#ifndef STB_IMAGE_COMMON_H
#define STB_IMAGE_COMMON_H

#include "stb_image.h"
#include "stb_image_write.h"

// Simple growable memory buffer for stbi write callbacks
typedef struct {
  unsigned char *data;
  size_t size;
  size_t cap;
} stbi_mem_buf;

static void stbi_mem_write(void *context, void *data, int size)
{
  stbi_mem_buf *buf = (stbi_mem_buf*)context;
  size_t needed = buf->size + (size_t)size;
  if (needed > buf->cap) {
    size_t new_cap = buf->cap ? buf->cap * 2 : 4096;
    while (new_cap < needed) new_cap *= 2;
    unsigned char *new_data = realloc(buf->data, new_cap);
    if (!new_data) return;
    buf->data = new_data;
    buf->cap = new_cap;
  }
  memcpy(buf->data + buf->size, data, (size_t)size);
  buf->size += (size_t)size;
}

#define IMAGE_DECODER(fmt) \
JSValue js_##fmt##_decode(JSContext *js, JSValue this_val, int argc, JSValueConst *argv) \
{ \
  size_t len; \
  void *raw = js_get_blob_data(js, &len, argv[0]); \
  if (raw == NULL) return JS_EXCEPTION; \
  if (!raw) return JS_ThrowReferenceError(js, "could not get " #fmt " data from blob"); \
  \
  int n, width, height; \
  void *data = stbi_load_from_memory(raw, len, &width, &height, &n, 4); \
  \
  if (!data) \
    return JS_ThrowReferenceError(js, "failed to decode " #fmt ": %s", stbi_failure_reason()); \
  \
  if (width <= 0 || height <= 0) { \
    stbi_image_free(data); \
    return JS_ThrowReferenceError(js, "decoded " #fmt " has invalid size: %dx%d", width, height); \
  } \
  \
  int pitch = width * 4; \
  size_t pixels_size = pitch * height; \
  \
  JSValue obj = JS_NewObject(js); \
  JS_SetPropertyStr(js, obj, "width", JS_NewInt32(js, width)); \
  JS_SetPropertyStr(js, obj, "height", JS_NewInt32(js, height)); \
  JS_SetPropertyStr(js, obj, "format", JS_NewString(js, "rgba32")); \
  JS_SetPropertyStr(js, obj, "pitch", JS_NewInt32(js, pitch)); \
  JS_SetPropertyStr(js, obj, "pixels", js_new_blob_stoned_copy(js, data, pixels_size)); \
  JS_SetPropertyStr(js, obj, "depth", JS_NewInt32(js, 8)); \
  JS_SetPropertyStr(js, obj, "hdr", JS_NewBool(js, 0)); \
  \
  stbi_image_free(data); \
  return obj; \
}

#define IMAGE_ENCODER(fmt) \
JSValue js_##fmt##_encode(JSContext *js, JSValue this_val, int argc, JSValueConst *argv) \
{ \
  if (argc < 1) \
    return JS_ThrowTypeError(js, #fmt ".encode requires an image object"); \
  \
  JSValue width_val = JS_GetPropertyStr(js, argv[0], "width"); \
  JSValue height_val = JS_GetPropertyStr(js, argv[0], "height"); \
  \
  if (JS_IsNull(width_val) || JS_IsNull(height_val)) { \
    JS_FreeValue(js, width_val); \
    JS_FreeValue(js, height_val); \
    return JS_ThrowTypeError(js, #fmt ".encode requires width and height properties"); \
  } \
  \
  int width, height; \
  if (JS_ToInt32(js, &width, width_val) < 0 || JS_ToInt32(js, &height, height_val) < 0) { \
    JS_FreeValue(js, width_val); \
    JS_FreeValue(js, height_val); \
    return JS_ThrowTypeError(js, "width and height must be numbers"); \
  } \
  JS_FreeValue(js, width_val); \
  JS_FreeValue(js, height_val); \
  \
  if (width < 1 || height < 1) \
    return JS_ThrowRangeError(js, "width and height must be at least 1"); \
  \
  JSValue pixels_val = JS_GetPropertyStr(js, argv[0], "pixels"); \
  size_t pixel_len; \
  void *pixel_data = js_get_blob_data(js, &pixel_len, pixels_val); \
  JS_FreeValue(js, pixels_val); \
  \
  if (pixel_data == NULL) return JS_EXCEPTION; \
  if (!pixel_data) return JS_ThrowTypeError(js, "pixels blob has no data"); \
  \
  size_t required_size = width * height * 4; \
  if (pixel_len < required_size) \
    return JS_ThrowRangeError(js, "pixels buffer too small (need %zu, got %zu)", required_size, pixel_len); \
  \
  stbi_mem_buf buf = {0}; \
  stbi_write_##fmt##_to_func(stbi_mem_write, &buf, width, height, 4, pixel_data); \
  \
  if (!buf.data || buf.size == 0) { \
    if (buf.data) free(buf.data); \
    return JS_ThrowInternalError(js, "failed to encode " #fmt); \
  } \
  \
  JSValue result = JS_NewObject(js); \
  JS_SetPropertyStr(js, result, "width", JS_NewInt32(js, width)); \
  JS_SetPropertyStr(js, result, "height", JS_NewInt32(js, height)); \
  JS_SetPropertyStr(js, result, "format", JS_NewString(js, #fmt)); \
  JS_SetPropertyStr(js, result, "pixels", js_new_blob_stoned_copy(js, buf.data, buf.size)); \
  \
  free(buf.data); \
  return result; \
}

#endif