#include "esp_camera.h"
#include "soc/soc.h"
#include "soc/rtc_cntl_reg.h"

// AI-THINKER Pins
#define PWDN_GPIO_NUM     32
#define RESET_GPIO_NUM    -1
#define XCLK_GPIO_NUM      0
#define SIOD_GPIO_NUM     26
#define SIOC_GPIO_NUM     27
#define Y9_GPIO_NUM       35
#define Y8_GPIO_NUM       34
#define Y7_GPIO_NUM       39
#define Y6_GPIO_NUM       36
#define Y5_GPIO_NUM       21
#define Y4_GPIO_NUM       19
#define Y3_GPIO_NUM       18
#define Y2_GPIO_NUM        5
#define VSYNC_GPIO_NUM    25
#define HREF_GPIO_NUM     23
#define PCLK_GPIO_NUM     22

void setup() {
  WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0); 
  Serial.begin(115200); 
  
  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = Y2_GPIO_NUM;
  config.pin_d1 = Y3_GPIO_NUM;
  config.pin_d2 = Y4_GPIO_NUM;
  config.pin_d3 = Y5_GPIO_NUM;
  config.pin_d4 = Y6_GPIO_NUM;
  config.pin_d5 = Y7_GPIO_NUM;
  config.pin_d6 = Y8_GPIO_NUM;
  config.pin_d7 = Y9_GPIO_NUM;
  config.pin_xclk = XCLK_GPIO_NUM;
  config.pin_pclk = PCLK_GPIO_NUM;
  config.pin_vsync = VSYNC_GPIO_NUM;
  config.pin_href = HREF_GPIO_NUM;
  config.pin_sscb_sda = SIOD_GPIO_NUM;
  config.pin_sscb_scl = SIOC_GPIO_NUM;
  config.pin_pwdn = PWDN_GPIO_NUM;
  config.pin_reset = RESET_GPIO_NUM;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;
  config.frame_size = FRAMESIZE_VGA; 
  config.jpeg_quality = 10; // Lower number = Higher Quality
  config.fb_count = 1;

  if (esp_camera_init(&config) != ESP_OK) {
    return;
  }
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();
    if (cmd == 'S') { // Snap Command
      
      // 1. FLUSH SENSOR (The "Double Tap")
      // We grab a frame and immediately discard it to ensure the sensor 
      // is awake and exposure is calculated for the CURRENT moment.
      camera_fb_t * fb = esp_camera_fb_get();
      if(fb) esp_camera_fb_return(fb); 
      
      // 2. REAL CAPTURE
      fb = esp_camera_fb_get();
      if (!fb) return;
      
      // 3. SEND DATA
      uint32_t len = fb->len;
      Serial.write((uint8_t*)&len, 4);   // Send Length
      Serial.write(fb->buf, fb->len);    // Send Image
      esp_camera_fb_return(fb);
    }
  }
}