#include "esp_camera.h"
#include "Arduino.h"
#include "FS.h"
#include "SD_MMC.h"
#include "soc/soc.h"
#include "soc/rtc_cntl_reg.h"
#include "driver/rtc_io.h"
#include <vector>
#include <tuple>
#include <cstdint>

// Define Pin numbers used by the camera.
#define FLASH_GPIO_NUM 4
#define HREF_GPIO_NUM 23
#define PCLK_GPIO_NUM 22
#define PWDN_GPIO_NUM 32
#define RESET_GPIO_NUM - 1
#define SIOC_GPIO_NUM 27
#define SIOD_GPIO_NUM 26
#define XCLK_GPIO_NUM 0
#define VSYNC_GPIO_NUM 25

#define Y2_GPIO_NUM 5
#define Y3_GPIO_NUM 18
#define Y4_GPIO_NUM 19
#define Y5_GPIO_NUM 21
#define Y6_GPIO_NUM 36
#define Y7_GPIO_NUM 39
#define Y8_GPIO_NUM 34
#define Y9_GPIO_NUM 35

// Structure to hold the camera configuration parameters.
camera_config_t config;

// Function prototypes.
void handleSerialInput();
void initializeCamera();
void processImage(camera_fb_t * frame_buffer);
void ditherImage(camera_fb_t * frame_buffer);
void savePictureToSDCard(camera_fb_t * frame_buffer);
void takePicture();

// Enumeration to represent the available dithering algorithms.
enum DitheringAlgorithm: uint8_t {
  FLOYD_STEINBERG,
  JARVIS_JUDICE_NINKE,
  STUCKI
};

// Holds the currently selected dithering algorithm.
DitheringAlgorithm ditherAlgorithm = FLOYD_STEINBERG;

// Flag to enable or disable dithering.
bool disableDithering = false;

// Flag to invert pixel colors.
bool invert = false;

// Flag to represent the flash state when saving pictures to the Flipper.
bool isFlashEnabled = false;

// Flag to represent whether the image is rotated.
bool rotated = false;

// Flag to stop or start the stream.
bool stopStream = false;

// Flag to store jpeg images to sd card.
bool storeJpeg = false;

void setup() {
  // Disable the brownout detector.
  WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0);
  // Start serial communication at 115200 baud rate.
  Serial.begin(115200); // Prev 230400
  initializeCamera();
}

void loop() {
  if (!stopStream) {
    // Set pixel format to GRAYSCALE for streaming
    sensor_t * s = esp_camera_sensor_get();
    s -> set_framesize(s, FRAMESIZE_QVGA); // Or your preferred resolution
    s -> set_pixformat(s, PIXFORMAT_GRAYSCALE); // For streaming

    camera_fb_t * frame_buffer = esp_camera_fb_get();
    if (frame_buffer) {
      // Process and Send Grayscale image
      processImage(frame_buffer);
      // Return the frame buffer back to the camera driver
      esp_camera_fb_return(frame_buffer);
    }
    delay(25); // Adjust delay as necessary
  } else {
    // Handle any available serial input commands
    handleSerialInput();
  }
}

void handleSerialInput() {
  if (Serial.available() > 0) {
    char input = Serial.read();
    sensor_t * cameraSensor = esp_camera_sensor_get();

    switch (input) {
    case '>': // Toggle dithering.
      disableDithering = !disableDithering;
      break;
    case '<': // Toggle invert.
      invert = !invert;
      break;
    case 'B': // Add brightness.
      cameraSensor -> set_contrast(
        cameraSensor,
        cameraSensor -> status.brightness + 1
      );
      break;
    case 'b': // Remove brightness.
      cameraSensor -> set_contrast(
        cameraSensor,
        cameraSensor -> status.brightness - 1
      );
      break;
    case 'C': // Add contrast.
      cameraSensor -> set_contrast(
        cameraSensor,
        cameraSensor -> status.contrast + 1
      );
      break;
    case 'c': // Remove contrast.
      cameraSensor -> set_contrast(
        cameraSensor,
        cameraSensor -> status.contrast - 1
      );
      break;
    case 'j': // Toggle store jpeg to sd card off.
      storeJpeg = false;
      break;
    case 'J': // Toggle store jpeg to sd card on.
      storeJpeg = true;
      break;
    case 'P': // Picture sequence.
      // Stop the IO stream before taking a picture.
      stopStream = true;
      if (!isFlashEnabled) {
        if (storeJpeg) {
          // Save jpeg image to sd card.
          takePicture();
        } else {
          // Turn on torch.
          pinMode(FLASH_GPIO_NUM, OUTPUT);
          digitalWrite(FLASH_GPIO_NUM, HIGH);
          // Give some time for Flipper to save locally with flash on.
          delay(50);
        }
        // Turn off torch.
        pinMode(FLASH_GPIO_NUM, OUTPUT);
        digitalWrite(FLASH_GPIO_NUM, LOW);
      }
      // Restart the stream after the picture is taken.
      stopStream = false;
      break;
    case 'M': // Toggle Mirror.
      cameraSensor -> set_hmirror(cameraSensor, !cameraSensor -> status.hmirror);
      break;
    case 'S': // Start stream.
      stopStream = false;
      break;
    case 's': // Stop stream.
      stopStream = true;
      break;
    case '0': // Use Floyd Steinberg dithering.
      ditherAlgorithm = FLOYD_STEINBERG;
      break;
    case '1': // Use Jarvis Judice dithering.
      ditherAlgorithm = JARVIS_JUDICE_NINKE;
      break;
    case '2': // Use Stucki dithering.
      ditherAlgorithm = STUCKI;
      break;
    default:
      // Do nothing.
      break;
    }
  }
}

void initializeCamera() {
  // Set initial camera configurations for grayscale.
  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_GRAYSCALE;
  config.frame_size = FRAMESIZE_QQVGA;
  config.fb_count = 1;

  // Initialize camera.
  esp_err_t err = esp_camera_init(&config);
  if (err != ESP_OK) {
    return;
  }

  // Make sure torch starts as off.
  pinMode(FLASH_GPIO_NUM, OUTPUT);
  digitalWrite(FLASH_GPIO_NUM, LOW);

  // Set initial contrast.
  sensor_t * s = esp_camera_sensor_get();
  s -> set_contrast(s, 0);

  // Set rotation
  s -> set_vflip(s, true); // Vertical flip
  s -> set_hmirror(s, true); // Horizontal mirror
}

void processImage(camera_fb_t * frame_buffer) {
  // If dithering is not disabled, perform dithering on the image. Dithering is the 
  // process of approximating the look of a high-resolution grayscale image in a 
  // lower resolution by binary values (black & white), thereby representing
  // different shades of gray.
  if (!disableDithering) {
    ditherImage(frame_buffer); // Invokes the dithering process on the frame buffer
  }

  uint8_t flipper_y = 0;

  // Iterating over specific rows of the frame buffer.
  for (uint8_t y = 28; y < 92; ++y) {
    Serial.print("Y:"); // Print "Y:" for every new row.
    Serial.write(flipper_y); // Send the row identifier as a byte.

    // Calculate the actual y index in the frame buffer 1D array by multiplying the 
    // y value with the width of the frame buffer. This gives the starting index 
    // of the row in the 1D array.
    size_t true_y = y * frame_buffer -> width;

    // Iterating over specific columns of each row in the frame buffer.
    for (uint8_t x = 16; x < 144; x += 8) { // step by 8 as we're packing 8 pixels per byte
      uint8_t packed_pixels = 0;
      // Packing 8 pixel values into one byte.
      for (uint8_t bit = 0; bit < 8; ++bit) {
        // Check the invert flag and pack the pixels accordingly.
        if (invert) {
          // If invert is true, consider pixel as 1 if it's more than 127.
          if (frame_buffer -> buf[true_y + x + bit] > 127) {
            packed_pixels |= (1 << (7 - bit));
          }
        } else {
          // If invert is false, consider pixel as 1 if it's less than 127.
          if (frame_buffer -> buf[true_y + x + bit] < 127) {
            packed_pixels |= (1 << (7 - bit));
          }
        }
      }
      Serial.write(packed_pixels); // Sending packed pixel byte.
    }

    ++flipper_y; // Move to the next row.
    Serial.flush(); // Ensure all data in the Serial buffer is sent before moving to the next iteration.
  }
}

void ditherImage(camera_fb_t* frame_buffer) {
  for (uint8_t y = 0; y < frame_buffer->height; ++y) {
    for (uint8_t x = 0; x < frame_buffer->width; ++x) {
      size_t current = (y * frame_buffer->width) + x;
      uint8_t oldpixel = frame_buffer->buf[current];
      uint8_t newpixel = oldpixel >= 128 ? 255 : 0;
      frame_buffer->buf[current] = newpixel;
      int8_t quant_error = oldpixel - newpixel;

      // Apply error diffusion based on the selected algorithm
      switch (ditherAlgorithm) {
        case JARVIS_JUDICE_NINKE:
          frame_buffer->buf[(y * frame_buffer->width) + x + 1] += quant_error * 7 / 48;
          frame_buffer->buf[(y * frame_buffer->width) + x + 2] += quant_error * 5 / 48;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x - 2] += quant_error * 3 / 48;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x - 1] += quant_error * 5 / 48;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x] += quant_error * 7 / 48;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x + 1] += quant_error * 5 / 48;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x + 2] += quant_error * 3 / 48;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x - 2] += quant_error * 1 / 48;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x - 1] += quant_error * 3 / 48;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x] += quant_error * 5 / 48;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x + 1] += quant_error * 3 / 48;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x + 2] += quant_error * 1 / 48;
          break;
        case STUCKI:
          frame_buffer->buf[(y * frame_buffer->width) + x + 1] += quant_error * 8 / 42;
          frame_buffer->buf[(y * frame_buffer->width) + x + 2] += quant_error * 4 / 42;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x - 2] += quant_error * 2 / 42;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x - 1] += quant_error * 4 / 42;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x] += quant_error * 8 / 42;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x + 1] += quant_error * 4 / 42;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x + 2] += quant_error * 2 / 42;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x - 2] += quant_error * 1 / 42;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x - 1] += quant_error * 2 / 42;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x] += quant_error * 4 / 42;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x + 1] += quant_error * 2 / 42;
          frame_buffer->buf[(y + 2) * frame_buffer->width + x + 2] += quant_error * 1 / 42;
          break;
        case FLOYD_STEINBERG:
        default:
          // Default to Floyd-Steinberg dithering if an invalid algorithm is selected
          frame_buffer->buf[(y * frame_buffer->width) + x + 1] += quant_error * 7 / 16;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x - 1] += quant_error * 3 / 16;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x] += quant_error * 5 / 16;
          frame_buffer->buf[(y + 1) * frame_buffer->width + x + 1] += quant_error * 1 / 16;
          break;
      }
    }
  }
}

void takePicture() {
    // Get camera sensor
    sensor_t * s = esp_camera_sensor_get();
    
    // Check if the sensor is valid
    if(!s) {
        Serial.println("Failed to acquire camera sensor");
        return;
    }

    // Set pixel format to JPEG for saving picture
    s->set_pixformat(s, PIXFORMAT_JPEG);

    // Set frame size based on available PSRAM
    if (psramFound()) {
        s->set_framesize(s, FRAMESIZE_UXGA);
    } else {
        s->set_framesize(s, FRAMESIZE_SVGA);
    }

    // Get a frame buffer from camera
    camera_fb_t * frame_buffer = esp_camera_fb_get();
    if (!frame_buffer) {
        Serial.println("Camera capture failed");
        return;
    }

    // Save the picture to SD card
    savePictureToSDCard(frame_buffer);
}

void savePictureToSDCard(camera_fb_t * frame_buffer) {
    if (!SD_MMC.begin()) {
        // SD Card Mount Failed.
        Serial.println("SD Card Mount Failed");
        esp_camera_fb_return(frame_buffer);
        return;
    }

    // Generate a unique filename
    String path = "/picture";
    path += String(millis());
    path += ".jpg";

    fs::FS & fs = SD_MMC;
    File file = fs.open(path.c_str(), FILE_WRITE);

    if (!file) {
        Serial.println("Failed to open file in writing mode");
    } else {
        if(file.write(frame_buffer->buf, frame_buffer->len) != frame_buffer->len) {
            Serial.println("Failed to write the image to the file");
        }
        file.close(); // Close the file in any case.
    }

    // Return the frame buffer back to the camera driver.
    esp_camera_fb_return(frame_buffer);
}