/**
 * @file    bsp_uart.c
 * @brief   UART1 DMA + IDLE interrupt driver
 */

#include "bsp_uart.h"
#include "bsp_cmd.h"
#include "usart.h"
#include <string.h>

/* External DMA handle */
extern DMA_HandleTypeDef hdma_usart1_rx;

/* DMA receive buffer */
uint8_t uart1_rx_buf[UART1_RX_BUF_SIZE];

/* IDLE interrupt sets this flag, main loop checks and processes */
static volatile uint16_t idle_rx_len = 0;

/**
 * @brief  Init UART1 for MQTT module with DMA
 */
void BSP_UART1_Init(void)
{
    /* Start DMA reception */
    HAL_UART_Receive_DMA(&huart1, uart1_rx_buf, UART1_RX_BUF_SIZE);

    /* Enable IDLE line detection interrupt */
    __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE);
}

/**
 * @brief  Send data via UART1 (blocking)
 */
uint16_t BSP_UART1_Send(uint8_t *data, uint16_t len)
{
    return HAL_UART_Transmit(&huart1, data, len, 1000);
}

/**
 * @brief  Send string via UART1
 */
uint16_t BSP_UART1_SendString(const char *str)
{
    return BSP_UART1_Send((uint8_t*)str, strlen(str));
}

/**
 * @brief  Get received data length in DMA buffer
 */
uint16_t BSP_UART1_GetRxLen(void)
{
    return UART1_RX_BUF_SIZE - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);
}

/**
 * @brief  Read data from DMA rx buffer (non-destructive copy)
 */
uint16_t BSP_UART1_Read(uint8_t *buf, uint16_t len)
{
    uint16_t head = UART1_RX_BUF_SIZE - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);

    uint16_t cnt = 0;
    while (cnt < len && cnt < head)
    {
        buf[cnt] = uart1_rx_buf[cnt];
        cnt++;
    }

    return cnt;
}

/**
 * @brief  Clear rx buffer (restart DMA)
 */
void BSP_UART1_ClearRxBuf(void)
{
    HAL_UART_AbortReceive(&huart1);
    HAL_UART_Receive_DMA(&huart1, uart1_rx_buf, UART1_RX_BUF_SIZE);
}

/**
 * @brief  Check if data received
 */
bool BSP_UART1_IsDataReceived(void)
{
    return (idle_rx_len > 0);
}

/**
 * @brief  Process received data (call in main loop)
 *         Copies data, parses JSON command, sends JSON response via UART1
 */
void BSP_UART1_Process(void)
{
    if (idle_rx_len == 0)
        return;

    /* Copy length and clear flag */
    uint16_t rx_len = idle_rx_len;
    idle_rx_len = 0;

    /* Copy data to local buffer so DMA restart won't overwrite */
    uint8_t local_buf[UART1_RX_BUF_SIZE];
    if (rx_len > sizeof(local_buf))
        rx_len = sizeof(local_buf);
    memcpy(local_buf, uart1_rx_buf, rx_len);

    /* Process JSON command */
    BSP_Cmd_ProcessJSON(local_buf, rx_len);

    /* Restart DMA for next frame */
    BSP_UART1_ClearRxBuf();
}

/**
 * @brief  Called from USART1 IDLE interrupt - saves length and restarts DMA
 */
void BSP_UART1_IDLE_IRQHandler(void)
{
    uint16_t rx_len = UART1_RX_BUF_SIZE - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);

    if (rx_len > 0)
    {
        idle_rx_len = rx_len;
    }

    /* Restart DMA immediately */
    HAL_UART_AbortReceive(&huart1);
    HAL_UART_Receive_DMA(&huart1, uart1_rx_buf, UART1_RX_BUF_SIZE);
}