// Wokwi Custom SPI Chip Example for Camera
//
// This chip simulates an OV5642-like camera, providing random image data over SPI.
//
// For information and examples see:
// https://docs.wokwi.com/chips-api/getting-started
//
// SPDX-License-Identifier: MIT
// Copyright (C) 2022 Uri Shaked / wokwi.com (original template)
// Adapted for OV5642 SPI camera simulation

#include "wokwi-api.h" // <--- This line MUST be here for custom chips
#include <stdio.h>
#include <stdlib.h> // For rand(), srand()

// Define a reasonable image resolution for simulation
#define IMAGE_WIDTH 120
#define IMAGE_HEIGHT 160
#define BUFFER_LEN (IMAGE_WIDTH * IMAGE_HEIGHT) // Total bytes for a grayscale image (one byte per pixel)

typedef struct {
  pin_t cs_pin;
  spi_dev_t spi_dev; // Use spi_dev_t for the SPI device ID
} chip_state_t;

// Global buffer for image data
uint8_t image_data[BUFFER_LEN];
// We don't need spi_buffer_read_index as spi_start handles the buffer directly.

// Function prototype
static void chip_pin_change(void *user_data, pin_t pin, uint32_t value);

// Fills the image_data buffer with dummy data
void generate_image_data() {
  // Use a fixed seed for reproducible random data in simulation
  srand(100);
  for (int i = 0; i < BUFFER_LEN; i++) {
    image_data[i] = rand() % 256; // Generate random byte (0-255)
  }
  printf("Generated %u bytes of dummy image data.\n", BUFFER_LEN);
}

void chip_init(void) {
  chip_state_t *chip = malloc(sizeof(chip_state_t));
  if (chip == NULL) {
    printf("Failed to allocate chip state\n");
    return;
  }

  // Initialize random image data once
  generate_image_data();

  chip->cs_pin = pin_init("CS", INPUT_PULLUP); // Chip Select pin

  const pin_watch_config_t watch_config = {
    .edge = BOTH, // Watch for both rising and falling edges
    .pin_change = chip_pin_change,
    .user_data = chip,
  };
  pin_watch(chip->cs_pin, &watch_config);

  const spi_config_t spi_config = {
    .sck = pin_init("SCK", INPUT),
    .miso = pin_init("MISO", OUTPUT), // MISO is an output from the chip's perspective
    .mosi = pin_init("MOSI", INPUT),
    .user_data = chip,
  };
  chip->spi_dev = spi_init(&spi_config); // Store the SPI device handle

  printf("OV5642 SPI Camera Chip initialized!\n");
}

// This function is called when the CS pin changes state
void chip_pin_change(void *user_data, pin_t pin, uint32_t value) {
  chip_state_t *chip = (chip_state_t*)user_data;
  if (pin == chip->cs_pin) {
    if (value == LOW) { // Chip Select is active (LOW)
      printf("OV5642 SPI Camera selected. Starting image data transfer.\n");
      // Start SPI transaction. The slave will send 'BUFFER_LEN' bytes from 'image_data'.
      // The MOSI buffer is NULL here as the camera is primarily sending, not receiving.
      spi_start(chip->spi_dev, image_data, BUFFER_LEN);
    } else { // Chip Select is inactive (HIGH)
      printf("OV5642 SPI Camera deselected.\n");
      spi_stop(chip->spi_dev); // Stop the SPI communication
    }
  }
}