//
// Implementation of the Wayland graphics driver.
//
// Copyright 2021-2023 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

#include "Fl_Wayland_Graphics_Driver.H"
#include "Fl_Wayland_Screen_Driver.H"
#include "Fl_Wayland_Window_Driver.H"
#include <sys/mman.h>
#include <unistd.h> // for close()
#include <errno.h>
#include <string.h> // for strerror()


extern "C" {
#  include "../../../libdecor/src/os-compatibility.h" // for os_create_anonymous_file()
}

// used by create_shm_buffer and buffer_release
static struct wl_shm_pool *pool = NULL; // the current pool


struct fl_wld_buffer *Fl_Wayland_Graphics_Driver::create_shm_buffer(int width, int height)
{
  struct fl_wld_buffer *buffer;
  int stride = cairo_format_stride_for_width(Fl_Cairo_Graphics_Driver::cairo_format, width);
  int size = stride * height;
  const int default_pool_size = 10000000; // larger pools are possible if needed
  int chunk_offset = 0; // offset to start of available memory in pool
  struct wld_shm_pool_data *pool_data = pool ? // data record attached to current pool
    (struct wld_shm_pool_data *)wl_shm_pool_get_user_data(pool) : NULL;
  int pool_size = pool ? pool_data->pool_size : default_pool_size; // current pool size
  if (pool) {
    // last fl_wld_buffer created from current pool
    struct fl_wld_buffer *record = wl_container_of(pool_data->buffers.next, record, link);
    chunk_offset = ((char*)record->data - pool_data->pool_memory) + record->data_size;
  }
  if (!pool || chunk_offset + size > pool_size) { // if true, a new pool is needed
    chunk_offset = 0;
    pool_size = default_pool_size;
    if (size > pool_size) pool_size = 2 * size; // a larger pool is needed
    int fd = os_create_anonymous_file(pool_size);
    if (fd < 0) {
      Fl::fatal("os_create_anonymous_file failed: %s\n", strerror(errno));
    }
    pool_data = (struct wld_shm_pool_data*)calloc(1, sizeof(struct wld_shm_pool_data));
    pool_data->pool_memory = (char*)mmap(NULL, pool_size, PROT_READ | PROT_WRITE,
                                         MAP_SHARED, fd, 0);
    if (pool_data->pool_memory == MAP_FAILED) {
      close(fd);
      Fl::fatal("mmap failed: %s\n", strerror(errno));
    }
    Fl_Wayland_Screen_Driver *scr_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
    pool = wl_shm_create_pool(scr_driver->wl_shm, fd, pool_size);
    close(fd); // does not prevent the mmap'ed memory from being used
//puts("wl_shm_create_pool");
    pool_data->pool_size = pool_size;
    wl_list_init(&pool_data->buffers);
    wl_shm_pool_set_user_data(pool, pool_data);
  }
  buffer = (struct fl_wld_buffer*)calloc(1, sizeof(struct fl_wld_buffer));
  buffer->stride = stride;
  buffer->wl_buffer = wl_shm_pool_create_buffer(pool, chunk_offset, width, height, stride, Fl_Wayland_Graphics_Driver::wld_format);
  // add this buffer to head of list of current pool's buffers
  wl_list_insert(&pool_data->buffers, &buffer->link);
  buffer->shm_pool = pool;
  buffer->data = (void*)(pool_data->pool_memory + chunk_offset);
//fprintf(stderr, "last=%p chunk_offset=%d ", pool_data->buffers.next, chunk_offset);
  buffer->data_size = size;
  buffer->width = width;
  buffer->draw_buffer = new uchar[buffer->data_size];
  buffer->draw_buffer_needs_commit = true;
//fprintf(stderr, "create_shm_buffer: %dx%d = %d\n", width, height, size);
  cairo_init(buffer, width, height, stride, Fl_Cairo_Graphics_Driver::cairo_format);
  return buffer;
}


// used to support both normal and progressive drawing
static void surface_frame_done(void *data, struct wl_callback *cb, uint32_t time);

static const struct wl_callback_listener surface_frame_listener = {
  .done = surface_frame_done,
};

static void surface_frame_done(void *data, struct wl_callback *cb, uint32_t time) {
  struct wld_window *window = (struct wld_window *)data;
//fprintf(stderr,"surface_frame_done:  destroy cb=%p draw_buffer_needs_commit=%d\n", cb, window->buffer->draw_buffer_needs_commit);
  wl_callback_destroy(cb);
  if (window->buffer) { // fix for issue #712
    window->buffer->cb = NULL;
    if (window->buffer->draw_buffer_needs_commit) {
      //fprintf(stderr,"surface_frame_done: new cb=%p \n", window->buffer->cb);
      Fl_Wayland_Graphics_Driver::buffer_commit(window);
    }
  }
}


// copy pixels in region r from the Cairo surface to the Wayland buffer
static void copy_region(struct wld_window *window, struct flCairoRegion *r) {
  struct fl_wld_buffer *buffer = window->buffer;
  float f = Fl::screen_scale(window->fl_win->screen_num()) *
    Fl_Wayland_Window_Driver::driver(window->fl_win)->wld_scale();
  for (int i = 0; i < r->count; i++) {
    int left = r->rects[i].x * f;
    int top = r->rects[i].y * f;
    int width = r->rects[i].width * f;
    int height = r->rects[i].height * f;
    int offset = top * buffer->stride + 4 * left;
    int W4 = 4 * width;
    for (int l = 0; l < height; l++) {
      if (offset + W4 >= (int)buffer->data_size) {
        W4 = buffer->data_size - offset;
        if (W4 <= 0) break;
      }
      memcpy((uchar*)buffer->data + offset, buffer->draw_buffer + offset, W4);
      offset += buffer->stride;
    }
    wl_surface_damage_buffer(window->wl_surface, left, top, width, height);
  }
}


void Fl_Wayland_Graphics_Driver::buffer_commit(struct wld_window *window,
                                struct flCairoRegion *r) {
  cairo_surface_t *surf = cairo_get_target(window->buffer->cairo_);
  cairo_surface_flush(surf);
  if (r) copy_region(window, r);
  else {
    memcpy(window->buffer->data, window->buffer->draw_buffer, window->buffer->data_size);
    wl_surface_damage_buffer(window->wl_surface, 0, 0, 1000000, 1000000);
  }
  wl_surface_attach(window->wl_surface, window->buffer->wl_buffer, 0, 0);
  wl_surface_set_buffer_scale(window->wl_surface,
                              Fl_Wayland_Window_Driver::driver(window->fl_win)->wld_scale());
  window->buffer->cb = wl_surface_frame(window->wl_surface);
  wl_callback_add_listener(window->buffer->cb, &surface_frame_listener, window);
  wl_surface_commit(window->wl_surface);
  window->buffer->draw_buffer_needs_commit = false;
//fprintf(stderr,"buffer_commit %s\n", window->fl_win->parent()?"child":"top");
}


void Fl_Wayland_Graphics_Driver::cairo_init(struct fl_wld_buffer *buffer, int width, int height, int stride, cairo_format_t format) {
  cairo_surface_t *surf = cairo_image_surface_create_for_data(buffer->draw_buffer, format,
                                                        width, height, stride);
  if (cairo_surface_status(surf) != CAIRO_STATUS_SUCCESS) {
    Fl::fatal("Can't create Cairo surface with cairo_image_surface_create_for_data()\n");
    return;
  }
  buffer->cairo_ = cairo_create(surf);
  cairo_status_t err;
  if ((err = cairo_status(buffer->cairo_)) != CAIRO_STATUS_SUCCESS) {
    Fl::fatal("Cairo error during cairo_create() %s\n", cairo_status_to_string(err));
    return;
  }
  cairo_surface_destroy(surf);
  memset(buffer->draw_buffer, 0, buffer->data_size); // useful for transparent windows
  cairo_set_source_rgba(buffer->cairo_, .0, .0, .0, 1.0); // Black default color
  cairo_save(buffer->cairo_);
}


void Fl_Wayland_Graphics_Driver::buffer_release(struct wld_window *window)
{
  if (window->buffer) {
    if (window->buffer->cb) wl_callback_destroy(window->buffer->cb);
    struct wl_shm_pool *my_pool = window->buffer->shm_pool;
    struct wld_shm_pool_data *pool_data =
      (struct wld_shm_pool_data*)wl_shm_pool_get_user_data(my_pool);
    wl_buffer_destroy(window->buffer->wl_buffer);
//printf("wl_buffer_destroy(%p)\n",window->buffer->wl_buffer);
    // remove fl_wld_buffer from list of pool's buffers
    wl_list_remove(&window->buffer->link);
//printf("last=%p\n", wl_list_empty(&pool_data->buffers) ? NULL : pool_data->buffers.next);
    if (wl_list_empty(&pool_data->buffers)) { // all buffers from pool are gone
      wl_shm_pool_destroy(my_pool);
      /*int err = */munmap(pool_data->pool_memory, pool_data->pool_size);
//printf("munmap(%p)->%d\n", pool_data->pool_memory, err);
      free(pool_data);
      if (my_pool == pool) pool = NULL;
    }
    delete[] window->buffer->draw_buffer;
    window->buffer->draw_buffer = NULL;
    cairo_destroy(window->buffer->cairo_);
    free(window->buffer);
    window->buffer = NULL;
  }
}

// this refers to the same memory layout for pixel data as does CAIRO_FORMAT_ARGB32
const uint32_t Fl_Wayland_Graphics_Driver::wld_format = WL_SHM_FORMAT_ARGB8888;


Fl_Wayland_Graphics_Driver::Fl_Wayland_Graphics_Driver () : Fl_Cairo_Graphics_Driver() {
  buffer_ = NULL;
}


void Fl_Wayland_Graphics_Driver::set_buffer(struct fl_wld_buffer *buffer, float scale) {
  this->buffer_ = buffer;
  set_cairo(buffer->cairo_, scale);
}


void Fl_Wayland_Graphics_Driver::copy_offscreen(int x, int y, int w, int h, Fl_Offscreen src, int srcx, int srcy) {
  // draw portion srcx,srcy,w,h of osrc to position x,y (top-left) of the graphics driver's surface
  struct fl_wld_buffer *osrc = (struct fl_wld_buffer *)src;
  cairo_matrix_t matrix;
  cairo_get_matrix(cairo_, &matrix);
  double s = matrix.xx;
  cairo_save(cairo_);
  cairo_rectangle(cairo_, x, y, w, h);
  cairo_clip(cairo_);
  cairo_surface_t *surf = cairo_get_target(osrc->cairo_);
  cairo_pattern_t *pat = cairo_pattern_create_for_surface(surf);
  cairo_set_source(cairo_, pat);
  cairo_matrix_init_scale(&matrix, s, s);
  cairo_matrix_translate(&matrix, -(x - srcx), -(y - srcy));
  cairo_pattern_set_matrix(pat, &matrix);
  cairo_mask(cairo_, pat);
  cairo_pattern_destroy(pat);
  cairo_restore(cairo_);
}