#include <Imlib2.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "renderer.h"
#include "types.h"
#include "utils.h"

/**
 * @brief 生成需要由 xcb 绘制的壁纸数据
 * @returns 壁纸数据，使用后记得释放
 */
uint32_t *generate_wallpaper(const wallpaper_config_t *wallpaper_config,
                             const monitor_t *monitors, const uint32_t index,
                             const uint32_t screen_width,
                             const uint32_t screen_height) {
  if (!wallpaper_config || !monitors) return NULL;

  Imlib_Image final_image = imlib_create_image(screen_width, screen_height);
  if (!final_image) return NULL;

  imlib_context_set_image(final_image);
  imlib_image_set_has_alpha(false);

  /* 填充背景色 */
  imlib_context_set_color(0, 0, 0, 255);
  imlib_image_fill_rectangle(0, 0, screen_width, screen_height);

  const monitor_t *monitor = monitors;
  uint32_t monitor_index = 0;
  while (monitor) {
    uint32_t img_index = (index + monitor_index) % wallpaper_config->count;
    const char *path = wallpaper_config->path_list[img_index];
    Imlib_Image wallpaper_img = imlib_load_image(path);
    if (!wallpaper_img) {
      monitor = monitor->next;
      monitor_index++;
      continue;
    }

    uint32_t dst_width = monitor->monitor_width;
    uint32_t dst_height = monitor->monitor_height;

    /* 获取图片原始尺寸 */
    imlib_context_set_image(wallpaper_img);
    uint32_t img_width = imlib_image_get_width();
    uint32_t img_height = imlib_image_get_height();

    /* 计算缩放比例，保持原始宽高比 */
    float width_ratio = (float)dst_width / img_width;
    float height_ratio = (float)dst_height / img_height;
    float scale = MAX(width_ratio, height_ratio);

    /* 图片居中显示，计算原图绘制区域 */
    int src_width = dst_width / scale;
    int src_height = dst_height / scale;
    int src_x = (img_width - src_width) / 2;
    int src_y = (img_height - src_height) / 2;

    /* 绘制图片到最终图像上 */
    imlib_context_set_image(final_image);
    imlib_blend_image_onto_image(wallpaper_img, 1, src_x, src_y, src_width,
                                 src_height, monitor->monitor_x,
                                 monitor->monitor_y, dst_width, dst_height);

    /* 释放图片资源 */
    imlib_context_set_image(wallpaper_img);
    imlib_free_image();

    monitor = monitor->next;
    monitor_index++;
  }

  /* 获取最终图像数据 */
  imlib_context_set_image(final_image);
  uint32_t *data = imlib_image_get_data_for_reading_only();

  /* 复制数据到自己分配的内存中（原数据会在图像释放后无效） */
  size_t data_size = screen_width * screen_height * sizeof(uint32_t);
  uint32_t *result = ecalloc(1, data_size);
  if (result) memcpy(result, data, data_size);

  /* 释放图像 */
  imlib_context_set_image(final_image);
  imlib_free_image();

  return result;
}