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#include <stdio.h>
#include <stdint.h>
#include "driver/uart.h"
#include "driver/gpio.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#define ID_VALUE 1
#define ZONE_REQUIREMENTS 1
#define FRAME_SIZE 8
#define UART_NUM UART_NUM_1  // Use UART1 for communication
#define TXD_PIN GPIO_NUM_4   // TX pin for UART1 (change as needed)
#define RXD_PIN GPIO_NUM_5   // RX pin for UART1 (change as needed)
#define BAUD_RATE 9600       // Baud rate (match with TTL device)
#define RS485_ENABLE_PIN GPIO_NUM_2  // RS485 Enable (Connect to DE & RE)

uint8_t response_buffer[32];
int prev_scene[16] = {-1}; // Array to store previous scene for each zone (0-15)
int active_button = 0;

uint16_t Read_Register_value = 6999;
uint16_t Write_Register_value = 5999;

// Function to calculate Modbus CRC-16
uint16_t calculate_modbus_crc(uint8_t *data, size_t length) {
    uint16_t crc = 0xFFFF;
    for (size_t i = 0; i < length; i++) {
        crc ^= data[i];
        for (int j = 0; j < 8; j++) {
            if (crc & 0x0001) {
                crc = (crc >> 1) ^ 0xA001;
            } else {
                crc >>= 1;
            }
        }
    }
    return crc;
}

void init_uart() {
    uart_config_t uart_config = {
        .baud_rate = BAUD_RATE,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE
    };
    uart_driver_install(UART_NUM, 256, 0, 0, NULL, 0);
    uart_param_config(UART_NUM, &uart_config);
    uart_set_pin(UART_NUM, TXD_PIN, RXD_PIN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);

    // Configure GPIO for RS485 TX/RX control
    gpio_set_direction(RS485_ENABLE_PIN, GPIO_MODE_OUTPUT);
}


void get_response_from_rs485(void *pvParameters) {
    uint8_t modbus_frames[ZONE_REQUIREMENTS][FRAME_SIZE];

    for (int i = 0; i < ZONE_REQUIREMENTS; i++) {
        
        uint16_t decimal_value = Read_Register_value + (i + 1);

        modbus_frames[i][0] = ID_VALUE;
        modbus_frames[i][1] = 0x03;// Read Holding Register command
        modbus_frames[i][2] = (decimal_value >> 8) & 0xFF;
        modbus_frames[i][3] = decimal_value & 0xFF;
        modbus_frames[i][4] = 0x00;
        modbus_frames[i][5] = 0x01;

        uint16_t crc = calculate_modbus_crc(modbus_frames[i], 6);
        modbus_frames[i][6] = crc & 0xFF;
        modbus_frames[i][7] = (crc >> 8) & 0xFF;
    }

    while (1) {
        for (int i = 0; i < ZONE_REQUIREMENTS; i++) {
            // Enable TX mode
            gpio_set_level(RS485_ENABLE_PIN, 1);
            vTaskDelay(pdMS_TO_TICKS(1)); // Small delay for RS485 control stabilization

            // Send data via UART
            // printf("----Sending Frame (ZONE - %d)---\n", i + 1);
            for (int j = 0; j < FRAME_SIZE; j++) {
                // printf("%02X ", modbus_frames[i][j]);
            }
            // printf("\n");

            uart_write_bytes(UART_NUM, (const char *)modbus_frames[i], FRAME_SIZE);

            vTaskDelay(pdMS_TO_TICKS(10)); // Allow time for transmission

            // Switch to RX mode to receive response
            gpio_set_level(RS485_ENABLE_PIN, 0);

            // Read response
            
            int len = uart_read_bytes(UART_NUM, response_buffer, sizeof(response_buffer), 100 / portTICK_PERIOD_MS);
            if (len > 0) {
                 printf("Response: ");
                for (int k = 0; k < len; k++) {
                    printf("%02X ", response_buffer[k]);
                }
                printf("\n");
            } else {
                printf("No response received.\n");
            }

            vTaskDelay(pdMS_TO_TICKS(500));  // Wait 2ms before sending next frame
        }
    }
}


void app_main() {
    init_uart();
     xTaskCreate(get_response_from_rs485, "get_response_from_rs485", 4096, NULL, 5, NULL);
}