events = POLLIN},
            {.fd = backend->pipe_fds[0], .events = POLLIN},
        };

        wl_display_flush(backend->display);

        printf("polling\n");
        poll(fds, sizeof(fds) / sizeof(fds[0]), -1);
        if (fds[0].revents & POLLIN) {
            //wl_display_cancel_read(backend->display);
            break;
        }

        if (fds[1].revents & POLLHUP) {
            LOG_WARN("disconnceted from wayland");
            write(_bar->abort_fd, &(uint64_t){1}, sizeof(uint64_t));
            break;
        }

        if (fds[2].revents & POLLIN) {
            uint8_t command;
            //wl_display_cancel_read(backend->display);
            read(backend->pipe_fds[0], &command, sizeof(command));

            if (command == 1) {
                printf("refresh\n");
                assert(command == 1);
                expose(_bar);
#if 0
                while (wl_display_prepare_read(backend->display) != 0) {
                    printf("queued wayland events\n");
                    wl_display_dispatch_pending(backend->display);
                }
                wl_display_flush(backend->display);
#endif
            }

            if (command == 2) {
                printf("mouse\n");
                int x, y;
                read(backend->pipe_fds[0], &x, sizeof(x));
                read(backend->pipe_fds[0], &y, sizeof(y));
                on_mouse(_bar, ON_MOUSE_CLICK, x, y);
            }
            continue;
        }

#if 0
        printf("wayland events\n");
        wl_display_read_events(backend->display);
        wl_display_dispatch_pending(backend->display);
#endif
        printf("wayland events\n");
        wl_display_dispatch(backend->display);
    }
}

static void frame_callback(
    void *data, struct wl_callback *wl_callback, uint32_t callback_data);

static const struct wl_callback_listener frame_listener = {
    .done = &frame_callback,
};

static void
frame_callback(void *data, struct wl_callback *wl_callback, uint32_t callback_data)
{
    printf("frame callback\n");
    struct private *bar = data;
    struct wayland_backend *backend = bar->backend.data;

    backend->render_scheduled = false;

    wl_callback_destroy(wl_callback);

    if (backend->pending_buffer != NULL) {
        struct buffer *buffer = backend->pending_buffer;
        assert(buffer->busy);

        wl_surface_attach(backend->surface, buffer->wl_buf, 0, 0);
        wl_surface_damage(backend->surface, 0, 0, backend->width, backend->height);

        struct wl_callback *cb = wl_surface_frame(backend->surface);
        wl_callback_add_listener(cb, &frame_listener, bar);
        wl_surface_commit(backend->surface);

        backend->pending_buffer = NULL;
        backend->render_scheduled = true;
    } else
        printf("nothing more to do\n");
}

static void
commit_surface(const struct bar *_bar)
{
    struct private *bar = _bar->private;
    struct wayland_backend *backend = bar->backend.data;

    printf("commit: %dxl%d\n", backend->width, backend->height);

    assert(backend->next_buffer != NULL);
    assert(backend->next_buffer->busy);

    if (backend->render_scheduled) {
        printf("already scheduled\n");

        if (backend->pending_buffer != NULL)
            backend->pending_buffer->busy = false;

        backend->pending_buffer = backend->next_buffer;
        backend->next_buffer = NULL;
    } else {

        printf("scheduling new frame callback\n");
        struct buffer *buffer = backend->next_buffer;
        assert(buffer->busy);

        wl_surface_attach(backend->surface, buffer->wl_buf, 0, 0);
        wl_surface_damage(backend->surface, 0, 0, backend->width, backend->height);

        struct wl_callback *cb = wl_surface_frame(backend->surface);
        wl_callback_add_listener(cb, &frame_listener, bar);
        wl_surface_commit(backend->surface);

        backend->render_scheduled = true;
    }

    backend->next_buffer = get_buffer(backend);
    assert(backend->next_buffer != NULL && backend->next_buffer->busy);

    bar->cairo_surface = backend->next_buffer->cairo_surface;
    bar->cairo = backend->next_buffer->cairo;
}

static void
refresh(const struct bar *_bar)
{
    const struct private *bar = _bar->private;
    const struct wayland_backend *backend = bar->backend.data;

    write(backend->pipe_fds[1], &(uint8_t){1}, sizeof(uint8_t));
}

static void
set_cursor(struct bar *_bar, const char *cursor)
{
}

const struct backend wayland_backend_iface = {
    .setup = &setup,
    .cleanup = &cleanup,
    .loop = &loop,
    .commit_surface = &commit_surface,
    .refresh = &refresh,
    .set_cursor = &set_cursor,
};