#include "display_lcd_decode_image.h"

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "esp_check.h"
#include "esp_heap_caps.h"
#include "esp_log.h"
#include "lvgl.h"
#include "png.h"

static const char *TAG = "lcd_png_dec";

extern const uint8_t lcd_demo_png_start[] asm("_binary_lcd_demo_png_start");
extern const uint8_t lcd_demo_png_end[] asm("_binary_lcd_demo_png_end");

static void lcd_fill_err(char *err, size_t err_len, const char *msg)
{
    if (err != NULL && err_len > 0) {
        snprintf(err, err_len, "%s", msg != NULL ? msg : "unknown");
    }
}

esp_err_t platform_lcd_decode_png_rgb565(const uint8_t *png,
                                         size_t png_len,
                                         uint16_t **out_pixels,
                                         uint16_t *out_width,
                                         uint16_t *out_height,
                                         char *err,
                                         size_t err_len)
{
    esp_err_t ret = ESP_OK;

    ESP_RETURN_ON_FALSE(out_pixels != NULL && out_width != NULL && out_height != NULL,
                        ESP_ERR_INVALID_ARG,
                        TAG,
                        "invalid output args");
    ESP_RETURN_ON_FALSE(png != NULL && png_len > 0, ESP_ERR_INVALID_ARG, TAG, "invalid png data");
    *out_pixels = NULL;
    *out_width = 0;
    *out_height = 0;

    png_image image;
    memset(&image, 0, sizeof(image));
    image.version = PNG_IMAGE_VERSION;

    if (!png_image_begin_read_from_memory(&image, png, png_len)) {
        const char *png_err = image.message[0] != '\0' ? image.message : "png header decode failed";
        lcd_fill_err(err, err_len, png_err);
        return ESP_FAIL;
    }
    ESP_GOTO_ON_FALSE(image.width > 0 && image.height > 0, ESP_ERR_INVALID_SIZE, fail, TAG, "invalid png size");
    ESP_GOTO_ON_FALSE(image.width <= UINT16_MAX && image.height <= UINT16_MAX,
                      ESP_ERR_INVALID_SIZE,
                      fail,
                      TAG,
                      "png dimensions too large");
    ESP_GOTO_ON_FALSE(image.width <= SIZE_MAX / image.height, ESP_ERR_INVALID_SIZE, fail, TAG, "png too large");

    image.format = PNG_FORMAT_RGBA;
    png_alloc_size_t rgba_size = PNG_IMAGE_SIZE(image);
    ESP_GOTO_ON_FALSE(rgba_size > 0, ESP_ERR_INVALID_SIZE, fail, TAG, "png output size invalid");

    uint8_t *rgba = (uint8_t *)heap_caps_malloc((size_t)rgba_size, MALLOC_CAP_SPIRAM | MALLOC_CAP_8BIT);
    if (rgba == NULL) {
        rgba = (uint8_t *)heap_caps_malloc((size_t)rgba_size, MALLOC_CAP_8BIT);
    }
    ESP_GOTO_ON_FALSE(rgba != NULL, ESP_ERR_NO_MEM, fail, TAG, "alloc rgba buffer failed");

    png_alloc_size_t stride = PNG_IMAGE_ROW_STRIDE(image);
    if (!png_image_finish_read(&image, NULL, rgba, stride, NULL)) {
        const char *png_err = image.message[0] != '\0' ? image.message : "png decode failed";
        lcd_fill_err(err, err_len, png_err);
        heap_caps_free(rgba);
        png_image_free(&image);
        return ESP_FAIL;
    }
    png_image_free(&image);

    size_t pixel_count = (size_t)image.width * (size_t)image.height;
    uint16_t *pixels = (uint16_t *)heap_caps_malloc(pixel_count * sizeof(uint16_t),
                                                    MALLOC_CAP_SPIRAM | MALLOC_CAP_8BIT);
    if (pixels == NULL) {
        pixels = (uint16_t *)heap_caps_malloc(pixel_count * sizeof(uint16_t), MALLOC_CAP_8BIT);
    }
    if (pixels == NULL) {
        lcd_fill_err(err, err_len, "alloc rgb565 buffer failed");
        heap_caps_free(rgba);
        return ESP_ERR_NO_MEM;
    }

    for (size_t i = 0; i < pixel_count; ++i) {
        const size_t base = i * 4u;
        uint8_t r = rgba[base];
        uint8_t g = rgba[base + 1u];
        uint8_t b = rgba[base + 2u];
        uint8_t a = rgba[base + 3u];
        if (a < 255u) {
            r = (uint8_t)((((uint32_t)r * (uint32_t)a) + (255u * (255u - (uint32_t)a)) + 127u) / 255u);
            g = (uint8_t)((((uint32_t)g * (uint32_t)a) + (255u * (255u - (uint32_t)a)) + 127u) / 255u);
            b = (uint8_t)((((uint32_t)b * (uint32_t)a) + (255u * (255u - (uint32_t)a)) + 127u) / 255u);
        }
        lv_color_t color = lv_color_make(r, g, b);
        pixels[i] = (uint16_t)color.full;
    }
    heap_caps_free(rgba);

    *out_pixels = pixels;
    *out_width = (uint16_t)image.width;
    *out_height = (uint16_t)image.height;
    return ESP_OK;

fail:
    lcd_fill_err(err, err_len, "invalid png");
    png_image_free(&image);
    if (ret == ESP_OK) {
        ret = ESP_FAIL;
    }
    return ret;
}

esp_err_t platform_lcd_decode_demo_png(uint16_t **out_pixels,
                                       uint16_t *out_width,
                                       uint16_t *out_height,
                                       char *err,
                                       size_t err_len)
{
    const size_t png_len = (size_t)(lcd_demo_png_end - lcd_demo_png_start);
    ESP_RETURN_ON_FALSE(png_len > 0, ESP_ERR_INVALID_SIZE, TAG, "empty png data");
    return platform_lcd_decode_png_rgb565(lcd_demo_png_start,
                                          png_len,
                                          out_pixels,
                                          out_width,
                                          out_height,
                                          err,
                                          err_len);
}